Co-reporter:Ruimin Zhu, Heyuan Liu, Li Shen, Dejun Sun, Xiyou Li
Journal of Physics and Chemistry of Solids 2017 Volume 103() pp:164-169
Publication Date(Web):April 2017
DOI:10.1016/j.jpcs.2016.12.018
Chemically decorating CH3NH3PbBr3 with a group of para-substituted arylamine (R-An) was investigated, where R ranges from electron-withdrawing trifluoromethoxy(-CF3O), to hydrogen or electron-donating ethoxy (-EtO). Different ratios of R-An ammonium bromide and methylammonium bromide (MA) (R-An/MA=3/7, 4/6, 5/5, 6/4 and 7/3) were tested. XRD patterns revealed that the perovskite nanocomposite were cubic with good crystallinity. TEM and photoluminescence suggested that the perovskite nanocrystals were composed of 2D layered and 3D bulk structures. 1H NMR and TGA experiments revealed that the non-substituted aniline can readily adsorb to the surface of perovskite at any ratios between R-An and MA. But an EtOAn/MA ratio ≥1 is needed to anchor the EOAn molecules on the surface of perovskite. For the arylamine with the electron-withdrawing -CF3O group, it cannot adsorb to the surface of the perovskite at any concentrations. This result reveals that both steric hindrance and alkalinity can affect the anchoring of arylamine on the surface of CH3NH3PbBr3 perovskite. I-V curves of the perovskite nanocrystal films prepared by spin coating suggest that proper surface modification can increase the conductivity significantly.
Co-reporter:Jingang Song;Haitao Zhao;Ranran Sun;Dejun Sun
Energy & Environmental Science (2008-Present) 2017 vol. 10(Issue 1) pp:225-235
Publication Date(Web):2017/01/18
DOI:10.1039/C6EE02414A
ZnxCd1−xS solid solutions have been successfully demonstrated as excellent visible light responsive catalysts for hydrogen evolution from water in the presence of sacrificial reagents. Especially Zn0.5Cd0.5S with a twin crystal structure is the best pristine sulphide catalyst ever reported so far due to the presence of the homo-junctions between the zinc blende (ZB) and wurtzite (WZ) segments, which improved the separation of the photon generated electron–hole pairs. However, a further improvement in the catalytic activities of the twin crystal Zn0.5Cd0.5S solid solution has never been reported. In the present work, palladium phosphorous sulphide (PdP∼0.33S∼1.67) was used for the first time as a co-catalyst and found that the photocatalytic H2 production rate and efficiency of the twin nanocrystal Zn0.5Cd0.5S solid solution in the presence of acidic or alkaline sacrificial reagents were significantly enhanced. The H2 production rates of Zn0.5Cd0.5S/PdP∼0.33S∼1.67 under visible light illumination (λ > 420 nm) in 0.75 M ascorbic acid (pH = 2.39) and 0.7 M Na2S/0.5 M Na2SO3 (pH = 13.86) aqueous solutions are measured to be 372.12 μmol h−1 mg−1 and 246.04 μmol h−1 mg−1, respectively, which are 67 and 5.8 times higher than those of pristine twinned Zn0.5Cd0.5S solid solution. Moreover, the H2 production rate of 372.12 μmol h−1 mg−1 is the highest value ever reported so far for sulphide photocatalysts in the presence of acidic sacrificial reagents. The examination on the morphology of the Zn0.5Cd0.5S/PdP∼0.33S∼1.67 hybrid catalyst using SEM, TEM and HRTEM techniques revealed the presence of hetero-junctions between the deposited PdP∼0.33S∼1.67 and Zn0.5Cd0.5S phases, as well as homo-junctions between the ZB and WZ phases in this hybrid catalyst. The synergistic effects of homo- and hetero-junctions on the separation of the generated electron–hole pairs are responsible for the significantly promoted catalytic activities of the hybrid catalyst. This result suggests that combination of both homo- and hetero-junctions in one catalyst is a promising strategy for improving the catalytic activities of sulphide catalysts for hydrogen evolution from water.
Co-reporter:Ting Sun, Jingang Song, Jiong Jia, Xiyou Li, Xuan Sun
Nano Energy 2016 Volume 26() pp:83-89
Publication Date(Web):August 2016
DOI:10.1016/j.nanoen.2016.04.058
•H2-evolution is markedly promoted with doping minute quantity of π-conjugate PDI molecules to the Zn0.5Cd0.5S semiconductor.•Mechanism is proposed that PDI functions as an electron collector and transporter to inhibit the charge recombination.•The charge separation and the H2-evolution efficiency depend heavily on the modulated molecular structure of PDIs.On account of the steps of water splitting reaction, suppression of the electron–hole recombination is one key factor to improve the photocatalytic activity. Composites with π-conjugated molecules are promising to inhibit the recombination process by delocalization of the photo-generated electron. In this study, we synthesized perylenetetracarboxylic diimide (PDI) decorated Zn0.5Cd0.5S hybrid photocatalysts to reveal the function of the PDI in promoting the charge separation by electron transfer process. To understand the mechanisms that govern the carrier separation, transport, extraction and their recombination within this inorganic/organic nanocomposite, three PDIs, namely PDI-1, PDI-2 and PDI-3 with different molecular structure were loaded in the Zn0.5Cd0.5S, respectively, and were investigated comparatively. It is demonstrated that PDIs play great roles in increasing the specific surface area and stabilizing the photogenerated electron–hole pairs, resulting in enhancement of the overall hydrogen production rate. The highest rate of 1.32 mmol h−1 g−1 was achieved on the Zn0.5Cd0.5S-PDI-1 composite, which is 6 times higher than the pristine Zn0.5Cd0.5S, owning to the effective photo-driven electron transport between the Zn0.5Cd0.5S and the PDI-1. The results of the current work are relevant in understanding the nature of charge-transfer pathways in photoinduced catalysis.Perylenetetracarboxylic diimide functions as an electron collector and transporter from the Zn0.5Cd0.5S semiconductor to greatly promote the catalyzed H2-evlution under visible light illumination by inhibiting the charge recombination.
Co-reporter:Li Shen, Yuhan Chen, Xiyou Li, Chungang Li
Journal of Molecular Graphics and Modelling 2016 Volume 66() pp:187-195
Publication Date(Web):May 2016
DOI:10.1016/j.jmgm.2016.04.007
•The stability of pentacene derivatives is discussed based on the frontier orbital energies.•Electron-withdrawing groups can stabilized pentacene derivatives efficiently.•Sulfur containing groups are efficient on stabilizing pentacene compounds.•Singlet fission of pentacenes are exothermic, no mater what kind of substituent is connected.Pentacene crystals or oligomers undergo efficient singlet exciton fission (SF) after photo-excitation, which is expected to be useful in overcoming the Shockley-Queisser theoretical limit of solar cells. However, pentacenes are extremely unstable in air due to oxidation by oxygen. In this work, we designed a group of pentacene compounds with different substituents at different positions. The energy levels of HOMO and LUMO, which are believed to be closely related to the stability of pentacene, were calculated. The relationship between the molecular structure and the stability was discussed. The driving force for SF was estimated from the difference between the energy of first singlet excited state (E(S1)) and the energy of two triplet excited state (2 × E(T1)) following equation E(S1) − 2E(T1). Strong electron-withdrawing groups can stabilize pentacene compounds significantly, but induce a decrease on the driving force of SF slightly. Electron-donating groups destabilize the pentacene compounds dramatically and hence the introduction of electron donating groups to pentacene is not recommended. TIPS is an ideal group to improve the stability of pentacene compounds. TIPS does not change the driving force of SF significantly. Sulfur containing groups are also efficient on stabilizing pentacene compounds. These groups increase the driving force of SF at ɑ position, and recued the driving force of SF at other positions. The results of this work provide a theoretical ground for rational design of new SF molecules based on pentacenes.
Co-reporter:Ruimin Zhu, Chengguang Gao, Tingting Sun, Li Shen, Dejun Sun, and Xiyou Li
Langmuir 2016 Volume 32(Issue 13) pp:3294-3299
Publication Date(Web):March 13, 2016
DOI:10.1021/acs.langmuir.5b04221
An organic dye-modified organolead halide CH3NH3PbBr3 nanoparticle (cubic) is prepared successfully by using a perylenetetracarboxylic diimide (PDI) bearing an -NH3+ headgroup as the capping ligand. The nanopartilces are homogeneous with high crystallinity. The photoluminescence of perovskite is quenched completely by the chemically adsorbed PDI molecules. This efficient fluorescence quenching has confirmed that the PDI molecules are anchored on the surface of CH3NH3PbBr3 nanoparticle. The resulting nanoparticles can be dispersed in organic solvents, and the resulting dispersion remains stable for days. This result provides a general guideline for surface engineering of organolead halide CH3NH3PbBr3 nanoparticles.
