Co-reporter:Xingmao Chang, Zhaolong Wang, Yanyu Qi, Rui Kang, Xinwen Cui, Congdi Shang, Kaiqiang Liu, and Yu Fang
Analytical Chemistry September 5, 2017 Volume 89(Issue 17) pp:9360-9360
Publication Date(Web):July 24, 2017
DOI:10.1021/acs.analchem.7b02170
Development of artificial complex molecular systems is of great importance in understanding complexity in natural processes and for achieving new functionalities. One of the strategies is to create them via optimized utilization of noncovalent interactions and dynamic covalent bonds. We report here on a new complex molecular system, which was constructed by integrating the multiple interactions containing a dynamic covalent interaction between 1,2-diol and boronic acid, a coordination interaction between the silver ion and pyridyl, and an easy accessible reaction between secondary amine and formaldehyde. By employing the three dynamic interactions, a pyrene (Py) labeled fluorophore, PPB, was designed and synthesized. The compound reacts with fructose (F), a monosaccharide, in aqueous phase and produces a fluorescent adduct, PPB-F, which can be further used as a sensing platform for formaldehyde (FA) and the silver ion. The respective dynamic interactions are accompanied with color changes due to the reversible switching between Py-monomer emission and excimer emission. The respective experimental detection limits (DLs) for the three analytes are much lower than 0.2 mM, 0.1 mM, and 2.5 μM, respectively. The presence of relevant compounds or ions shows little effect upon the sensing. No doubt, the results as presented show that the integration of supramolecular interactions including dynamic covalent bonds can be employed as a general strategy to develop new functional molecular systems or materials.
Co-reporter:Li Wang, Gang Wang, Congdi Shang, Rui Kang, and Yu Fang
ACS Applied Materials & Interfaces October 11, 2017 Volume 9(Issue 40) pp:35419-35419
Publication Date(Web):September 19, 2017
DOI:10.1021/acsami.7b10565
A naphthalimide-based low-molecular-mass fluorophore (NA) was designed and synthesized by introducing an azetidine unit onto the aromatic ring of the compound as an electron-donating structure, and a hydrophilic (2-(2-aminoethyl-amino)ethanol) moiety into the “N-imide site” of the core structure. UV–vis absorption and fluorescence measurements revealed that the fluorophore is soluble in water and shows a fluorescent quantum yield of ∼20% and lifetime of ∼3.7 ns in the solvent within a wide pH range. Moreover, the fluorescence emission and anisotropy of the fluorophore as produced are both dependent upon the viscosity and polarity of the medium. Further studies demonstrated that NA can be used as a selective probe to monitor the aggregation of anionic surfactants owing to its accumulation onto the anionic surfaces of the aggregates as formed. Inspired by the discovery, NA was successfully applied for detection of cell membranes and E. coli via monitoring of their negatively charged surfaces, which is important for fast checking of biological contamination of water. Importantly, all the tests could be performed in a visualized manner. We believe that the new, low-molecular-mass fluorophore as created may find applications in chemical and biochemical sensing and imaging.Keywords: anionic interfaces; anionic surfactants; fluorescent probe; naphthalimide; visualization test;
Co-reporter:Rong Miao, Junxia Peng, and Yu Fang
Langmuir October 10, 2017 Volume 33(Issue 40) pp:10419-10419
Publication Date(Web):February 27, 2017
DOI:10.1021/acs.langmuir.6b04655
Low-molecular-mass organic gelator (LMOG)-based molecular gels are known as one of the most attractive soft materials and have received great attention since the early 1990s. In the last few decades, many LMOGs have been synthesized, and a series of theories have been proposed to better understand molecular gels. However, only limited applications of LMOGs have been realized for a variety of reasons, such as their lack of stability compared to chemical gels. Therefore, efforts to explore the applications of these materials are especially meaningful. As an example, this feature article mainly introduces studies on the application of LMOGs as intermediates in porous materials and fluorescent sensing films. Particular attention will be paid to gelator design, LMOG emulsion preparation, solid surface modification, and the practical application of the obtained materials. Concepts that are related to these studies, such as organic gel–water interface equilibria and molecular gel strategies, will be comprehensively illustrated. Finally, we will conclude with a study of LMOG-based intermediates. Some challenges and future perspectives related to these research areas will also be presented. It is anticipated that this feature article will not only contribute to the further understanding of LMOG-based intermediates but also will help to promote the practical application of molecular gels and facilitate development in related research areas.
Co-reporter:Yanyu Qi, Rui Kang, Jie Huang, Weidong Zhang, Gang He, Shiwei Yin, and Yu Fang
The Journal of Physical Chemistry B June 29, 2017 Volume 121(Issue 25) pp:6189-6189
Publication Date(Web):June 9, 2017
DOI:10.1021/acs.jpcb.7b02405
We demonstrated for the first time that, at temperatures below the melting point of a given polar solvent, the emission of some four-coordinate monoboron complexes containing monoanionic bidentate (NO) ligands shifted to lower wavelengths, but no such shift was observed for studies conducted in nonpolar solvents. This means that the emission from a polar solvent appears at shorter wavelengths if compared with that from a nonpolar solvent when the measurement was performed at low temperatures, a phenomenon totally different from that observed for conventional solvatochromic fluorophores. The finding was rationalized by considering the temperature-dependent conformational relaxation of the tetrahedron monoboron complexes from their local excited (LE) state to their relaxed excited (RE) state. Further studies revealed that variating the structure of the chelating ligands could result in remarkable changes in the fluorescent colors of the monoboron complexes. However, changing the structure of other two monodentate ligands showed little effect upon the fluorescence property of the compounds. Therefore, it is anticipated that the monoboron complexes may be taken as a platform to construct a variety of functional molecular systems via alternating the structure of the chelating ligand and that of the monodentate ligand. As an example, naphthalene was introduced as a monodentate ligand, and independent emissions from naphthalene unit and the other part of the monoboron complex as well as intramolecular energy transfer between them were observed. It is believed that the present work provides a new insight into the monoboron complexes, laying the foundation for them to be explored for developing novel molecular systems.
Co-reporter:Rong Miao, Shaofei Zhang, Jianfei Liu, and Yu Fang
Chemistry of Materials July 25, 2017 Volume 29(Issue 14) pp:5957-5957
Publication Date(Web):June 29, 2017
DOI:10.1021/acs.chemmater.7b01580
Carbon quantum dots (CQDs) have attracted considerable interest because of their advantages of low cost, nontoxicity, easy preparation, and diverse optical properties. Photophysical properties and stability are two key issues that affect the further use of CQDs, especially for solid-state applications. Here, we report a facile and effective method to enhance the fluorescence and moisture-resistance of CQDs. CQDs were synthesized by the thermolysis of citric acid on a multigram scale and were readily used to react with zinc powder in an aqueous solution to produce zinc-reduced CQDs (Zn-CQDs). The process was operated under mild conditions and completed in 10 min. The fluorescence intensity of the CQDs increased more than three times after reacting with zinc. In contrast to the pristine CQD solids, which easily absorbed moisture and turned into viscous liquids, the as-prepared Zn-CQD blocks possessed an ordered porous structure and were immune to moisture in the air. They remained stable under ambient conditions for months. Comprehensive studies were carried out to explore the reaction mechanism and material properties. It was revealed that zinc likely served as a reductant in the process. On the basis of the satisfactory properties of the Zn-CQD blocks, their solid-state applications were studied. A Zn-CQD-based fluorescent film for temperature monitoring was fabricated with favorable linear response and reversibility. Moreover, the as-obtained Zn-CQD blocks showed remarkable adsorption of particulate matter (PM). Therefore, it is expected that they may find practical use in the purification of PM-polluted air.
Co-reporter:Chunmeng Yu, Min Xue, Ke Liu, Gang Wang, and Yu Fang
Langmuir February 11, 2014 Volume 30(Issue 5) pp:1257-1265
Publication Date(Web):January 20, 2014
DOI:10.1021/la4046836
Three novel terthiophene derivatives of cholesterol (TtGC, TtLPC, TtDPC), of which the two building blocks are linked by a structure of glycine, l-phenylalanine, or d-phenylalanine, respectively, were designed and prepared, and their gelation behaviors in 26 liquids were tested. It was demonstrated that the compounds show different gelation abilities with the variation of the linker structures even though the variation is small. FTIR, 1H NMR, and UV–vis measurements revealed that intermolecular hydrogen bonding and van der Waals interaction are the main driving forces for the gel formation. As for TtDPC, CD and AFM measurements revealed that it aggregated into chiral structures of left-helical feature in benzene. Importantly, the morphologies of the gel networks could be subtly adjusted via alteration of the gelator concentration. Considering the brightness in fluorescence and the unique micro/nanostructures of the gel networks, a fluorescent film (film 1) was fabricated by simple dip-coating of TtDPC/benzene solution (before gelation) onto a glass plate surface. Fluorescent studies demonstrated that the film is photochemically unstable. Two hours UV irradiation of the film results in film 2, which is almost fluorescent silence. However, the presence of HAc vapor or the vapors of some other volatile organic liquids induces new fluorescence emission, laying the foundation for creating a turn-on type fluorescent sensor of the organic vapors. Furthermore, as a new type of low-molecular-mass gelators (LMMGs), of which oligothiophene was employed as a building block, the present study has provided a possibility to explore the photo-/electronic applications of oligothiophenes via a molecular gel strategy.
Co-reporter:Huirong Yang, Hongxia Zhang, Junxia Peng, Yuanyuan Zhang, Guanqun Du, Yu Fang
Journal of Colloid and Interface Science 2017 Volume 485() pp:213-222
Publication Date(Web):1 January 2017
DOI:10.1016/j.jcis.2016.09.023
This study presents the general method to formulate magnetically responsive ionic liquid (IL)-based Pickering emulsions that are stabilized by amphiphilic Fe3O4 nanoparticles. The magnetic nanoparticle stabilizer (MN-CHOL) was synthesized using the surface-initiated ATRP method with further modification that uses a specially designed cholesteryl derivative, and characterized by FT-IR, XPS, TGA, and magnetization measurements. It is confirmed that the resulting MN-CHOL shows a stronger interfacial activity, efficiently emulsifying C4mim [PF6] and water, and resultantly forming stable Pickering emulsions without the help of any co-surfactant. Due to its super paramagnetism and high saturation magnetization, MN-CHOL attached on the IL interface enables droplets of IL to be moved very conveniently on their target for as many times by an external magnetic field without demulsification, indicating high controllability and excellent stability. The resulting Pickering emulsion is a good extraction system that efficiently separates chlorobenzene, phenol, and methyl orange from aqueous solution. Subsequently, the simple magnetic separation was applied, to produce purified water due as a result of the rapid removal of organic pollutants from contaminated water.
Co-reporter:Congdi Shang;Li Wang;Yanqin An;Ping Chen;Xingmao Chang;Yanyu Qi;Rui Kang
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 35) pp:23898-23904
Publication Date(Web):2017/09/13
DOI:10.1039/C7CP04235C
Fast, sensitive and selective detection of diamines in the vapor phase is of pivotal importance for air and food quality monitoring. In this work, an electron-poor fluorophore, perylene bisimide (PBI), was modified with hydrophilic residues at its bay positions, resulting in an amphiphilic derivative, PEBBO. Photophysical studies revealed that the compound shows a strong aggregation tendency in various solvents, but the aggregates could be highly fluorescent provided suitable solvents are used. Accordingly, a fluorescent film was constructed via utilization of the well-known Langmuir–Blodgett technique. Sensing performance studies revealed that the film as prepared is sensitive and selective to the presence of diamines in air. Specifically, (1) the experimental detection limit is lower than 0.016 g m−3 and the linear range of the analysis extends from 0.33 g m−3 to 8.20 g m−3 when ethylenediamine was adopted as an example analyte; (2) the presence of other amines and solvents shows little effect upon detection; (3) the response time is less than 5 s. Considering the importance of diamine sensing, the convenience of fluorescence techniques and the superiorities of the film and method as developed, it is believed that the present work is of great importance for promoting technical progress in diamine sensing.
Co-reporter:Rui Kang;Rong Miao;Yanyu Qi;Xingmao Chang;Congdi Shang;Li Wang
Chemical Communications 2017 vol. 53(Issue 72) pp:10018-10021
Publication Date(Web):2017/09/05
DOI:10.1039/C7CC05645A
Host–guest interaction and chemical modification are found to be effective in tuning the formation of reductive species of perylene-bisimide (PBI) derivatives in DMF. Moreover, some of the PBI derivatives as synthesized produce radical anions in the solvent without the need of a base.
Co-reporter:Suansuan Wang;Kaiqiang Liu;Sheng Gao;Jinqiang Wang;Ravi Kumar Marella
Soft Matter (2005-Present) 2017 vol. 13(Issue 45) pp:8609-8617
Publication Date(Web):2017/11/22
DOI:10.1039/C7SM02013A
A new class of bisurea derivatives bearing tetrahydroxy groups have been proven to be non-gelators in water and various organic solvents even under long-term sonication or efficient heating treatment. We found that it is possible to trigger physical gelation behaviour by constructing dynamic covalent bonding. The results show that formation of dynamic covalent bonding between the borate anion and ethanediol substituent in these bisurea derivatives brings about rapid physical gelation at ambient temperature in a mixture of DMSO and water. During dynamic covalent bonding-triggered gelation, the stepgrowth polymerization from the B–O bonds would increase the size of the molecules and reduce the entropy of mixing as well as facilitate ion–dipole interactions in the linear polymeric gelators. They would drive a self-assembly transition and boost the construction of gel networks in coordination with α-tape urea–urea hydrogen bonding. The gelation mechanism was explored by 1H NMR, FTIR and rheology techniques. Moreover, the resulting gels are transparent and thixotropic, and could be turned into the sol state under CO2 or water-stimulus. Furthermore, they are stable in the presence of HAuCl4 and alkali. Therefore, they would afford another new medium for the growth of Au nanocrystals via in situ reduction and a new sensing medium for detecting Hg2+ ions.
Co-reporter:Huijing Liu;Rongrong Huang
Chinese Journal of Chemistry 2017 Volume 35(Issue 5) pp:707-715
Publication Date(Web):2017/05/01
DOI:10.1002/cjoc.201600732
AbstractFour new fluorescent dyes based on bis(phenyl-ethynyl-)-2-naphthyl (BPEN) were designed and synthesized. To improve the solvatochromic property and enhance the brightness of the fluorescent BPEN, an electron-donating unit of azetidine and/or an electron deficient group of -NO2 was introduced. The corresponding fluorophores are denoted as T1, T2, T3 and T4, respectively. Moreover, to facilitate derivatization of the probes, two ethoxy carbonyl residues were grafted onto the side positions of BPEN. Spectroscopic studies demonstrated that introduction of azetidine leads to superior solvatochromic properties and largely enhanced fluorescence quantum yields as evidenced by the fact that T3 shows more than 150 nm shift in its maximum emission when dissolved in solvents of very different polarities and displays high fluorescence quantum yields in the solvents studied. However, T2, which is the one bearing a -NO2 group, is non-fluorescent. Theoretical analysis and Lippert-Mataga modeling revealed the intra-molecular charge transfer (ICT) nature of the solvatochromic behavior of the compounds. Further test reveals that the fluorophores, in particular T3, are sensitive to the presence of trace water in less polar solvents, such as THF and 1,4-dioxane. Moreover, it is believed that the new fluorophores may serve as building blocks for creating environment-sensitive fluorescent sensors.
Co-reporter:Xiangli Chen, Lingling Liu, Kaiqiang Liu, Qing Miao, Yanchao Lü and Yu Fang
Journal of Materials Chemistry A 2016 vol. 4(Issue 2) pp:684-684
Publication Date(Web):09 Dec 2015
DOI:10.1039/C5TA90256H
Correction for ‘Compressible porous hybrid monoliths: preparation via a low molecular mass gelators-based gel-emulsion approach and exceptional performances’ by Xiangli Chen et al., J. Mater. Chem. A, 2015, DOI: 10.1039/c5ta08342g.
Co-reporter:Qingqing Sun, Yanchao Lü, Lingling Liu, Kaiqiang Liu, Rong Miao, and Yu Fang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 42) pp:29128
Publication Date(Web):October 5, 2016
DOI:10.1021/acsami.6b08642
The supramolecular approach plays a pivotal role in the construction of smart and functional materials due to the reversible nature of noncovalent interactions. In the present work, two compounds, cholesterol-functionalized calix[4]pyrrole (CCP) and perylene bisimide diacid (PDA), were synthesized. Little fluorescence is observed in the ethanol solution of the mixture of CCP and PDA, while the solution turns fluorescent upon introduction of ammonia, which is attributed to the formation of a supramolecular ensemble, PDA/(CCP)2/NH3. The fluorescence emission of the as-formed ensemble is sensitive to the presence of phenol, an electron-rich analyte. Interestingly, the sensing can also be observed in the film state, and the relevant detection limit (DL) is lower than 1 ppb. Moreover, the sensing could also be performed in a visualized manner. Upon the basis of the findings, a sensor device with instant response and good reversibility was developed. Further studies revealed that the as-developed fluorescent ensemble is also sensitive to the presence of TNT, an electron-poor compound. The DL for this sensing is ∼80 nM. To our knowledge, this is the first report that a fluorescent sensor could be used for phenol sensing in the vapor state, and for sensing of both electron-rich and electron-poor analytes in solution state. It is believed that the present study presents a distinctive example that demonstrates how smart sensing is realized via combination of the host–guest chemistry of calix[4]pyrrole and the aggregation and disaggregation property of PBI derivatives.Keywords: calix[4]pyrrole; fluorescent sensing; host−guest interaction; perylene bisimide; supramolecular ensemble
Co-reporter:Jiayun Fan, Xingmao Chang, Meixia He, Congdi Shang, Gang Wang, Shiwei Yin, Haonan Peng, and Yu Fang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 28) pp:18584-18592
Publication Date(Web):June 27, 2016
DOI:10.1021/acsami.6b04915
Modification of naphthalene diimide (NDI) resulted in a photochemically stable, fluorescent 3,4,5-tris(dodecyloxy)benzamide derivative of NDI (TDBNDI), and introduction of the long alkyl chains endowed the compound with good compatibility with commonly found organic solvents and in particular superior self-assembly in the solution state. Further studies revealed that TDBNDI forms gels with nine of the 18 solvents tested at a concentration of 2.0% (w/v), and the critical gelation concentrations of five of the eight gels are lower than 1.0% (w/v), indicating the high efficiency of the compound as a low-molecular mass gelator (LMMG). Transmission electron microscopy, scanning electron microscopy, and confocal laser scanning microscopy studies revealed the networked fibrillar structure of the TDBNDI/methylcyclohexane (MCH) gel. On the basis of these findings, a fluorescent film was developed via simple spin-coating of the TDBNDI/MCH gel on a glass substrate surface. Fluorescence behavior and sensing performance studies demonstrated that this film is photochemically stable, and sensitive and selective to the presence of aniline vapor. Notably, the response is instantaneous, and the sensing process is fully and quickly reversible. This case study demonstrates that derivatization of photochemically stable fluorophores into LMMGs is a good strategy for developing high-performance fluorescent sensing films.
