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81.
Synthesis of One‐Dimensional Schiff Base Polymers that Contain an Oligothiophene Building Block on the Graphite Surface 下载免费PDF全文
Xiu‐Ling Sun Li‐Xia Fan Yong‐Jing Yang Dr. Zongxia Guo Prof. Wei Quan Tian Prof.Dr. Shengbin Lei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6898-6905
Surface‐mediated Schiff base coupling reactions between oligothiophenes equipped with an aldehyde group and aromatic diamines were investigated on highly oriented pyrolytic graphite (HOPG) by means of scanning tunneling microscopy (STM) under ambient conditions. To investigate the evolution process from monomers to resultant polymers and the mechanism of reactions, we controlled the ratio of precursors and the reactive temperature, and we obtained high‐resolution STM images of different stages of the surface reaction. The results suggest that preferential adsorption of one kind of monomer has a great influence on the on‐ surface Schiff base reaction. 相似文献
82.
Jousselme B Blanchard P Gallego-Planas N Levillain E Delaunay J Allain M Richomme P Roncali J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(21):5297-5306
Photodynamic molecular architectures have been synthesized by covalent fixation of a photoisomerizable dimethylazobenzene group at two fixed points of conformationally flexible pi-conjugated quater- and sexithiophene chains. Theoretical geometry optimization shows, in excellent agreement with crystallographic structures, that the mode of fixation of the azo group plays a determining role in the geometry of the final molecular architecture and on its ability to perform the expected photoinduced molecular motion. Thus, covalent fixation of meta-dimethylazobenzene on a quaterthiophene chain results in a conformationally locked system in which photoisomerization of the azo group is hindered. However, the experimental results of optical, (1)H NMR spectroscopic, and electrochemical investigations show that when an azobenzene group is connected at the para positions of the phenyl rings, trans-to-cis photoisomerization of the azo group induces a conformational transition and dimensional changes in the underlying pi-conjugated oligothiophene chain. These experimental results unequivocally show that the photochemically induced geometrical changes produce in turn an increase in the HOMO level and a narrowing of the HOMO-LUMO gap. This therefore provides the first evidence of photomechanical control of the electronic properties of linear pi-conjugated systems. 相似文献
83.
《Comptes Rendus Chimie》2016,19(5):646-653
The molecular geometries and electronic properties of a series of bis(aminoalkyl) end-capped oligothiophenes (BRnTs) were investigated by means of the density functional theory (DFT). The calculations were performed on dimers up to octamers in the neutral and ionic species using the B3LYP/6-31G(d,p) level of theory. The results obtained show that the conjugated systems in the p- and n-doped oligomers had more aromaticity, with expanded and planar chains. The calculated energy gap values between the frontier molecular orbitals for the end-capped oligomers were larger than those for the unsubstituted oligomers, in which with increase in the oligomer chain length, the conduction band gap decreased. The calculated first excitation energies of BRnTs at the TD-B3LYP/6-31G(d,p) level indicated that both doped oligomers (p- and n-type) had lower excitation energies than the neutral states, and that they displayed red shifts in their absorption spectra. Moreover, the results obtained for the natural bond orbital (NBO) analysis showed that closing the end-side oligothiophene chains with the aminoalkyl groups eased the hole or electron transfer, owning to better charge delocalization through the backbone structures of BRnTs. 相似文献
84.
The fluorescence quantum yields of vapor-deposited (VD) films of -oligothiophenes,nT, with ring numbers ofn=3–8 and layer thicknesses ofd=3–50 nm were determined at room temperature andT=77 K and compared to the yields of dilute solutions and small (5T)x clusters. The yields of highly oriented ultrathin films are of the order of F=5*10–5-1*10–4. The yields increase strongly with the layer thickness and also upon cooling, but do not reach the values in dilute solution. The main nonradiative deactivation step S1 T1 in solution was quantified by1O2 production, the yields of which systematically decrease withn from F (3T) to 0.36 (6T), in contrast to the fluorescence yields, which increase from F=0.01 (2T) to 0.40 (6T). In films or clusters the S1 T1 deactivation step must be a very unimportant side reaction: neither1O2 nor any signal of triplet-triplet absorption could be positively identified. 相似文献
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86.