Co-reporter:Heyuan Liu, Valerie M. Nichols, Li Shen, Setarah Jahansouz, Yuhan Chen, Kerry M. Hanson, Christopher J. Bardeen and Xiyou Li
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 9) pp:6523-6531
Publication Date(Web):28 Jan 2015
DOI:10.1039/C4CP05444J
A covalently linked tetracene dimer has been prepared and its molecular structure is characterized by 1H NMR and MALDI-TOF mass spectroscopy, and elemental analysis. The minimized molecular structure reveals that the tetracene subunits in a dimer adopt a “face-to-face” stacked configuration. Its absorption spectrum differs significantly from that of the monomeric counterpart in solution, suggesting the presence of strong interactions between the two tetracene subunits. In solution, the fluorescence spectrum is dominated by a band at around 535 nm, due to an oxidative impurity. In the longer wavelength range, a short-lived lower energy emission can be identified as the intrinsic emission of the dimer. In a polystyrene matrix or at low temperatures, the lifetime of the lower energy emission lengthens and it becomes more prominent. We suggest that the interactions between the two tetracene subunits produce a short-lived, lower energy “excimer-like” state. The fluorescence decays show no observable dependence on an applied magnetic field, and no obvious evidence of significant singlet fission is found in this dimer. This research suggests that even though there are strong electronic interactions between the tetracene subunits in the dimer, singlet fission cannot be achieved efficiently, probably because the formation of “excimer-like” states competes effectively with singlet fission.
Co-reporter:Ying Zhang, Liangliang Zhang, Heyuan Liu, Di Sun and Xiyou Li
CrystEngComm 2015 vol. 17(Issue 6) pp:1453-1463
Publication Date(Web):02 Jan 2015
DOI:10.1039/C4CE02392G
A series of perylenetetracarboxylic diimide (PDI) derivatives connected with two bulky polyhedral oligosilsesquioxanes (POSSs) were designed and synthesized for the purpose of revealing the effect of bulky and well-defined side groups on the self-aggregation behaviour of PDIs. The properties of these compounds in solution were investigated by UV-vis absorption spectroscopy, fluorescence spectroscopy, and fluorescence quantum yield measurement. The results indicate that the POSS groups do not show large effects on the spectroscopic properties of PDIs in solution. However, the solid state spectroscopic properties of these compounds are significantly affected by the bulky POSS groups. The presence of bulky POSS groups changes the packing structure of the molecules in the solid state and thus affects the solid state emission properties. Our results revealed that the introduction of bulky POSS groups into the molecules will not inevitably lead to promoted solid state fluorescence quantum yield as expected. It is the packing structure of the molecules in the solid state which determines the solid state fluorescence quantum yield. If the presence of bulky POSS groups leads to the formation of “J” aggregates in the solid state, then the solid state fluorescence quantum yields will be improved significantly. Otherwise, if the bulky POSS groups cause “H” type aggregation of the molecules, the solid state fluorescence quantum yields will be small.
Co-reporter:Wenmiao Chen, Zhen Dai, Haiquan Liu, Heyuan Liu, Yan Shi, Xiyou Li
Journal of Luminescence 2015 Volume 168() pp:192-198
Publication Date(Web):December 2015
DOI:10.1016/j.jlumin.2015.07.046
•Intramolecular electron and energy transfer within a pyrene-perylenediimide dyad are studied.•The energy and electron transfer are competitive in solution and in polymer matrixes.•The rigid environment favors energy transfer rather than electron transfer.To investigate the effects of polymer matrixes on the competition between energy and electron transfer, a covalently linked pyrene-perylenediimide dyad (PDI-PY) has been prepared. Competition between the energy and electron transfer from PY to PDI within PDI-PY is revealed by steady state absorption and fluorescence spectra, as well as time resolved fluorescence spectra. Polar solvents accelerate the electron transfer while non-polar solvents favor the energy transfer. When PDI-PY is embedded in a non-polar polymer matrix, the energy transfer becomes the only photoinduced process between PY and PDI, whereas the electron transfer is almost completely hindered. In a polar polymer matrix, the energy transfer is still a dominating process, but with a remarkably decreased efficiency. The electron transfer in a polar polymer matrix is much slower and less efficient with respect to that in solutions, but faster and more efficient than that in non-polar polymer matrixes. This result suggests that polymer matrixes are ideal environment for constructing light harvesting systems, which in some case can reduce the disturbance from electron transfer.
Co-reporter:Ruimin Zhu;Yingyuan Zhao;Tingting Sun;Heyuan Liu
Colloid and Polymer Science 2015 Volume 293( Issue 9) pp:2469-2475
Publication Date(Web):2015 September
DOI:10.1007/s00396-015-3639-z
Photoinduced electron transfer (PET) between self-assembled trans- or cis-isomer of 4,4′-stilbenedicarboxylic acid (SDBA) and [N,N′-di(2-(trimethylammoniumiodide)ethylene)]perylenediimide (PDI-I) in water has been investigated. Both trans-SDBA and cis-SDBA molecules can form stable complexes with columnar PDI-I aggregates in water with a 1:1 stoichiometry via ionic interactions, but the complex of cis-isomer is more stable as revealed by the UV-vis absorption and fluorescence spectroscopy. The electrochemical experiments suggest that cis-SDBA is a better electron donor than its trans-isomer. However, fluorescence quenching experiments suggest that the electron transfer from trans-SDBA is more efficient than that from cis-SDBA, which is obviously contradictory to the results of binding constant and the electrochemical experiments. The contradictory results can be attributed to that the columnar aggregates (PDI-I)n are utterly destroyed in cis-SDBA-(PDI-I)n system caused by stronger ionic interaction between cis-SDBA and (PDI-I)n. Also, the bending conformation of cis-SDBA probably results in a larger distance between cis-SDBA and the surface of (PDI-I)n. The results of this research suggest that the electron transfer can be tuned by the aggregation and/or configuration of the donors and acceptors.
Co-reporter:Chengguang Gao;Lin Xue;Yuhan Chen
Colloid and Polymer Science 2015 Volume 293( Issue 1) pp:35-48
Publication Date(Web):2015 January
DOI:10.1007/s00396-014-3388-4
Two new perylenetetracarboxylic diimide (PDI) derivatives, namely, trimer 1 and trimer 2, composed of three PDI units with different tail groups, are prepared. Solubility of these two trimers is significantly different due to the different tail groups. The aggregation behavior of these two compounds in solution was investigated using absorption and fluorescence spectra. The results indicate that both trimers 1 and 2 can form large molecular aggregates via an intermolecular process in either good solvent or poor solvent. Trimer 1 can form gel in a mixed solvent of methanol and tetrahydrofuran (THF), while trimer 2 can only form gel in non-polar solvents, such as hexane and toluene. This can be ascribed to the multiple long alkyl chains in trimer 2, which have introduced extra hydrophobic interactions besides the π–π interactions between the molecules of trimer 2. The morphology examination of the dried gel of trimer 1 by atomic force microscopy (AFM) reveals simply long fibers. But, the dried gel of timer 2 shows network-like morphology, which can be ascribed to the hydrophobic interactions between the multiple alkyl chains.
Co-reporter:Heyuan Liu, Li Shen, Zhaozhen Cao and Xiyou Li
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 31) pp:16399-16406
Publication Date(Web):14 Apr 2014
DOI:10.1039/C4CP01002G
Covalently linked perylenetetracarboxylic diimide (PDI) dimers (D1 and D2) and trimers (T1 and T2) with slipped “face-to-face” stacked structure are prepared and their molecular structures are characterized by 1H NMR, MALDI-TOF mass spectroscopy and elemental analysis. The rigid molecular structures of these compounds make it easier to establish a direct correlation between the aggregate structure and the photophysical properties. The minimized molecular structures of these compounds reveal that they are all “face-to-face” stacked aggregates with large longitudinal displacement. Their absorption spectra show red-shifted bands, suggesting the presence of “J” type excitonic coupling between the PDI subunits in these compounds. However, their steady state and time resolved fluorescence spectra revealed that the emission from the “excimer-like” states dominates the fluorescence of these compounds, this is similar to that of “H-type” aggregates and may be ascribed to the “face-to-face” stacked structure. In the fluorescence spectra of these compounds, a minor “J-type” emission can be identified for the compounds with a relatively large longitudinal displacement. An increase in the number of subunits in one aggregate from 2 to 3 also brings about distinctive changes in their photophysical properties, which can be ascribed to the changes in the stacking structure caused by the steric hindrance.