Co-reporter:Huijing Liu, Xiaojie Xu, Zijun Shi, Kaiqiang Liu, and Yu Fang
Analytical Chemistry 2016 Volume 88(Issue 20) pp:10167
Publication Date(Web):September 29, 2016
DOI:10.1021/acs.analchem.6b02721
Four highly fluorescent derivatives of bis(phenyl-ethynyl-)-2-naphthyl (BPEN) with push–pull structures were designed and synthesized, of which azetidine was adopted as an electron-donating unit. For the electron withdrawing moiety, it varies from hydrogen, to formyl, then to the 2-ethoxyethyl derivative of dicyanovinyl, and finally to dicyanovinyl itself, and the corresponding fluorophores are denoted as A1, A2, A3, and A4, respectively. To enhance the solubility of the compounds, two n-hexadecyl residues were grafted onto the side positions of BPEN. Interestingly, introduction of azetidine not only improves the fluorescence quantum yield and enlarges the Stoke’s shift of the parent compound but also endows them, in particular A2 and A4, exceptional capability to distinguish structurally relevant organic liquids, such as ethylbenzene and its isomers (o-xylenes, m-xylenes, and p-xylenes), monoalkyl-substituted benzene derivatives, gasolines of different grades, and other organic liquids. Theoretical calculation and Lippert-Mataga equation-based tests revealed the intramolecular charge transfer (ICT) nature of the solvatochromic properties of the compounds. Further quantitative analysis of the data obtained from studies of the probes/n-hexane–dioxane systems revealed the big differences in the dipole moments between the excited and ground states of A1, A2, A3, and A4, which are about 23, 29, 43, and 38 D, respectively. Moreover, the four novel fluorophores possess exceptional photochemical stability as demonstrated by the fact that more than 2 h of UV light illumination did not result in detectable reduction in the fluorescence emission of the fluorophores. It is the long wavelength absorption (>380, ≈400, >410, and >430 nm), large molar absorption coefficient (>59 000, >52 000, >39 000, and >34 000 cm–1 M–1), great color change (400–620 nm), and good solubility in common organic liquids that makes the as developed compounds, in particular A2 and A4, very competitive solvatochromic probes.
Co-reporter:Gang Wang, Weina Wang, Rong Miao, Congdi Shang, Meixia He, Haonan Peng, Gang He and Yu Fang
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 17) pp:12221-12230
Publication Date(Web):31 Mar 2016
DOI:10.1039/C6CP01447J
A perylene bisimide (PBI) derivative (C-PBI-Py) of pyrene (Py) and cholesteryl residue (C) possessing intra-molecular energy transfer properties and three reference compounds (C-Py, C-PBI, PBI-Py) were designed and synthesized, where C was introduced in order to enhance the solubility of the relevant compounds in organic solvents. UV-vis absorption, steady-state fluorescence, cyclic voltammetric and theoretical calculation studies revealed that: (1) the PBI unit and Py moiety of C-PBI-Py could act as two individual chromophores, (2) the excited state energy of Py could transfer to PBI within a single molecule of the compound, and (3) the PBI moiety of the compound tends to form aggregates and shows PBI excimer emission. Time-resolved and temperature-dependent emission spectroscopy studies revealed the presence of both H-type excimer and J-type excimer, and formation of them via either the Birks' scheme or the pre-formed scheme due to strong π–π stacking that was elucidated by concentration-dependent 1H NMR spectroscopy measurement. In addition, the studies also indicated that the energy transfer occurs via an electron exchange mechanism (Dexter scheme). Results of this study will be useful in the development of new solvatochromic and other environment-sensitive fluorophores based on alteration of intra-molecular energy transfer efficiency.
Co-reporter:Shaofei Zhang, Hui Yang, Ying Ma, Yu Fang
Sensors and Actuators B: Chemical 2016 Volume 227() pp:271-276
Publication Date(Web):May 2016
DOI:10.1016/j.snb.2015.12.016
•Ag+ and HCHO could be selectively and sensitively detected via a synthesized fluorophore.•The duel sensing process is based upon switchable complexation and reduction of Ag+.•Alternative sensing of the two chemicals can be repeated for many times.•The detection can also be performed in a visualized manner.A bis-nitrobenzoxadiazole (NBD) derivative of calix[4]arene (L1) and a control compound (L2), mono-NBD derivative of the calixarene were designed and prepared via click chemistry. Fluorescence studies demonstrated that L1 as created can function as a switch with the presence of Ag+ in THF, of which the free state of L1 emits at ∼527 nm, but the binding state at 576 nm. Based upon this discovery, L1 was studied as a chemo-sensor of Ag+ in a mixture solvent of THF and H2O with a detection limit (DL) of ∼6.2 × 10−7 mol/L. Presence of other commonly found metal ions shows little effect upon the determination. Moreover, the L1 in the Ag+-L1 complex could be fully released with introduction of HCHO, a bases for the sensitive and selective detection of the toxic chemical. The DL of this test is 6.6 × 10−7 mol/L. Interestingly, binding and releasing of the fluorescent ligand could be repeated for at least 5 times. Furthermore, both sensing could be performed in a visualized manner. It is believed that the fluorescent compound as created should have a potential to find real-life applications.
Co-reporter:Meixia He, Haonan Peng, Gang Wang, Xingmao Chang, Rong Miao, Wenliang Wang, Yu Fang
Sensors and Actuators B: Chemical 2016 Volume 227() pp:255-262
Publication Date(Web):May 2016
DOI:10.1016/j.snb.2015.12.048
•A fluorescent film with porous networked structures was fabricated.•Fast, selective, and highly sensitive detection to N-methamphetamine(MAPA) in vapor phase was realized.•Sensing performances strongly depend on adjusting the molecular assembly and molecular energy level.•A conceptual MAPA detector based on the fluorescent film was developed, representing its potential for practical applications.A super-sensitive fluorescent film for N-methamphetamine (MAPA), one of the most widely abused drugs throughout the world, was designed and fabricated. The film was realized through the self-assembly of a newly developed fluorescent compound, PDC, onto a glass plate surface, where PDC is a rational combination of a new perylene bisimide derivative and cholesterol. The film as prepared exhibits unprecedented sensing performances: (1) the film is super-sensitive to the presence of either N-methyl-phenethylamine (MPEA, a simulant of MAPA) or MAPA in vapor state, and the detection limit (DL) of MPEA is ∼5.5 ppb, a lowest value in vapor state detection reported till now, (2) the presence of potential interferences (amines, organic solvents, water, apple pomace and etc) shows little effect on MAPA sensing, (3) the sensing process is highly fast and fully reversible. Moreover, the film as developed is photo-chemically stable. Based on this favorable film, a conceptual MAPA detector for practical application was successfully developed and presented.
Co-reporter:Gang Wang, Congdi Shang, Li Wang, Haonan Peng, Shiwei Yin, and Yu Fang
The Journal of Physical Chemistry B 2016 Volume 120(Issue 46) pp:11961-11969
Publication Date(Web):October 31, 2016
DOI:10.1021/acs.jpcb.6b08684
A pyrenyl unit (Py) was chemically connected to a perylene bisimide (PBI) moiety through a long and flexible linker, 4,7,10-trioxa-1,13-tridecanediamine (TOA), resulting in a fluorescent dyad, PBI–TOA–Py. Ultraviolet–visible absorption and fluorescence studies revealed that the two fluorescent units of PBI–TOA–Py behave independently. However, efficient Förster resonance energy transfer (FRET) from the Py unit to the PBI moiety in solution state was also observed. Temperature and solvent effect studies demonstrated that the energy transfer efficiency is highly dependent upon solution temperature and solvent nature. Specifically, for the dimethylformamide (DMF) solution of PBI–TOA–Py, the FRET efficiency is close to 88% at temperatures below ∼40 °C, but the efficiency greatly decreases to nearly zero when the temperature exceeds ∼80 °C. Moreover, addition of HAc into the DMF solution at room temperature could reduce the energy transfer efficiency to nearly zero, suggesting that the excited state energy of Py cannot be directly transferred to the PBI structure even though they are properly and chemically bonded. On the basis of the observations and time-resolved studies, it is believed that the observed efficient FRET from the Py unit to the PBI moiety occurs mainly through Py excimer formation, which could be a result of intermolecular association of the compound. Thus, the applications of the fluorescent dyad in solvent discrimination and trace water determination in organic solvents were verified through example studies.
Co-reporter:Xiangli Chen, Lingling Liu, Kaiqiang Liu, Qing Miao, Yanchao Lü and Yu Fang
Journal of Materials Chemistry A 2015 vol. 3(Issue 48) pp:24322-24332
Publication Date(Web):2015/11/04
DOI:10.1039/C5TA08342G
A cholesteryl derivative, BuDphe, which is a low molecular mass gelator (LMMG), was synthesized and used as a stabilizer for the creation of a number of water/oil gel-emulsions, of which the oil could be a mixture of butyl methacrylate (t-BMA) and p-divinylbenzene (DVB), a mixture of t-BMA, DVB and polydimethylsilane (PDMS), or that of t-BMA, DVB, PDMS and trimethoxymethylsilane (MTMS). Polymerization of these mixtures resulted in porous polymeric or hybrid monoliths, M-1, M-2, M-3, M-4 and M-5, respectively, of which the first is a pure poly-t-BMA monolith, the second to the fourth ones contain an increasing amount of PDMS, and the last is a hybrid of poly-t-BMA, PDMS and hydrolyzed MTMS. The hybrid monoliths, in particular M-5, as prepared possess not only hydrophobicity, porosity, and low-density, but also an unprecedented flexibility in the dry state with a maximum shape recovery corresponding to 100% of the original thickness after more than 70% compression strain. Moreover, silylanization also improves the thermo-stability of the porous materials. An absorption test demonstrated that M-5 is an excellent absorbent for a number of organic solvents and oils. The material after absorption can be re-generated and the liquids absorbed can be recovered by simple squeezing. Furthermore, the absorption-separation process with CH2Cl2 as an example solvent could be repeated at least 10 times with no significant reduction of its absorption capacity. Combination of the excellent flexibility, great absorptivity, easiness in preparation, and low-energy consumption in drying makes the hybrid monoliths, in particular M-5, possess the potential to find real-life applications.
Co-reporter:Chunmeng Yu, Xingmao Chang, Jing Liu, Liping Ding, Junxia Peng, and Yu Fang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 20) pp:10718
Publication Date(Web):May 6, 2015
DOI:10.1021/acsami.5b00155
Two low-cost, micropatterned, solution-gated field effect transistors (modified FET and unmodified FET) based on reduced graphene oxide (RGO) were developed and used for detection and discrimination of nucleoside triphosphates (NTPs). The modified FET was realized by simple deposition of a positively charged bis-pyrenyl derivative, py-diIM-py, onto the conducting RGO strips of the unmodified FET. The electrical properties and sensing behaviors of the as-prepared devices were studied comprehensively. Electrical transfer property tests revealed that both of the two FETs exhibit V-shaped ambipolar field effect behavior from p-type region to n-type region. Sensing performance studies demonstrated that modification of the native FET with py-diIM-py improves its sensing ability to NTPs—GTP and ATP in particular. The detection limit of GTP and ATP was as low as 400 nM, which is the lowest value for graphene-based electronic sensors reported so far. Furthermore, based on the cross-reactive responses of the two devices to NTPs, NTPs can be conveniently distinguished via combining use of the two devices. The enhancement of the modifier (py-diIM-py) to the sensing performance of the FET is tentatively attributed to its possible mediation role in sticking onto RGO strips and accumulating analytes by electrostatic association with the relevant species. Because they are sensitive and fast in response, simple and low-cost in preparation, and possibly useful in sensor-array fabrication, the developed sensors show great potential in real-life application.Keywords: field-effect transistors; nanoelectronic sensor; noncovalent modification; nucleoside triphosphates detection; reduced graphene oxide;
Co-reporter:Lingling Liu, Xiangli Chen, Kaiqiang Liu, Meixia He, Gang Wang, Xingmao Chang, and Yu Fang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 38) pp:21364
Publication Date(Web):September 8, 2015
DOI:10.1021/acsami.5b06011
On the basis of proton transfer in aqueous phase, we prepared a water-soluble and highly fluorescent ionic complex of 3,4,9,10-perylene tetracarboxylic acid (PTCA) and 6-deoxy-6-amino-β-CD (β-CDNH2) and studied its fluorescence behavior. It was found that the fluorescence emission of the complex is sensitive and selective to the presence of trace amount of toxic phenolic compounds, in particular phenol, which is crucial for water quality control. The detection limit (DL) of the method to the analyte is ∼0.03 μM, a lowest value reported in literatures for similar techniques. Interestingly, the detection at an unprecedented subnanogram (DL, ∼0.12 ng/cm2) level can also be conducted in a visualized manner, which may provide a simple and low-cost protocol for on-site and real-time detection of the analyte. Moreover, the complex is humidity sensitive in dry state, and its color changes from bright yellow to bright green when exposed to wet vapor. Unlike other PTCA bisimide derivatives, preparation of the ionic complex of PTCA/β-CDNH2 is simple and avoids complicated synthetic burden. Furthermore, introduction of methanol into the aqueous solution of the complex resulted in aggregation as indicated by solution color change and proved by transmission electron microscopy and dynamic light scattering studies, which explains why the compound in dry state is sensitive to the presence of water and water vapor. X-ray diffraction, UV–vis, and fluorescence studies uncovered the H-packing nature of the structure of the aggregate.Keywords: 3,4,9,10-perylene tetracarboxylic acid; 6-deoxy-6-amino-β-cyclodextrin; fluorescence; ionic complex; phenol
Co-reporter:Junlin Yan, Jing Liu, Hairui Lei, Yang Kang, Chuan Zhao, Yu Fang
Journal of Colloid and Interface Science 2015 Volume 448() pp:374-379
Publication Date(Web):15 June 2015
DOI:10.1016/j.jcis.2015.02.044
Low-molecular-mass gelators and relevant molecular gels have been employed for water purification owing to their convenience and efficiency, but the process is time consuming due to low extraction efficiency originated from limited contact of the two phases. In this work, two novel di-cholesterol-based gelators, 1 and 2, with a ferrocenyl unit were synthesized and the gels based on 2 possess a smart thixotropic property. In particular, 2/heptane gel, the shear force induced phase transition is fast (within seconds) and fully reversible without the need of heating–cooling cycle. Based upon the thixotropic molecular gel, a novel separation strategy, which combines the great efficiency of liquid–liquid extraction and the convenience of liquid–solid separation, has been successfully conducted for removing iodine from wastewater. It was demonstrated that iodine was removed within several minutes and the extraction efficiency (72%) was the same with the one using corresponding liquid. Furthermore, 2/heptane gel is also responsive to chemical oxidation and variation in temperature. FTIR, NMR, CD and XRD studies revealed that helical fibers were formed via intermolecular hydrogen bonding and van der Waals interaction. It is believed that the results presented in this work are of importance for extending real-life applications of molecular gels.
Co-reporter:Gang Wang, Xingmao Chang, Junxia Peng, Kaiqiang Liu, Keru Zhao, Chunmeng Yu and Yu Fang
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 7) pp:5441-5449
Publication Date(Web):13 Jan 2015
DOI:10.1039/C4CP04860A
A new fluorescent derivative of cholesterol, N,N′-(N-(2-(3β-cholest-5-en-3yl-formamido)ethyl) pyrene-1-sulfonamido)ethyl perylene-3,4:9,10-tetracarboxylic acid bisimide (CPPBI), was designed and synthesized. In the design, pyrene (Py) and perylene bisimide (PBI) were specially chosen as the energy donor and the acceptor, respectively. Fluorescence studies revealed that (1) CPPBI shows a strong tendency to form supra-molecular assemblies, (2) the assemblies possess a high efficiency of fluorescence resonance energy transfer (FRET) via intermolecular interactions, and (3) the profile and position of its fluorescence emission are highly dependent upon the nature of its medium, but the medium shows little effect on the efficiency of the energy transfer, suggesting that the chromophores including both Py and PBI units enjoy some rotational and/or translational mobility in the aggregated state of the compound. Temperature- and concentration-dependent 1H NMR spectroscopy studies revealed that both hydrogen-bonding and π–π stacking play a great role in stabilizing the assemblies of the compound, and confirmed the existence of π–π stacking between the Py moieties and between the PBI residues of the compound, of which the donor and the acceptor may have arranged in an appropriate orientation and at a suitable distance which are the key factors to determine the FRET efficiency. Moreover, the CPPBI-based film possesses unusual photochemical stability, and its emission is sensitive to the presence of some organic vapors, in particular aniline.
Co-reporter:Ying Wu, Kaiqiang Liu, Xiangli Chen, Yongping Chen, Shaofei Zhang, Junxia Peng and Yu Fang
New Journal of Chemistry 2015 vol. 39(Issue 1) pp:639-649
Publication Date(Web):03 Nov 2014
DOI:10.1039/C4NJ01517G
A calix[4]arene-based dimeric-cholesteryl derivative with naphthalene in the linkers (C2N2C) was designed and synthesized. The gelation behaviors of the compound in 36 liquids were evaluated. It was demonstrated that C2N2C could gel 16 of the liquids tested, which include both polar and apolar liquids. SEM and AFM studies revealed that the morphologies of the gel networks are dependent on the concentrations of C2N2C and the nature of the liquids under study. Importantly, rheological studies revealed that the gel of the compound in benzene possesses sensitive, fast and fully reversible thixotropic property. More importantly, the Tgel of the C2N2C/benzene gel could be at least more than 60 degrees higher than the boiling point of benzene when the gelator concentration is greater than 6% (w/v), a result never reported before. CD measurements revealed the chiral nature of the assemblies of the gel networks. Further investigation by AFM measurements confirmed the right-hand helical structures of the gel networks of C2N2C/benzene gel. As anticipated, hydrogen bonding and π–π stacking are the two main driving forces for the formation of the gels.
