Co-reporter:Xiaoman Bi, Bin Liu, Lucas McDonald, and Yi Pang
The Journal of Physical Chemistry B May 18, 2017 Volume 121(Issue 19) pp:4981-4981
Publication Date(Web):April 6, 2017
DOI:10.1021/acs.jpcb.7b01885
Flavonoids have emerged to be an important molecular frame for chemical sensors, due to their capability to give dual emission and their compatibility to biological cells. Two flavonoid compounds with Me2N- and Et2N-substituents were examined by acquiring their fluorescence at different temperatures, in order to evaluate the impact of intramolecular charge transfer (ICT) on ESIPT. By freezing the sample solution in liquid N2, the study detected the “locally excited” state at λem ≈ 460 nm, in which both ICT and ESIPT processes were not present. As temperature was warmed up (to about −90 °C), ICT process became gradually allowed and emission was shifted to λem ≈ 510 nm, which was attributed to the normal form N* of flavonoid. Emission from tautomeric form T* (λem ≈ 575 nm) could only be observed at a higher temperature, when ESIPT became allowed. With the aid of a model compound (without R2N-substituent) and computational study, the study led to improved understanding on the photophysical properties of flavonoid materials in general.
Co-reporter:Dipendra Dahal;Lucas McDonald;Xiaoman Bi;Chathura Abeywickrama;Farai Gombedza;Michael Konopka;Sailaja Paruchuri
Chemical Communications 2017 vol. 53(Issue 26) pp:3697-3700
Publication Date(Web):2017/03/28
DOI:10.1039/C7CC00700K
An NIR-emitting probe (λem ∼ 700 nm) with a large Stokes shift (Δλ ≈ 234 nm) is synthesized by using excited-state intramolecular proton transfer (ESIPT). The phenolic proton, which controls ESIPT, acts as a switch to give strong fluorescence at pH ≈ 5. The probe can selectively show lysosome organelles, therefore leading to a lysosome probe without exhibiting “an alkalinizing effect”.
Co-reporter:Chathura S. Abeywickrama;Kaveesha J. Wijesinghe;Robert V. Stahelin
Chemical Communications 2017 vol. 53(Issue 43) pp:5886-5889
Publication Date(Web):2017/05/30
DOI:10.1039/C7CC03417B
A highly fluorescent red-emitting pyrene derivative was synthesized and found to exhibit a large Stokes shift (λem ≈ 610 nm, Δλ ∼ 130 nm, Δν ∼ 4597 cm−1). The probe molecule showed remarkable selectivity to stain the nucleus in both live and fixed cells, with higher sensitivity than commercial dye DRAQ5.
Co-reporter:Chathura S. Abeywickrama, Yi Pang
Tetrahedron Letters 2017 Volume 58, Issue 16(Issue 16) pp:
Publication Date(Web):19 April 2017
DOI:10.1016/j.tetlet.2017.03.030
•Impact of regiochemistry on fluorescence response.•Optical respond to fluoride anion.•Correlation of intramolecular hydrogen bonding with the fluoride binding.Development of fluorescent chemical sensors for fluoride is important due to increased use of fluoride in environment. A fused bis[2-(2′-hydroxyphenyl)benzoxazole] 5, which is capable of giving ESIPT emission, is found to be a useful fluorescent sensor for fluoride detection. Upon binding to fluoride, bis(HBO) 5 shows a large spectral shift in both fluorescence (from ∼490 nm to ∼440 nm) and absorption (from 353 nm to 392 nm). In comparison with the isomeric 4, bis(HBO) 5 dramatically improves the sensitivity in fluoride binding (by an order of magnitude), revealing a large impact of regiochemistry on the sensor performance. 1H NMR has been used to study the fluoride binding, and to correlate the intramolecular hydrogen bonding with the fluoride response. Sensitivity of 5 towards fluoride is as low as 10−5 M. Bis(HBO) 5 also showed excellent selectivity towards fluoride while being silent to other anions (Cl−, Br−, HS− and PO43−), thus making 5 a potentially useful probe.Meta-bis(HBO) increases the fluoride detection sensitivity by over 20-fold than the para-isomer, due to its strong intramolecular H-bonding.Download high-res image (192KB)Download full-size image
Co-reporter:Chathura S. Abeywickrama, Yi Pang
Tetrahedron Letters 2016 Volume 57(Issue 31) pp:3518-3522
Publication Date(Web):3 August 2016
DOI:10.1016/j.tetlet.2016.06.098
•Efficient ESIPT—nearly exclusively keto emission.•Impact of regiochemistry on luminescence (quantum yield and emission wavelength).•Optical response to Zn2+.A fused bis[2-(2′-hydroxyphenyl)benzoxazole] bis(HBO) 3 was synthesized via reaction of 4,6-dihydroxyisopthalic acid with 2-amnophenol in the presence polyphosphoric acid (PPA). In bis(HBO) 3, two benzoxazol-2-yl groups are connected via meta-phenylene, in comparison with para-phenylene in its isomer 5, in order to examine the effect of regiochemistry on optical properties. UV–vis and fluorescence spectra show that bis(HBO) 3 gave emission nearly exclusively from its keto tautomer, indicating more effective ‘excited-state intramolecular proton transfer (ESIPT)’ than mono HBO. Bis(HBO) 3 gave blue ESIPT fluorescence (λem ≈ 480 nm), while 5 gave orange-red emission at 597 nm, showing a large effect of regiochemistry on emission. The effect was further evaluated through binding with Zn2+ cation, with 3 showing spectral blue shift upon zinc binding while 5 did not. In addition, 3 revealed ability to detect different stages of zinc binding, giving different spectral response to (3)2–Zn (with 2:1 ligand-to-metal ratio) and 3–Zn species (with 1:1 ligand-to-metal ratio).
Co-reporter:Lucas McDonald, Junfeng Wang, Nick Alexander, Hui Li, Tianbo Liu, and Yi Pang
The Journal of Physical Chemistry B 2016 Volume 120(Issue 4) pp:766-772
Publication Date(Web):January 13, 2016
DOI:10.1021/acs.jpcb.5b10909
A nonfluorescent Schiff base compound (4) in an aprotic solvent (e.g., CH3CN) is found to give blue fluorescence turn-on (λem ≈ 475 nm) upon addition of H2O. By using a wide range of spectroscopic methods, including 1H NMR and dynamic light scattering, the fluorescence response is shown to be not originating from the molecular aggregation-induced emission (AIE). Spectroscopic studies at low temperatures further reveal a dynamic response of 4 to temperature, showing that the excited state intramolecular proton transfer (ESIPT) can be ON or OFF through interaction with protic solvent. In the binary solvent (with composition CH3CN/H2O = 3:1), the Schiff base gives ESIPT emission (λem ≈ 524 nm) only at extremely low temperature (below −80 °C), which is turned off when being warmed to −60 °C, attributing to the increasing photoinduced electron transfer (PET) effect. When the temperature is further raised to −20 °C, ESIPT emission is reactivated to give blue emission (λem ≈ 475 nm) that is observed at room temperature. The observed dynamic fluorescence response reveals that ESIPT could be a predominant mechanism in the fluorescence turn-on of Schiff base compounds, although both AIE and ESIPT mechanisms could operate. The assumption is further verified by examining the response of Schiff base to Al3+ cation.