Co-reporter:Jingang Song, Qingwen Tian, Jian Gao, Haixia Wu, Yanli Chen and Xiyou Li
CrystEngComm 2014 vol. 16(Issue 7) pp:1277-1286
Publication Date(Web):28 Nov 2013
DOI:10.1039/C3CE41977K
Langmuir monolayers of two amphiphilic perylene tetracarboxylic diimide (PDI) derivatives, PDI-1 and PDI-2, which are modified with different numbers of hydrophilic polyoxyethylene/hydrophobic alkoxy side-chains, have been used as not only organic templates but also good functional organic materials to produce the first examples of rose- and petal-like nano-particle arrays of cadmium sulfide (CdS)–PDI composites with a controllable and tunable size (from 40, 60 to 80 nm for nano-roses; from 20 to 30 nm for nano-petals), respectively. These newly fabricated CdS–PDI hybrid nanostructures were comparatively studied using a wide range of methods including SEM, TEM, electronic absorption, fluorescence emission and X-ray diffraction analysis. The crystalline regions for CdS were identified to be hexagonal wurtzite with (101) and (001) face preferred growth on the PDI-1 and PDI-2 monolayers, respectively, associated with the polyoxyethylene side chains architecture changing from parallel to the subphase surface for PDI-1 to perpendicular to the subphase surface for PDI-2. Furthermore, electron-transfer from PDI molecules to CdS nanocrystals is established by both quenching the photoluminescence intensity and changing the lifetime of photoluminescence emission of PDI in the hybrid nanoparticle arrays. In particular, a significantly enhanced conductivity for both nano-roses and nano-petals of CdS–PDI nanocomposites was achieved, relative to that of the individual component, due to the existence of the densely packed molecular architecture in the film matrix and the large interfacial area between the two components that removed the charge transporting bottleneck by creating an interpenetrating network of the hybrid materials, implying the potential of providing synergetic semiconducting properties of the present hybrid organic–inorganic nanomaterials.
Co-reporter:Yan Shi, Xiyou Li
Organic Electronics 2014 Volume 15(Issue 1) pp:286-293
Publication Date(Web):January 2014
DOI:10.1016/j.orgel.2013.11.017
•A kind of new ambipolar organic semiconductor for high performance OTFTs is developed.•Extending on π-conjugation network tuned the HOMO and LUMO energy levels efficiently.•Thin solid films of this new material can be fabricated by solution-processed method.•Air-stable electron and hole mobilities of 1.7 × 10−1 and 2.3 × 10−4 cm2 V−1 s−1 were achieved.A soluble binuclear phthalocyaninato copper (II) complex, Cu2[Pc(COOC8H17)6]2 (1), with planar molecular structure and extended conjugation system, has been designed and synthesized. By fusing two phthalocyanine rings side by side and introducing electron withdrawing groups at periphery positions, the energy levels of HOMO and LUMO have been tuned successfully into the range of an air-stable ambipolar organic semiconductor required as revealed by the electrochemical studies. With the help of a solution-based quasi-Langmuir–Shäfer (QLS) method, thin solid films of this compound were fabricated and organic field effect transistors (OFETs) based on these QLS thin solid films were constructed. Because of the promising electrochemical properties as well as the high ordered packing structure of the molecules in the thin solid films, the OFETs performed excellent ambipolar operating properties, with the electron and hole mobility in air as high as 1.7 × 10−1 and 2.3 × 10−4 cm2 V−1 s−1, respectively. For comparison purpose, mononuclear compound Cu[Pc(COOC8H17)8] (2) was comparatively studied. The QLS thin solid films of this compound possess similar ordered structure with that of Cu2[Pc(COOC8H17)6]2 (1), but the OFETs based on the thin solid films of this compound can only show n-type properties under nitrogen atmosphere with an extremely small electron mobility of 1.6 × 10−4 cm2 V−1 s−1. This result suggests that extension on the conjugation system of an aromatic compound with multiple electron withdrawing groups can tune the molecule into an air stable ambipolar organic semiconductor.Graphical abstract
Co-reporter:Limin Wang, Yan Shi, Yingyuan Zhao, Heyuan Liu, Xiyou Li, Ming Bai
Journal of Molecular Structure 2014 Volumes 1056–1057() pp:339-346
Publication Date(Web):6 January 2014
DOI:10.1016/j.molstruc.2013.10.004
•Three new naphthalic anhydride compounds with linear triphenylamino oligomer were prepared.•The enhanced electron donating ability of the donor leads to excited state changes from ICT state to electron transfer.•Theoretical calculation reveals that a higher ICT states may responsible for the weak emission of 3.In this paper, the “push–pull” molecules consisting of different number of triphenylamino groups and 1,8-naphthalic anhydride ring were designed and synthesized. The UV–vis absorption and emission spectra of these compounds were recorded. Along with the increase on the number of the electron donating triphenylamino groups, both the absorption and emission bands show significant red shift. More importantly, the fluorescence quantum yields drop sharply along with the increase on the number of triphenylamino groups. The molecular structure, the frontier molecular orbital energies and the energy gaps between the highest occupied molecular orbital (HOMO) and the lowest un-occupied molecular orbital (LUMO) were calculated with DFT method. The calculated results indicate that the connection of more electron donating triphenylamino groups in molecule caused a change for the first excited state from an intramolecular charge transfer (ICT) state to an intramolecular electron transfer state (ET). This change on the first excited state has led to the fluorescence quenching.
Co-reporter:Li Shen, Yuhan Chen, Xiyou Li, Jun Gao
Journal of Molecular Graphics and Modelling 2014 Volume 51() pp:86-96
Publication Date(Web):June 2014
DOI:10.1016/j.jmgm.2014.04.017
•Tetracene stabilities were discussed based on frontier molecular orbital energies.•Singlet fission ability was discussed based on SF activation energies.•Electron-withdrawing groups lead to high stabilities.•Electron-withdrawing groups at the α-position lead to smaller SF activation energies.Tetracene is well known for its high singlet fission (SF) efficiency, which could be used to enhance the energy conversion efficiency in solar cells. However, its photoinstability toward oxygen must be improved before it can be used as a light-harvesting component. In this work, a series of substituted tetracenes were designed to identify tetracene compounds with not only good stability toward oxidation but also small SF activation energies. The stabilities were evaluated using the frontier molecular orbital energies, whereas the SF activation energies were deduced from the energy differences between the first excited singlet state and twice the first excited triplet state. Substitution strategies on tetracene are proposed for the purpose of simultaneously improving stability and reducing the SF activation energy.
Co-reporter:Yuhan Chen, Li Shen, and Xiyou Li
The Journal of Physical Chemistry A 2014 Volume 118(Issue 30) pp:5700-5708
Publication Date(Web):July 9, 2014
DOI:10.1021/jp503114b
The effects of the introduction of an sp2-hybridized nitrogen atom (═N—) and thiophene ring on the structure geometries, frontier molecular orbital energies, and excited state energies related to singlet fission (SF) for some tetracene and pentacene derivatives were theoretically investigated by quantum chemical methods. The introduction of a nitrogen atom significantly decreases the energies of frontier molecular orbitals and hence improves their stabilities in air and light illumination. More importantly, it is helpful for reducing the energy loss of the exothermic singlet fission of pentacene derivatives. For fused benzene-thiophene structures, the (α, β) connection pattern could stabilize the frontier molecular orbitals, while the (β, β) connection pattern can promote the thermodynamic driving force of singlet fission. These facts provide a theoretical ground for rational design of SF materials.
