Centro S3 CNR Istituto di Nanoscienze, via G. Campi 213∕a, 41125 Modena, Italy.
J Chem Phys. 2012 Sep 28;137(12):124307. doi: 10.1063/1.4753810.
Azobenzene (di-phenyl-diazene) is well-known as a photoisomerisable molecule and has been widely studied as a molecular photoswitcher. Molecular rods, where di-phenyl arms are bound to the diazene moiety, have been also synthesized. In this article we explore by first principle density functional theory calculations the chiroptical properties (electronic circular dichroism spectra, ECD) of azobenzene and its homologues with polyphenyl arms. In particular, we demonstrate that for molecules in the cis configuration the intrinsic chirality of the distorted cis diazene group dominates the ECD response, while for trans species the non-planarity of the polyphenyl arms induces peaks in the ECD spectrum. Finally, the possibility of obtaining a light-controlled chiral switch by proper functionalization is also speculated.
偶氮苯（二苯基二氮烯）是一种众所周知的光致异构分子，已被广泛研究作为分子光开关。其中，二苯基臂连接到偶氮部分的分子棒也已被合成。在本文中，我们通过第一性原理密度泛函理论计算探索了偶氮苯及其多苯基臂同系物的手性光学性质（电子圆二色光谱，ECD）。特别地，我们证明对于处于顺式构型的分子，扭曲的顺式偶氮基团的固有手性主导 ECD 响应，而对于反式物种，多苯基臂的非平面性导致 ECD 光谱中出现峰。最后，还推测了通过适当的功能化获得光控手性开关的可能性。