Co-reporter:Xingmao Chang, Chunmeng Yu, Gang Wang, Jiayun Fan, Jianyun Zhang, Yanyu Qi, Kaiqiang Liu, and Yu Fang
The Journal of Physical Chemistry B 2015 Volume 119(Issue 22) pp:6721-6729
Publication Date(Web):May 18, 2015
DOI:10.1021/acs.jpcb.5b02664
Inspired by the concept of constitutional dynamic chemistry, we propose a new and well-adaptable strategy for developing molecular beacon (MB)-like fluorescent probes. To demonstrate the strategy, we synthesized and used an amino group containing pyrenyl derivative of cholesterol (CP) for the construction of new fluorescent probes with EDTA and sulfuric acid. The probes as created were successfully used for n-hexane purity checking and Ba2+and Pb2+sensing, respectively.
Co-reporter:Xingmao Chang, Gang Wang, Chunmeng Yu, Yanru Wang, Meixia He, Juan Fan, Yu Fang
Journal of Photochemistry and Photobiology A: Chemistry 2015 Volume 298() pp:9-16
Publication Date(Web):1 February 2015
DOI:10.1016/j.jphotochem.2014.10.008
•The photochemical stability of a number of pyrene and pyrenyl derivatives-based fluorescent films was studied systematically.•Mechanism studies revealed that photochemically the pyrene and pyrenyl derivatives-based films decomposed via two channels.•1H NMR, FTIR and high-resolution MS studies revealed that ring-opening and oxidation of the saturated carbon next to pyrenyl structure are two of the important results of the photochemical degradation of the fluorophores tested.Photo-degradation is one of the most challenging problems to limit the re-usability of fluorescent film sensors, and thereby, it is a necessity to evaluate the photochemical stability of a fluorescent film before it is put into practical uses. Accordingly, the photochemical stability of some widely used pyrene and its derivatives-based fluorescent films were studied under mild conditions (i.e., in air and at room temperature) with ultraviolet (UV) or visible light as the light source. It was found that the fluorophores based films fabricated in physical ways are all un-stable to the irritation of light, in particular when UV is employed as a light source. 1H NMR, FTIR and high-resolution MS studies revealed that ring-opening and oxidation of the saturated carbon next to pyrenyl structure are two of the important results of the photochemical degradation of the fluorophores tested. But it is to be noted that photo-chemically pyrene is much more stable than its derivatives no matter what kind of substituent is introduced. Furthermore, the films are only sensitive to the illumination of UV light rather than visible light. Mechanism studies revealed that the pyrene and pyrene derivatives-based films decomposed via two channels under light irritation. One is the photo-decomposition without the participation of other chemicals, and the other is photo-degradation via reaction with the chemicals. Kinetic study demonstrated that the films lost their fluorescence mainly via the second channel. It is believed that this finding is of interest to the development of novel pyrenyl derivatives-based fluorescent film sensors.
Co-reporter:Xiangli Chen, Lingling Liu, Kaiqiang Liu, Qing Miao and Yu Fang
Journal of Materials Chemistry A 2014 vol. 2(Issue 26) pp:10081-10089
Publication Date(Web):04 Apr 2014
DOI:10.1039/C4TA00137K
A series of water in oil (W/O) gel emulsions was prepared by using a low-molecular mass gelator (LMMG), a ferrocene derivative of cholesterol, as a stabilizer and tertiary butylmethacrylate (t-BMA) as the continuous phase. Via polymerization of the emulsions as created, a series of porous polymeric monoliths with different internal structures was prepared. SEM observation reveals that the internal structures of the monoliths could be largely adjusted via simple variation of the compositions of the gel emulsions. Importantly, introduction of hydrolysable silanes into the continuous phase of the gel emulsion before polymerization significantly alters the mechanical strengths of the porous materials, and remarkably promotes the sorption of the porous materials to some water-immiscible and -miscible liquids, such as benzene, kerosene, already-used transformer oil, ethanol, tetrahydrofuran, etc., of which kerosene is a representative of oils of lower viscosities and the transformer oil a representative of oils of higher viscosities. Furthermore, the oil absorbed by the monoliths could be recovered by centrifugation or squeezing, and the monoliths could be reused by washing them with alcohol or some other suitable volatile organic liquids. The sorption and desorption process could be repeated at least 13 times. More importantly, the LMMGs-based gel emulsion approach established in the present study for preparing porous polymeric or composite monoliths is facile, versatile and environmentally benign, showing a bright future for real-life uses.
Co-reporter:Xiaohuan Sun, Yanyu Qi, Huijing Liu, Junxia Peng, Kaiqiang Liu, and Yu Fang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 22) pp:20016
Publication Date(Web):October 14, 2014
DOI:10.1021/am505588x
Achieving high sensing performance and good photostability of fluorescent films based on adlayer construction represents a significant challenge in the area of functional fluorescent film research. A solution may be offered by “Yin and Yang”, a balance idea from Chinese philosophy, for the design of a fluorophore and the relevant assembly. Accordingly, a 1,4-bis(phenylethynyl)benzene (BPEB) derivative (C2) with two cholesteryl residues in the side chains and two glucono units in the head and tail positions was designed and synthesized. As a control, compound C1 was also prepared. The only difference between C1 and C2 is that the hydroxyl groups in the glucono residues of C1 are fully acetylated. Studies of the fluorescence behaviors of the two compounds in solution revealed that both the profile and the intensity of the fluorescence emission of the compounds, in particular C2, are dependent on their concentration and on the nature of solvents employed. Presence of HCl also alters the emission of the compounds in solution. On the basis of the studies, three fluorescent films were prepared, and their sensing performances to HCl in vapor state were studied. Specifically, Film 1 and Film 3 were fabricated via physical coating, separately, of C2 and C1 on glass plate surfaces. As another comparison, Film 2 was also fabricated with C2 as a fluorophore but at a much lower concentration if compared to that for the preparation of Film 1. As revealed by SEM and fluorescent microscopy studies, Film 1 and Film 2 exhibit well-defined microstructures, which are spherical particles and spherical pores, respectively, while Film 3 is characterized by irregular aggregates of C1. Fluorescence measurements demonstrated that Film 1 and Film 3 both display an aggregation emission, of which the emission from Film 1 is supersensitive to the presence of HCl vapor (detection limit: 0.4 ppb, a lowest value reported in the literatures). For Film 3, however, its emission is insensitive to the presence of the vapor. Similarly, the emission from the nonaggregated state of C2, a characteristic emission of Film 2, is also insensitive to the presence of the vapor. Furthermore, the sensing process of Film 1 to the vapor is highly selective and fully reversible, which lays foundation for its real-life uses. As for C2, the results from solution studies and those from film studies demonstrate clearly that introduction of auxiliary structures with opposite properties onto a typical fluorophore is a good strategy to develop fluorescent supramolecular motifs with rich assembly properties and great potential of applications.Keywords: 1,4-bis(phenylethynyl)benzene (BPEB); cholesterol; fluorescence; glucose; self-assembly
Co-reporter:Hairui Lei, Jing Liu, Junlin Yan, Shihuan Lu, and Yu Fang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 16) pp:13642
Publication Date(Web):August 7, 2014
DOI:10.1021/am5031424
A novel amphiphilic Tb3+ complex (TbL3+(I)) consisting of a +3 charged head and a hydrophobic alkyl chain has been developed. It spontaneously self-assembles in water and forms stable vesicles at neutral pH. TbL3+(I) has no aromatic groups (functioning as an antenna), and its intrinsic luminescence is thus minimized. These features lead to the self-assembling TbL3+(I) receptor molecules demonstrating an increased luminescence intensity upon binding of nucleotides. Upon addition of guanosine triphosphate (GTP), the luminescence from Tb3+ was notably promoted (127-fold), as the light energy absorbed by the guanine group of GTP was efficiently transferred to the Tb3+ center. In the case of guanosine diphosphate (GDP) and guanosine monophosphate (GMP), respectively, 78-fold and 43-fold increases in luminescence intensity were observed. This enhancement was less significant than that observed for GTP, due to fewer negative charges on GDP and GMP. No other nucleotides or the tested nonphosphorylated nucleosides affected the luminescence intensity to any notable extent. In marked contrast, all tested nucleotides, including guanine nucleotides, barely promoted the luminescence of molecularly dispersed receptors, TbL3+(II), indicating that the confinement and organization of molecules in a nanointerface play vital roles in improving the performance of a sensing system. This Tb3+ complex nanointerface is successfully used for monitoring the GTP-to-GDP conversion.Keywords: luminescent probes; molecular recognition; nanointerface; nucleotides; terbium complex
Co-reporter:Yuan Cao, Liping Ding, Shihuai Wang, Yuan Liu, Junmei Fan, Wenting Hu, Ping Liu, and Yu Fang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 1) pp:49
Publication Date(Web):December 13, 2013
DOI:10.1021/am405157k
A dansyl-functionalized fluorescent film sensor was specially designed and prepared by assembling dansyl on a glass plate surface via a long flexible spacer containing oligo(oxyethylene) and amine units. The chemical attachment of dansyl moieties on the surface was verified by contact angle, XPS, and fluorescence measurements. Solvent effect examination revealed that the polarity-sensitivity was retained for the surface-confined dansyl moieties. Fluorescence quenching studies in water declared that the dansyl-functionalized SAM possesses a higher sensitivity towards Hg2+ and Cu2+ than the other tested divalent metal ions including Zn2+, Cd2+, Co2+, and Pb2+. Further measurements of the fluorescence responses of the film towards Cu2+ and Hg2+ in three solvents including water, acetonitrile, and THF evidenced that the present film exhibits cross-reactive responses to these two metal ions. The combined signals from the three solvents provide a recognition pattern for both metal ions at a certain concentration and realize the identification between Hg2+ and Cu2+. Moreover, using principle component analysis, this method can be extended to identify metal ions that are hard to detect by the film sensor in water such as Co2+ and Ni2+.Keywords: interface; metal ions; pattern recognition; self-assembled monolayer; sensor array;
Co-reporter:Somnath Mukherjee, Congdi Shang, Xiangli Chen, Xingmao Chang, Kaiqiang Liu, Chunmeng Yu and Yu Fang
Chemical Communications 2014 vol. 50(Issue 90) pp:13940-13943
Publication Date(Web):04 Sep 2014
DOI:10.1039/C4CC06024E
Two simple, eco-friendly and efficient phase-selective gelators were developed for instant (<45 s) gelation of oil (either commercial fuels or pure organic liquids) from an oil–water mixture at room temperature to combat marine oil spills.
Co-reporter:Hang Yu, Yanchao Lü, Xiangli Chen, Kaiqiang Liu and Yu Fang
Soft Matter 2014 vol. 10(Issue 45) pp:9159-9166
Publication Date(Web):17 Sep 2014
DOI:10.1039/C4SM01869A
Two nitrobenzoxadiazole (NBD)-containing cholesteryl (Chol) derivatives were prepared by introducing D/L-phenylalanine into the linkers between the NBD and Chol units. The compounds were denoted as NLC and NDC, respectively. The gelation behaviors of them were tested in 34 liquids. It was found that the chirality of the linkers shows a great effect on the gelation ability and the gel properties of the two compounds. SEM studies demonstrated that the gelator in the gel of NDC/DMSO aggregated into uniform fibrous structures. FTIR, 1H NMR and UV-Vis spectroscopy measurements revealed that intermolecular hydrogen bonding and π–π stacking are two main driving forces to promote the gel formation. Interestingly, the NDC/DMSO gel exhibits rapid and reproducible gel–sol phase transition and fluorescence quenching upon introduction of ammonia. Furthermore, both the gel and the fluorescence emission could be fully recovered upon evaporation of the ammonia gas introduced. Spectroscopy and model system studies revealed the association of ammonia with the nitro group of the NBD unit of the compound, which is recognized as the main reason for the chemical responses of the gel system. On the basis of the discovery, an ammonia sensing film had been fabricated and made into a device. Furthermore, a device-based and conceptual “ammonia leaking” monitoring instrument was developed. A preliminary test demonstrated that the performance of the system is exceptionally good, a typical and persuasive example to show the important real-life applications of molecular gels.
Co-reporter:Lei Zhang, Hongmei Qin, Dong Li, Yu Fang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 444() pp:307-313
Publication Date(Web):5 March 2014
DOI:10.1016/j.colsurfa.2013.12.080
•Prepared two novel surfactant-like pyrene derivatives.•Monitored the transition between different surfactant aggregates.•One of them shows selective sensing to the presence of lanthanum and europium ions.•The compounds are more powerful multifunctional fluorescent probes.Two novel non-ionic surfactant-like pyrene derivatives containing a triazole unit, 2-(4-((bis(2-hydroxyethyl)amino)methyl)-1H-1,2,3-triazol-1-yl)-N-(4-(pyrene-1-sulfonamido)butyl)acetamide (PSDA-TDEA) and 2-(4-(((2-hydroxyethyl)amino)methyl)-1H-1,2,3-triazol-1-yl)-N-(4-(pyrene-1-sulfonamido)butyl)acetamide (PSDA-TEA) were designed and synthesized. Fluorescence studies revealed that the two fluorophores aggregate in aqueous phase, and the critical aggregation concentrations (CACs) of them are ∼1.2 × 10−4 M and ∼8.5 × 10−5 M, respectively. It was demonstrated that the profiles of the emission spectra of the two compounds are both dependent on the micro-polarities of their mediums. Specifically, the ratio of I399/I380, of which the two emissions appearing at 399 and 380 nm, respectively, are both coming from the monomer emissions of the pyrene residue of the compounds, increases gradually and significantly with increasing the micro-polarity of the medium at which the probes stay. As expected, PSDA-TDEA and PSDA-TEA could probe the formation and transformation of the aggregates of some typical amphiphiles. Meanwhile, PSDA-TDEA also shows selective sensing to the presence of lanthanum ion and europium ion, and the detection limits (DL) are 1.48 and 1.14 ppm, respectively. Clearly, PSDA-TDEA and PSDA-TEA as created could be used as multi-functional fluorescent probes, at least for sensing polarity and some lanthanide ions. These probes are superior to others in using due to their better solubility in aqueous phase, which must bring convenience for pre-treatment of the samples under test.The application of two novel newly designed and prepared surfactant-like pyrene derivatives in the transition of the aggregates of amphiphilic compounds, especially between micelles and vesicles, were investigated systematically by using the compounds as probes. Meanwhile, one of them also shows selective sensing to the presence of lanthanum ion and europium ion, and the detection limits (DL) are 1.48 and 1.14 ppm, respectively.
Co-reporter:Qing Miao, Xiangli Chen, Lingling Liu, Junxia Peng, and Yu Fang
Langmuir 2014 Volume 30(Issue 45) pp:13680-13688
Publication Date(Web):October 22, 2014
DOI:10.1021/la502988x
A polymerizable cholesteryl derivative (COA) was synthesized and used as a stabilizer for creating gel-emulsions with water in polymerizable monomers, of which they are styrene (ST), tert-butyl methacrylate (t-BMA), ethylene glycol dimethyl acrylate (EGDMA), and methyl methacrylate (MMA), etc. Interestingly, in addition to COA, the presence of a small amount of Span-80 is a necessity for the formation of the monomers containing gel-emulsions. Unlike conventional ones, the volume fraction of the dispersed phase in the gel-emulsions as created could be much lower than 74%, a critical value for routine gel-emulsions. Stabilization of these gel-emulsions as created has been attributed to the synergetic effect between COA, a typical low-molecular-mass gelator (LMMG), and Span-80, a surfactant, of which the former gels the continuous phase and the latter minimizes the interfacial energy of the continuous phase and the dispersed phase. SEM observation confirmed the network structures of COA in the gel-emulsions. Rheological tests demonstrated that the storage modulus, G′, and the yield stress of the gel-emulsions decrease along with increasing the volume fraction of the dispersed phase, water, provided it is not greater than 74%—a result inconsistent with the theory explaining formation of routine gel-emulsions and in support of the conclusion that the systems under study follow a different mechanism. Furthermore, unlike LMMG-based stabilizers reported earlier, the gelator, COA, created in the present study has been functioning not only as a stabilizer but also a monomer. To illustrate the conceptual advantages, the gel-emulsions of water in ST/DVB/AIBN were polymerized. As expected, the densities and internal structures of the monoliths as prepared are highly adjustable, functionalization of the materials with cholesterol has been realized, and at the same time the problem of stabilizer leaking has been avoided. A preliminary test for gas adsorption demonstrated that the monoliths as prepared are good adsorbents for some volatile organic compounds (VOCs), in particular benzene, toluene, ethylbenzene, and xylene—the famous and toxic BTEX. It is believed that the findings reported in the present work provide not only a new strategy for creating novel gel-emulsions but also a new route for functionalizing porous polymeric monoliths.
Co-reporter:BaoLong Hu;KaiQiang Liu;XiangLi Chen
Science China Chemistry 2014 Volume 57( Issue 11) pp:1544-1551
Publication Date(Web):2014 November
DOI:10.1007/s11426-014-5135-6
A scorpion-shaped di-NBD (4-substituted-7-nitrobenzoxadiazole) derivative of cholesterol (Chol-2NBD) was designed and synthesized. The gelation behaviors of the compound in a series of single and mixed liquids were tested. It was shown that the compound is an effective gelator for mixture liquids of THF and benzene at room temperature. Furthermore, FT-IR and temperature-/concentration-dependent 1H NMR spectroscopy studies revealed that hydrogen bonding and π-π stacking among the molecules of Chol-2NBD are two main driving forces for the physical gelation of the mixture liquids. Interestingly, as observed in the gelation test and confirmed by rheological studies, the Chol-2NBD-THF/benzene gel systems, at least the one with 2:8 of the volume ratio of THF to benzene, are mechanically stable, but very sensitive to the stimulus of shear stress, which means that the gel changes into a liquid upon shaking. More interestingly, the liquid returns to gel instantly once the shear stress is removed. This phase transition process could be repeated for many times at room temperature. In addition, primary tests demonstrated that the fluorescence emission of Chol-2NBD is significantly quenched by the presence of water, ammonia water, or ammonia gas, but the emission recovers after evaporation of them. Further detailed investigation is under progress.