Co-reporter:Yingyuan Zhao
Colloid and Polymer Science 2014 Volume 292( Issue 3) pp:687-698
Publication Date(Web):2014 March
DOI:10.1007/s00396-013-3100-0
A group of novel fluorescent surfactants, N-n-alkyl-4-(1-methylpiperazine)-1,8-naphthalimide iodine [Cnndi]I (n = 8, 10, and 12), have been synthesized and their aggregation behavior in aqueous solution have been explored by surface tension, electric conductivity, hydrogen-1 NMR spectra, absorption, and fluorescence spectra. Compared with traditional cationic surfactants, the [Cnndi]I have a rather lower critical micelle concentration and higher surface activity. Absorption and fluorescence spectra were proved to be facile method to monitor directly the aggregation states of fluorescent surfactant molecules in solution and revealed clearly the formation of face-to-face stacked structure of the [Cnndi]I molecules driven by the π–π interactions. The micelle formation process for [Cnndi]I was demonstrated to be enthalpy-driven in the temperature range investigated. Possible aggregation process was given based on the experimental results. The combination of dye and surfactant provides a way for monitoring the formation process of micelle directly by fluorescence spectra.
Co-reporter:Yingyuan Zhao
Colloid and Polymer Science 2014 Volume 292( Issue 7) pp:1577-1584
Publication Date(Web):2014 July
DOI:10.1007/s00396-014-3209-9
A novel fluorescent probe labeled with cation, N-n-alkyl-4-(1-methylpiperazine)-1,8-naphthalimide iodide ([C8ndi]I), has been applied as a colorimetric and fluorometric probe for detecting the micellization of anionic surfactants. The critical micellization concentration (cmc) of anionic surfactants can be conveniently determined by the change on absorption and fluorescence spectra of [C8ndi]I. The probe displays highly sensitive and selective spectroscopic responses accompanied with distinctive color change (from colorless to light green). These methods are proved to be reliable as the results are in accordance with those of the standard methods. Besides the advantage of visual detection, the multiple spectroscopic methods (absorption and fluorescence) by using [C8ndi]I as probe are also simple and convenient. One can choose any spectroscopic parameter, such as position or intensity of the absorption and emission peaks, to monitor the micelle formation process of anionic surfactants.
Co-reporter:Guiju Qi, Lilin Jiang, Yingyuan Zhao, Yanqiang Yang and Xiyou Li
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 40) pp:17342-17353
Publication Date(Web):22 Aug 2013
DOI:10.1039/C3CP52941J
A series of novel light-harvesting compounds (namely PO–PN, PO–PO–PN and PO–PO–PO–PN) were synthesized with a linear-shaped phenoxy group-substituted perylenetetracarboxylic diimide (PO) oligomer as donor and a pyrrolidinyl group-substituted perylenetetracarboxylic diimide (PN) as acceptor. The photophysical properties of these linear-shaped compounds are investigated by steady state electronic absorption, fluorescence spectra and lifetime measurements. The ground state interactions between the neighbor PO subunits within these three compounds are weak. No matter which PO subunit is excited in these linear molecules, the excitation energy is finally collected by the PN subunit. The excitation energy can transfer as long as 47 Å without any decrease in efficiency. The energy transfer rate constants determined by femtosecond transient absorption experiments are fast and close to that of the energy transfer from B800 to B850 in LH II of natural photosynthesis.
Co-reporter:Lin Xue;Yan Shi;Liangliang Zhang ; Xiyou Li
ChemPhysChem 2013 Volume 14( Issue 14) pp:3319-3326
Publication Date(Web):
DOI:10.1002/cphc.201300602
Abstract
A perylenetetracarboxylic diimide hexamer (6PDI) and a dimer (2PDI) linked with the same hexaphenylbenzene group were prepared, and the structures were fully characterized by 1H NMR spectroscopy, mass spectrometry, and elemental analysis. Due to the similar molecular structure of these two compounds, similar interactions between/among the PDI subunits as well as similar photophysical properties are expected. However, the stationary UV/Vis absorption spectra reveal that the interactions among/between the PDI subunits in 6PDI are significantly stronger than those in 2PDI. This can be attributed to blocked rotation along the long axis of the PDI subunits in 6PDI due to steric hindrance of the two neighboring PDI subunits. The stronger interactions among the PDI subunits in 6PDI lead to long-wavelength emission, which can be assigned to “excimer-like” excited states. A similar conclusion can also be deduced from the fluorescence quantum yields and the fluorescence lifetimes. Electrochemical studies revealed that interactions between/among the PDI subunits in both 2PDI and 6PDI are still in the range of weak interactions. Ultrafast transient anisotropy decay dynamics revealed that excitation delocalization between the PDI subunits within 2PDI and 6PDI is quick and efficient. More interestingly, delocalization is faster in 6PDI than in 2PDI, probably because of the stronger interactions among the PDI subunits in the former.
Co-reporter:Li Chen, Rui Hu, Jian Xu, Shuangqing Wang, Xiyou Li, Shayu Li, Guoqiang Yang
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2013 Volume 105() pp:577-581
Publication Date(Web):15 March 2013
DOI:10.1016/j.saa.2012.12.063
The third-order nonlinear optical properties of a series of phthalocyanine–porphyrin complexes containing a sandwich-type bis(phthalocyaninato) europium(III) core and one or two zinc(II) porphyrin unit(s) were investigated by Z-scan techniques at 1064 nm. The second-order molecular hyperpolarizabilities of these complexes are in the order of 10−30 esu. The enhanced nonlinear properties are induced by the high delocalization of the electrons in the sandwich molecular structure, which may result in charge transfer between the central metal and the phthalocyanine ligands.Graphical abstractThird-order nonlinear optical properties of a series of phthalocyanine–porphyrin complexes containing a sandwich-type bis(phthalocyaninato) europium(III) core and one or two zinc(II) porphyrin unit(s) were investigated by Z-scan techniques at 1064 nm. The second-order molecular hyperpolarizabilities of these complexes are in the order of 10−30 esu.Highlights► Third-order nonlinear properties of porphyrin-bisphthalocyanines were investigated. ► Porphyrin-bisphthalocyanines are good materials with nonlinear optical properties. ► The enhanced nonlinearities are induced by high electron density and charge transfer.
Co-reporter:Haixia Wang, Lin Yang, Wenbo Zhang, Yu Zhou, Bing Zhao, Xiyou Li
Inorganica Chimica Acta 2012 Volume 381() pp:111-116
Publication Date(Web):15 February 2012
DOI:10.1016/j.ica.2011.07.039
A novel fluorescent probe with naphthalimide as fluorophore and di(2-picolyl)amino unit as receptor for Cu(II) was designed and synthesized. In water/acetonitrile solution, the presence of Cu2+ ions induced significant blue shift on the maximum absorption band as well as complete fluorescence quenching due to the formation of a 1:1 metal–ligand complex. It exhibited high selectivity toward Cu(II) and no interference from other metal ions was observed. The structure of the complex was characterized by single crystal X-ray diffraction experiments. The results of this research demonstrate successfully that excellent sensing properties can be achieved by a small organic compound with very simple structure. This is also the first single crystal structure which reveals directly the coordination pattern of fluorescent probe bearing di-2-picoly-amine unit with Cu(II).Graphical abstractA 1,8-naphthalimide fluorescent probe bearing di(2-picolyl)amino unit was designed and synthesized based on internal charge transfer. The resulted probe showed high selectivity towards Cu2+ over other transition metal ions in aqueous acetonitrile solution. The structure of the 1:1 metal–ligand complex was revealed for the first time by single crystal XRD experiments.Highlights► A 1,8-naphthalimide fluorescent probe based on internal charge transfer was designed. ► The probe shows high selectivity towards Cu2+ over other transition metal ions. ► The structure of the 1:1 metal–ligand complex was revealed for the first time by XRD experiments.
Co-reporter:Jun Zhou, Lin Xue, Yan Shi, Xiyou Li, Qingbin Xue, and Shuangqing Wang
Langmuir 2012 Volume 28(Issue 40) pp:14386-14394
Publication Date(Web):September 18, 2012
DOI:10.1021/la303061r
Three perylenetetracarboxylic diimide (PDI) derivatives consisting of a short oligo(l-lactic acid)n (O-LLA) segment at one imide nitrogen were synthesized. The polymers were characterized by 1H NMR and gel permeation chromatography (GPC). Their properties were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) experiments, scanning electron microscopy (SEM), electronic absorption, and circular dichroism (CD) spectroscopy. The self-assembly behavior of these PDIs in molten state as well as in solvent was examined. It was found that the structure and the morphology of the self-assembly of these polymers depend on the relative length of the O-LLA segment. The PDIs with longer O-LLA chains present liquid crystal properties with an obvious phase transition from disordered phase to an ordered (α) phase, which cannot be found for the PDIs with short O-LLA segments. The long O-LLA segments also caused a left-handed helicity for the aggregates of the PDIs from solution. This research demonstrated that one can control the order, aggregation mode, and morphology of the molecular aggregates by changing the length of the O-LLA chains. This information can be useful in the design of new organic materials that exhibit molecular aggregation.