Co-reporter:Xiaoman Bi and Yi Pang
The Journal of Physical Chemistry B 2016 Volume 120(Issue 13) pp:3311-3317
Publication Date(Web):March 10, 2016
DOI:10.1021/acs.jpcb.6b00515
Terpyridine (tpy) ligands are popular building blocks to bind metal ions. Several tpy ligands with different substituents were synthesized and examined for their binding with zinc cation. The study revealed a large substituent effect on the zinc binding-induced fluorescence quenching. With the aid of a liquid nitrogen Dewar, the tpy molecules were frozen to their ground-state conformation, preventing (or minimizing) molecular reorganization in the photoinduced excited state. This allowed us to detect the fluorescence spectra from the locally excited state (having a minimum of charge transfer interaction) and the temperature-dependent fluorescence. The fluorescence response to low temperature provided useful information about the intramolecular charge transfer (ICT) interaction between the donor and acceptor groups. Furthermore, a strong donor substituent (such as Me2N) played an essential role in observed fluorescence quenching. The study also provides a useful example to elucidate the ICT mechanism by using low-temperature fluorescence spectroscopy.
Co-reporter:Chen Zhao, Bin Liu, Xiaoman Bi, Danqing Liu, Chengjun Pan, Lei Wang, Yi Pang
Sensors and Actuators B: Chemical 2016 Volume 229() pp:131-137
Publication Date(Web):28 June 2016
DOI:10.1016/j.snb.2016.01.116
•A fluorescent bioprobe for copper detection based on flavonoid was firstly reported.•This bioprobe shows a good sensitivity and selectivity toward copper ions, and its copper complex achieves secondary sensing for pyrophosphate.•This bioprobe exhibits a great biocompatibility, enabling recognition of copper ions and pyrophosphate in living cells.Copper is a trace metal nutrient essential for most forms of life. The dysregulation of copper homeostasis is associated with various diseases, such as Menkes disease, Alzheimer's disease, Wilson disease, gastrointestinal disorders, and kidney damage. Therefore, detection of copper ions in biological system is of great significance for fundamental study in biology and medicine field. To address this critical need, we herein developed a novel flavonoid-based bioprobe 6-(bis(pyridin-2-ylmethyl)amino)-2-(4-(dimethylamino)phenyl)-3-methoxy-4H-chromen-4-one (DPA-FL) for copper detection. The DPA-FL showed highly fluorescent response towards copper ions with a high tolerance of other competitive metal ions. The fluorescence intensity at 510 nm are linearly proportional to the amount of Cu2+ from 0 to 10 μM with a detection limit lower than 100 nM (S/N rule). The intracellular recognition of copper ions was successfully achieved in HUVECs. Furthermore, the DPA-FL-Cu2+ complex could also be used for secondary sensing of pyrophosphate in living cells, thus providing a powerful imaging tool for tracking of copper ions and pyrophosphate in biological system.
Co-reporter:Bin Liu, Lucas McDonald, Qin Liu, Xiaoman Bi, Jie Zheng, Lei Wang, Yi Pang
Sensors and Actuators B: Chemical 2016 Volume 235() pp:309-315
Publication Date(Web):1 November 2016
DOI:10.1016/j.snb.2016.05.079
•A wash-free fluorescence imaging method based on the light-up flavonoid was first reported.•The solvatochromism, photostability, and the anti-interference properties of flavonoid bioprobe were carefully studied.•The wash-free imaging for living cells and zebrafish embryos were achieved.Wash-free imaging methods can simplify the experimental procedures and facilitate the continuous observation of the targets by eliminating washing process. In this work, we present a flavonoid-based light-up bioprobe with intramolecular charge transfer characteristics. The probe could be easily synthesized by the methylation of its flavone derivative, which was initially prepared via the Claisen-Schmidt condensation and Algar-Flynn-Oyamada reaction. The probe possessed a large Stokes shift, positive solvatochromism, high photostability, high tolerance for metal ions, and light-up fluorescence properties towards protein and tissue lysate. Moreover, the signal-to-noise ratio of fluorescence bioimaging in living cells and zebrafish by using this probe could reach 4–15 without washing process, providing a new candidate for efficient wash-free imaging method in vivo.The wash-free fluorescence imaging based on flavonoid dye FL309 for zebrafish embryos
Co-reporter:Bin Liu, Xiaoman Bi, Lucas McDonald, Yi Pang, Danqing Liu, Chengjun Pan, Lei Wang
Sensors and Actuators B: Chemical 2016 Volume 236() pp:668-674
Publication Date(Web):29 November 2016
DOI:10.1016/j.snb.2016.06.056
•The design of a series of novel amide-functionalized flavonoid probes for HSA.•The structure-property relationship between probes and HSA-sensing abilities.•A quantitive response range from 0 to 10 μM of HSA and a detection limit of 94 nM.•The high tolerance of environmental pH, anti-interference property, and time-insensitivity towards simulated HSA samples.Human serum albumin (HSA) as the most abundant protein in human blood plasma, serves many physiological functions. The dysregulation of HSA in serum or in urine is associated with various diseases, such as cirrhosis of liver, multiple myeloma, and cardiovascular disease. Therefore, to quantify HSA in body fluids with high selectivity and sensitivity is of great significance for disease diagnosis and preventive medicine. We herein developed a series of amide-functionalized flavonoids probes, 1–3, for recognition of human serum albumin. All flavonoids could be easily prepared by a Claisen-Schmidt condensation and Algar-Flynn-Oyamada reaction, and showed positive solvatochromism on their dual emissions. The chemical structure of flavonoids played an important role on their HSA-sensing abilities. Among three probes, the compound 1 showed the highest sensitivity, the remarkable selectivity, and the quantitive response for HSA in aqueous solution. Together with its high tolerance of environmental pH, anti-interference properties, and time-insensitivity, thus it provides a promising sensing method for HSA.
Co-reporter:Kanokthorn Boonkitpatarakul, Junfeng Wang, Nakorn Niamnont, Bin Liu, Lucas Mcdonald, Yi Pang, and Mongkol Sukwattanasinitt
ACS Sensors 2016 Volume 1(Issue 2) pp:144
Publication Date(Web):November 23, 2015
DOI:10.1021/acssensors.5b00136
A series of bishydrazide compounds have been developed for selective turn-on detection of Al3+ cation, based on metal chelation-enhanced fluorescence (CHEF) effects that inhibit the nonradiative PET and ESIPT processes. In aqueous solution, Al3+ selectively induces strong fluorescence of these compounds with large Stokes shifts up to ∼133 nm and emission colors varying from blue to orange. In the solid phase, both Al3+ and Zn2+ give apparent fluorescence which is simultaneously detected based on chromatographic separation.Keywords: aluminum ion; fluorescence sensor; hydrazide; paper chromatography; zinc ion
Co-reporter:Bin Liu, Yi Pang, Rachida Bouhenni, Ernest Duah, Sailaja Paruchuri and Lucas McDonald
Chemical Communications 2015 vol. 51(Issue 55) pp:11060-11063
Publication Date(Web):27 May 2015
DOI:10.1039/C5CC03516C
In this study, we report a series of novel flavone-based sensors that exhibit a superior fluorescence response when interacting with serum albumin in real serum samples and in acrylamide gels. The detection limit of probe 4 for serum albumin solution is 0.09 μg mL−1, and the detectable volume for monkey serum reaches as low as 0.03 μL.
