Misra Rajneesh, Gautam Prabhat
Department of Chemistry, Indian Institute of Technology, Indore 452 017, India.
Org Biomol Chem. 2014 Aug 7;12(29):5448-57. doi: 10.1039/c4ob00629a.
This article reports the design and synthesis of donor-substituted symmetrical and unsymmetrical benzothiadiazoles (BTDs) of 5-12 type D-π-A-D, D1-π-A-D2, D1-A1-A2-D2, D-A1-A2-D and D-A1-A2-A1-D by Ullmann, Suzuki and cycloaddition-retroelectrocyclization reactions. The photophysical, electrochemical and computational properties were studied and show substantial donor-acceptor interaction. Their single photon absorption show strong charge transfer bands in the near-infrared (NIR) region and the electrochemical reduction show multiple reduction waves. The optical HOMO-LUMO gap of BTDs 5-12 was found to be a function of the number and nature of the acceptors. Computational studies reveal that strong cyano-based acceptors, dicyanoquinodimethane (DCNQ) and tetracyanobutadiene (TCBD) lower the LUMO level in BTDs 7-12, which results in a low HOMO-LUMO gap compared to acetylene linked BTDs 5 and 6. The BTDs with carbazole and single TCBD and DCNQ acceptors show better thermal stability.
本文报道了通过乌尔曼反应、铃木反应以及环加成-逆电环化反应设计与合成供体取代的5-12型对称和不对称苯并噻二唑（BTDs），包括D-π-A-D、D1-π-A-D2、D1-A1-A2-D2、D-A1-A2-D和D-A1-A2-A1-D。研究了其光物理、电化学和计算性质，结果表明存在显著的供体-受体相互作用。它们的单光子吸收在近红外（NIR）区域显示出强电荷转移带，电化学还原显示出多个还原波。发现BTDs 5-12的光学HOMO-LUMO能隙是受体数量和性质的函数。计算研究表明，强氰基受体二氰基喹二甲烷（DCNQ）和四氰基丁二烯（TCBD）降低了BTDs 7-12中的LUMO能级，与乙炔连接的BTDs 5和6相比，导致较低的HOMO-LUMO能隙。含有咔唑以及单个TCBD和DCNQ受体的BTDs表现出更好的热稳定性。