Inside Cover: Thiophene‐Based,Radial π‐Conjugation: Synthesis,Structure, and Photophysical Properties of Cyclo‐1,4‐phenylene‐2′,5′‐thienylenes (Angew. Chem. Int. Ed. 1/2015) 下载免费PDF全文
87.
Qingwei Meng Dr. Xiao‐Hua Sun Dr. Zhengyu Lu Ping‐Fang Xia Zehua Shi Dongzhong Chen Prof. Dr. Man Shing Wong Prof. Dr. Salem Wakim Dr. Jianping Lu Dr. Jean‐Marc Baribeau Dr. Ye Tao Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(14):3474-3487
Supramolecular chirality and liquid crystalline OFET : Achiral end‐capped oligothiophenes can be tuned to exhibit supramolecular chirality with unique striped textures showing distinct circular dichroism signals as well as a highly ordered SmE phase that leads to high hole carrier mobility.
88.
Dr. Marcus Bäck Dr. Robert Selegård Yogesh Todarwal Dr. Sofie Nyström Prof. Patrick Norman Dr. Mathieu Linares Prof. Per Hammarström Prof. Mikael Lindgren Prof. K. Peter R. Nilsson 《ChemistryOpen》2020,9(11):1100-1108
Control over the photophysical properties and molecular organization of π-conjugated oligothiophenes is essential to their use in organic electronics. Herein we synthesized and characterized a variety of anionic pentameric oligothiophenes with different substitution patterns of L- or D-tyrosine at distinct positions along the thiophene backbone. Spectroscopic, microscopic, and theoretical studies of L- or D-tyrosine substituted pentameric oligothiophene conjugates revealed the formation of optically active π-stacked self-assembled aggregates under acid conditions. The distinct photophysical characteristics, as well as the supramolecular structures of the assemblies, were highly influenced by the positioning of the L- or D-tyrosine moieties along the thiophene backbone. Overall, the obtained results clearly demonstrate how fundamental changes in the position of the enantiomeric side-chain functionalities greatly affect the optical properties as well as the architecture of the self-assembled supramolecular structures. 相似文献
89.
设计了四个以四联噻吩为中心给电子单元,联二噻吩为末端给电子单元,不同功能的苯并噻二唑(DOBT,BT,FBT和FFBT)为吸电子单元的有机小分子太阳能电池给体材料,分别称为DOBT-8T,BT-8T,FBT-8T和FFBT-8T.在B3LYP/6-31G(d)基组的水平上利用密度泛函和含时密度泛函理论对四个小分子进行了理论计算.详细分析了吸电子单元苯并噻二唑的结构修饰对小分子给体材料性能的影响.理论计算结果显示,不同功能的苯并噻二唑单元的引入对小分子给体材料的几何结构、禁带宽度、HOMO与LUMO能级、轨道电子密度分配、能量驱动力、开路电压和分子中的原子电荷(NPA)都有重要调节作用.相比于其它分子,以FBT为吸电子单元的FBT-8T,显示了最窄的带隙和较低的HOMO能级值.以FFBT为吸电子单元的FFBT-8T,获得了最低的HOMO能级和较为合适的禁带宽度.利用Scharber模型分别计算了基于小分子/PC61BM为活性层的光伏器件的能量转换效率(PCE),基于FBT-8T/PC61BM和FFBT-8T/PC61BM的光伏器件,将获得的PCE分别高达约4.7%和5.2%.在以上研究的基础上,推测FBT-8T和FFBT-8T是潜在的高性能的有机小分子体异质结光伏给体材料. 相似文献
90.
Piacenza M Della Sala F Fabiano E Maiolo T Gigli G 《Journal of computational chemistry》2008,29(3):451-457
The influence of methyl or phenyl substitution in beta-position of dioxygenated terthiophene and diphenylthiophene on the optical properties is investigated by first-principles calculations. We compare the approximated singles and doubles coupled cluster (CC2) approach with time-dependent density functional theory methods. CC2 reproduces experimental excitation energies with an accuracy of 0.1 eV. We find that the different substituents modify the inter-ring torsional angle which in turn strongly influences the excitation energies. The steric contribution to the excitation energies have been separated from the total substituent effects. 相似文献