Synthesis and Optical Properties of 2,2'-Biimidazole and Benzo[d]imidazole Derivatives: Changing π-Conjugation by Photoexcitation
作者:Shoji Matsumoto、Yu Zhao、Motohiro Akazome
DOI:10.3987/com-13-s(s)12
日期:——
1,1',5,5'-Tetraaryl-2,2'-biimidazole and benzo [d] imidazole derivatives were synthesized. Symmetrical and unsymmetrical benzo[d]imidazole derivatives could be obtained by the Pd-catalyzed coupling reaction between 2-iodo-benzo[d]imidazole and the corresponding (benzo)imidazole anion. Hypsochromic shifts in absorption and fluorescence spectra of 1,1',5,5'-tetraaryl-2,2'-biazole were observed by switching pyrrole rings for imidazole and benzo[d]imidazole rings, resulting in compounds with various Stokes shifts. Based on the (TD)DFT calculation, it was reasoned that changing the conformation of each single bond from a twisted to planar structure by photoexcitation led to larger Stokes shifts.