Co-reporter:Guiju Qi, Renjie Li, Limin Wang, Xiyou Li
Journal of Photochemistry and Photobiology A: Chemistry 2012 Volume 239() pp:28-36
Publication Date(Web):1 July 2012
DOI:10.1016/j.jphotochem.2012.04.019
We report here a series of linear perylenetetracarboxylic imide derivatives (PDIs), abbreviated as PN, PO–PN and PO–PO–PN, with high molar extinction coefficients and broad absorptions in visible to near-infrared (NIR) region. These new dyes are designed for the use as sensitizers in dye sensitized solar cell (DSSC) with a motive to enhance the optical absorption of mesoporous titania film and light collecting efficiency. Energy transfer from PO parts to PN unit is revealed by absorption and fluorescence spectra. The energy transfer efficiencies estimated from the fluorescence quenching efficiencies are almost 100%. The mesoporous titania film loaded with these dyes exhibit broad absorption bands in the visible to NIR region. The IPCE spectra revealed distinctively the contribution of PO parts to the solar energy conversion, which suggests that the intramolecular singlet–singlet energy transfer is a reliable strategy to improve the light absorbing abilities of a dye adsorbed on titania films. The necessary efforts to further improve the efficiency of cells by the molecular design of PDI derivatives are discussed.Graphical abstractHighlights► A series of linear D–A perylene dyes were developed for dye-sensitized solar cells. ► The extended π-conjugation improves the light-harvesting capability of perylene dyes. ► The energy transfer efficiencies from the donor parts to acceptor unit are almost 100%. ► The energy transfer contributes to the solar energy conversion process.
Co-reporter:Junqian Feng, Delou Wang, Shuangqing Wang, Liangliang Zhang, Xiyou Li
Dyes and Pigments 2011 Volume 89(Issue 1) pp:23-28
Publication Date(Web):April 2011
DOI:10.1016/j.dyepig.2010.08.014
Two novel fluorescent dyes based on perylenetetracarboxylic diimde (PDI) with methylpyridine or methylquinoline group at the carbonyl position were designed and synthesized. Their structures were confirmed by 1H NMR, 13C NMR, MS, and elementary analysis. The resulted new compounds show longer wavelength absorption with relative high extinction coefficient and red-shifted emission with high fluorescence quantum yields. These compounds can further react with BF3·Et2O to form novel dyes containing BODIPY (difluoroboradiazaindacene) analogue unit, by which both the absorption and emission maximum have been red-shifted further. The minimized structures based on density function theory (DFT) calculation show planar configurations for the compounds. The calculated molecular orbital correlates well with their red-shifted absorption and emission spectra.
Co-reporter:Haixia Wu, Haixia Wang, Lin Xue, Xiyou Li
Journal of Colloid and Interface Science 2011 Volume 353(Issue 2) pp:476-481
Publication Date(Web):15 January 2011
DOI:10.1016/j.jcis.2010.09.069
A perylenetetracarboxylic diimide (PDI) compound with an attached hydrophilic polyoxyethylene group at the imide nitrogen position was designed and synthesized. Photoinduced electron and energy transfer between coumarin 153 (C-153) and PDI in a ternary microemulsion with an ionic liquid (bmimPF6/TX-100/H2O) were investigated by steady state electronic absorption and fluorescence spectroscopy. The results revealed that both PDI and C-153 resided at the interface between the surfactant TX-100 and the ionic liquid bmimPF6 in the ternary microemulsions. The absorption spectra suggested no interactions between C-153 and PDI in the ground states, but the fluorescence spectra revealed the presence of an efficient electron transfer and a less efficient energy transfer from C-153 to PDI. Moreover, the electron transfer was much more efficient in microemulsions than that in homogeneous conventional organic solvents due to the unique micro-environment of the microemulsion.Graphical abstractBoth C-153 and PDI stay at the interface between IL and TX-100 in confined microemulsions. The fluorescence quenching of C-153 by PDI is much more efficient in microemulsions than that in homogeneous conventional organic solvents by accelerating the electron transfer process.Research highlights► A perylenetetracarboxylic diimide (PDI) which can dissolve in ionic liquids (ILs) has been prepared. ► PDI adsorbs at the interface between IL and the surfactant TX-100 in the microemulsions. ► The additive coumarin C-153 transfers energy and electrons efficiently to PDI under photo-excitation. ► The microemulsion environment favors the electron transfer process.
Co-reporter:Haixia Wang, Haixia Wu, Lin Xue, Yan Shi and Xiyou Li
Organic & Biomolecular Chemistry 2011 vol. 9(Issue 15) pp:5436-5444
Publication Date(Web):28 Apr 2011
DOI:10.1039/C1OB05481C
A novel 4-amino-1,8-naphthalimide (NDI) with two different metal cation receptors connected at 4-amino or imide nitrogen positions respectively was designed and prepared. Significant internal charge transfer (ICT) as well as photoinduced electron transfer (PET) from the receptors to NDI is revealed by the shifted UV-vis absorption spectra and significant fluorescence quenching. Both Zn2+ and Cu2+ can coordinate selectively with the two cation receptors in this molecule with different affinities. The coordination of Zn2+ with the receptor at imide nitrogen hindered the PET process and accordingly restored the quenched fluorescence of NDI. But the coordination of Zn2+ at 4-amino position blocked the ICT process and caused significant blue-shift on the absorption peak with the fluorescence intensity unaffected. Similarly, coordination of Cu2+ with the receptor at imide nitrogen can block the PET process, but can not restore the quenched fluorescence of compound 3 due to the paramagnetic properties of Cu2+, which quench the fluorescence significantly instead. With Cu2+ and Zn2+ as two chemical inputs and absorption or fluorescence as output, several logic gate operations, such as OR, NOR and INHIBIT, can be achieved.
Co-reporter:Junqian Feng;Delou Wang;Hailong Wang;Daopeng Zhang;Liangliang Zhang
Journal of Physical Organic Chemistry 2011 Volume 24( Issue 8) pp:621-629
Publication Date(Web):
DOI:10.1002/poc.1799
Abstract
Four compounds 1–4 connected with cyclic amino groups at the bay positions of perylenetetracarboxylic diimide (PDI) have been prepared and the isomers with 1,7- and 1,6-substituted PDIs were successfully separated by conventional column chromatography. The structures of 1,7-dipyrrolidinyl-substituted PDI (1) and 1,7-dipiperidinyl-substituted PDI (3) were further characterized by single crystal X-ray diffraction experiments. The crystal structure revealed that the small difference in the molecular structure has caused significant difference on the absorption and emission spectra as well as the electrochemical properties. The shorter bond length of C1N3, together with the more sp2 hybrid atomic orbital characteristics of the nitrogen atom in pyrrolidine relative to those in piperidine is found to be responsible for this large property difference between 1 and 3. Copyright © 2010 John Wiley & Sons, Ltd.
Co-reporter:Haixia Wu, Lin Xue, Yan Shi, Yanli Chen, and Xiyou Li
Langmuir 2011 Volume 27(Issue 6) pp:3074-3082
Publication Date(Web):February 14, 2011
DOI:10.1021/la104888p
Three new perylenetetracarboxylic diimide (PDI) compounds substituted with hydrophobic and/or hydrophilic groups at the two imide nitrogen positions, namely N,N′-di[N-(4-aminophenyl)-3,4,5-tris(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)benzamide]-1,7-di(4-tert-butylphenoxy)perylene-3,4;9,10-tetracarboxylic diimide (1), N,N′-di[N-amido-3,4,5-tris(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)benzamide]-1,7-di(4-tert-butylphenoxy)perylene-3,4;9,10-tetracarboxylic diimide (2), and N-amido-3,4,5-tris(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)benzamide-N′-amido-3,4,5-tris(dodecyloxy)benzamide-1,7-di(4-tert-butylphenoxy)perylene-3,4;9,10-tetracarboxylate diimide (3), have been designed and prepared. The gelating abilities of them in different solvents have been investigated, and the results indicated that compounds 1 and 3 can form fluorescent gels whereas compound 2 cannot. The properties of the gels of compounds 1 and 3 have been investigated by UV−vis absorption and emission spectra. The results indicate that the gel of compound 1 is composed of H-aggregates, whereas the gel of compound 3 is composed of J-aggregates. The reversible transformation between gel and solution states induced by temperature change is observed. The structure of dried gel has been investigated by X-ray diffraction (XRD) experiments, and the morphology has been measured by atomic force microscopy (AFM). This research revealed successfully the crucial roles of amphiphilic properties and the side-chain conformations in controlling the gelating properties of PDI molecules. This information may be useful for the design of novel organogels based on perylenetetracarboxylic diimides.