Co-reporter:Benlei Wang, Xinfu Zhang, Chao Wang, Lingcheng Chen, Yi Xiao and Yi Pang
Analyst 2015 vol. 140(Issue 16) pp:5488-5494
Publication Date(Web):29 Jun 2015
DOI:10.1039/C5AN01063B
Polarization/depolarization levels of different single mitochondria in a cell are inhomogeneous, and always varying. Because depolarization is an indicator of mitochondrial dysfunction, tracing local depolarization is highly desirable. The existing fluorescent probes, however, are not well suited for this task, although they are applicable to assess the average polarization extents of whole cells. A multifunctional and bipolar probe MITFPS is thus developed, which includes a positively charged hydrophilic group and an environment sensitive fluorophore. In the probe design, the hydrophilic anchoring unit is chemically immobilized on a membrane protein, while the lipophilic fluorophore can be inserted deep into the phospholipid layer. The probe exhibits a sensitive response to the local variation in polarization by changing its fluorescence lifetime. MITFPS's applicability is confirmed by real-time in situ imaging of the complete process of an uncoupler-induced depolarization under a two-photon fluorescence lifetime microscope. The imaging result reveals that one mitochondrion could have quite different polarization than the other, even though they are in the same cell.
Co-reporter:Junfeng Wang, Weihua Chen, Xiumin Liu, Chrys Wesdemiotis and Yi Pang
Journal of Materials Chemistry A 2014 vol. 2(Issue 21) pp:3349-3354
Publication Date(Web):25 Apr 2014
DOI:10.1039/C4TB00020J
A mononuclear zinc complex has been found to exhibit unexpected selectivity for biologically important diphosphate anions (PPi and ADP). The diphosphate binding could turn-on excited state intramolecular proton transfer (ESIPT), whose study reveals mechanistic insight to aid the future design of new sensors.
Co-reporter:Junfeng Wang, Yingbo Li, Ernest Duah, Sailaja Paruchuri, Demin Zhou and Yi Pang
Journal of Materials Chemistry A 2014 vol. 2(Issue 14) pp:2008-2012
Publication Date(Web):28 Feb 2014
DOI:10.1039/C3TB21339K
A rational design has led to a highly selective and cell-permeable zinc sensor, which exhibits not only a large fluorescence turn-on at ∼545 nm but also the desirable NIR emission (∼720 nm) with a large Stokes' shift, providing a practical sensor platform with two emission channels for reliable zinc detection.
Co-reporter:Junfeng Wang, Xiumin Liu and Yi Pang
Journal of Materials Chemistry A 2014 vol. 2(Issue 38) pp:6634-6638
Publication Date(Web):07 Aug 2014
DOI:10.1039/C4TB01109K
A benzothiazole derivative 2 bearing two 2,2′-dipicolylamine (DPA) groups was examined for its zinc-binding and subsequent anion sensing properties. The study revealed the anion sensing mechanism of polyphosphate anions via sequential binding to two zinc centers, on the basis of both 1H NMR and mass spectral evidence. The mechanistic insight would provide valuable information for the future design of new excited state intramolecular proton transfer (ESIPT) sensors. In addition, the zinc complex exhibited solvent-switchable selectivity, responding to pyrophosphate (PPi) in EtOH and adenosine 5′-triphosphate (ATP) in water.
Co-reporter:Bin Liu, Junfeng Wang, Ge Zhang, Ruke Bai, and Yi Pang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 6) pp:4402
Publication Date(Web):February 27, 2014
DOI:10.1021/am500102s
We have designed and synthesized a novel ratiometric fluorescent chemodosimeter MHF-based ESIPT process for specific detection of cysteine among the biological thiols. The probe MHF shows very weak blue fluorescence under UV excitation. Upon addition of cysteine (Cys), the reaction of Cys with MHF induces acrylate hydrolysis, thereby enabling the ESIPT process to shift the weak blue emission to a strong green emission with about 20-fold enhancement. We utilized 1H NMR spectra to elucidate the fluorescence sensing mechanism. Moreover, the cellular imaging experiment indicated the MHF possessed excellent selectivity, low cytotoxicity, and desirable cell permeability for biological applications.Keywords: bioimaging; chemodosimeter; cysteine; fluorescence; ratiometric; selectivity;
Co-reporter:Bin Liu, Mickey Shah, Ge Zhang, Qin Liu, and Yi Pang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 23) pp:21638
Publication Date(Web):November 7, 2014
DOI:10.1021/am506698f
Mitochondria, vital organelles existing in almost all eukaryotic cells, play a crucial role in energy metabolism and apoptosis of aerobic organisms. In this work, we report two new flavone-based fluorescent probes, MC-Mito1 and MC-Mito2, for monitoring mitochondria in living cells. These two probes exhibit remarkably low toxicity, good cell permeability, and high specificity; these probes complement the existing library of mitochondrial imaging agents. The new dyes give nearly no background fluorescence, and their application does not require tedious postwashing after cell staining. The appreciable tolerance of MC-Mito2 encourages a broader range of biological applications for understanding the cell degeneration and apoptosis mechanism.Keywords: biocompatibility; flavone; fluorescence; imaging agents; mitochondria; wash-free
Co-reporter:Junfeng Wang, Yingbo Li, Nikul G. Patel, Ge Zhang, Demin Zhou and Yi Pang
Chemical Communications 2014 vol. 50(Issue 82) pp:12258-12261
Publication Date(Web):26 Aug 2014
DOI:10.1039/C4CC04731A
An ESIPT based fluorescent sensor 1 was developed, which could selectively detect and differentiate trivalent metal ions Cr3+, Al3+ and Fe3+ in aqueous medium. The cell imaging experiments confirmed that 1 can be used for monitoring intracellular Cr3+ and Al3+ levels in living cells.
Co-reporter:Junfeng Wang, Bin Liu, Xiumin Liu, Matthew J. Panzner, Chrys Wesdemiotis and Yi Pang
Dalton Transactions 2014 vol. 43(Issue 37) pp:14142-14146
Publication Date(Web):29 Jul 2014
DOI:10.1039/C4DT01799D
A hydroxybenzohydrazide-based Schiff base ligand was conveniently synthesized. Upon addition of Zn2+ cations, the ligand exhibited a high tendency to form a binuclear structure with a 2:2 ligand-to-zinc ratio, which was accompanied by a large fluorescence turn-on (λem = 507 nm, ϕfl ≈ 0.28). The reactivity of the zinc complex was examined using different phosphate anions, which reveals a higher response to acid pyrophosphate anions. Detailed spectroscopic studies show that the pyrophosphate response is based on the ligand displacement mechanism.
Co-reporter:Junfeng Wang and Yi Pang
RSC Advances 2014 vol. 4(Issue 12) pp:5845-5848
Publication Date(Web):18 Dec 2013
DOI:10.1039/C3RA47104G
A highly selective and sensitive fluorescent sensor for Al3+ has been developed. The sensor shows great fluorescence turn-on upon binding Al3+ in complete water, giving strong blue emission. In addition, the sensor's turn-on exhibits excellent selectivity to the Al3+ cation, with only a slight interference from Zn2+. These findings suggest that the developed Al3+ sensor could be a useful molecular probe for practical applications.
Co-reporter:Guangzhuo Rong;Yusheng Chen;Lei Wang;Joanne Li;Junfeng Wang;Matthew J. Panzer
Journal of Applied Polymer Science 2014 Volume 131( Issue 6) pp:
Publication Date(Web):
DOI:10.1002/app.39699
ABSTRACT
A benzoxazole sulfenamide and its related zinc compound were synthesized and characterized, which are shown to be useful accelerators for sulfur vulcanization. In comparison with the benzothiazole accelerator, the benzoxazole sulfenamide revealed nearly no reversion, an improved feature that is desirable for tire industry. Through the synthesis of the zinc complex 9, which was assumed to be an accelerator-activator for vulcanization, the study aimed to shed some light on the vulcanization mechanism. The crystal structure of the zinc complex 9 showed that two benzoxazole-2-thiol ligands were attached to the zinc center in different isomeric forms, with one in the thio form (linked via sulfur atom) while the other in thio–keto form (linked via nitrogen atom). Lack of the vulcanization accelerator activity from 9 led to the assumption that the sulfurating species might be zinc complexes containing only one benzoxazole-2-thiol ligand. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39699.
