1,6- And 1,7-Regioisomers of Perylene Tetracarboxylic Dianhydride and Diimide: The Effects of Neutral Bay Substituents on the Electrochemical and Structural Properties

The electrochemical and structural properties of a series of 1,6- and 1,7-regioisomers of different sized bay-appended perylene diimides (PDIs) and perylene tetracarboxylic dianhydrides (PTCDs) were assessed. Steric effects by large bay substituents triphenylsilylacetylene and tritylacetylene play a major role in the geometry of the solid and solution states. New triphenylsilylacetyene and 1-pentynyl derivatives were prepared and characterized. Suitable crystals for X-ray analysis of tritylacetylene and n-hexyl compounds illustrated the structural alterations in the bay region. The bulky tritylacetylene appended PDI assumed a nearly planar π-configuration, equivalent to an unsubstituted PDI. In contrast, a slender and less bulky hexyl chain incorporated PDI underwent a significant twisting of the central core of PDI. Neutral and conjugated groups at the bay region of PDI enhanced its reductive capability. In contrast, incorporation of neutral and nonconjugated groups at the bay region slightly diminished the reductive capability of resulting PDI derivative. PTCDs consisting of both bulky and slender groups were reduced significantly more readily in relation to the respective PDIs. Electrochemical reductive properties of selected PDIs and PTCDs were obtained along with optical properties of 1,6- and 1,7-PDIs.

本研究评估了一系列不同尺寸的湾位取代苝二酰亚胺（perylene diimides, PDIs）和苝四羧酸二酐（perylene tetracarboxylic dianhydrides, PTCDs）的1,6-与1,7-位区域异构体的电化学与结构性质。大体积湾位取代基三苯基硅基乙炔与三苯甲基乙炔所产生的空间位阻效应，对该类化合物的固态与溶液态几何构型具有显著影响。本研究合成并表征了新型三苯基硅基乙炔与1-戊炔基衍生物。用于X射线分析的三苯甲基乙炔与正己基取代化合物的合格晶体，揭示了湾位区域的结构变化。带有大体积三苯甲基乙炔取代基的PDI呈现出近乎平面的π共轭构型，与未取代的PDI一致。与之相反，带有纤细且体积更小的己基链的PDI，其苝环中心骨架发生了显著扭曲。PDI湾位的中性共轭基团可提升其还原能力；与之相反，在湾位引入中性非共轭基团则会略微降低所得PDI衍生物的还原能力。同时带有大体积与纤细取代基的PTCDs，相比对应的PDIs更易被还原。本研究测定了所选PDIs与PTCDs的电化学还原性质，以及1,6-与1,7-PDIs的光学性质。