2,5-Diphenyl-1,4-distyrylbenzene (DPDSB) with all-cis (cis-DPDSB) and all-trans double bonds (trans-DPDSB) were synthesized by Wittig reaction and the differences in structural and optical properties between the cis- and trans-isomers are discussed in detail. Both compounds were fully characterized by NMR spectroscopy, FT-IR spectroscopy, x-ray crystallography, differential scanning calorimetry (DSC) and electrochemical methods. X-ray analysis and molecular simulation revealed that the structure of cis-DPDSB obviously deviates from planarity along both the distyrylbenzene and terphenyl directions, and less intermolecular interaction exists in crystal. The cis-isomer shows a large blue shift in the absorption spectrum in comparison with that of the trans-isomer, and cyclic voltammetric measurements give bandgaps of 3.16 and 2.97 eV for cis- and trans-DPDSB, respectively. Both compounds show unusually strong blue fluorescence in the solid state, probably due to the weak intermolecular interaction existing in both isomers owing to the large steric hindrance induced by the substituted phenyl groups. DSC experiments determined that both isomers have excellent thermal stability, which indicates that they can be used as active layers to make stable devices. Quantum chemical calculations for the frontier molecular orbital and the cation and anion properties reveal that the HOMO and LUMO are completely localized in the distyrylbenzene direction and the distyrylbenzene segment has more sensitive electroactivity than the terphenyl segment whether it is cis- or trans-DPDSB. Copyright © 2005 John Wiley & Sons, Ltd.

中文翻译：

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具有全顺式和全反式双键的2,5-二苯基-1,4-二苯乙烯基苯的实验和理论研究：化学结构测定和光学性质

通过Wittig反应合成了具有全顺式（顺式-DPDSB）和全反式双键（反式-DPDSB）的2,5-二苯基-1,4-二苯乙烯基苯（DPDSB），以及顺式之间的结构和光学性质的差异-和反式异构体被详细讨论。两种化合物均已通过NMR光谱，FT-IR光谱，x射线晶体学，差示扫描量热法（DSC）和电化学方法进行了全面表征。X射线分析和分子模拟表明，顺-DPDSB的结构沿二苯乙烯基苯和三联苯方向均明显偏离平面度，且晶体间的分子间相互作用较少。这与反式异构体相比，顺式异构体在吸收光谱中显示出较大的蓝移，并且循环伏安法测量得出，顺式和反式的带隙分别为3.16和2.97 eV-DPDSB。两种化合物在固态下均显示出异常强的蓝色荧光，这可能是由于两个异构体之间存在弱的分子间相互作用，这是由于被取代的苯基基团引起的大位阻所致。DSC实验确定两种异构体均具有出色的热稳定性，这表明它们可以用作活性层以制造稳定的器件。对前沿分子轨道以及阳离子和阴离子性质的量子化学计算表明，HOMO和LUMO完全位于二苯乙烯基苯方向，并且无论是顺式-还是反式-DPDSB ，二苯乙烯基苯段都比三联苯段具有更高的敏感电活性。版权所有©2005 John Wiley＆Sons，Ltd.