Co-reporter:Chunmeng Yu, Min Xue, Ke Liu, Gang Wang, and Yu Fang
Langmuir 2014 Volume 30(Issue 5) pp:1257-1265
Publication Date(Web):January 20, 2014
DOI:10.1021/la4046836
Three novel terthiophene derivatives of cholesterol (TtGC, TtLPC, TtDPC), of which the two building blocks are linked by a structure of glycine, l-phenylalanine, or d-phenylalanine, respectively, were designed and prepared, and their gelation behaviors in 26 liquids were tested. It was demonstrated that the compounds show different gelation abilities with the variation of the linker structures even though the variation is small. FTIR, 1H NMR, and UV–vis measurements revealed that intermolecular hydrogen bonding and van der Waals interaction are the main driving forces for the gel formation. As for TtDPC, CD and AFM measurements revealed that it aggregated into chiral structures of left-helical feature in benzene. Importantly, the morphologies of the gel networks could be subtly adjusted via alteration of the gelator concentration. Considering the brightness in fluorescence and the unique micro/nanostructures of the gel networks, a fluorescent film (film 1) was fabricated by simple dip-coating of TtDPC/benzene solution (before gelation) onto a glass plate surface. Fluorescent studies demonstrated that the film is photochemically unstable. Two hours UV irradiation of the film results in film 2, which is almost fluorescent silence. However, the presence of HAc vapor or the vapors of some other volatile organic liquids induces new fluorescence emission, laying the foundation for creating a turn-on type fluorescent sensor of the organic vapors. Furthermore, as a new type of low-molecular-mass gelators (LMMGs), of which oligothiophene was employed as a building block, the present study has provided a possibility to explore the photo-/electronic applications of oligothiophenes via a molecular gel strategy.
Co-reporter:Ni Yan ; Zhiyan Xu ; Kevin K. Diehn ; Srinivasa R. Raghavan ; Yu Fang ;Richard G. Weiss
Journal of the American Chemical Society 2013 Volume 135(Issue 24) pp:8989-8999
Publication Date(Web):June 4, 2013
DOI:10.1021/ja402560n
The self-assembly behavior of a series of glucono-appended 1-pyrenesulfonyl derivatives containing α,ω-diaminoalkane spacers (Pn, where n, the number of methylene units separating the amino groups, is 2, 3, 4, 6, 7, and 8) in v:v tetrahydrofuran (THF):water mixtures is examined at room temperature. The Pn at 2 w/v % concentrations do not dissolve in either THF or water at room temperature. However, the Pn can be dissolved in some THF:water mixtures, and they form gels spontaneously in other compositions without dissolving completely. The self-assembly of the Pn in the liquid mixtures has been investigated using a variety of techniques. The particle sizes of the Pn in their solutions/sols, critical gelation concentrations, microstructures, thermal and mechanical stabilities of the gels, and molecular packing modes of Pn molecules in their gel networks are found to be very dependent on the composition of the liquid mixtures. Correlations between the self-assembly behavior of the Pn and the polarity of the liquid mixtures, as probed by ET(30) and Hansen solubility parameters, yield both qualitative and quantitative insights into why self-assembly of the Pn can or cannot be achieved in different liquid compositions. As revealed by UV–vis and fluorescence spectroscopy studies, π–π stacking of the pyrenyl groups occurs as part of the aggregation process. Correlations between the rheological properties of the gels and the Hansen solubility parameters of the Pn and the solvent mixtures indicate that hydrogen-bonding interactions are a major contributor to the mechanical stability. Overall, the results of this study offer a new strategy to investigate the balance between dissolution and aggregation of molecular gelators. To the best of our knowledge, this is the first example of the spontaneous formation of molecular gels without heating by placing gelators in mixtures of liquids in which they are insoluble in the neat components.
Co-reporter:Ping Jing, Xiaohua Fang, Junlin Yan, Jie Guo and Yu Fang
Journal of Materials Chemistry A 2013 vol. 1(Issue 35) pp:10135-10141
Publication Date(Web):21 Jun 2013
DOI:10.1039/C3TA11761H
Ultra-low density porous polystyrene monoliths have been prepared via using water/styrene gel-emulsions, which were stabilized by a low-molecular mass gelator (LMMG), as templates. It was demonstrated that the porous materials as prepared possess a number of superior features such as highly adjustable internal structure and density, the lowest density could be lower than 0.01 g cm−3. Moreover, such materials can be used as excellent absorbents for many organic liquids including viscous oils like mineral oil and high-density oils such as dichloromethane. In particular, the absorption process is fast, selective and efficient when they are used in the purification of oil contaminated water. Importantly, the oils absorbed in the absorbent can be easily squeezed out, and furthermore the wet absorbent as obtained can be reused by suitable washing and natural drying. More importantly, the LMMG-based gel-emulsions employed as templates are simple in preparation, only mixing and agitation at ambient temperature are required. Moreover, further treatment of the wet porous materials as prepared from the templates is just washing and natural drying, which is completely different from those such as freeze-drying or supercritical drying widely adopted by others in the preparation of low density materials via routine approaches. It is believed that the LMMG-based gel-emulsion template method developed in the present work may have created a novel and facile way for preparing low density materials with ideal properties.
Co-reporter:Chunmeng Yu, Yunlong Guo, Hongtao Liu, Ni Yan, Zhiyan Xu, Gui Yu, Yu Fang and Yunqi Liu
Chemical Communications 2013 vol. 49(Issue 58) pp:6492-6494
Publication Date(Web):30 May 2013
DOI:10.1039/C3CC42377H
Swift fabrication of a non-covalently modified reduced graphene oxide electronic sensor has been developed. An unparalleled detection limit is demonstrated for Hg2+, down to the picomolar range.
Co-reporter:Ke Liu, Taihong Liu, Xiangli Chen, Xiaohuan Sun, and Yu Fang
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 19) pp:9830
Publication Date(Web):September 12, 2013
DOI:10.1021/am4030774
A pyrene-capped terthiophene of cholesteryl derivative (CholG-3T-Py) was designed, synthesized, and utilized for the fabrication of a fluorescent film. Unlike the commonly adopted direct-coating method, the film was fabricated by the physical immobilization of the fluorophore, CholG-3T-Py, onto a glass plate surface via preformed low-molecular-mass gelator (LMMGs)-based molecular-gel networks. The photophysical behavior of the film as prepared and its sensing performances to nitrobenzene (NB) were conducted after activation with toluene. It was found that the film as prepared and activated is sensitive to the presence of NB, and the sensing process is fully reversible. Furthermore, the effects of commonly found interferents, including structural analogues, raw materials, which are commonly used for the production of NB, and other nitroaromatics (NACs), on the sensing process were also tested. It was shown that only aniline and phenol possess slight interference. The present work not only extends the applications of LMMGs-based molecular gels but also provids a new approach for preparation of micro- and nano-structure-based fluorescent sensing films.Keywords: fluorescence films; low-molecular-mass gelator (LMMGs); micro- and nanostructures; nitrobenzene; pyrene-capped terthiophene (Py-3T);
Co-reporter:Xiuqin Cai, Ying Wu, Liya Wang, Ni Yan, Jing Liu, Xiaohua Fang and Yu Fang
Soft Matter 2013 vol. 9(Issue 24) pp:5807-5814
Publication Date(Web):15 May 2013
DOI:10.1039/C3SM50577D
Two novel cholesteryl derivatives of calix[4]arene with L- or D-phenylalanine residues in the linkers (1 and 2, respectively) were designed and synthesized. The gelation behaviors of the compounds in 30 organic solvents were tested. It was demonstrated that 1 gels n-butanol and n-pentanol at room temperature, but 2 gels isopropanol only under the treatment of heating–cooling cycling or energy supplementing via sonication, vortex or agitation at room temperature. AFM and SEM measurements revealed that the structures of the gel networks are greatly affected by the spatial configurations of the linkers contained in the calix[4]arene derivatives. Furthermore, mechanical treatment not only promotes the gelation of the system of 2–isopropanol, but also enhances the strength of the gel. Specifically, 18 min of agitation at room temperature makes the storage modulus and the yield stress of the gel (3.5%, w/v) exceed 1 × 106 Pa and 6 × 103 Pa, respectively, which are second only to the mechanically strongest low molecular mass gelator-based molecular gel reported until now. XRD analysis revealed the hexagonal packing structure of 1 in its n-pentanol gel.
Co-reporter:Zhiyan Xu, Junxia Peng, Ni Yan, Hang Yu, Shasha Zhang, Kaiqiang Liu and Yu Fang
Soft Matter 2013 vol. 9(Issue 4) pp:1091-1099
Publication Date(Web):19 Nov 2012
DOI:10.1039/C2SM27208C
Four nitrobenzoxadiazole (NBD)-containing cholesteryl (Chol) derivatives were prepared, and their gelation behaviors were tested. It was demonstrated that the compounds show a remarkable gelling ability. In particular, a subtle change in the length of the spacers connecting the two structural units of the compounds, which are NBD and Chol, respectively, produced a dramatic change in the gelation ability and the gel properties of the compounds. As for gelation, compound 1 is much more powerful than others, especially in the gelation of methanol-containing organic mixtures. It is to be noted that the gel of 1/pyridine–methanol exhibits superior mechanical strength with a yield stress higher than 6300 Pa at a gelator concentration of 2.5% (w/v), and the value exceeds 23000 Pa when the gelator concentration reaches 5.0% (w/v), a result never reported before in the field of molecular gels based on low-molecular mass gelators (LMMGs). More importantly, the gel shows a rapid self-healing property as evidenced by the fact that the gel heals up immediately upon cutting, provided the segments from the cutting are squeezed together. No doubt, our findings establish a benchmark for LMMG-based molecular gels in their rheological performances. FTIR, 1H NMR and XRD studies revealed that intermolecular hydrogen bonding and π–π stacking are two of the main driving forces to promote the gelation of the system and the self-assembling of the molecules of the gelator.
Co-reporter:Yuan Cao, Liping Ding, Wenting Hu, Lin Wang, Yu Fang
Applied Surface Science 2013 Volume 273() pp:542-548
Publication Date(Web):15 May 2013
DOI:10.1016/j.apsusc.2013.02.077
Abstract
A fluorescent film sensor for Cu(II) and Hg(II) ions was designed and prepared by chemical attaching pyrene moieties on an epoxy-terminated surface via a long flexible and hydrophilic spacer. The chemical attachment of pyrene moieties on the surface was verified by contact angle, XPS, and fluorescence characterization. The fluorescence responses of the present film to a series of metal ions in aqueous solution indicate that this film sensor is sensitive to both copper and mercury ions. Presence of other metal ions, including Ni(II), Fe(III), Pb(II), Mg(II), Ba(II), Zn(II), La(II) and Eu(II), has little effect upon the fluorescence emission of the film. The sensitivity of the present film sensor is quite high toward both Cu(II) and Hg(II) ions in the form of inorganic salts as revealed by the large KSV values. Moreover, the presence of organic anions produces little influence on the sensitivity of the film sensor toward metal ions, suggesting the introduction of the hydrophilic spacer weakens the spacer layer screening effect in aqueous solution. The novel fluorescent film sensor may have potentials as Cu(II) and Hg(II) sensors to probe natural environments.
Co-reporter:Ni Yan, Zhiyan Xu, Kevin K. Diehn, Srinivasa R. Raghavan, Yu Fang, and Richard G. Weiss
Langmuir 2013 Volume 29(Issue 2) pp:793-805
Publication Date(Web):December 19, 2012
DOI:10.1021/la304957n
A series of glucono-appended 1-pyrenesulfonyl derivatives containing α,ω-diaminoalkane spacers (Pn, where n, the number of methylene units separating the amino groups, is 2, 3, 4, 6, 7, and 8) have been prepared. Careful analyses of correlations between the structures of these molecules and their gels have provided important insights into the factors responsible for one-dimensional aggregation of small molecules containing both lipophilic and hydrophilic parts. The gelation behavior has been examined in 30 liquids of diverse structure and polarity, and the properties of their gels and the gelation mechanisms have been investigated using a variety of techniques. Possible reasons are discussed regarding why the Pn are better gelators than the corresponding naphthyl analogues (Nn) which had been investigated previously. P2 and P3 are ambidextrous gelators (i.e., they gelate both water and some organic liquids), and P4–P8 gelate some organic liquids which are protic and aprotic, but not water. In at least one of the liquids examined, P3, P4, P6, P7, and P8 form gels at less than 1 w/v % concentrations, and some of the gels in 1-decanol are thixotropic. Analyses of the gelation abilities using Hansen solubility parameters yield both qualitative and quantitative insights into the role of liquid-gelator interactions. For example, the critical gelation concentrations increase generally with increasing polar and hydrogen bonding interactions between the gelators and their liquid components. As revealed by FT-IR, 1H NMR, UV–vis, and fluorescence spectra, hydrogen-bonding between glucono units and π–π stacking between pyrenyl groups are important in the formation and maintenance of the gel networks. The results from this study, especially those relating the aggregation modes and liquid properties, offer insights for the design of new surfactant-containing low-molecular-mass gelators with predefined gelating abilities.
Co-reporter:Ping Jing;JunLin Yan;XiuQin Cai;Jing Liu;BaoLong Hu
Science China Chemistry 2013 Volume 56( Issue 7) pp:982-991
Publication Date(Web):2013 July
DOI:10.1007/s11426-013-4869-x
The gelation behaviors of four recently reported amphiphilic cholesteryl derivatives (1, 2, 3 and 4) have been evaluated. It was found that the gel formation process can be controlled by introduction of water at room temperature. Addition of water to an acetone solution of 4 immediately results in the system becoming turbid, and a gel subsequently forms within a few minutes. Interestingly, 4 is a super-gelator for a mixed solvent of acetone and water at room temperature, in particular when their volume ratio is close to 1:1 at which the critical gelation concentration (CGC) is 0.06% (w/v). It was found that the introduction of water favors the formation of gel networks, and the gel possesses smart and reversible thixotropic properties. FTIR and 1H NMR spectroscopy confirmed that hydrogen bonding is one of the main driving forces for the gelation of the solvents. XRD demonstrated that 4 self-assembled into a layered structure within the acetone-water mixed solvent gel. Furthermore, 1 and 2 can be used as excellent stabilizers for gel emulsions of alkanes and water. The maximum of the dispersed phase, water, in one of the gel-emulsions can be as high as 97% (v/v).
Co-reporter:Keru Zhao, Taihong Liu, Gang Wang, Xingmao Chang, Dong Xue, Kevin D. Belfield, and Yu Fang
The Journal of Physical Chemistry B 2013 Volume 117(Issue 18) pp:5659-5667
Publication Date(Web):April 12, 2013
DOI:10.1021/jp312318b
A butterfly-shaped pyrene derivative of cholesterol, namely, N,N′-(ethane-1,2-diyl)-bis(N-(2-(chol-amino)ethyl)pyrene-1-sulfonamide) (ECPS), has been designed and synthesized. Solvent effect studies revealed that in good solvents such as n-hexane, benzene, and 1,4-dioxane, the profile of the fluorescence emission of the compound is characterized by pyrene monomer emission, but in poor solvent such as water, the emission is dominated by pyrene excimer emission. Quantitatively speaking, the ratio of the excimer emission to monomer emission changes from 50 to 0 when ECPS is dissolved in water and n-hexane, respectively. In contrast, for a commonly used polarity probe pyrene, the ratio of I3/I1 varies only from ∼0.6 to ∼1.7, where I3 and I1 stand for the intensities of the fluorescence emission at peak 3 and peak 1, respectively. This value suggests that a more powerful discriminating ability of the new compound in polarity sensing. Furthermore, unlike the main components of the compound, pyrene and cholesterol, its main chain is composed of multiple hydrophilic structures, and it is this structure that makes the emission of the compound in organic solvents sensitive to the presence of water. Accordingly, the applicability of the compound in determination of the trace amount of water in some organic solvents was evaluated. As expected, the detection limit of the compound toward water in acetonitrile reaches 7 ppm, a result never reached before. Furthermore, the fluorescence emission of the compound is also sensitive to viscosity variation. Therefore, it is assumed that ECPS may be used both as a polarity probe and a viscosity probe. On the bases of a series of steady-state and time-resolved fluorescence, as well as dynamic light scattering studies, a structural model was proposed to rationalize the fluorescence behavior of the compound in different solvents and its polarity and viscosity probing performances.
Co-reporter:Hongyue Wang;Hong Cui;Xinglei Liu;Lanlan Li;Yuan Cao;Dr. Taihong Liu ;Dr. Yu Fang
Chemistry – An Asian Journal 2013 Volume 8( Issue 1) pp:101-107
Publication Date(Web):
DOI:10.1002/asia.201200561
Abstract
A novel fluorescently active co-oligomer (P1) was designed and prepared by alternative co-polymerization of oligo(p-phenyleneethynylene) (OPE), possessing two cholesterol-containing side chains, and ethanediamine. A control co-oligomer (P2) possessing similar structure to P1 was also prepared, but in this case the OPE bears no side chains. P1 and P2 have been used for the fabrication of two fluorescent films, film 1 and film 2, respectively. Fluorescence studies demonstrated that the emission of film 1 is sensitive and selective to the presence of trace amounts of HCl in air. In contrast, film 2 shows no such response. The quenching has been attributed to the protonation of the imino groups within the oligomer chains, and the difference in the sensing behaviors of the two films was rationalized by supposing the existence of molecular channels in film 1. The proposed mechanism is supported by the results from additional experiments and theoretical calculations. Furthermore, the film as fabricated is robust, and thereby it is believed that film 1 has the potential to be developed into a new generation of sensitive and selective HCl sensor.
Co-reporter:Liping Ding, Yuan Liu, Yuan Cao, Lingling Wang, Yunhong Xin and Yu Fang
Journal of Materials Chemistry A 2012 vol. 22(Issue 23) pp:11574-11582
Publication Date(Web):03 Apr 2012
DOI:10.1039/C2JM30697B
A fluorescent self-assembled monolayer film sensor with discriminatory power was specially designed and prepared by using pyrene as a reporting unit and a oligo(oxyethylene) unit as a hydrophilic spacer. The chemical attachment of pyrene moieties on the surface was verified by contact angle, XPS, UV-vis and fluorescence measurements. The fluorescence responses of the present film to nitroaromatic compounds (NACs) including picric acid, 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and nitrobenzene were measured. Significantly, the present film exhibits cross-reactive responses to different NACs, and the array of fluorescence variation at four specific wavelengths (peaks for pyrene's monomer emission and excimer emission) provides a distinct recognition pattern for each NAC. The results from principle component analysis reveal that the present film has discriminatory power to identify structurally similar NACs. Moreover, the present film exhibits a high sensitivity, selectivity and reversibility towards NACs, and provides great potential in instrumentation and miniaturization. The use of multiple signals of a single film sensor based on fluorophore's different aggregation states (e.g., pyrene's monomer, distorted excimer, and perfect excimer in the present work) instead of an array of sensor elements provides a novel strategy for developing discriminatory materials and remarkably simplifies the process of identifying similar chemicals.