Co-reporter:Haixia Wang, Delou Wang, Qi Wang, Xiyou Li and Christoph A. Schalley
Organic & Biomolecular Chemistry 2010 vol. 8(Issue 5) pp:1017-1026
Publication Date(Web):05 Jan 2010
DOI:10.1039/B921342B
Two novel “turn-on” fluorescent probes with perylene tetracarboxylic diimide (PDI) as the fluorophore and two different di-(2-picolyl)-amine (DPA) groups as the metal ion receptor (PDI-1 and PDI-2) were successfully synthesized with satisfactory yields. PDI-1 exhibited high selectivity toward Ni2+ in the presence of various other metal cations including Zn2+, Cd2+ and Cu2+ which were expected to interfere significantly. A 1:2 stoichiometry was found for the complex formed by PDI-1 and Ni2+ by a Job's plot and by non-linear least square fitting of the fluorescence titration curves. By introducing an extra diamino ethylene group between DPA and the phenyl bridge, the receptor was modified and the high selectivity of the sensor toward Ni2+ shifted to Fe3+. The enhancement factor of the fluorescence response of PDI-2 to Fe3+ was as high as 138. The binding behavior of the receptors in these two compounds is affected significantly by the PDI fluorophores. Most interestingly, both Ni2+ and Fe3+ are paramagnetic metal ions, which are known as fluorescence quenchers and are rarely targeted with “turn-on” fluorescence probes. This result suggests that PDIs are favorable fluorophores for a “turn-on” fluorescence probe for paramagnetic transition metal ions because of their high oxidation potential.
Co-reporter:Haixia Wu, Haixia Wang, Lin Xue, Yan Shi, and Xiyou Li
The Journal of Physical Chemistry B 2010 Volume 114(Issue 45) pp:14420-14425
Publication Date(Web):April 8, 2010
DOI:10.1021/jp101240a
Three perylene tetracarboxylic diimide (PDI) compounds, namely, N,N′- di(2-N′′,N′′-dimethylamino)ethylperylene-3,4:9,10-tetracarboxylic diimide (1), N,N′-di(2-N′′,N′′-dimethylamino)propylperylene-3,4:9,10-tetracarboxylic diimide (2), and N,N′- dicyclohexyl-1,7-pyrrolidinylperylene-3,4:9,10-tetracarboxylic diimide (3), have been desgined and prepared. Their photophyscial properties in room-temperature ionic liquid (RTILs) were studied by steady-state absorption and emission spectra and fluorescence lifetime measurements. The intramolecular photoinduced electron transfer from dimethylamine to PDI in 1 and 2 has been efficiently hindered because of the solvation of RTILs. A two-conformation mechanism for the PET in 1 and 2 is proposed, which explains the results of the fluorescence lifetime measurements well. The solvation of RTILs to 3 resembled that of a normal polar organic solvent with polarity larger than that of DMF.
Co-reporter:Yanli Chen, Lina Chen, Guiju Qi, Haixia Wu, Yuexing Zhang, Lin Xue, Peihua Zhu, Pan Ma and Xiyou Li
Langmuir 2010 Volume 26(Issue 15) pp:12473-12478
Publication Date(Web):July 2, 2010
DOI:10.1021/la102094d
A perylenetetracarboxylic diimide derivative, N-n-hexyl-N′-(2-hydroxyethyl)-1,7-di(4′-t-butyl)phenoxy-perylene-3,4:9,10-tetracarboxylic diimide (HO-PDI), was synthesized and self-assembled as a monolayer thin solid film on the modified surface of a quartz substrate by an ester bond between −OH groups of HO-PDI molecules and −COOH groups of p-phthalic acid grafted onto the hydrophilic pretreated SiO2 surface. An analysis of the spectral change revealed the J-aggregate nature of HO-PDI molecules in the obtained thin solid film. With this thin solid film of HO-PDI as a template, CdS nanoparticles were deposited on it in situ, which were further characterized by electronic absorption, fluorescence, and energy-dispersive X-ray spectroscopy (EDS). The morphology of CdS nanoparticles is disklike, and the diameter is ca. 140 nm as determined by atomic force microscopy (AFM). Furthermore, electron transfer between the organic layer and CdS nanoparticles was deduced through fluorescence quenching and theoretical analysis.
Co-reporter:Baolong Liang, Yuexing Zhang, Yanfeng Wang, Wei Xu, Xiyou Li
Journal of Molecular Structure 2009 Volume 917(2–3) pp:133-141
Publication Date(Web):15 January 2009
DOI:10.1016/j.molstruc.2008.07.005
Density functional theory (DFT) calculations were carried out to describe the molecular structures, molecular orbitals, atomic charges, UV–vis absorption and IR spectra of 1,7-disubstituted-perylene-3,4;9,10-tetracarboxylic diimide (1,7-disubstituted PDI) with different substituents, namely unsubstituted PDI (PDI-0), 1,7-dimethylthio PDI (S-a), 1,7-dithiophenyl PDI (S-b), 1,7-dimethoxy PDI (O-a), 1,7-diphenoxy PDI (O-b), 1,7-dimethylamino PDI (N-a), 1-methoxy-7-methylthio PDI (OS-a), 1-phenoxy-7-thiophenyl PDI (OS-b), and 1-methoxy-7-methylamino PDI (ON-a). Good consistency was found between the calculated results and experimental data. The substitutional effects of the side groups on both the structure twisting and the electronic absorption spectra depend mainly on the linking atoms rather than the side groups as a whole. The charge distribution, the ionization energy (IE) and electronic affinity (EA) are found to be varied significantly along with the change of the electron donating abilities of the side groups. The effects of the side groups on the vibration spectra of these compounds are also discussed based on both the simulated and experimental results. The present work, representing the first systemic DFT study on the PDI derivatives, sheds further light on clearly understanding structure and spectroscopic properties of PDI compounds.
Co-reporter:Delou Wang, Yan shi, Chuntao Zhao, Baolong Liang, Xiyou Li
Journal of Molecular Structure 2009 938(1–3) pp: 245-253
Publication Date(Web):
DOI:10.1016/j.molstruc.2009.09.035
Co-reporter:Wei Xu;Hailong Chen;Yanfeng Wang;Chuntao Zhao Dr.;Shuangqing Wang Dr.;Yuxiang Weng Dr.
ChemPhysChem 2008 Volume 9( Issue 10) pp:1409-1415
Publication Date(Web):
DOI:10.1002/cphc.200800028
Abstract
Two compounds containing a porphyrin dimer and a perylene tetracarboxylic diimide (PDI) linked by phenyl (1) or ethylene groups (2) are prepared. The photophysical properties of these two compounds are investigated by steady state electronic absorption and fluorescence spectra and lifetime measurements. The ground state absorption spectra reveal intense interactions between the porphyrin units within the porphyrin dimer, but no interactions between the porphyirn dimer and PDI. The fluorescence spectra suggest efficient energy transfer from PDI to porphyrin accompanied by less efficient electron transfer from porphyrin to PDI. The energy transfer is not affected by the dimeric structure of porphyrin or the linkage between the porphyrin dimer and PDI. However, the electron transfer from porphyrin to PDI is significantly affected by either the linkage between the donor and the acceptor or the polarity of the solvents. The dimeric structure of the porphyrin units in these compounds significantly promotes electron transfer in nonpolar, but not in polar solvents.
