Enhanced Photochemical Sensitivity in Photochromic Diarylethenes Based on a Benzothiophene/Thiophene Nonsymmetrical Structure
Enhanced Photochemical Sensitivity in Photochromic Diarylethenes Based on a Benzothiophene/Thiophene Nonsymmetrical Structure
复制标题
DOI：
10.1002/ejoc.201402774
复制
发表时间：
2014-11
影响因子：
2.8
通讯作者：
O. Galangau;Yuka Kimura;Rui Kanazawa;T. Nakashima;T. Kawai
中科院分区：
文献类型：
--
作者：
O. Galangau;Yuka Kimura;Rui Kanazawa;T. Nakashima;T. Kawai
分子的光敏性是有机光化学的中心课题之一。在这篇文章中，我们提出了如何和为什么苯并噻吩部分影响光致变色量子产率的光化学周环环的环关闭的己三烯部分。制备两种化合物：包含两个芴基噻吩单元的对称结构，和其相应的非对称结构，其中噻吩单元之一被苯并噻吩基取代。有趣的是，后者呈现出相对较高的环化量子产率（0.74），该值接近迄今报道的最大值。基于晶体结构，VT-NMR数据和DFT计算，我们证明，在分子支架中引入苯并噻吩通过CH-π相互作用和空间排斥诱导骨架硬化，并导致在环境条件下反应性构象体的数量增加。
Photosensitivity of molecules is one of the central subjects of organic photochemistry. In this article, we present how and why a benzothiophene moiety impacts the photochromic quantum yield for the photochemical pericyclic ring closing of the hexatriene moiety. Two compounds were prepared: a symmetrical one incorporating two fluorenylthiophene units, and its corresponding nonsymmetrical partner, where one of the thiophene units was replaced by a benzothiophene group. Interestingly, the latter presents relatively high cyclization quantum yield (0.74), a value close to the largest one so far reported. Based on crystal structures, VT-NMR data and DFT calculations, we demonstrate that introducing a benzothiophene in the molecular scaffold induces skeleton stiffening by means of CH–π interactions and steric repulsions, and leads to increased population of the reactive conformer in the ambient conditions.