Co-reporter:Hongyue Wang, Gang He, Xiangli Chen, Taihong Liu, Liping Ding and Yu Fang
Journal of Materials Chemistry A 2012 vol. 22(Issue 15) pp:7529-7536
Publication Date(Web):
DOI:10.1039/C2JM16637B
Co-reporter:Taihong Liu, Liping Ding, Keru Zhao, Wenliang Wang and Yu Fang
Journal of Materials Chemistry A 2012 vol. 22(Issue 3) pp:1069-1077
Publication Date(Web):15 Nov 2011
DOI:10.1039/C1JM14022A
A terthiophene (3T) derivative of 5-(1-pyrenyl)-2,2′:5′,2′′-terthiophene (Py-3T) was synthesized and chemically immobilized onto a glass wafer surface via a flexible spacer by employing a single-layer chemistry technique. Unlike the film fabricated in the same way but with 3T as the fluorophore, the film fabricated in the present study possesses unprecedented photochemical stability at ambient conditions. Fluorescence studies revealed that the emission of the film as fabricated is significantly and selectively quenched by the presence of nitroaromatic compounds (NACs), a group of typical explosives, both in the vapor phase and in aqueous solution. Experimental and theoretical studies demonstrated that the quenching may be a result of electron transfer from the electron-rich Py-3T to the electron-deficient NACs. It was found that for vapor phase sensing, the response time and the quenching efficiency of the systems are dominantly determined by the vapor pressures of the NACs tested. The sensing performances of the film to NACs in aqueous phase were also investigated. In this case, however, the specific binding of the film to picric acid (PA), a typical NAC, makes the compound show a superior quenching efficiency than other NACs. Moreover, the response is fast and reaches equilibrium within 90 s. Furthermore, acids, bases, apple juice, perfume, and commonly found organic solventsetc. show little effect upon the sensing in aqueous phase. Both the vapor phase sensing and the aqueous solution sensing are reversible. Furthermore, the film is stable for at least 6 months provided it is properly preserved. The basic contribution of the present work is not only creating a new fluorescent film of superior sensing properties to NACs in the vapor phase, in particular to PA in the aqueous phase, but also providing a new photochemically stable fluorophore, which may combine the advantages of small molecular fluorophores and those of conjugated polymers/oligomers, for developing new fluorescent sensing films.
Co-reporter:Hong Cui, Gang He, Hongyue Wang, Xiaohuan Sun, Taihong Liu, Liping Ding, and Yu Fang
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 12) pp:6935
Publication Date(Web):November 14, 2012
DOI:10.1021/am302069p
A self-assembled monolayer (SAM)-based fluorescent film was designed and prepared by chemical immobilization of a novel oligo(p-phenylene- ethynylene) (OPE) with cholic acid moieties at the ends of its side chains (Film 1). As a control, a similar film, Film 2, of which OPE brings no side chains, was also prepared. The structures of the films were characterized by contact angle, XPS, ATR-IR and fluorescence measurements. Fluorescence studies revealed that the emission of Film 1 is sensitive to the presence of trace amount of some inorganic acids in acetone, such as HCl, H2SO4, HNO3, and H3PO4, etc., whereas the acids as studied showed little effect on the emission of Film 2. The difference in the sensing performances of the two films have been rationalized by considering presence or absence of a possible cavity, a substructure appearing above the OPE adlayer which is something like a dimer of cholic acid (CholA) formed at specific environment.Keywords: cholic acid (CholA); fluorescence films; oligo(p-phenyleneethynylene) (OPE); organic medium; pH determination; self-assembled monolayer (SAM);
Co-reporter:Yunhong Xin, Qi Wang, Taihong Liu, Lingling Wang, Jia Li and Yu Fang
Lab on a Chip 2012 vol. 12(Issue 22) pp:4821-4828
Publication Date(Web):04 Sep 2012
DOI:10.1039/C2LC40804J
A multichannel fluorescence detector used to detect nitroaromatic explosives in aqueous phase has been developed, which is composed of a five-channel sample-sensor unit, a measurement and control unit, a microcontroller, and a communication unit. The characteristics of the detector as developed are mainly embedded in the sensor unit, and each sensor consists of a fluorescent sensing film, a light emitting diode (LED), a multi-pixel photon counter (MPPC), and an optical module with special bandpass optical filters. Due to the high sensitivity of the sensing film, the small size and low cost of LED and MPPC, the developed detector not only has a better detecting performance and small size, but also has a very low cost – it is an alternative to the device made with an expensive high power lamp and photomultiplier tube. The wavelengths of the five sensors covered extend from the upper UV through the visible spectrum, 370–640 nm, and thereby it possesses the potential to detect a variety of explosives and other hazardous materials in aqueous phase. An additional function of the detector is its ability to function via a wireless network, by which the data recorded by the detector can be sent to the host computer, and at the same time the instructions can be sent to the detector from the host computer. By means of the powerful computing ability of the host computer, and utilizing the classical principal component analysis (PCA) algorithm, effective classification of the analytes is achieved. Furthermore, the detector has been tested and evaluated using NB, PA, TNT and DNT as the analytes, and toluene, benzene, methanol and ethanol as interferent compounds (concentration various from 10 and 60 μM). It has been shown that the detector can detect the four nitroaromatics with high sensitivity and selectivity.
Co-reporter:Junlin Yan, Jing Liu, Ping Jing, Chengkun Xu, Jiamin Wu, Di Gao and Yu Fang
Soft Matter 2012 vol. 8(Issue 46) pp:11697-11703
Publication Date(Web):27 Sep 2012
DOI:10.1039/C2SM26332G
Ionic liquids are solvents of future. One of the promising methods to boost their uses is to solidify them in a physical way but with little interruption of their properties. It is therefore of interest to create gels of ionic liquids by using low-molecular mass compounds as gelators (LMMGs). Herein, we report a number of ionic liquid gels (ionogels) of which specially designed and synthesized cholesteryl derivatives were employed as gelators. The ionogels as obtained are thermo-reversible. In particular, the one with 1-butyl-3-methylimidazolium tetrafluoroborate (IL2) as solvent and a cholesteryl derivative containing a D-phenylalanine residue (1D) as a gelator is very stable both in neutral and acidic mediums as demonstrated by a yield stress of 76 Pa for a self-standing cylinder of the ionogel. Furthermore, the ionogel can be easily converted into a hydrogel via simple replacement of the solvent with water in situ. More interestingly, the conversion is reversible, a phenomenon never reported before. At the same time, the critical gelation concentration (CGC) of 1D for IL2 is only 0.06%, w/w, which is almost the lowest value reported for ionogels till now, and falls into the category of “super-gelator”. Magnetization of the ionogel has been realized by introduction of micro-/nano-Fe3O4 particles. As expected, the magnetic gel as obtained is responding to external magnetic field. Specifically, it changes into fluid with the presence of a magnetic field exceeding certain strength, and retains to gel upon removing the magnetic field and with a treatment of sonication and heating–cooling cycle. SEM and TEM observations revealed the continuous fibrous network structures of the molecules of the gelator in the ionogels. To the best of our knowledge, this is the first report on ionogels possessing stimulus-responsive properties, good mechanical strength, and super-gelation talent.
Co-reporter:Xiuqin Cai, Kaiqiang Liu, Junlin Yan, Helan Zhang, Xiaoyu Hou, Zhang Liu and Yu Fang
Soft Matter 2012 vol. 8(Issue 14) pp:3756-3761
Publication Date(Web):15 Feb 2012
DOI:10.1039/C2SM07251C
A novel calix[4]arene-based dimeric-cholesteryl derivative was synthesized, and its gelation behaviour in thirty organic solvents was investigated. It has been shown that the compound cannot gel any of the pure solvents tested. However, it gels a mixture of solvents n-decane and acetonitrile efficiently, provided the volume ratio of the two solvents in a mixture is within 9:1 and 3:2. AFM and SEM measurements revealed that the molecules of the compound aggregate into micro-/nano-rods first, then fine fibers, and then thick fibers, and finally networked structures in the mixture solvents. Interestingly, the gel with a composition of 1 to 1 (Vn-Decane:VAcetonitrile) and 2.5% (w/v) of the compound exhibits super-smart and fully reversible thixotropic properties, a phenomenon never reported before. Furthermore, the mechanical strength of the gel could be easily adjusted by altering the concentration of the gelator and the composition of the mixture solvents. Further interrogation of the gel revealed that structurally the gel is a gel-emulsion with acetonitrile dispersed in n-decane, a rarely found O/O (oil in oil) gel-emulsion which may find uses in the templated preparation of low-density materials with complicated internal structures.
Co-reporter:Haonan Peng;Dr. Liping Ding;Taihong Liu;Xiangli Chen;Lan Li;Dr. Shiwei Yin ;Dr. Yu Fang
Chemistry – An Asian Journal 2012 Volume 7( Issue 7) pp:1576-1582
Publication Date(Web):
DOI:10.1002/asia.201100958
Abstract
A stable, ultrasensitive, and fully reversible fluorescent sensing film for organic amines has been fabricated by assembling cholesterol (Chol)-derived perylene bisimide on a glass plate surface. The compound exhibits excellent film formation properties and forms well-defined nanofibers, as evidenced by SEM and AFM measurements. It has been revealed that besides the molecular structure of the specially designed perylene derivative, the existence of nanofibers in the film is another key factor to endow the film with superior sensing ability for organic amines, including aniline. The detection limit of the amine is ca. 150.0 ppt in the vapor phase and at room temperature. Furthermore, the sensing process is free of interference from common organic solvents, nitroaromatics, and particularly phenols, which makes the film a potential candidate to be used in lung cancer diagnoses and related applications.
Co-reporter:Lei Zhang, Lining Gao, Qiaojun Liu, Feipeng Yang, Yu Fang
Journal of Photochemistry and Photobiology A: Chemistry 2012 Volume 245() pp:58-65
Publication Date(Web):1 October 2012
DOI:10.1016/j.jphotochem.2012.07.001
A novel surfactant-like non-ionic fluorophore, 3-(bis(2-hydroxyethyl)amino)-N-(4-(pyrene-1-sulfonamido)butyl) propanamide (PSDA-DEA), was designed and prepared. Fluorescence and surface tension studies revealed that the fluorophore aggregates in aqueous medium, and its critical aggregation concentration (CAC) is ∼3.3 × 10−5 M. Cryogenic transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS) and atomic force microscopy (AFM) measurements demonstrated that the diameter of the aggregates as formed is of a few hundred nano-meters. It was also shown that the profile of the emission spectrum of the compound is well dependent upon the polarity of its medium, as indicated by a change up to 53% of its intensity ratio at 399 nm and 380 nm (I399/I380) when the solvent changed from water to ethanol. It is of the polarity sensitive property that the fluorophore can be used for monitoring micelle formation of several anionic, cationic and non-ionic surfactants. Furthermore, PSDA-DEA is also a valuable probe for sensing transition of different aggregates such as micelles to vesicles. Comparative studies demonstrated that the present probe is more versatile than pyrene when it is used as a fluorescence probe.Graphical abstractThe applications of a newly synthesized surfactant-like fluorophore in the transition of the aggregates of amphiphilic compounds, especially between micelles and vesicles, were investigated systematically by using the compound as a probe.Highlights► Prepared a novel surfactant-like non-ionic fluorophore. ► Studied the aggregation behavior of the fluorophore in aqueous phase. ► Monitored the transition between different surfactant aggregates. ► The compound is more powerful fluorescent probe than known probes.
Co-reporter:Xiangli Chen, Kaiqiang Liu, Panli He, Helan Zhang, and Yu Fang
Langmuir 2012 Volume 28(Issue 25) pp:9275-9281
Publication Date(Web):May 31, 2012
DOI:10.1021/la300856h
A series of novel and stable water in oil (W/O) gel-emulsions was created by utilizing a new cholesteryl derivative, a low-molecular mass gelator (LMMGs), as a stabilizer. In the emulsions, n-heptane, n-octane, n-nonane, n-decane, tertiary butyl methacrylate (t-BMA), methyl methacrylate (MMA), or styrene can be used as a continuous phase, water as a dispersed phase, and the stabilizer in the continuous phase is only 2% (w/v). Importantly, the gel-emulsions could be prepared by simple agitation of the mixtures at room temperature, while heating, cooling, and addition of a cosolvent or other additional component are unnecessary. SEM and optical microscopy studies revealed the foam-like structures of the gel-emulsions. Rheological measurements demonstrated that the gel-emulsions are mechanically stable and exhibit typical viscoelastic properties. Surprisingly, the storage modulus, G′, and the yield stress of the gel-emulsions with the alkanes as continuous phase decrease along with increasing the volume ratio of the dispersed phase, water, a property different from those of conventional gel-emulsions reported in the literature. From the viewpoint of application, the gel-emulsions as prepared are superior to others due to their simplicity in preparation, less amount of stabilizer needed, and the nonionic nature of the stabilizer, which must benefit practical applications. Furthermore, porous polymer monoliths could be prepared by polymerizing gel-emulsions with organic monomers as a continuous phase.
Co-reporter:Shujuan Zhang, Liping Ding, Fengting Lü, Taihong Liu, Yu Fang
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2012 Volume 97() pp:31-37
Publication Date(Web):November 2012
DOI:10.1016/j.saa.2012.04.041
The detection of nitroaromatics in aqueous solutions by a novel pyrene-functionalized film has been investigated in the present study. The pyrene moieties were attached on the glass surface via a long flexible spacer based on self-assembled monolayer technique. Steady-state fluorescence measurements revealed that these surface-attached pyrene moieties exhibited both monomer and excimer emission. Nitroaromatics such as 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and 2,4,6-trinitrophenol (picric acid) were found to efficiently quench the fluorescence emission of this film. The quenching results demonstrated that the excimer emission of these surface-confined pyrene moieties is more sensitive to the presence of nitroaromatics than the monomer emission. The quenching mechanism was examined through fluorescence lifetime measurement and it revealed that the quenching is static in nature and may be caused by electron transfer from the polycyclic aromatics to the nitroaromatics. Furthermore, the response of the film to nitroaromatics is fast and reversible, and the obtained film shows promising potentials in detecting explosives in aqueous environment.Graphical abstractHighlights► A pyrene-functionalized film sensor with high stability was prepared via self-assembled monolayer (SAM) technique. ► Nitroaromatics such as picric acid, TNT, and DNT can dramatically quench the fluorescence of pyrene-functionalized SAM film. ► Pyrene-functionalized SAM film can be used as sensitive and reversible sensors to nitroaromatics in aqueous solution.
Co-reporter:Ni Yan;HeLan Zhang;ZhiYan Xu
Science Bulletin 2012 Volume 57( Issue 33) pp:4310-4321
Publication Date(Web):2012 November
DOI:10.1007/s11434-012-5449-8
To investigate the effect of spatial configuration on the gelation properties of low molecular mass gelators (LMMGs), four novel di-cholesteryl derivatives have been specially designed and synthesized by introducing the cis-/trans-isomers of butene diacid and the optical isomers of D/L-phenylalanine into the linker between two cholesteryl moieties. These isomers have been denoted as MaDC, FaDC, MaLC and FaLC, respectively. The gelation properties of the compounds were examined in 26 organic solvents, and it was found that the trans-configuration is more favorable for the gelation, but the chirality of the linker shows little effect to the gelation. FaDC has the strongest gelation ability among the four isomers. Interestingly, FaDC and FaLC display phase-selective gelation of benzene, toluene and xylene from their mixtures with water at room temperature, which establishes a foundation for the purification of water contaminated by oil or aromatic solvents. SEM and CD spectroscopy studies revealed that the spatial configuration of the linkers of the gelators affects significantly the aggregation mode, the morphologies and the chirality of the network of the gels. Moreover, the different aggregation behaviors also have an impact on mechanical properties of the gels, which are consistent with the results from rheological studies. Furthermore, temperature- and concentration-dependent 1H NMR and FTIR measurements demonstrated that intermolecular hydrogen bonding and π-π stacking are the main driving forces for the formation of the gels.
Co-reporter:Taihong Liu, Liping Ding, Gang He, Yang Yang, Wenliang Wang, and Yu Fang
ACS Applied Materials & Interfaces 2011 Volume 3(Issue 4) pp:1245
Publication Date(Web):March 30, 2011
DOI:10.1021/am2000592
To improve the photochemical stability of α-terthiophene (3T) in air, we purposely introduced a naphthalene unit into its conjugated backbone, resulting in a fluorescent compound, 5-(1-naphthyl)-2,2′:5′,2′′-terthiophene (NA-3T). The compound was further employed as a sensing element for the fabrication of a monolayer-chemistry based fluorescent sensing film. It was demonstrated that the fabricated film is highly sensitive and selective to the presence of picric acid (PA). The detection limit was found to be 3.2 × 10−7 mol/L. The high sensitivity of the film to PA has been attributed to the specific binding of the film to the analyte because of proton transfer from PA to the amino group in the spacer, which is in accordance with the static nature of the quenching as revealed by fluorescence lifetime measurements. Further experiments demonstrated that the sensing process is fully reversible and free of interference from common organic solvents, acids and bases, etc. In addition, the film is stable, at least, within half a year provided it is properly preserved. More importantly, the present work makes it possible to use oligothiophenes as a new class of sensing elements, which may combine the advantages of conjugated polymers or oligomers and those of fluorescent compounds of low-molecular masses. This effort enlarges, definitely, the applications of oligothiophenes and the space for creating monolayer-chemistry based fluorescent sensing films.Keywords: film sensor; fluorescence quenching; monolayer-chemistry; naphthyl-capped terthiophene; picric acid
Co-reporter:Gang He, Ni Yan, Hongyan Kong, Shiwei Yin, Liping Ding, Shixian Qu, and Yu Fang
Macromolecules 2011 Volume 44(Issue 4) pp:703-710
Publication Date(Web):January 20, 2011
DOI:10.1021/ma102769b
A fluorescence behavior controllable conjugated polymer (CP)-based fluorescent film was developed by chemical attaching poly(2,5-dihexadecyloxyphenyleneethynylene) (M-PPEs) onto a glass plate surface. It was revealed that the profile of the fluorescence emission spectrum of the film depended upon the polarity of its medium. This dependence has been attributed to the alteration of the conformation of the side chains of the polymer in immobilized state. In “poor” solvents or vapors, the side chains may adopt a compact coil conformation, resulting in aggregation of the immobilized polymers, and thereby fluorescence emission of the film is reduced because of the so-called aggregation-induced fluorescence quenching effect. Whereas in “good” solvents or vapors, the side chains tend to be swollen and adopt extended or loose coil structure, thereby preventing aggregation of the polymers, coupled with increasing of the fluorescence emission. Interestingly, this alteration process is fully reversible, and the retention time for each equilibration is less than 1 min. The film is also responsible for the changes in the compositions of mixture solvents, such as THF/methanol. In particular, two-input INH and OR logic gates were presented on the basis of the film. No doubt, this finding can be taken as a new strategy for the design of CPs and self-assembled monolayer (SAM)-based fluorescent sensing films and will definitely expand their applications.