Co-reporter:Yongqian Xu, Benhao Li, Weiwei Li, Jie Zhao, Shiguo Sun and Yi Pang
Chemical Communications 2013 vol. 49(Issue 42) pp:4764-4766
Publication Date(Web):10 Apr 2013
DOI:10.1039/C3CC41994K
The first “off–on” and ratiometric fluorescent method based on ICT mechanism for picric acid (PA) recognition in the near infrared region was constructed. Key advantages of the unique molecular architecture can fulfil the ratiometric response to electron-deficient featured PA which inclines to quench fluorescence of all reported sensors for PA.
Co-reporter:Yongqian Xu, Benhao Li, Pan Han, Shiguo Sun and Yi Pang
Analyst 2013 vol. 138(Issue 4) pp:1004-1007
Publication Date(Web):04 Jan 2013
DOI:10.1039/C2AN36475A
The first “off-on” dual-output fluorescent assay based on reaction-promoted self-assembly approach for glutathione recognition in near infrared region over other relative thiols including cysteine and homocysteine was constructed with high selectivity and large Stocks shift (about 220 nm). The fluorescence enhancement is attributed to the intermolecular interaction, which manipulates the squaraine's aggregates and results in FRET for NIR emission. The sensitivity of the sensing ensemble was further improved in buffer solution containing cationic surfactant.
Co-reporter:Junfeng Wang and Yi Pang
RSC Advances 2013 vol. 3(Issue 26) pp:10208-10212
Publication Date(Web):12 Apr 2013
DOI:10.1039/C3RA41080C
A versatile synthetic route has been developed to prepare 2, 5-bis(benzoxazole-2-yl)benzene-1,4-diol derivatives 2. Although one of the derivatives (2b) has recently been shown to exhibit an excellent response to Zn2+ cations, the low yielding synthetic route will likely prevent its wide application. This report describes an improved synthetic procedure to obtain 2, thereby making this class of compounds available for biologically relevant studies. An effective synthesis has been developed for 2-aminophenol derivative 6, which bears a carboxylate group in the desired position. The strategy allows construction of bis(benzoxazole) compound 5, where the built-in ester group can be easily converted to either a hydroxymethyl or a bromomethyl group to introduce the zinc-chelating ligand.
Co-reporter:Yusheng Chen, Rosi N. Gunasinghe, Xiao-Qian Wang and Yi Pang
RSC Advances 2013 vol. 3(Issue 47) pp:25097-25102
Publication Date(Web):15 Oct 2013
DOI:10.1039/C3RA43654C
Three single-walled carbon nanotubes (SWNTs), (8,4), (7,5) and (7,6), are significantly enriched via selective dispersion of SWNTs using a cationic surfactant, where the electronic donor–acceptor interaction with the nanotube is assumed to play an important role in the observed selectivity.
Co-reporter:Tengfei Xiang;Xiumin Liu;Ping Yi;Mingming Guo;Yusheng Chen;Chrys Wesdemiotis;Jie Xu
Polymer International 2013 Volume 62( Issue 10) pp:1517-1523
Publication Date(Web):
DOI:10.1002/pi.4452
Abstract
Polymerization of 2,5-diformylfuran with two primary amines was carried out in acetonitrile and ethanol at room temperature. The reaction was characterized using a combination of mass spectroscopy and NMR spectroscopy, which revealed the clean formation of the imine –CHN− functional group. Although some cyclic products were detected from mass spectroscopy, the ring size was limited to products that have the −CHN− group only in anti-geometry. The furan Schiff bases exhibit good thermal stability. While mass spectra evidenced oligomers of different lengths, cross-polarization magic angle spinning 13C NMR spectra of the insoluble polymer revealed the linear structure as proposed. © 2013 Society of Chemical Industry
Co-reporter:Jiping Ma, Yi Pang, Min Wang, Jie Xu, Hong Ma and Xin Nie
Journal of Materials Chemistry A 2012 vol. 22(Issue 8) pp:3457-3461
Publication Date(Web):12 Jan 2012
DOI:10.1039/C2JM15457A
Furan-based copolyesters were synthesized via polytransesterification of 2,5-furandicarboxylic acid (FDCA) with ethylene glycol (EG) and 1,4-butylene glycol (BG). The composition and thermal properties of the obtained copolyesters were characterized in detail by 1H NMR and elemental analysis, differential scanning calorimeters (DSC) and thermogravimetric analysis (TGA). The 1H NMR results showed that the ethylene segment content was consistently lower than that of butylene in the obtained copolyesters in comparison with the comonomer feeds. The reactivities of EG and BG with FDCA were intensively investigated. On the basis of kinetic studies, EG was found to be less reactive than BG. The thermal properties of the obtained copolyesters could be adjusted by variation of the EG/BG molar ratios in the copolyesters.
Co-reporter:Yongqian Xu, Qin Liu, Xiaopeng Li, Chrys Wesdemiotis and Yi Pang
Chemical Communications 2012 vol. 48(Issue 92) pp:11313-11315
Publication Date(Web):08 Oct 2012
DOI:10.1039/C2CC36285F
A novel squaraine dye (SQ) exhibits improved fluorescence response toward protein detection by incorporation of a zwitterionic structure. With the aid of a dansylamide (DNSA) substituent, the new probe (DNSA-SQ) exhibits remarkable selectivity in binding to site I (a specific substructure in protein).
Co-reporter:Weihua Chen, Brian D. Wright and Yi Pang
Chemical Communications 2012 vol. 48(Issue 32) pp:3824-3826
Publication Date(Web):23 Feb 2012
DOI:10.1039/C2CC30240C
By using the substituent effect to tune the palladium(II)-involved reactivity, a new probe is found to respond quantitatively to Pd(II). Unexpectedly, the probe gave an emission band in the desirable near-infrared (NIR) region (780 nm), thus providing the first NIR sensor for palladium detection.
Co-reporter:Yongqian Xu;Qin Liu;Bairui Dou;Brian Wright;Jingyun Wang
Advanced Healthcare Materials 2012 Volume 1( Issue 4) pp:485-492
Publication Date(Web):
DOI:10.1002/adhm.201200025
Abstract
In order to facilitate the in vivo study of zinc-related biology, it is essential to develop a zinc-selective sensor that exhibits both near-infrared (NIR) emission and larger Stokes shift. A fluorescent sensor, Zinhbo-5, has been constructed by using bis(benzoxazole) ligand with 2, 2'-dipicolylamine (DPA) as metal ion receptor. In aqueous solution, Zinhbo-5 exhibits high sensitivity (Kd = 2.58 nM2) and selectivity for Zn2+ cation, revealing about 14-fold fluorescence enhancement upon zinc binding to give green emission. Remarkably, Zn2+ binding to Zinhbo-5 switches on the excited state intramolecular proton transfer (ESIPT), producing the desirable near-infrared region (over 710 nm) with large Stokes shift (ca. 240 nm). The new probe is demonstrated to be useful for in vivo imaging of the intracellular Zn2+ ion. The Zinhbo-5 is also useful for detecting zinc ion distribution during the development of living zebrafish embryos.