Co-reporter:Junqian Feng;Yuexing Zhang;Chuntao Zhao;Renjie Li;Wei Xu, ;Jianzhuang Jiang
Chemistry - A European Journal 2008 Volume 14( Issue 23) pp:7000-7010
Publication Date(Web):
DOI:10.1002/chem.200800136
Abstract
Cyclophanes of perylene tetracarboxylic diimides (PDIs) with different substituents at the bay positions, namely four phenoxy groups at the 1,7-positions (1), four piperidinyl groups at the 1,7-positions (2), and eight phenoxy groups at the 1,6,7,12-positions (3) of the two PDI rings, have been synthesized by the condensation of perylene dianhydride with amine in a dilute solution. These novel cyclophanes were characterized by 1H NMR spectroscopy, MALDI-TOF mass spectrometry, electronic absorption spectroscopy, and elemental analysis. The conformational isomers of cyclophanes substituted with four piperidinyl groups at the 1,7-positions (2 a and 2 b) were successfully separated by preparative TLC. The main absorption band of the cyclophanes shifts significantly to the higher energy side in comparison with their monomeric counterparts, which indicates significant π–π interaction between the PDI units in the cyclophanes. Nevertheless, both the electronic absorption and fluorescence spectra of the cyclophanes were found to change along with the number and nature of the side groups at the bay positions of the PDI ring. Time-dependent DFT calculations on the conformational isomers 2 a and 2 b reproduce well their experimental electronic absorption spectra. Electrochemical studies reveal that the first oxidation and reduction potentials of the PDI ring in the cyclophanes increase significantly compared with those of the corresponding monomeric counterparts, in line with the change in the energy of the HOMO and LUMO according to the theoretical calculations.
Co-reporter:Junqian Feng, Baolong Liang, Delou Wang, Haixia Wu, Lin Xue and Xiyou Li
Langmuir 2008 Volume 24(Issue 19) pp:11209-11215
Publication Date(Web):August 27, 2008
DOI:10.1021/la801463u
Three perylene tetracarboxylic diimide (PDI) trimers substituted with different side groups at the bay positions were prepared with the triazine ring as a linkage. The free rotation of C−N−C bonds between the triazine ring and the PDI unit provide these molecules with some flexibility. The UV−vis absorption and fluorescence spectra of these three compounds show different concentration-dependent behaviors, which depend on the side groups at the bay positions. Significant aggregation in organic solvents was revealed by the electronic absorption and emission spectra as well as the fluorescence quantum yield calculation. The aggregation behavior of these compounds in the solid state were investigated by X-ray diffraction (XRD), and the morphology of the aggregates was examined by atomic force microscopy (AFM). The aggregation of trimer 1 with two phenoxy groups at the 1 and 7 positions results in long nanofibers whereas trimers 2 and 3 with dipiperidinyl groups or tetraphenoxyl groups at the bay positions form only particles. The results of this research revealed that PDI trimers with flexible structures can also self-assemble into large ordered aggregates such as those with rigid structure. This information is believed to be useful in the design of novel nanoorganic materials.
Co-reporter:Yongzhong Bian Dr.;Xinghai Chen;Dongying Wang;Chi-Fung Choi;Yang Zhou;Peihua Zhu Dr.;Dennis K. P. Ng ;Jianzhuang Jiang ;Yuxiang Weng
Chemistry - A European Journal 2007 Volume 13(Issue 15) pp:
Publication Date(Web):16 FEB 2007
DOI:10.1002/chem.200601668
Mixed cyclization of 3-mono-, 4-mono-, or 4,5-di(porphyrinated) phthalonitrile compounds 2, 3, or 6 and unsubstituted phthalonitrile with the half-sandwich complex [EuIII(acac)(Pc)] (Pc=phthalocyaninate, acac=acetylacetonate) as the template in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in n-pentanol afforded novel porphyrin-appended europium(III) bis(phthalocyaninato) complexes 7–9 in 30–40 % yield. These mixed tetrapyrrole triads and tetrad were spectroscopically and electrochemically characterized and their photophysical properties were also investigated with steady-state and transient spectroscopic methods. It has been found that the fluorescence of the porphyrin moiety is quenched effectively by the double-decker unit through an intramolecular photoinduced electron-transfer process, which takes place in several hundred femtoseconds, while the recombination of the charge-separated state occurs in several picoseconds. By using different phthalocyanines containing different numbers of porphyrin substituents at the peripheral or nonperipheral position(s) of the ligand, while the other unsubstituted phthalocyanine remains unchanged in these double-deckers, the effects of the number and the position of the porphyrin substituents on these photophysical processes were also examined.
Co-reporter:Wei Su;Yuexing Zhang ;Chuntao Zhao;Jianzhuang Jiang
ChemPhysChem 2007 Volume 8(Issue 12) pp:1857-1862
Publication Date(Web):6 JUL 2007
DOI:10.1002/cphc.200700246
Three perylene-3,4;9,10-tetracarboxydiimide (PTCDI) compounds with two dodecyloxy or thiododecyl chains attached at the bay positions of the perylene ring, PTCDIs 1–3, were fabricated into nanoassemblies by a solution injection method. The morphologies of these self-assembled nanostructures were determined by transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), and atomic force microscopy (AFM). PTCDI compound 1, with two dodecyloxy groups, forms long, flexible nanowires with an aspect ratio of over 200, while analogue 3, with two thiododecyl groups, self-assembles into spherical particles. In line with these results, PTCDI 2, with one dodecyloxy group and one thiododecyl group, forms nanorods with an aspect ratio of around 20. Electronic absorption and fluorescence spectroscopy results reveal the formation of H-aggregates in the nanostructures of these PTCDI compounds owing to the π–π interaction between the substituted perylene molecules and also suggest a decreasing π–π interaction in the order 1>2>3, which corresponds well with the morphology of the corresponding nanoassemblies. On the basis of DFT calculations, the effect of different substituents at the bay positions of the perylene ring on the π–π interaction between substituted perylene molecules and the morphology of self-assembled nanostructures is rationalized by the differing degree of twisting of the conjugated perylene system caused by the different substituents and the different bending of the alkoxy and thioalkyl groups with respect to the plane of the naphthalene.
Co-reporter:Yanli Chen, Ying Zhang, Peihua Zhu, Yingju Fan, Yongzhong Bian, Xiyou Li, Jianzhuang Jiang
Journal of Colloid and Interface Science 2006 Volume 303(Issue 1) pp:256-263
Publication Date(Web):1 November 2006
DOI:10.1016/j.jcis.2006.07.043
A series of five carefully designed tris(phthalocyaninato) gadolinium triple-decker complexes [Pc(R)8]Gd[Pc(R′)8]Gd[Pc(R″)8] (R=R′=R″=HR=R′=R″=H; R=R′=HR=R′=H, R″=OC8H17R″=OC8H17; R=R″=HR=R″=H, R′=OC8H17R′=OC8H17; R = H, R′=R″=OC8H17R′=R″=OC8H17; R=R′=R″=OC8H17R=R′=R″=OC8H17) (1–5) were prepared and the film forming properties on water surface were systematically investigated. The limited mean molecular area obtained by π–Aπ–A isotherms revealed an “edge-on” conformation for all these compounds. UV–vis absorption spectra showed red-shifted Q bands, indicating the formation of J aggregates and effective intermolecular interaction in solid film. Phthalocyanine rings were found to take tilted orientation with respect to the normal of substrate according to the polarized absorption spectroscopic measurements. Low angle X-ray diffraction results provide direct evidence and therefore clearly clarify the point, for the first time, that unsymmetrical triple-decker molecules pack on the water surface with the unsubstituted phthalocyanine ring set close to the water surface and the substituted phthalocyanine ligand with octyloxy groups lies on the top.
Co-reporter:Yanli Chen, Shuying Zhao, Xiyou Li, Jianzhuang Jiang
Journal of Colloid and Interface Science 2005 Volume 289(Issue 1) pp:200-205
Publication Date(Web):1 September 2005
DOI:10.1016/j.jcis.2005.03.051
Amphiphilic phthalocyanines with one crown ether and three alkyl chain substitutions can form stable monolayers on a water surface. This monolayer can be transferred to a substrate by a vertical dipping method. The arrangement of phthalocyanine molecules in LB films was affected by the length of alkyl chains and the coordination of alkali ions in crown ether. Davydov splitting was observed in the absorption spectra of the LB films of phthalocyanine with the shortest alkyl chain substitutions, and this splitting was affected by the alkali ions in the subphase.