Co-reporter:KaiQiang Liu;PanLi He
Science China Chemistry 2011 Volume 54( Issue 4) pp:575-586
Publication Date(Web):2011 April
DOI:10.1007/s11426-011-4250-x
This article is intended to provide an overview of recent progress in the studies of cholesterol-based low-molecular mass gelators (LMMGs) with unusual properties, in particular, gelation and selective gelation at room temperature, gel emulsions and gel film formation, etc. Potential applications of the LMMGs in spilled oil collection and water purification are briefly presented.
Co-reporter:Xiaoyu Hou, Di Gao, Junlin Yan, Ying Ma, Kaiqiang Liu, and Yu Fang
Langmuir 2011 Volume 27(Issue 19) pp:12156-12163
Publication Date(Web):August 25, 2011
DOI:10.1021/la2022819
Three novel LS2-type dimeric-cholesteryl derivatives (1–3), where S is a steroidal residue and L stands for a linker connecting the two S residues and contains three benzene rings and two amide and two carbamate groups, were designed and prepared. The compounds can gel a wide variety of organic solvents via three different ways, including mixing at room temperature, a heating–cooling cycle, and ultrasound treatment. SEM measurements revealed that the structures and the concentrations of the gelators, the nature of the solvent, and the preparation method employed have a great effect on the morphologies of the gel networks. It was revealed that 1 is a supergelator for DMSO (cgc = 0.04% w/v) and that the 1/DMSO gel can be prepared via any of the three methods mentioned above. Furthermore, the gel possesses excellent mechanical strength and a very smart thixotropic property. FT-IR and temperature- and concentration-dependent 1H NMR spectroscopy studies revealed that hydrogen bonding and π–π stacking among the molecules of 1 are two important driving forces for the physical gelation of DMSO. In addition, XRD analysis confirmed the layered packing structure of 1 in its DMSO gel.
Co-reporter:KaiQiang Liu;JunXia Peng;Min Xue;Ni Yan;Jing Liu
Science China Chemistry 2011 Volume 54( Issue 3) pp:475-482
Publication Date(Web):2011 March
DOI:10.1007/s11426-010-4208-4
Five new diacid amides of di-cholesteryl l-glycinates were designed and prepared. The compounds with linkers containing 0, 1, 2, 3, or 4 methylene units are denoted as 1, 2, 3, 4, and 5, respectively. Their gelation behaviors in 25 solvents were tested as novel low-molecular-mass organic gelators (LMOGs). It was shown that the length of the linker connecting the two-cholesteryl residues in a gelator plays a crucial role in the gelation behavior of the compound. 1 gels 11 of the 25 solvents tested at a concentration lower than 1.0%, while 2 gels 17 of the solvents tested. 4 and 5, however, gel only 2 and 4 of them, respectively. SEM observation reveals that the lengths of the linkers and the identity of the solvents are the main factors affecting the structures of the aggregates in the gels. Experimentally, a clear linker effect on the microstructures of the gels was observed. As example, the aggregates of 1, 2 and 3 in benzene or 1-heptanol adopt structures of thin fibers, rods or lamellas, respectively. Furthermore, it was found that the gelation and aggregation behaviors of 2, 3, 4, and 5 in DMSO showed an even-odd effect.
Co-reporter:Gang He, Ni Yan, Jiayu Yang, Hongyue Wang, Liping Ding, Shiwei Yin, and Yu Fang
Macromolecules 2011 Volume 44(Issue 12) pp:4759-4766
Publication Date(Web):May 31, 2011
DOI:10.1021/ma200953s
Two poly(pyrene-co-phenyleneethynylene)s of different compositions (PyPE-1 and PyPE-2) were synthesized and characterized. The two polymers had been casted, separately, onto glass plate surfaces to fabricate films (film 1, film 2) for sensing performance studies. It has been demonstrated that the fluorescence emissions of the two films are sensitive to the presence of 2,4,6-trinitrotoluene (TNT) in aqueous phase. Interestingly, TNT shows little effect upon the emission of the parent polymer, poly(phenyleneethynylene) (PPE). The difference was explained by considering (1) the π–π interaction between pyrene moieties contained in the copolymers and the analyte, TNT, molecules, and (2) more suitable matching of the LUMOs (lowest unoccupied molecular orbital) of the pyrene-containing conjugated polymers with that of TNT molecules. Further experiments demonstrated that the sensing is reversible and rarely encounters interference from commonly found compounds, including other nitroaromatics (NACs). Fluorescence lifetime measurements revealed that the quenching is static in nature. The smart performance of the films and the easiness of their preparation guarantee that the films may be developed into sensor devices for the supersensitive detection of TNT in groundwater or seawater.
Co-reporter:Gang He, Ni Yan, Hong Cui, Taihong Liu, Liping Ding, and Yu Fang
Macromolecules 2011 Volume 44(Issue 18) pp:7096-7099
Publication Date(Web):September 1, 2011
DOI:10.1021/ma201625u
Co-reporter:Haiying Du, Gang He, Taihong Liu, Liping Ding, Yu Fang
Journal of Photochemistry and Photobiology A: Chemistry 2011 Volume 217(2–3) pp:356-362
Publication Date(Web):25 January 2011
DOI:10.1016/j.jphotochem.2010.11.004
A fluorescent sensing film was fabricated by chemical assembling pyrene moieties on a glass plate surface via a spacer containing a benzene ring. The film was used for the detection of nitroaromatic compounds (NACs), particularly picric acid (PA), in aqueous phase. Introduction of benzene structure in the spacer favors π–π stacking between pyrene moieties on the end of each spacer, which encourages direct exposure of the fluorophore residues to aqueous phase, and thus the film is able to quickly monitor NACs. The advantages of this design have been demonstrated experimentally in terms of the highly sensitive response of the above-mentioned film to the presence of trace amounts of NACs in aqueous solution. The detection limit (DL) of the film to PA reaches 1.0 × 10−8 mol/L. Further experiments demonstrated that the sensing process is fully reversible and is free of interference from common chemicals like toluene, benzene, trichlormethane, ethanol, artificial seawater, NaOH, HCl, etc. Furthermore, fluorescence lifetime measurement revealed that the quenching is static in nature.
Co-reporter:Liping Ding and Yu Fang
Chemical Society Reviews 2010 vol. 39(Issue 11) pp:4258-4273
Publication Date(Web):28 Sep 2010
DOI:10.1039/C003028G
The development of fluorescent chemical sensors has been an active research topic for many research fields. Design strategies play an important role in the sensing performance of the desired sensors. The use of chemically assembled monolayers of fluorophores to fabricate film sensors has shown several advantages: highly stable, re-useable, non-consumptive, and easy to be made into devices, etc. The present tutorial review gives an overview of the fluorescent film sensors based on chemical monolayer assemblies of fluorophores that have been developed in our laboratory along with some representative publications of others over the past decade. Different sensing mechanisms were taken into account in the sensor designs, including hydrogen-bond formation, static complex with quenchers, and more interestingly, the “spacer layer screening effect”. Various neutral organic chemicals and anions were targeted by these film sensors with great selectivity and sensitivity. In particular, the specific “spacer layer screening effect” imparts these particular type of films with tuned selectivity, opening a novel direction in developing fluorescent film sensors.
Co-reporter:Di Gao, Min Xue, Junxia Peng, Jing Liu, Ni Yan, Panli He, Yu Fang
Tetrahedron 2010 66(16) pp: 2961-2968
Publication Date(Web):
DOI:10.1016/j.tet.2010.02.070
Co-reporter:Junlin Yan, Jing Liu, Yuanhui Sun, Ping Jing, Panli He, Di Gao, and Yu Fang
The Journal of Physical Chemistry B 2010 Volume 114(Issue 41) pp:13116-13120
Publication Date(Web):September 21, 2010
DOI:10.1021/jp1032838
With ever-increasing need for thin, flexible, and functional materials in electrochemical systems, various techniques have been explored for creating materials used in fuel cells, batteries, electrochromic devices, solar cells, and sensors. In the present study, a novel ferrocene (Fc) and cholesterol (Chol)-containing oligomer, oligo(FcDC-co-CholDEA), was specially designed and prepared by putting Fc in the main chain and Chol as a side group. MALDI-TOF MS and freezing point depression measurements revealed that in average each oligomer contains three Fc units and three Chol units. Cyclic voltammetric measurements revealed that the oligomer displays superior electrochemical stability if compared with other Fc derivatives containing only one Fc unit and one or two Chol unit and with poly(ferrocenylsilane) with Fc in the main chain. In particular, the Fc-containing oligomer possesses an unusual oxidation center, of which the oxidation potential could be as high as 1.81 V. The oligomer is also superior in self-assembly, as demonstrated by forming an LB film of layered structures. Furthermore, supramolecular films with high mechanical strength in the wet state can be prepared by employing a simple solution casting method. This finding demonstrates that self-assembly is a simple but effective way to create films of potential uses in real-life applications provided proper building blocks are designed and employed.
Co-reporter:Ni Yan, Gang He, Helan Zhang, Liping Ding and Yu Fang
Langmuir 2010 Volume 26(Issue 8) pp:5909-5917
Publication Date(Web):December 23, 2009
DOI:10.1021/la903853u
Five novel glucose-based naphthalene derivatives with linkers containing hydrazine, ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, and 1,6-hexanediamine, respectively (1, 2, 3, 4, and 5) were designed and prepared. The gelation test revealed the following points: (1) within the 30 solvents tested, 1 gels water only; (2) in contrast, 2 gels not only water, but also 11 of the organic solvents tested, a typical “ambidextrous gelator”; (3) 3, 4, and 5, however, gel organic solvents only, and the numbers of solvents gelled are 11, 11 and 13, respectively. Clearly, these compounds are effective low-molecular mass gelators, and show transitions from a low-molecular mass hydrogelator to an ambidextrous gelator and then to low-molecular mass organogelators with a slight increase in the length of the spacers. Interestingly, 5 is a super gelator to acetonitrile, of which the minimum gelation concentration is only 0.07%, w/v. The morphology, microstructure and molecular aggregation of the system strongly depend on the transition, as revealed by SEM, contact angle, energy dispersive X-ray spectroscopy, and XRD measurements. More interestingly, an aggregation-induced enhanced emission was observed along with gelation. Furthermore, the system appeared as a supramolecular chiroptical switch in the sol−gel process that is the chirality disappeared when the gel was heated to solution, whereas it reappeared when cooled to a gel.
Co-reporter:Gang He, Guofang Zhang, Fengting Lü and Yu Fang
Chemistry of Materials 2009 Volume 21(Issue 8) pp:1494
Publication Date(Web):March 24, 2009
DOI:10.1021/cm900013f
A fluorescent film sensor was prepared by chemical assembly of oligo(diphenylsilane)s on a glass plate surface and was used for the detection of nitroaromatic compounds (NACs) in vapor phase. This design combines the advantages of fluorescent films based on single-layer chemistry and the signal amplification effect of conjugated polymers and provides an effective way to create novel fluorescence sensing films for NACs explosives. The advantages have been demonstrated experimentally by the super sensitive response of the above-mentioned film to the presence of trace amounts of NACs in vapor phase. Further experiments showed that the sensing process is reversible, and the commonly encountered interfering substances have no interference to the process. Fluorescence lifetime measurements revealed that the quenching is static in nature. The super sensitive response, and the reversibility and interference free of the sensing process, make the film a promising NACs sensor.
Co-reporter:Gang He, Haonan Peng, Taihong Liu, Meini Yang, Yuan Zhang and Yu Fang
Journal of Materials Chemistry A 2009 vol. 19(Issue 39) pp:7347-7353
Publication Date(Web):27 Aug 2009
DOI:10.1039/B906946A
A novel fluorescent film was fabricated by doping the aggregates of hexaphenylsilole (HPS) into a chitosan film. It was demonstrated that the fluorescence emission of the film is stable, sensitive and highly selective to the presence of picric acid (PA). The detection limit for PA is about 2.1 × 10−8 mol/L. Introduction of 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), nitrobenzene (NB), phenol, benzene, toluene, methanol, ethanol, and zinc nitrate (Zn(NO3)2) had little effect upon the fluorescence emission of the film. The selectivity of the film was attributed to the specific electrostatic association effect of the protonated substrate film to picrate anion and the screening effect of the film to the interferents. The network structure of the substrate film is also favourable for the stabilization of the fluorescence emission of the hybrid film, by preventing the further aggregation of silole aggregates. Fluorescence lifetime measurements revealed that the quenching is static in nature. Furthermore, the quenching process is fully reversible. Considering the simplicity of the preparation and the outstanding performance of the hybrid film, it is anticipated that it could be developed into a real-life PA sensor.
Co-reporter:Song Sun;Xi Chen;Jing Liu;Junlin Yan
Polymer Engineering & Science 2009 Volume 49( Issue 1) pp:99-103
Publication Date(Web):
DOI:10.1002/pen.21225
Abstract
A two-component physical organogel was produced by interactions of 6-deoxy-6-amino-β-cyclodextrin (β-CDNH2) and poly(acrylic acid). The microstructure and morphology of the gels were characterized by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. It was revealed that the intermolecular hydrogen bonds between the molecules of β-CDNH2 and the electrostatic interaction between the carboxyl groups of PAA and amino group of β-CDNH2 were the main driving forces for the formation and maintenance of the network structures of the gel. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
Co-reporter:Min Xue, Di Gao, Kaiqiang Liu, Junxia Peng, Yu Fang
Tetrahedron 2009 65(17) pp: 3369-3377
Publication Date(Web):
DOI:10.1016/j.tet.2009.02.056
Co-reporter:Taihong Liu, Gang He, Meini Yang, Yu Fang
Journal of Photochemistry and Photobiology A: Chemistry 2009 Volume 202(2–3) pp:178-184
Publication Date(Web):25 February 2009
DOI:10.1016/j.jphotochem.2008.12.004
A novel oligothiophene, specifically 2,2′:5′,2″-terthiophene (3T), functionalized film was fabricated by monomolecular layer assembly of 3T onto an amine-terminated glass wafer surface. Contact angle, XPS and steady-state fluorescence measurements demonstrated that the fluorophore was successfully immobilized on the substrate surface. The fluorescence emission of the film, however, is not stable in air, and it decreased along with increasing scanning number. Continuous irradiation of the film with UV light (365 nm) decreased, but stabilized the fluorescence emission of the film. Exposure of the specially treated film into formaldehyde (HCHO) vapor generated a new fluorescence emission, which appeared in a shorter wavelength in comparison with that of the original one. The intensity of the emission increased along with increasing the exposure time. Furthermore, interference experiments revealed that the sensitization is selective, and solvents including common acids, base and alcohols have little effect upon the process. More interestingly, the process is reversible. Accordingly, it is believed that the 3T functionalized film should be a strong candidate for developing a novel and sensitive HCHO fluorescent film sensor.
Co-reporter:Fengting Lü, Yu Fang, G.J. Blanchard
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2009 Volume 74(Issue 4) pp:991-999
Publication Date(Web):November 2009
DOI:10.1016/j.saa.2009.09.010
We have constructed a novel molecular assembly attached to quartz, oxidized silicon and indium-doped tin oxide coated substrates, where a tethered pyrene derivative is co-immobilized with oligo-N-isopropyl acrylamide (oligo-NIPAM). The addition of tethered oligo-NIPAM to the adlayer creates two different, temperature-dependent microenvironments for the surface-bound pyrene. X-ray photoelectron spectroscopy (XPS) and ellipsometry measurements demonstrate the covalent attachment of both oligo-NIPAM and pyrene in our adlayers. Contact angle results confirm the thermo-responsive nature of the oligo-NIPAM on the substrate surface. Steady-state fluorescence data show that the presence of oligo-NIPAM moieties reduces the extent of pyrene excimer formation and provides different environments for the chromophore at temperatures above and below the phase transition. Fluorescence lifetime decay data on surface-bound pyrene are biexponential, consistent with multiple local environments, regardless of whether tethered oligo-NIPAM is present or not. Quenching studies reveal that we can manipulate the sensing properties of this new film simply by adjusting the conformations of oligo-NIPAM.
Co-reporter:Jing Liu;Panli He;Junlin Yan;Xiaohua Fang;Junxia Peng;Kaiqiang Liu
Advanced Materials 2008 Volume 20( Issue 13) pp:2508-2511
Publication Date(Web):
DOI:10.1002/adma.200703195
Co-reporter:Liping Ding, Monika Domińska, Yu Fang, G.J. Blanchard
Electrochimica Acta 2008 Volume 53(Issue 23) pp:6704-6713
Publication Date(Web):1 October 2008
DOI:10.1016/j.electacta.2007.12.010
We have synthesized a series of pyrene/cholesterol co-functionalized adlayers on quartz, oxidized silicon, indium-doped tin oxide and gold substrates. The pyrene derivative is N-1-pyrenesulfonyl-ethylenediamine (PSEDA) and the cholesterol derivative is cholesterol-ethylenediamine (Chol-NH2), which was bound covalently to substrates through epoxide functionalities. X-ray photoelectron spectroscopy shows covalent attachment of both moieties. Optical ellipsometry shows an increase of ca. 5 Å with pyrene/cholesterol co-attachment on oxidized silicon wafers, and an increase of ca. 12 Å when only pyrene was added. Steady-state fluorescence measurements indicate the presence of cholesterol reduces the efficiency of pyrene excimer formation and provides a less polar environment as sensed by the PSEDA I1/I3 band ratio. The amount of pyrene excimer formed depends on the reaction time for the adlayer co-deposition reaction. Cyclic voltammetry shows that covalently bound PSEDA is oxidized at ca. 540 mV and physisorbed PSEDA is oxidized at ca. 780 mV. AC voltammetry shows that Chol-NH2 in the adlayer reduces the electron transfer rate for the PSEDA redox reaction.