Co-reporter:Yusheng Chen, Yongqian Xu, Kelly Perry, Alexei P. Sokolov, Karren More, and Yi Pang
ACS Macro Letters 2012 Volume 1(Issue 6) pp:701
Publication Date(Web):May 21, 2012
DOI:10.1021/mz3001308
A water-soluble poly[(m-phenylenevinylene)-alt-(p-phenylenevinylene)] (PmPV) 2 has been synthesized, which exhibits an unsymmetrical substitution pattern on the para-phenylene unit. With one substituent being hydrophilic while the other being hydrophobic, the polymer chain has a higher tendency to fold in aqueous solution, thereby promoting helical conformation. The polymer is found to selectively disperse the single-walled nanotubes (SWNTs) of small diameters (d = 0.75–0.84 nm), in sharp contrast to PmPV 1 with a symmetrical substitution pattern. The intriguing diameter-based selectivity is believed to be associated with the confined helical conformation, which provides a suitable cavity to host the SWNT of proper sizes. The study thus provides a useful demonstration that the polymer conformation can have a profound impact on the SWNT sorting.
Co-reporter:Yusheng Chen, Andrey Malkovskiy, Xiao-Qian Wang, Marisabel Lebron-Colon, Alexei P. Sokolov, Kelly Perry, Karren More, and Yi Pang
ACS Macro Letters 2012 Volume 1(Issue 1) pp:246
Publication Date(Web):December 29, 2011
DOI:10.1021/mz2001093
Electronic and mechanic properties of single-walled carbon nanotubes (SWNTs) are uniquely dependent on the tube’s chiralities and diameters. Isolation of different type SWNTs remains one of the fundamental and challenging issues in nanotube science. Herein, we demonstrate that SWNTs can be effectively enriched to a narrow diameter range by sequential treatment of the HiPco sample with nitric acid and a π-conjugated copolymer poly(phenyleneethynylene) (PPE)–co-poly(phenylenevinylene) (PPV). On the basis of Raman, fluorescence, and microscopic evidence, the nitric acid is found to selectively remove the SWNTs of small diameter. The polymer not only effectively dispersed carbon nanotubes but also exhibited a good selectivity toward a few SWNTs. The reported approach thus offers a new methodology to isolate SWNTs, which has the potential to operate in a relatively large scale.
Co-reporter:Jiping Ma, Xinfei Yu, Jie Xu, Yi Pang
Polymer 2012 Volume 53(Issue 19) pp:4145-4151
Publication Date(Web):31 August 2012
DOI:10.1016/j.polymer.2012.07.022
Poly(butylene 2,5-furandicarboxylate) (PBF) was obtained by esterification of 2,5-furandicarboxylic acid (FDCA) and 1,4-butylene glycol (BG). By using 1H NMR at 750 MHz to recognize the trace end groups at different polymerization stages, the study provides a clear picture that the polymerization proceeds cleanly to give the desirable linear structure. On the basis of the end group analysis, the degree of polymerization of PBF was determined to be as high as 125, which is in agreement with the molecular weight from the viscosity study. Solid state 13C NMR revealed that one of the furan carbons is sensitive to local morphology. DSC and X-ray diffraction further revealed that the polymer had high tendency to form crystalline materials (Tm = 130 °C & 169 °C; Tg = 32 °C). On the basis of DSC and NMR evidences, the two crystalline states are assumed to be β-phase (less stable) and α-phase (more stable), respectively, by analogy with the crystalline structure of PBT. High tendency of forming crystalline structure allows the continuous fibers to be drawn from the PBF's melt. The results thus raise the hope that the biomass-derived PBF could be a promising furan counterpart of the petroleum-based poly(butylene terephthalate) (PBT).Graphical abstract
Co-reporter:Weihua Chen, Eric B. Twum, Linlin Li, Brian D. Wright, Peter L. Rinaldi, and Yi Pang
The Journal of Organic Chemistry 2012 Volume 77(Issue 1) pp:285-290
Publication Date(Web):November 21, 2011
DOI:10.1021/jo201890f
2-(2′-Hydroxyphenyl)benzoxazole (HBO) derivatives represent an important class of luminescent materials, as they can undergo excited state intramolecular proton transfer (ESIPT). The material’s ESIPT properties are dependent on the ratio of two different rotamers, whose interconversion is poorly understood. By using HBO derivative 4, the rotational energy barrier of 2- (2′,6′-hydroxyphenyl)benzoxazole is determined to be 10.5 kcal/mol by variable-temperature NMR. Although a HBO derivative typically exhibits two rotamers with O···H–O (e.g., 1a) and N···H–O bonding (e.g., 1b), correlation of NMR with fluorescence data reveals that the rotamer with N···H–O bonding is predominant in the solution.
Co-reporter:Yongqian Xu, Mingming Guo, Xiaopeng Li, Andrey Malkovskiy, Chrys Wesdemiotis and Yi Pang
Chemical Communications 2011 vol. 47(Issue 31) pp:8883-8885
Publication Date(Web):14 Jun 2011
DOI:10.1039/C1CC12599K
Cucurbit[n]urils (n = 7, 8) and thiazole orange (TO) dyes in aqueous media were found to form host–guest inclusions in different stoichiometries. Supramolecular structures and linear supramolecular polymers were observed through the hydrophobic effect and π–π interactions in aqueous solution.
Co-reporter:Yongqian Xu, Andrey Malkovskiy and Yi Pang
Chemical Communications 2011 vol. 47(Issue 23) pp:6662-6664
Publication Date(Web):11 May 2011
DOI:10.1039/C1CC11355K
Chemically converted graphene (CCG) was found to greatly enhance the fluorescence response of squaraine (SQ) dyes to bovine serum albumin (BSA). Addition of BSA to the SQ–CCG solution, where squaraine dyes absorbed on the CCG surface, raised the fluorescence intensity by as much as 80 fold.
Co-reporter:Yongqian Xu and Yi Pang
Dalton Transactions 2011 vol. 40(Issue 7) pp:1503-1509
Publication Date(Web):18 Jan 2011
DOI:10.1039/C0DT01376E
Near-infrared (NIR) emission can offer distinct advantages for biological applications. A fluorescent sensor, Zinhbo-1, based on bis(benzoxazole) ligand with 2,2′-dipicolylamine (DPA) as receptor, was synthesized. In aqueous solution, Zinhbo-1 demonstrates high sensitivity and selectivity for sensing Zn2+ with about 10-fold enhancement and nanomolar sensitivity (Kd = 0.29 nM). Moreover, sensor Zinhbo-1 can detect Zn2+ in near-infrared region (over 700 nm) with large Stokes shift (ca. 230 nm) attributing to the Zn2+-induced excited state intramolecular proton transfer (ESIPT).
Co-reporter:Yongqian Xu, Andrey Malkovskiy, Qiuming Wang and Yi Pang
Organic & Biomolecular Chemistry 2011 vol. 9(Issue 8) pp:2878-2884
Publication Date(Web):03 Mar 2011
DOI:10.1039/C0OB01061H
A novel fluorescent system has been assembled by using ATP, surfactant, and a squaraine dye in an aqueous buffer solution. In the system, a cationic surfactant such as cetyl trimethyl ammonium bromide (CTAB) forms a sphere-like micelle, whose positive charge at the surface of the micelle attracts the negatively charged ATP to form a unique organized nanostructure. Such an organized system is shown to interact with the squaraine dye (SQ) to perturb its aggregate structure, thereby generating the optical response. The nanostructure of the assembly has been characterized by dynamic light-scattering (DLS) and atomic force microscopy (AFM). The unique feature of the developed sensing system is that the analytes ATP form part of the assembly structure. The system utilizes forces such as electrostatic interaction and π–π stacking of the aromatic segment of ATP and SQ to achieve the selective detection of ATP.