Co-reporter:Yanan Du ; Lilin Jiang ; Jun Zhou ; Guiju Qi ; Xiyou Li ;Yanqiang Yang
Organic Letters () pp:
Publication Date(Web):June 5, 2012
DOI:10.1021/ol300985h
A series of perylenetetracarboxylic diimide (PDI) compounds linked with spirobifluorene have been prepared. The orthogonal configuration of the PDI subunits efficiently hindered their molecular aggregation in solution. Energy transfer from a 1,7-diphenoxyl group substituted PDI (PO-PDI) to a 1,7-dipyrrolidinyl group substituted PDI (PY-PDI) occurred with a large efficiency when PO-PDI was selectively excited, despite the orthogonal orientation of the two units. This observation was in direct conflict with predictions derived from the Förster theory. More interestingly, this efficient energy transfer also occurred in the solid state.
Co-reporter:Guiju Qi, Lilin Jiang, Yingyuan Zhao, Yanqiang Yang and Xiyou Li
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 40) pp:NaN17353-17353
Publication Date(Web):2013/08/22
DOI:10.1039/C3CP52941J
A series of novel light-harvesting compounds (namely PO–PN, PO–PO–PN and PO–PO–PO–PN) were synthesized with a linear-shaped phenoxy group-substituted perylenetetracarboxylic diimide (PO) oligomer as donor and a pyrrolidinyl group-substituted perylenetetracarboxylic diimide (PN) as acceptor. The photophysical properties of these linear-shaped compounds are investigated by steady state electronic absorption, fluorescence spectra and lifetime measurements. The ground state interactions between the neighbor PO subunits within these three compounds are weak. No matter which PO subunit is excited in these linear molecules, the excitation energy is finally collected by the PN subunit. The excitation energy can transfer as long as 47 Å without any decrease in efficiency. The energy transfer rate constants determined by femtosecond transient absorption experiments are fast and close to that of the energy transfer from B800 to B850 in LH II of natural photosynthesis.
Co-reporter:Heyuan Liu, Li Shen, Zhaozhen Cao and Xiyou Li
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 31) pp:NaN16406-16406
Publication Date(Web):2014/04/14
DOI:10.1039/C4CP01002G
Covalently linked perylenetetracarboxylic diimide (PDI) dimers (D1 and D2) and trimers (T1 and T2) with slipped “face-to-face” stacked structure are prepared and their molecular structures are characterized by 1H NMR, MALDI-TOF mass spectroscopy and elemental analysis. The rigid molecular structures of these compounds make it easier to establish a direct correlation between the aggregate structure and the photophysical properties. The minimized molecular structures of these compounds reveal that they are all “face-to-face” stacked aggregates with large longitudinal displacement. Their absorption spectra show red-shifted bands, suggesting the presence of “J” type excitonic coupling between the PDI subunits in these compounds. However, their steady state and time resolved fluorescence spectra revealed that the emission from the “excimer-like” states dominates the fluorescence of these compounds, this is similar to that of “H-type” aggregates and may be ascribed to the “face-to-face” stacked structure. In the fluorescence spectra of these compounds, a minor “J-type” emission can be identified for the compounds with a relatively large longitudinal displacement. An increase in the number of subunits in one aggregate from 2 to 3 also brings about distinctive changes in their photophysical properties, which can be ascribed to the changes in the stacking structure caused by the steric hindrance.
Co-reporter:Heyuan Liu, Valerie M. Nichols, Li Shen, Setarah Jahansouz, Yuhan Chen, Kerry M. Hanson, Christopher J. Bardeen and Xiyou Li
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 9) pp:NaN6531-6531
Publication Date(Web):2015/01/28
DOI:10.1039/C4CP05444J
A covalently linked tetracene dimer has been prepared and its molecular structure is characterized by 1H NMR and MALDI-TOF mass spectroscopy, and elemental analysis. The minimized molecular structure reveals that the tetracene subunits in a dimer adopt a “face-to-face” stacked configuration. Its absorption spectrum differs significantly from that of the monomeric counterpart in solution, suggesting the presence of strong interactions between the two tetracene subunits. In solution, the fluorescence spectrum is dominated by a band at around 535 nm, due to an oxidative impurity. In the longer wavelength range, a short-lived lower energy emission can be identified as the intrinsic emission of the dimer. In a polystyrene matrix or at low temperatures, the lifetime of the lower energy emission lengthens and it becomes more prominent. We suggest that the interactions between the two tetracene subunits produce a short-lived, lower energy “excimer-like” state. The fluorescence decays show no observable dependence on an applied magnetic field, and no obvious evidence of significant singlet fission is found in this dimer. This research suggests that even though there are strong electronic interactions between the tetracene subunits in the dimer, singlet fission cannot be achieved efficiently, probably because the formation of “excimer-like” states competes effectively with singlet fission.
Co-reporter:Haixia Wang, Delou Wang, Qi Wang, Xiyou Li and Christoph A. Schalley
Organic & Biomolecular Chemistry 2010 - vol. 8(Issue 5) pp:NaN1026-1026
Publication Date(Web):2010/01/05
DOI:10.1039/B921342B
Two novel “turn-on” fluorescent probes with perylene tetracarboxylic diimide (PDI) as the fluorophore and two different di-(2-picolyl)-amine (DPA) groups as the metal ion receptor (PDI-1 and PDI-2) were successfully synthesized with satisfactory yields. PDI-1 exhibited high selectivity toward Ni2+ in the presence of various other metal cations including Zn2+, Cd2+ and Cu2+ which were expected to interfere significantly. A 1:2 stoichiometry was found for the complex formed by PDI-1 and Ni2+ by a Job's plot and by non-linear least square fitting of the fluorescence titration curves. By introducing an extra diamino ethylene group between DPA and the phenyl bridge, the receptor was modified and the high selectivity of the sensor toward Ni2+ shifted to Fe3+. The enhancement factor of the fluorescence response of PDI-2 to Fe3+ was as high as 138. The binding behavior of the receptors in these two compounds is affected significantly by the PDI fluorophores. Most interestingly, both Ni2+ and Fe3+ are paramagnetic metal ions, which are known as fluorescence quenchers and are rarely targeted with “turn-on” fluorescence probes. This result suggests that PDIs are favorable fluorophores for a “turn-on” fluorescence probe for paramagnetic transition metal ions because of their high oxidation potential.
Co-reporter:Haixia Wang, Haixia Wu, Lin Xue, Yan Shi and Xiyou Li
Organic & Biomolecular Chemistry 2011 - vol. 9(Issue 15) pp:NaN5444-5444
Publication Date(Web):2011/04/28
DOI:10.1039/C1OB05481C
A novel 4-amino-1,8-naphthalimide (NDI) with two different metal cation receptors connected at 4-amino or imide nitrogen positions respectively was designed and prepared. Significant internal charge transfer (ICT) as well as photoinduced electron transfer (PET) from the receptors to NDI is revealed by the shifted UV-vis absorption spectra and significant fluorescence quenching. Both Zn2+ and Cu2+ can coordinate selectively with the two cation receptors in this molecule with different affinities. The coordination of Zn2+ with the receptor at imide nitrogen hindered the PET process and accordingly restored the quenched fluorescence of NDI. But the coordination of Zn2+ at 4-amino position blocked the ICT process and caused significant blue-shift on the absorption peak with the fluorescence intensity unaffected. Similarly, coordination of Cu2+ with the receptor at imide nitrogen can block the PET process, but can not restore the quenched fluorescence of compound 3 due to the paramagnetic properties of Cu2+, which quench the fluorescence significantly instead. With Cu2+ and Zn2+ as two chemical inputs and absorption or fluorescence as output, several logic gate operations, such as OR, NOR and INHIBIT, can be achieved.
![Perylo[3,4-cd:9,10-c'd']dipyran-1,3,8,10-tetrone, 5,6,12,13-tetrakis[4-(1,1-dimethylethyl)phenoxy]-](/data/chemimg/102800/156028-30-7.png)
![Perylo[3,4-cd:9,10-c'd']dipyran-1,3,8,10-tetrone, 5,6,12,13-tetrakis[4-(1,1-dimethylethyl)phenoxy]-](/data/chemimg/102800/156028-30-7_b.png)
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![1H-Benz[de]isoquinoline-1,3(2H)-dione, 6-bromo-2-octyl-](/data/chemimg/110700/865443-57-8_b.png)
![Anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone, 2,9-dioctyl-](/data/chemimg/709500/78151-58-3.png)
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