Cyclopenta[c]selenophene based cooligomers and their polymers: comparative study with thiophene analogues
作者:Soumyajit Das、Anjan Bedi、G. Rama Krishna、C. Malla Reddy、Sanjio S. Zade
DOI:10.1039/c1ob05866e
日期:——
Selenophene and thiophene capped cyclopenta[c]selenophenes were synthesized and characterized. Crystal structure determination of some representative compounds revealed that the substitution at 3,4-position in the form of cyclopentane ring of selenophene or thiophene does not make any significant twist in the trimer backbone, making the cooligomer nearly planar. All the cooligomers were electrochemically polymerized and compared with thiophene capped cyclopenta[c]thiophene polymer. DFT calculations predict that the cyclopentane substitution on the third repeating unit (and in general) of one dimensional polymer neither disturb the planarity nor causes any significant twist on the polymeric backbone unlike the 3,4-dialkyl substitution. The electrochemically prepared selenophene based polymers showed low band gap compared to that of thiophene analogues. Cyclopentane substitution on selenophene as well as thiophene makes the resulting polymer oxidatively more stable when compared to more familiar poly-ethylenedioxythiophene (PEDOT) or poly-ethylenedioxyselenophene (PEDOS) systems. Alternate polymers of cyclopenta[c]selenophenes (CPS)/cyclopenta[c]thiophene (CPT) and thiophene/selenophene possess the energy of HOMO and LUMO significantly lower than that of homopolymers of CPS and CPT, however, possess higher band gap than PCPS.
对硒吩和噻吩封端的环戊并[c]硒吩进行了合成和表征。一些代表性化合物的晶体结构测定结果表明,硒吩或噻吩的环戊烷环形式的 3,4 位取代不会使三聚体骨架产生任何明显的扭曲,从而使酷聚体接近平面。所有酷聚物都经过了电化学聚合,并与噻吩封端的环戊并[c]噻吩聚合物进行了比较。DFT 计算表明,与 3,4-二烷基取代不同,环戊烷取代一维聚合物的第三个重复单元(一般情况下)既不会破坏平面性,也不会对聚合物骨架造成任何明显的扭曲。与噻吩类似物相比,电化学制备的硒吩基聚合物显示出较低的带隙。硒吩和噻吩上的环戊烷取代使得所制备的聚合物与人们更熟悉的聚亚乙二氧基噻吩(PEDOT)或聚亚乙二氧基硒吩(PEDOS)系统相比,氧化稳定性更高。环戊并[c]硒(CPS)/环戊并[c]噻吩(CPT)和噻吩/硒的替代聚合物的 HOMO 和 LUMO 能明显低于 CPS 和 CPT 的均聚物,但其带隙却高于 PCPS。