Co-reporter:Jiping Ma;Dr. Zhongtian Du; Jie Xu;Dr. Qinghui Chu;Dr. Yi Pang
ChemSusChem 2011 Volume 4( Issue 1) pp:51-54
Publication Date(Web):
DOI:10.1002/cssc.201000273
Co-reporter:Yongqian Xu, Matthew J. Panzner, Xiaopeng Li, Wiley J. Youngs and Yi Pang
Chemical Communications 2010 vol. 46(Issue 23) pp:4073-4075
Publication Date(Web):20 Apr 2010
DOI:10.1039/C002219P
The binding interactions between SQ2 squaraine dye and cucurbit[8]uril (CB8) effectively removes the aggregation of SQ2 in aqueous solution by forming a 1:1 inclusion complex. The resulting SQ2·CB8 complex exhibits highly selective fluorescence quenching by Hg2+ ions, as a result of the synergetic binding between CB8, SQ2 and metal cation.
Co-reporter:Yongqian Xu and Yi Pang
Chemical Communications 2010 vol. 46(Issue 23) pp:4070-4072
Publication Date(Web):15 Apr 2010
DOI:10.1039/C003230A
A bis(benzoxazole) derivative with metal-chelating ligand (DPA), Zinhbo-1, exhibits a large fluorescence turn-on effect (up to 10-fold) upon zinc-binding. The metal chelation enables excited state intramolecular proton transfer (ESIPT), giving an additional emission band in the near-IR region (∼710 nm) with a large Stokes shift (ca. 230 nm).
Co-reporter:Wei-Hua Chen, Yi Pang
Tetrahedron Letters 2010 Volume 51(Issue 14) pp:1914-1918
Publication Date(Web):7 April 2010
DOI:10.1016/j.tetlet.2010.02.043
2-(2′,6′-Dihydroxyphenyl)benzoxazole (DHBO) has been synthesized by using palladium-catalyzed oxidative cyclization. The compound utilizes both O–H···N and O–H···O bonds to ensure a coplanar structure between the benzoxazole and phenol fragments. Optical comparison with the parent compound 2-(2′-hydroxyphenyl)benzoxazole (HBO) reveals that the dual hydrogen bonding in DHBO plays an essential role in raising the desirable keto emission for ESIPT and tuning the polarity sensitivity toward the molecular environment. DHBO also exhibits a higher quantum yield (ϕfl = 0.108 in methanol) than HBO (ϕfl = 0.0025) in the same solvent.
Co-reporter:Wenhui Yi, Andrey Malkovskiy, Yongqian Xu, Xiao-Qian Wang, Alexei P. Sokolov, Marisabel Lebron-Colon, Michael A. Meador, Yi Pang
Polymer 2010 Volume 51(Issue 2) pp:475-481
Publication Date(Web):21 January 2010
DOI:10.1016/j.polymer.2009.11.052
A soluble π-conjugated polymer cis-PmPV is found to be twice as effective as its trans-PmPV isomer in dispersing SWNTs into organic solvents. The improved efficiency is related to the specific conformation of cis-vinylene-enriched PmPV, which facilitates a planar π–π interaction with SWNT surface and leads to improved nanotube dispersion. 1H NMR spectra indicate that the cis-CHCH bonds are partially converted to the trans-CHCH, thereby providing necessary conformational cavity for SWNT wrapping. Irradiation triggers a precipitation from SWNT dispersion, providing a purified SWNT/conjugated polymer composite.
Co-reporter:Jun Hong Yao;Yusheng Chen
Journal of Polymer Science Part A: Polymer Chemistry 2010 Volume 48( Issue 22) pp:5254-5257
Publication Date(Web):
DOI:10.1002/pola.24301
Co-reporter:Yongqian Xu, Zhiyong Li, Andrey Malkovskiy, Shiguo Sun and Yi Pang
The Journal of Physical Chemistry B 2010 Volume 114(Issue 25) pp:8574-8580
Publication Date(Web):June 7, 2010
DOI:10.1021/jp1029536
A series of squaraine dyes are found to be in H- or J-aggregates and are almost nonfluorescent in aqueous solution. Upon addition of bovine serum albumin (BSA), however, the fluorescence intensity (at λem ≈ 690 nm) increases by a factor of up to 200. Transformation of the dye molecules from the aggregates to the monomeric species appears to be responsible for the large fluorescence turn-on. While both H- and J-aggregates contribute to the observed fluorescence turn-on, the former appears to play a more important role. Electrophoresis imaging shows that these probes are good BSA indicators.
Co-reporter:Wei-Hua Chen, Yi Pang
Tetrahedron Letters 2009 50(48) pp: 6680-6683
Publication Date(Web):
DOI:10.1016/j.tetlet.2009.09.084
Co-reporter:Victor Banjoko, Yongqian Xu, Eric Mintz, Yi Pang
Polymer 2009 50(9) pp: 2001-2009
Publication Date(Web):
DOI:10.1016/j.polymer.2009.02.045
Co-reporter:Qinghui Chu
Journal of Polymer Science Part A: Polymer Chemistry 2006 Volume 44(Issue 7) pp:2338-2345
Publication Date(Web):21 FEB 2006
DOI:10.1002/pola.21350
Soluble, fluorescent, terpyridine-substituted, conjugated polymers were prepared and characterized. The polymer chains included a defined oligo(phenylenevinylene) fragment, on which the terpyridine-functional group was attached. The polymers were blue-fluorescent with emission peaks at 400–427 nm in tetrahydrofuran solutions. Upon chelation with the Zn(II) cation, the emission maxima were shifted to a longer wavelength by as much as 113 to 506–526 nm. A model compound was also prepared to aid the structural characterization. The ratio of terpyridine to Zn2+ in the polymer complex was found to be 1:1 on the basis of spectroscopic evidence, which included mass spectrometry, 1H NMR, and Job titration. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2338–2345, 2006
Co-reporter:Liang Liao;Ali Cirpan;Liming Ding;Frank E. Karasz
Journal of Polymer Science Part A: Polymer Chemistry 2006 Volume 44(Issue 7) pp:2307-2315
Publication Date(Web):21 FEB 2006
DOI:10.1002/pola.21347
New poly(phenylene vinylene) derivatives with a 5-diphenylamino-1,3-phenylene linkage (including polymers 2, 3, and 5) have been synthesized to improve the charge-injection properties. These polymers are highly photoluminescent with fluorescent quantum yields as high as 76% in tetrahydrofuran solutions. With effective π-conjugation interruption at adjacent m-phenylene units, chromophores of different conjugation lengths can be incorporated into the polymer chain in a controllable manner. In polymer 2, the structural regularity leads to an isolated, well-defined emitting chromophore. Isomeric polymer 3 of a random chain sequence, however, allows the effective emitting chromophores to be joined in sequence by sharing a common m-phenylene linkage (as shown in a molecular fragment). Double-layer light-emitting-diode devices using 2, 3, and 5 as emitting layers have turn-on voltages of about 3.5 V and produce blue-green emissions with peaks at 493, 492, and 482 nm and external quantum efficiencies up to 1.42, 0.98, and 1.53%, respectively. In comparison with a light-emitting diode using 2, a device using 3 shows improved charge injection and displays increased brightness by a factor of ∼3 to 1400 cd/m2 at an 8-V bias. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2307–2315, 2006
Co-reporter:Yongqian Xu, Mingming Guo, Xiaopeng Li, Andrey Malkovskiy, Chrys Wesdemiotis and Yi Pang
Chemical Communications 2011 - vol. 47(Issue 31) pp:NaN8885-8885
Publication Date(Web):2011/06/14
DOI:10.1039/C1CC12599K
Cucurbit[n]urils (n = 7, 8) and thiazole orange (TO) dyes in aqueous media were found to form host–guest inclusions in different stoichiometries. Supramolecular structures and linear supramolecular polymers were observed through the hydrophobic effect and π–π interactions in aqueous solution.