Co-reporter:Fengting Lü, Yu Fang and G. J. Blanchard
Langmuir 2008 Volume 24(Issue 16) pp:8752-8759
Publication Date(Web):July 8, 2008
DOI:10.1021/la801022h
We have fabricated a set of self-assembled monolayers consisting of naphthalene and dansyl derivatives in a range of surface loading ratios for the purpose of examining excitation transport in mixed self-assembled monolayer systems. Both tethered chromophores were immobilized on an epoxide-terminated adlayer on silica via an identical spacer, where the linking chemistry produced an amide linkage. X-ray photoelectron spectroscopy (XPS), ellipsometry, and contact angle measurements were used to characterize these chromophore-containing layers. The excitation transfer behavior of these monolayers has been examined using steady-state and time-resolved fluorescence spectroscopy. Steady-state fluorescence measurements show that excitation transfer from the naphthalene to dansyl chromophores occurs, with the efficiency of excitation transport scaling with chromophore surface loading densities, as expected. The donor lifetimes decrease with increasing acceptor loading density, and the functional form of the acceptor decay was independent of the donor/acceptor ratio. Our findings are not consistent with a homogeneous adlayer, but do provide information on the structural heterogeneity that is characteristic of these interfaces.
Co-reporter:Li HuiHui;Lü FengTing;Zhang ShuJuan;He Gang;Fang Yu
Science Bulletin 2008 Volume 53( Issue 11) pp:1644-1650
Publication Date(Web):2008 June
DOI:10.1007/s11434-008-0176-x
Pyrene was chemically assembled on a glass plate surface in a monolayer manner via spacers containing triethylenetetramine (TETA) subunits. It has been demonstrated that the fluorescence emission of the film is sensitive to the presence of trace amount of nitroaromatic compound (NAC) vapors. As discovered in the present work, the response selectivity of the pyrene-functionalized film depends on the length of the spacer, the vapor pressure of a given NAC, and the quencher size. The film shows faster response to those quenchers which have higher vapor pressure and smaller size. Compared to the film with shorter spacers, the present film with longer flexible spacers shows a slower response to the NACs, but higher selectivity to the quencher size. Additionally, the detection limits to common explosives in vapor phase, 2,4,6-trinitrotoluene (TNT) and 2,4-dinitrotoluene (DNT), are 7.14×10−12 and 5.49×10−11 g·mL−1, respectively. Further examinations indicated that the sensing process is fully reversible, and the vapors of those common interference such as benzene, toluene, ethanol, and perfume have little effect upon the sensing performances of the film.
Co-reporter:Jing Liu;Junlin Yan;Xi Chen
Colloid and Polymer Science 2007 Volume 285( Issue 8) pp:881-889
Publication Date(Web):2007 May
DOI:10.1007/s00396-006-1634-0
An acenaphthylene (ACE)-labeled, β-cyclodextrin (β-CD)-modified poly(acrylamide) (PAM), (P(AM-co-β-CD)/ACE), was prepared in the present study. The conformational behavior of the ACE-labeled polymer in aqueous solution was studied by employing various fluorescence techniques, including fluorescence anisotropy and fluorescence quenching with different quenchers. It was demonstrated that the copolymer is partially hydrolyzed even though the charge density of the copolymer might be low, and the intra- and intermolecular complexation occurs in the copolymer solution due to the host–guest interaction between β-CD and ACE appended on the polymer backbone. The supramolecular interaction also exists in solid state as confirmed by the studies of the solid samples, which were obtained by freeze–drying the solution samples, by using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. It is expected that this kind of copolymers may be used as building blocks for the construction of novel supramolecular structures and for the preparation of smart soft solid like stimuli-responsive hydrogels.
Co-reporter:Liping Ding, Jianping Kang, Fengting Lü, Lining Gao, Xiong Yin, Yu Fang
Thin Solid Films 2007 Volume 515(Issue 5) pp:3112-3119
Publication Date(Web):22 January 2007
DOI:10.1016/j.tsf.2006.05.035
A fluorescent film was prepared by chemically immobilizing 5-dimethylamino-1-naphthalenesulfonyl (dansyl) onto an epoxide-terminated self-assembled monolayer on glass. Steady-state fluorescence emission measurements demonstrated that the sensing molecules were homogenously and stably immobilized on the substrate surface. Fluorescence quenching results showed that the film is sensitive to the presence of nitrobenzene and has a great selectivity to it as compared with other commonly used quenchers like nitromethane, sodium nitrite, potassium iodide and acrylamide. An assumption that a less polar intermediate phase, which was composed of the long flexible spacers, the dansyl moieties and the solvent within the layer, was formed on the substrate surface was proposed to rationalize the different response of the film to those common quenchers. The explanation was supported by the results from fluorescence anisotropy studies and fluorescence quenching experiments performed in different solvents. Fluorescence lifetime studies showed that the quenching of nitrobenzene to the emission of the film is static in nature, which has been attributed to the formation of a charge transfer complex between the quencher and the fluorophore. Furthermore, the response of the film to nitrobenzene is fast and reversible, suggesting that the film might be used as a sensing film for the compound and its analogs.
Co-reporter:Huiyun Xia;Ying Zhang;Song Sun
Colloid and Polymer Science 2007 Volume 285( Issue 15) pp:1655-1663
Publication Date(Web):2007 December
DOI:10.1007/s00396-007-1737-2
Novel silver-poly(acrylamide-co-methacrylic acid) [Ag-P(AM-co-MAA)] composite microspheres, in tens of micrometer size range, with patterned surface and core/shell structures were prepared by chemical reduction of Ag2CrO4-P(AM-co-MAA) composite microspheres in ethanol. Characterization with various techniques revealed that the chemical composition of the “shell” is dominated by Ag, but the “core” is dominated by the template, P(AM-co-MAA). It was also demonstrated that the surface morphology of the Ag-polymer composite microspheres is similar to that of their precursors and can be controlled to a certain extent by varying the composition of template copolymer, approaches, and amount of Ag2CrO4 deposited. This morphology transfer technique is also applicable for other silver salts-polymer composite microspheres. The same silver-polymer composite microspheres with very different morphology have also been prepared by utilizing this technique, but the different precursor microspheres, Ag3PO4-P(AM-co-MAA), were used.
Co-reporter:Xi Chen;Jing Liu;Jun-Lin Yan
Chinese Journal of Chemistry 2006 Volume 24(Issue 12) pp:
Publication Date(Web):4 DEC 2006
DOI:10.1002/cjoc.200690316
A novel water soluble ditopic guest, the quaternary ammonium salt of N,N′-bis(ferrocenylmethylene)-diami- nobutane (1), and a known water soluble ditopic host, benzenetetracarboxylic dianhydride bridged bis(β-cyclo-dextrin)s (2), have been synthesized and characterized. 1H NMR spectra and cyclic voltammogram (CV) studies revealed the host-guest interactions between them in aqueous solution. The supramolecular interaction also exists in solid state as confirmed by the studies of the solid samples, which were obtained by frozen-drying the solution samples, using FTIR spectroscopy and differential scanning calorimetry (DSC) techniques. TEM measurement demonstrated that wire-shaped supramolecular aggregates exist in the aqueous solution of the two compounds. The lengths of the aggregates could reach micrometers.
Co-reporter:Junxia Peng, Ying Zhang, Huiyun Xia, Chaoliang Bai, Yu Fang
Acta Physico-Chimica Sinica 2006 Volume 22(Issue 4) pp:424-429
Publication Date(Web):April 2006
DOI:10.1016/S1872-1508(06)60014-4
AbstractN-isopropylacrylamide (NIPAM) and methacrylic acid (MAA) copolymer microspheres with various compositions were prepared by inverse suspension polymerization technique. The prepared microgels were employed as templates for the deposition of MS (M=Cu, Cd, or Zn). In this way, a number of MS (M=Cu, Cd, or Zn)-P(NIPAM-co-MAA) composite microspheres with different surface morphologies were prepared successfully. The effects of surfactants and the composition of the microgels upon the surface morphologies of the composite microspheres were studied in detail. It was demonstrated that the structures of the surfactants and the compositions of the microgels employed in the preparation have a great effect upon the surface morphologies of the composite microspheres. As for the model systems, the surface structures of the composite microspheres tend to be coarse with the structures of the surfactants becoming complex, or with their HLB values decreasing (Span-20, Span-80, and Span-85). Even so, the surface structures of the composite microspheres prepared in the presence of Span-85 are still highly ordered. It was also demonstrated that finer surface structures were formed with increasing the MAA content in the template microgels. Thus, it may be concluded that the surface structures of the composite microspheres can be tailored to certain extent by simply varying the types of surfactants, and changing the composition of monomer units in the template microgels.
Co-reporter:Shouxin Liu, Yu Fang, Gailing Gao, Mingzhu Liu, Daodao Hu
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2005 Volume 61(Issue 5) pp:887-892
Publication Date(Web):March 2005
DOI:10.1016/j.saa.2004.06.018
The complexation between poly(methacrylic acid) (PMAA) and poly(N, N-diethylacrylamide) (PDEAM) in aqueous phase was studied by UV–vis and fluorescence probe techniques. It was demonstrated that the complexation of PMAA with PDEAM occurs within a pH range of 1–6.5 and along with the complexation, the conformation of PMAA changed from a hypercoiled to a loose coiled form. The complex ratio between the two polymers is 1:1 (PMAA:PDEAM, in monomer unit). Salt effect studies showed that the complexation occurred due to formation of hydrogen bonds between the two polymers. Based upon these conclusions and the “compact micelle-like structure” for PMAA at low pH, a “ladder” model was proposed for the structure of PMAA–PDEAM complex formed at low pH.
Co-reporter:Fengting Lü, Yu Fang, Lining Gao, Liping Ding, Linling Jiang
Journal of Photochemistry and Photobiology A: Chemistry 2005 Volume 175(2–3) pp:207-213
Publication Date(Web):31 October 2005
DOI:10.1016/j.jphotochem.2005.05.004
Co-reporter:Liping Ding, Yu Fang, Linling Jiang, Lining Gao, Xiong Yin
Thin Solid Films 2005 Volume 478(1–2) pp:318-325
Publication Date(Web):1 May 2005
DOI:10.1016/j.tsf.2004.07.013
A new fluorescent chitosan film bearing dansyl as a fluorophore has been prepared. The film shows dual fluorescence phenomenon due to twisted intra-molecular charge transfer (TICT) in the excited state of the fluorophore. The position of the maximum emission of the film depends on the polarity of the medium, and it shifts from 460 nm in ethanol to 505 nm in water. The two emissions have been attributed to the emission from the “locally excited” state or non-charge transfer excited state of dansyl and that from the TICT excited state of the fluorophore, respectively. Existence of TICT phenomenon of the immobilized dansyl has been confirmed and studied by various fluorescence techniques, such as fluorescence lifetime measurement, steady-state and time-resolved fluorescence emission spectroscopy measurements, etc. The ratio, I505/I460, of the intensities of the two emission bands depends linearly on the concentration of water in ethanol–water mixture provided the concentration is less than 40%. Furthermore, the sensing property of the film to the mixture is reversible.
Co-reporter:Yu Fang, Chaoliang Bai and Ying Zhang
Chemical Communications 2004 (Issue 7) pp:804-805
Publication Date(Web):23 Feb 2004
DOI:10.1039/B314533F
CuS–poly(N-isopropylacrylamide), CuS–poly(N-isopropylacrylamide-co-methacrylic acid), Ag2S–poly(N-isopropylacrylamide) and Ag2S–poly(N-isopropylacrylamide-co-methacrylic acid) composite microspheres exhibiting complex surface morphologies were prepared by employing the minigel template method.
Co-reporter:Ying Zhang, Yu Fang, Shan Wang, Shuyu Lin
Journal of Colloid and Interface Science 2004 Volume 272(Issue 2) pp:321-325
Publication Date(Web):15 April 2004
DOI:10.1016/j.jcis.2004.01.053
Spherical poly(methacrylic acid)/PbS (PMAA/PbS) composites with a fishnet-like surface and core–shell structure were prepared by a microgel template method. The composites were prepared in two steps. Pb(Ac)2 was dissolved in MAA solution before it was polymerized into microgels in an inverse suspension system. In this way, Pb2+ was trapped within the microgel network. Then, H2S was introduced slowly into the system, and the metal ions were deposited within the microgels as PbS. The presence of PbS was confirmed by X-ray diffraction (XRD) and thermogravimetric measurements, and the morphology of the composites was characterized by scanning electron microscopy (SEM). It was found that the surface structure of the microparticles depends largely on the nature of the continuous phase of the system. The microparticles from xylene have a fishnet-like surface structure, and the inner structure and composition of the particles are different from the outer structure and composition. The surface of the particles from cyclohexane, however, appears smoother and denser than the surface of the particles from xylene. The different structure of the particle surfaces from the two systems has been attributed to the differences in template structure.
Co-reporter:Zhang Shu-Juan;Fang Yu;Hu Dao-Dao;Gao Gai-Ling
Chinese Journal of Chemistry 2003 Volume 21(Issue 3) pp:249-252
Publication Date(Web):26 AUG 2010
DOI:10.1002/cjoc.20030210308
Investigation of the fluorescence behavior of a pyrene functionalized chitosan film (PSC-CS) to some quenchers, including KI, CH3NO2 and Cu(NO3)2, has revealed that the monomer emission from the PSC-CS film increased rather than decreased, whereas the excimer emission decreased with the increase of time of duration after addition of KI or Cu(NO3)2. Both the increasing and decreasing processes could last as long as 20 min to 40 min. Unlike that observed in the system containing KI or Cu(NO3)2, for CH3NQ2 system, both the monomer emission and the excimer emission increased with introduction of the quencher, but the excimer emission only started to increase after an hour-long induction period. The position of the excimer emission of the PSC-CS film did not change very much with addition of KI or Cu(NO3)2. However, addition of CH3NO2 made the excimer emission blue shifted for at least 20 nm indicating formation of distorted excimers or partially overlapped excimers. The fluorescence response of the film to external additions is sensitive but is low in selectivity. This property may make the film use as a novel sensing material for monitoring the purity of water.
Co-reporter:Daodao Hu;Shouxin Liu;Gailing Gao;Jianbiao Ma
Journal of Applied Polymer Science 2001 Volume 82(Issue 3) pp:620-627
Publication Date(Web):10 AUG 2001
DOI:10.1002/app.1890
The complexation between poly(methacrylic acid) (PMAA) and poly(vinylpyrrolidone) (PVP) in aqueous phase was studied by various fluorescence techniques, including fluorescence anisotropy measurements, fluorescence probe studies, and nonradiation energy transfer. It was demonstrated that the complexation of PMAA with PVP occurs within a pH range of 1 to 5 and along with complexation, the conformation of PMAA changed from a hypercoiled to a loosely coiled form. The complex ratio between the two polymers is 2:1 (PMAA/PVP, in monomer unit). Salt effect studies showed that the complexation occurred due to formation of hydrogen bonds between the two polymers. Based on these conclusions and the “connected cluster model” for PMAA at low pH, a “ladder with connected cluster” model was proposed for the structure of PMAA/PVP complex formed at low pH. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 620–627, 2001
Co-reporter:Mingzhen Wang;Junchao Qiang;Yali Cui;Daodao Hu;Xiangu Fu
Journal of Polymer Science Part A: Polymer Chemistry 2000 Volume 38(Issue 3) pp:474-481
Publication Date(Web):21 JAN 2000
DOI:10.1002/(SICI)1099-0518(20000201)38:3<474::AID-POLA12>3.0.CO;2-B
Chitosan (CS), CS-poly(N-isopropylacrylamide)(PNIPAM) and their dyed (pyrene) hydrogels were prepared using glutaraldehyde (Glu) as a crosslinker. The gelation rate, swelling behaviors in ethanol/water mixtures, electricity-induced contraction and thermoresponse of the gels were investigated using fluorescence probe technique. Results showed that CS/Glu, and PNIPAM-containing CS/Glu gels exhibited similar properties in all aspects examined, except that the transparence of the CS-PNIPAM/Glu gel is very dependent upon the temperature. The CS-PNIPAM/Glu gel is transparent below 30°C, whereas opaque above 32°C. It is expected that this observation may be useful for the design and preparation of new kinds of hydrogel devices. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 474–481, 2000
Co-reporter:Yu Fang, Guanghui Ning, Daodao Hu, Jiuru Lu
Journal of Photochemistry and Photobiology A: Chemistry 2000 Volume 135(2–3) pp:141-145
Publication Date(Web):26 July 2000
DOI:10.1016/S1010-6030(00)00305-1
Pyrenesulfonylchloride (PSC) was prepared and convalently bound to glutaraldehyde (Glu) crosslinked chitosan (CS) films by a post modification method. The monomer emission of pyrene (Py) immobilized on the CS films was weak both at dry and wet state if super-pure water was used to wet the films. However, upon addition of salts or replacing the super-pure water with tap water the monomer emission increased dramatically whereas the change in the excimer emission was hardly observed. Furthermore, the increasing process could last as long as 7 h. In contrast, the emission returned to the original intensity at once when the films were washed with super-pure water three to four times. The process could be repeated for at least five times.
Co-reporter:Jing Hu, Meini Yang, Fengting Lü, Liping Ding, Shujuan Zhang, Yu Fang
Acta Physico-Chimica Sinica (December 2007) Volume 23(Issue 12) pp:1839-1845
Publication Date(Web):December 2007
DOI:10.1016/S1872-1508(07)60087-4
Co-reporter:Xuwei Fu, Pei Wang, Qing Miao, Kaiqiang Liu, Huijing Liu, Jianfei Liu and Yu Fang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 39) pp:NaN15223-15223
Publication Date(Web):2016/08/30
DOI:10.1039/C6TA05070K
Compressible porous monoliths are important for isolation and separation processes. However, preparation via a gel-emulsion method suffers from high cost, partially due to the consumption of too much stabilizer and less tunability in both mechanical properties and internal structures. To cope with the challenges, a polymerizable cholesteryl derivative (CEA) was designed and used as a stabilizer of gel-emulsions. In addition, a derivative of poly(oligo)-dimethylsiloxane with two olefinic bonds at its ends (D-PDMS) was also purposely prepared and employed as a cross-linker for the system. In this way, gel-emulsions with a mixture of toluene, n-heptane, CEA, and D-PDMS as the continuous phase and water as the dispersed phase were prepared. As expected, polymerization of the continuous phase resulted in porous polymeric monoliths. Interestingly, the internal structures of the materials could be largely adjusted via simple variation of the ratio of n-heptane to toluene in the continuous phase. Moreover, utilization of the specially synthesized cross-linker endows the monoliths with flexibility, which must bring convenience for real-life applications. Adsorption tests demonstrated that the porous materials were good adsorbents of formaldehyde (∼1300 mg g−1) and toluene (∼900 mg g−1) at ambient conditions, and they were reusable after simple washing and drying. Considering the simplest material in the preparation including ambient pressure drying without solvent exchange, the superior performance in the adsorption tests and the fact that the as-created CEA could function both as a monomer and a stabilizer, it is believed that the work presented here represents substantial progress of the techniques used for the preparation of porous polymeric materials. Moreover, the monolith demonstrates new records for the adsorption of toxic formaldehyde and toluene from contaminated air.