Co-reporter:Yongqian Xu, Andrey Malkovskiy and Yi Pang
Chemical Communications 2011 - vol. 47(Issue 23) pp:NaN6664-6664
Publication Date(Web):2011/05/11
DOI:10.1039/C1CC11355K
Chemically converted graphene (CCG) was found to greatly enhance the fluorescence response of squaraine (SQ) dyes to bovine serum albumin (BSA). Addition of BSA to the SQ–CCG solution, where squaraine dyes absorbed on the CCG surface, raised the fluorescence intensity by as much as 80 fold.
Co-reporter:Yongqian Xu, Qin Liu, Xiaopeng Li, Chrys Wesdemiotis and Yi Pang
Chemical Communications 2012 - vol. 48(Issue 92) pp:NaN11315-11315
Publication Date(Web):2012/10/08
DOI:10.1039/C2CC36285F
A novel squaraine dye (SQ) exhibits improved fluorescence response toward protein detection by incorporation of a zwitterionic structure. With the aid of a dansylamide (DNSA) substituent, the new probe (DNSA-SQ) exhibits remarkable selectivity in binding to site I (a specific substructure in protein).
Co-reporter:Weihua Chen, Brian D. Wright and Yi Pang
Chemical Communications 2012 - vol. 48(Issue 32) pp:NaN3826-3826
Publication Date(Web):2012/02/23
DOI:10.1039/C2CC30240C
By using the substituent effect to tune the palladium(II)-involved reactivity, a new probe is found to respond quantitatively to Pd(II). Unexpectedly, the probe gave an emission band in the desirable near-infrared (NIR) region (780 nm), thus providing the first NIR sensor for palladium detection.
Co-reporter:Lucas McDonald, Bin Liu, Alexandra Taraboletti, Kyle Whiddon, Leah P. Shriver, Michael Konopka, Qin Liu and Yi Pang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 48) pp:NaN7908-7908
Publication Date(Web):2016/11/23
DOI:10.1039/C6TB02456D
Visualization of subcellular organelles in vivo is critical for basic biomedical research and clinical applications. Two new flavonoids with an amide substituent were synthesized and characterized. The flavonoids were nearly non-fluorescent in aqueous environment, but exhibited two emission peaks (one λem at 495–536 nm and the other at 570–587 nm) in organic solvents, which were assigned to the excited normal (N*) and tautomer (T*) emission. When the dyes were examined on oligodendrocyte cells, they were found to selectively accumulate in the endoplasmic reticulum (ER), a eukaryotic organelle involved in lipid and protein synthesis, giving fluorescence turn-on. The ER-selective flavonoids could be a valuable tool due to its low molecular mass (<500), large Stokes' shift, low toxicity, and biocompatibility.
Co-reporter:Bin Liu, Yi Pang, Rachida Bouhenni, Ernest Duah, Sailaja Paruchuri and Lucas McDonald
Chemical Communications 2015 - vol. 51(Issue 55) pp:NaN11063-11063
Publication Date(Web):2015/05/27
DOI:10.1039/C5CC03516C
In this study, we report a series of novel flavone-based sensors that exhibit a superior fluorescence response when interacting with serum albumin in real serum samples and in acrylamide gels. The detection limit of probe 4 for serum albumin solution is 0.09 μg mL−1, and the detectable volume for monkey serum reaches as low as 0.03 μL.
Co-reporter:Yongqian Xu and Yi Pang
Chemical Communications 2010 - vol. 46(Issue 23) pp:NaN4072-4072
Publication Date(Web):2010/04/15
DOI:10.1039/C003230A
A bis(benzoxazole) derivative with metal-chelating ligand (DPA), Zinhbo-1, exhibits a large fluorescence turn-on effect (up to 10-fold) upon zinc-binding. The metal chelation enables excited state intramolecular proton transfer (ESIPT), giving an additional emission band in the near-IR region (∼710 nm) with a large Stokes shift (ca. 230 nm).
Co-reporter:Yongqian Xu, Matthew J. Panzner, Xiaopeng Li, Wiley J. Youngs and Yi Pang
Chemical Communications 2010 - vol. 46(Issue 23) pp:NaN4075-4075
Publication Date(Web):2010/04/20
DOI:10.1039/C002219P
The binding interactions between SQ2 squaraine dye and cucurbit[8]uril (CB8) effectively removes the aggregation of SQ2 in aqueous solution by forming a 1:1 inclusion complex. The resulting SQ2·CB8 complex exhibits highly selective fluorescence quenching by Hg2+ ions, as a result of the synergetic binding between CB8, SQ2 and metal cation.
Co-reporter:Junfeng Wang, Yingbo Li, Ernest Duah, Sailaja Paruchuri, Demin Zhou and Yi Pang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 14) pp:NaN2012-2012
Publication Date(Web):2014/02/28
DOI:10.1039/C3TB21339K
A rational design has led to a highly selective and cell-permeable zinc sensor, which exhibits not only a large fluorescence turn-on at ∼545 nm but also the desirable NIR emission (∼720 nm) with a large Stokes' shift, providing a practical sensor platform with two emission channels for reliable zinc detection.
Co-reporter:Junfeng Wang, Weihua Chen, Xiumin Liu, Chrys Wesdemiotis and Yi Pang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 21) pp:NaN3354-3354
Publication Date(Web):2014/04/25
DOI:10.1039/C4TB00020J
A mononuclear zinc complex has been found to exhibit unexpected selectivity for biologically important diphosphate anions (PPi and ADP). The diphosphate binding could turn-on excited state intramolecular proton transfer (ESIPT), whose study reveals mechanistic insight to aid the future design of new sensors.
Co-reporter:Yongqian Xu, Andrey Malkovskiy, Qiuming Wang and Yi Pang
Organic & Biomolecular Chemistry 2011 - vol. 9(Issue 8) pp:NaN2884-2884
Publication Date(Web):2011/03/03
DOI:10.1039/C0OB01061H
A novel fluorescent system has been assembled by using ATP, surfactant, and a squaraine dye in an aqueous buffer solution. In the system, a cationic surfactant such as cetyl trimethyl ammonium bromide (CTAB) forms a sphere-like micelle, whose positive charge at the surface of the micelle attracts the negatively charged ATP to form a unique organized nanostructure. Such an organized system is shown to interact with the squaraine dye (SQ) to perturb its aggregate structure, thereby generating the optical response. The nanostructure of the assembly has been characterized by dynamic light-scattering (DLS) and atomic force microscopy (AFM). The unique feature of the developed sensing system is that the analytes ATP form part of the assembly structure. The system utilizes forces such as electrostatic interaction and π–π stacking of the aromatic segment of ATP and SQ to achieve the selective detection of ATP.
Co-reporter:Chathura S. Abeywickrama, Kaveesha J. Wijesinghe, Robert V. Stahelin and Yi Pang
Chemical Communications 2017 - vol. 53(Issue 43) pp:NaN5889-5889
Publication Date(Web):2017/05/16
DOI:10.1039/C7CC03417B
A highly fluorescent red-emitting pyrene derivative was synthesized and found to exhibit a large Stokes shift (λem ≈ 610 nm, Δλ ∼ 130 nm, Δν ∼ 4597 cm−1). The probe molecule showed remarkable selectivity to stain the nucleus in both live and fixed cells, with higher sensitivity than commercial dye DRAQ5.
Co-reporter:Dipendra Dahal, Lucas McDonald, Xiaoman Bi, Chathura Abeywickrama, Farai Gombedza, Michael Konopka, Sailaja Paruchuri and Yi Pang
Chemical Communications 2017 - vol. 53(Issue 26) pp:NaN3700-3700
Publication Date(Web):2017/03/15
DOI:10.1039/C7CC00700K
An NIR-emitting probe (λem ∼ 700 nm) with a large Stokes shift (Δλ ≈ 234 nm) is synthesized by using excited-state intramolecular proton transfer (ESIPT). The phenolic proton, which controls ESIPT, acts as a switch to give strong fluorescence at pH ≈ 5. The probe can selectively show lysosome organelles, therefore leading to a lysosome probe without exhibiting “an alkalinizing effect”.
Co-reporter:Jiping Ma, Yi Pang, Min Wang, Jie Xu, Hong Ma and Xin Nie
Journal of Materials Chemistry A 2012 - vol. 22(Issue 8) pp:NaN3461-3461
Publication Date(Web):2012/01/12
DOI:10.1039/C2JM15457A
Furan-based copolyesters were synthesized via polytransesterification of 2,5-furandicarboxylic acid (FDCA) with ethylene glycol (EG) and 1,4-butylene glycol (BG). The composition and thermal properties of the obtained copolyesters were characterized in detail by 1H NMR and elemental analysis, differential scanning calorimeters (DSC) and thermogravimetric analysis (TGA). The 1H NMR results showed that the ethylene segment content was consistently lower than that of butylene in the obtained copolyesters in comparison with the comonomer feeds. The reactivities of EG and BG with FDCA were intensively investigated. On the basis of kinetic studies, EG was found to be less reactive than BG. The thermal properties of the obtained copolyesters could be adjusted by variation of the EG/BG molar ratios in the copolyesters.
Co-reporter:Junfeng Wang, Xiumin Liu and Yi Pang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 38) pp:NaN6638-6638
Publication Date(Web):2014/08/07
DOI:10.1039/C4TB01109K
A benzothiazole derivative 2 bearing two 2,2′-dipicolylamine (DPA) groups was examined for its zinc-binding and subsequent anion sensing properties. The study revealed the anion sensing mechanism of polyphosphate anions via sequential binding to two zinc centers, on the basis of both 1H NMR and mass spectral evidence. The mechanistic insight would provide valuable information for the future design of new excited state intramolecular proton transfer (ESIPT) sensors. In addition, the zinc complex exhibited solvent-switchable selectivity, responding to pyrophosphate (PPi) in EtOH and adenosine 5′-triphosphate (ATP) in water.
Co-reporter:Yongqian Xu and Yi Pang
Dalton Transactions 2011 - vol. 40(Issue 7) pp:NaN1509-1509
Publication Date(Web):2011/01/18
DOI:10.1039/C0DT01376E
Near-infrared (NIR) emission can offer distinct advantages for biological applications. A fluorescent sensor, Zinhbo-1, based on bis(benzoxazole) ligand with 2,2′-dipicolylamine (DPA) as receptor, was synthesized. In aqueous solution, Zinhbo-1 demonstrates high sensitivity and selectivity for sensing Zn2+ with about 10-fold enhancement and nanomolar sensitivity (Kd = 0.29 nM). Moreover, sensor Zinhbo-1 can detect Zn2+ in near-infrared region (over 700 nm) with large Stokes shift (ca. 230 nm) attributing to the Zn2+-induced excited state intramolecular proton transfer (ESIPT).
Co-reporter:Junfeng Wang, Bin Liu, Xiumin Liu, Matthew J. Panzner, Chrys Wesdemiotis and Yi Pang
Dalton Transactions 2014 - vol. 43(Issue 37) pp:NaN14146-14146
Publication Date(Web):2014/07/29
DOI:10.1039/C4DT01799D
A hydroxybenzohydrazide-based Schiff base ligand was conveniently synthesized. Upon addition of Zn2+ cations, the ligand exhibited a high tendency to form a binuclear structure with a 2:2 ligand-to-zinc ratio, which was accompanied by a large fluorescence turn-on (λem = 507 nm, ϕfl ≈ 0.28). The reactivity of the zinc complex was examined using different phosphate anions, which reveals a higher response to acid pyrophosphate anions. Detailed spectroscopic studies show that the pyrophosphate response is based on the ligand displacement mechanism.
Co-reporter:Yongqian Xu, Benhao Li, Weiwei Li, Jie Zhao, Shiguo Sun and Yi Pang
Chemical Communications 2013 - vol. 49(Issue 42) pp:NaN4766-4766
Publication Date(Web):2013/04/10
DOI:10.1039/C3CC41994K
The first “off–on” and ratiometric fluorescent method based on ICT mechanism for picric acid (PA) recognition in the near infrared region was constructed. Key advantages of the unique molecular architecture can fulfil the ratiometric response to electron-deficient featured PA which inclines to quench fluorescence of all reported sensors for PA.
Co-reporter:Junfeng Wang, Yingbo Li, Nikul G. Patel, Ge Zhang, Demin Zhou and Yi Pang
Chemical Communications 2014 - vol. 50(Issue 82) pp:NaN12261-12261
Publication Date(Web):2014/08/26
DOI:10.1039/C4CC04731A
An ESIPT based fluorescent sensor 1 was developed, which could selectively detect and differentiate trivalent metal ions Cr3+, Al3+ and Fe3+ in aqueous medium. The cell imaging experiments confirmed that 1 can be used for monitoring intracellular Cr3+ and Al3+ levels in living cells.
![Phenol,4,5-dimethoxy-2-[4-[[(2-pyridinylmethyl)amino]methyl]-2-benzoxazolyl]-](http://img.cochemist.com/ccimg/658100/658053-22-6.png)
![Phenol,4,5-dimethoxy-2-[4-[[(2-pyridinylmethyl)amino]methyl]-2-benzoxazolyl]-](http://img.cochemist.com/ccimg/658100/658053-22-6_b.png)
![2-FURANCARBOXYLIC ACID, [(2,5-DIHYDROXYPHENYL)METHYLENE]HYDRAZIDE](http://img.cochemist.com/ccimg/413000/412957-12-1.png)
![2-FURANCARBOXYLIC ACID, [(2,5-DIHYDROXYPHENYL)METHYLENE]HYDRAZIDE](http://img.cochemist.com/ccimg/413000/412957-12-1_b.png)
![Benzenamine, N,N-diphenyl-4-[2,2':6',2''-terpyridin]-4'-yl-](/data/chemimg/117200/408359-98-8.png)
![Benzenamine, N,N-diphenyl-4-[2,2':6',2''-terpyridin]-4'-yl-](/data/chemimg/117200/408359-98-8_b.png)
![Benzenamine, N,N-dimethyl-4-[2,2':6',2''-terpyridin]-4'-yl-](/data/chemimg/560000/362595-93-5.png)
![Benzenamine, N,N-dimethyl-4-[2,2':6',2''-terpyridin]-4'-yl-](/data/chemimg/560000/362595-93-5_b.png)
![N-[(6-oxocyclohexa-2,4-dien-1-ylidene)methyl]furan-2-carbohydrazide](http://img.cochemist.com/ccimg/93000/92982-43-9.png)
![N-[(6-oxocyclohexa-2,4-dien-1-ylidene)methyl]furan-2-carbohydrazide](http://img.cochemist.com/ccimg/93000/92982-43-9_b.png)