Co-reporter:Huijing Liu, Xiaojie Xu, Haonan Peng, Xingmao Chang, Xuwei Fu, Qianshu Li, Shiwei Yin, Gary J. Blanchard and Yu Fang
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 36) pp:NaN25220-25220
Publication Date(Web):2016/08/19
DOI:10.1039/C6CP04293G
A new fluorescent conjugate (PNBD) with a structure of D–π–A was designed and synthesized, where the donor (D), the acceptor (A) and the bridge (π) are naphthalyl, dicyanovinyl and phenylethynyl–phenylethynyl, respectively. To improve the solubility of the conjugate, two long alkyl chains were introduced as substituents of the central aromatic ring. Spectroscopic studies demonstrated that PNBD is a strongly solvatochromic probe which is characterized by a large molar absorption coefficient (>32000 cm−1 M−1), long wavelength absorption (>410 nm), large solvatochromic emission range (470–650 nm), high photochemical stability, and good solubility in common organic solvents. The fluorescent quantum yield of PNBD is limited in some polar solvents due to dual emission, a phenomenon ascribed to radiative decay from a higher excited singlet state. To eliminate dual emission, a covalently bound dimer (BPNBD) of PNBD characterized by weak vibronic coupling, was designed and synthesized. The dimer constituents are linked by a single bond between the naphthalyl moieties of the two PNBD monomers. As expected, BPNBD maintains almost all the strong points of the monomer, exhibits a substantial increase in fluorescence quantum yield, and eliminates dual emission by facilitating efficient internal conversion. Importantly, the use of PNBD and BPNBD in concert provides unprecedented discrimination among solvents of similar structures, such as (CH2Cl2, CHCl3, CCl4), (ethyl ether, THF, dioxane), or (methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-decanol), allowing rapid and selective visual identification.
Co-reporter:Somnath Mukherjee, Congdi Shang, Xiangli Chen, Xingmao Chang, Kaiqiang Liu, Chunmeng Yu and Yu Fang
Chemical Communications 2014 - vol. 50(Issue 90) pp:NaN13943-13943
Publication Date(Web):2014/09/04
DOI:10.1039/C4CC06024E
Two simple, eco-friendly and efficient phase-selective gelators were developed for instant (<45 s) gelation of oil (either commercial fuels or pure organic liquids) from an oil–water mixture at room temperature to combat marine oil spills.
Co-reporter:Chunmeng Yu, Yunlong Guo, Hongtao Liu, Ni Yan, Zhiyan Xu, Gui Yu, Yu Fang and Yunqi Liu
Chemical Communications 2013 - vol. 49(Issue 58) pp:NaN6494-6494
Publication Date(Web):2013/05/30
DOI:10.1039/C3CC42377H
Swift fabrication of a non-covalently modified reduced graphene oxide electronic sensor has been developed. An unparalleled detection limit is demonstrated for Hg2+, down to the picomolar range.
Co-reporter:Xiangli Chen, Lingling Liu, Kaiqiang Liu, Qing Miao, Yanchao Lü and Yu Fang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 2) pp:NaN684-684
Publication Date(Web):2015/12/09
DOI:10.1039/C5TA90256H
Correction for ‘Compressible porous hybrid monoliths: preparation via a low molecular mass gelators-based gel-emulsion approach and exceptional performances’ by Xiangli Chen et al., J. Mater. Chem. A, 2015, DOI: 10.1039/c5ta08342g.
Co-reporter:Xiangli Chen, Lingling Liu, Kaiqiang Liu, Qing Miao and Yu Fang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 26) pp:NaN10089-10089
Publication Date(Web):2014/04/04
DOI:10.1039/C4TA00137K
A series of water in oil (W/O) gel emulsions was prepared by using a low-molecular mass gelator (LMMG), a ferrocene derivative of cholesterol, as a stabilizer and tertiary butylmethacrylate (t-BMA) as the continuous phase. Via polymerization of the emulsions as created, a series of porous polymeric monoliths with different internal structures was prepared. SEM observation reveals that the internal structures of the monoliths could be largely adjusted via simple variation of the compositions of the gel emulsions. Importantly, introduction of hydrolysable silanes into the continuous phase of the gel emulsion before polymerization significantly alters the mechanical strengths of the porous materials, and remarkably promotes the sorption of the porous materials to some water-immiscible and -miscible liquids, such as benzene, kerosene, already-used transformer oil, ethanol, tetrahydrofuran, etc., of which kerosene is a representative of oils of lower viscosities and the transformer oil a representative of oils of higher viscosities. Furthermore, the oil absorbed by the monoliths could be recovered by centrifugation or squeezing, and the monoliths could be reused by washing them with alcohol or some other suitable volatile organic liquids. The sorption and desorption process could be repeated at least 13 times. More importantly, the LMMGs-based gel emulsion approach established in the present study for preparing porous polymeric or composite monoliths is facile, versatile and environmentally benign, showing a bright future for real-life uses.
Co-reporter:Taihong Liu, Liping Ding, Keru Zhao, Wenliang Wang and Yu Fang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 3) pp:NaN1077-1077
Publication Date(Web):2011/11/15
DOI:10.1039/C1JM14022A
A terthiophene (3T) derivative of 5-(1-pyrenyl)-2,2′:5′,2′′-terthiophene (Py-3T) was synthesized and chemically immobilized onto a glass wafer surface via a flexible spacer by employing a single-layer chemistry technique. Unlike the film fabricated in the same way but with 3T as the fluorophore, the film fabricated in the present study possesses unprecedented photochemical stability at ambient conditions. Fluorescence studies revealed that the emission of the film as fabricated is significantly and selectively quenched by the presence of nitroaromatic compounds (NACs), a group of typical explosives, both in the vapor phase and in aqueous solution. Experimental and theoretical studies demonstrated that the quenching may be a result of electron transfer from the electron-rich Py-3T to the electron-deficient NACs. It was found that for vapor phase sensing, the response time and the quenching efficiency of the systems are dominantly determined by the vapor pressures of the NACs tested. The sensing performances of the film to NACs in aqueous phase were also investigated. In this case, however, the specific binding of the film to picric acid (PA), a typical NAC, makes the compound show a superior quenching efficiency than other NACs. Moreover, the response is fast and reaches equilibrium within 90 s. Furthermore, acids, bases, apple juice, perfume, and commonly found organic solventsetc. show little effect upon the sensing in aqueous phase. Both the vapor phase sensing and the aqueous solution sensing are reversible. Furthermore, the film is stable for at least 6 months provided it is properly preserved. The basic contribution of the present work is not only creating a new fluorescent film of superior sensing properties to NACs in the vapor phase, in particular to PA in the aqueous phase, but also providing a new photochemically stable fluorophore, which may combine the advantages of small molecular fluorophores and those of conjugated polymers/oligomers, for developing new fluorescent sensing films.
Co-reporter:Hongyue Wang, Gang He, Xiangli Chen, Taihong Liu, Liping Ding and Yu Fang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 15) pp:
Publication Date(Web):
DOI:10.1039/C2JM16637B
Co-reporter:Gang Wang, Xingmao Chang, Junxia Peng, Kaiqiang Liu, Keru Zhao, Chunmeng Yu and Yu Fang
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 7) pp:NaN5449-5449
Publication Date(Web):2015/01/13
DOI:10.1039/C4CP04860A
A new fluorescent derivative of cholesterol, N,N′-(N-(2-(3β-cholest-5-en-3yl-formamido)ethyl) pyrene-1-sulfonamido)ethyl perylene-3,4:9,10-tetracarboxylic acid bisimide (CPPBI), was designed and synthesized. In the design, pyrene (Py) and perylene bisimide (PBI) were specially chosen as the energy donor and the acceptor, respectively. Fluorescence studies revealed that (1) CPPBI shows a strong tendency to form supra-molecular assemblies, (2) the assemblies possess a high efficiency of fluorescence resonance energy transfer (FRET) via intermolecular interactions, and (3) the profile and position of its fluorescence emission are highly dependent upon the nature of its medium, but the medium shows little effect on the efficiency of the energy transfer, suggesting that the chromophores including both Py and PBI units enjoy some rotational and/or translational mobility in the aggregated state of the compound. Temperature- and concentration-dependent 1H NMR spectroscopy studies revealed that both hydrogen-bonding and π–π stacking play a great role in stabilizing the assemblies of the compound, and confirmed the existence of π–π stacking between the Py moieties and between the PBI residues of the compound, of which the donor and the acceptor may have arranged in an appropriate orientation and at a suitable distance which are the key factors to determine the FRET efficiency. Moreover, the CPPBI-based film possesses unusual photochemical stability, and its emission is sensitive to the presence of some organic vapors, in particular aniline.
Co-reporter:Gang Wang, Weina Wang, Rong Miao, Congdi Shang, Meixia He, Haonan Peng, Gang He and Yu Fang
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 17) pp:NaN12230-12230
Publication Date(Web):2016/03/31
DOI:10.1039/C6CP01447J
A perylene bisimide (PBI) derivative (C-PBI-Py) of pyrene (Py) and cholesteryl residue (C) possessing intra-molecular energy transfer properties and three reference compounds (C-Py, C-PBI, PBI-Py) were designed and synthesized, where C was introduced in order to enhance the solubility of the relevant compounds in organic solvents. UV-vis absorption, steady-state fluorescence, cyclic voltammetric and theoretical calculation studies revealed that: (1) the PBI unit and Py moiety of C-PBI-Py could act as two individual chromophores, (2) the excited state energy of Py could transfer to PBI within a single molecule of the compound, and (3) the PBI moiety of the compound tends to form aggregates and shows PBI excimer emission. Time-resolved and temperature-dependent emission spectroscopy studies revealed the presence of both H-type excimer and J-type excimer, and formation of them via either the Birks' scheme or the pre-formed scheme due to strong π–π stacking that was elucidated by concentration-dependent 1H NMR spectroscopy measurement. In addition, the studies also indicated that the energy transfer occurs via an electron exchange mechanism (Dexter scheme). Results of this study will be useful in the development of new solvatochromic and other environment-sensitive fluorophores based on alteration of intra-molecular energy transfer efficiency.
Co-reporter:Gang He, Haonan Peng, Taihong Liu, Meini Yang, Yuan Zhang and Yu Fang
Journal of Materials Chemistry A 2009 - vol. 19(Issue 39) pp:NaN7353-7353
Publication Date(Web):2009/08/27
DOI:10.1039/B906946A
A novel fluorescent film was fabricated by doping the aggregates of hexaphenylsilole (HPS) into a chitosan film. It was demonstrated that the fluorescence emission of the film is stable, sensitive and highly selective to the presence of picric acid (PA). The detection limit for PA is about 2.1 × 10−8 mol/L. Introduction of 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), nitrobenzene (NB), phenol, benzene, toluene, methanol, ethanol, and zinc nitrate (Zn(NO3)2) had little effect upon the fluorescence emission of the film. The selectivity of the film was attributed to the specific electrostatic association effect of the protonated substrate film to picrate anion and the screening effect of the film to the interferents. The network structure of the substrate film is also favourable for the stabilization of the fluorescence emission of the hybrid film, by preventing the further aggregation of silole aggregates. Fluorescence lifetime measurements revealed that the quenching is static in nature. Furthermore, the quenching process is fully reversible. Considering the simplicity of the preparation and the outstanding performance of the hybrid film, it is anticipated that it could be developed into a real-life PA sensor.
Co-reporter:Ping Jing, Xiaohua Fang, Junlin Yan, Jie Guo and Yu Fang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 35) pp:NaN10141-10141
Publication Date(Web):2013/06/21
DOI:10.1039/C3TA11761H
Ultra-low density porous polystyrene monoliths have been prepared via using water/styrene gel-emulsions, which were stabilized by a low-molecular mass gelator (LMMG), as templates. It was demonstrated that the porous materials as prepared possess a number of superior features such as highly adjustable internal structure and density, the lowest density could be lower than 0.01 g cm−3. Moreover, such materials can be used as excellent absorbents for many organic liquids including viscous oils like mineral oil and high-density oils such as dichloromethane. In particular, the absorption process is fast, selective and efficient when they are used in the purification of oil contaminated water. Importantly, the oils absorbed in the absorbent can be easily squeezed out, and furthermore the wet absorbent as obtained can be reused by suitable washing and natural drying. More importantly, the LMMG-based gel-emulsions employed as templates are simple in preparation, only mixing and agitation at ambient temperature are required. Moreover, further treatment of the wet porous materials as prepared from the templates is just washing and natural drying, which is completely different from those such as freeze-drying or supercritical drying widely adopted by others in the preparation of low density materials via routine approaches. It is believed that the LMMG-based gel-emulsion template method developed in the present work may have created a novel and facile way for preparing low density materials with ideal properties.
Co-reporter:Xiangli Chen, Lingling Liu, Kaiqiang Liu, Qing Miao, Yanchao Lü and Yu Fang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 48) pp:NaN24332-24332
Publication Date(Web):2015/11/04
DOI:10.1039/C5TA08342G
A cholesteryl derivative, BuDphe, which is a low molecular mass gelator (LMMG), was synthesized and used as a stabilizer for the creation of a number of water/oil gel-emulsions, of which the oil could be a mixture of butyl methacrylate (t-BMA) and p-divinylbenzene (DVB), a mixture of t-BMA, DVB and polydimethylsilane (PDMS), or that of t-BMA, DVB, PDMS and trimethoxymethylsilane (MTMS). Polymerization of these mixtures resulted in porous polymeric or hybrid monoliths, M-1, M-2, M-3, M-4 and M-5, respectively, of which the first is a pure poly-t-BMA monolith, the second to the fourth ones contain an increasing amount of PDMS, and the last is a hybrid of poly-t-BMA, PDMS and hydrolyzed MTMS. The hybrid monoliths, in particular M-5, as prepared possess not only hydrophobicity, porosity, and low-density, but also an unprecedented flexibility in the dry state with a maximum shape recovery corresponding to 100% of the original thickness after more than 70% compression strain. Moreover, silylanization also improves the thermo-stability of the porous materials. An absorption test demonstrated that M-5 is an excellent absorbent for a number of organic solvents and oils. The material after absorption can be re-generated and the liquids absorbed can be recovered by simple squeezing. Furthermore, the absorption-separation process with CH2Cl2 as an example solvent could be repeated at least 10 times with no significant reduction of its absorption capacity. Combination of the excellent flexibility, great absorptivity, easiness in preparation, and low-energy consumption in drying makes the hybrid monoliths, in particular M-5, possess the potential to find real-life applications.
Co-reporter:Liping Ding and Yu Fang
Chemical Society Reviews 2010 - vol. 39(Issue 11) pp:NaN4273-4273
Publication Date(Web):2010/09/28
DOI:10.1039/C003028G
The development of fluorescent chemical sensors has been an active research topic for many research fields. Design strategies play an important role in the sensing performance of the desired sensors. The use of chemically assembled monolayers of fluorophores to fabricate film sensors has shown several advantages: highly stable, re-useable, non-consumptive, and easy to be made into devices, etc. The present tutorial review gives an overview of the fluorescent film sensors based on chemical monolayer assemblies of fluorophores that have been developed in our laboratory along with some representative publications of others over the past decade. Different sensing mechanisms were taken into account in the sensor designs, including hydrogen-bond formation, static complex with quenchers, and more interestingly, the “spacer layer screening effect”. Various neutral organic chemicals and anions were targeted by these film sensors with great selectivity and sensitivity. In particular, the specific “spacer layer screening effect” imparts these particular type of films with tuned selectivity, opening a novel direction in developing fluorescent film sensors.
Co-reporter:Liping Ding, Yuan Liu, Yuan Cao, Lingling Wang, Yunhong Xin and Yu Fang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 23) pp:NaN11582-11582
Publication Date(Web):2012/04/03
DOI:10.1039/C2JM30697B
A fluorescent self-assembled monolayer film sensor with discriminatory power was specially designed and prepared by using pyrene as a reporting unit and a oligo(oxyethylene) unit as a hydrophilic spacer. The chemical attachment of pyrene moieties on the surface was verified by contact angle, XPS, UV-vis and fluorescence measurements. The fluorescence responses of the present film to nitroaromatic compounds (NACs) including picric acid, 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and nitrobenzene were measured. Significantly, the present film exhibits cross-reactive responses to different NACs, and the array of fluorescence variation at four specific wavelengths (peaks for pyrene's monomer emission and excimer emission) provides a distinct recognition pattern for each NAC. The results from principle component analysis reveal that the present film has discriminatory power to identify structurally similar NACs. Moreover, the present film exhibits a high sensitivity, selectivity and reversibility towards NACs, and provides great potential in instrumentation and miniaturization. The use of multiple signals of a single film sensor based on fluorophore's different aggregation states (e.g., pyrene's monomer, distorted excimer, and perfect excimer in the present work) instead of an array of sensor elements provides a novel strategy for developing discriminatory materials and remarkably simplifies the process of identifying similar chemicals.
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![Acetic acid, 2,2'-[[5,11,17,23-tetrakis(1,1-dimethylethyl)-26,28-dihydroxypentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecaene-25,27-diyl]bis(oxy)]bis-, 1,1'-diethyl ester](/data/chemimg/909300/97600-49-2.png)
![Acetic acid, 2,2'-[[5,11,17,23-tetrakis(1,1-dimethylethyl)-26,28-dihydroxypentacyclo[19.3.1.13,7.19,13.115,19]octacosa-1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecaene-25,27-diyl]bis(oxy)]bis-, 1,1'-diethyl ester](/data/chemimg/909300/97600-49-2_b.png)
