Ito Masato, Ito Emi, Hirai Masato, Yamaguchi Shigehiro
Department of Chemistry, Graduate School of Science and Integrated Research Consortium on Chemical Sciences (IRCCS) , Nagoya University , Furo, Chikusa , Nagoya 464-8602 , Japan.
Institute of Transformative Bio-Molecules (WPI-ITbM) , Nagoya University , Furo, Chikusa , Nagoya 464-8601 , Japan.
J Org Chem. 2018 Aug 3;83(15):8449-8456. doi: 10.1021/acs.joc.8b01015. Epub 2018 Jun 12.
A two-step synthesis to prepare tricoordinate organoboron compounds bearing three different aryl groups has been developed. After the first aryl substitution to an aryl boronic ester took place, the intermediate species, that is, bis(diarylborinate) species, was isolated as an air- and moisture-stable solid, which allowed the second aryl substitution to carry out in a selective manner. Subsequently, a series of unsymmetrical triarylboranes possessing a sterically bulky aryl group, triarylamine moiety, and para-functionalized phenyl ring was synthesized. Not only did these triarylboranes exhibit remarkable solvent-dependent fluorescence as expected for donor-π-acceptor (D-π-A) systems, they were also accompanied by profound persistence against photoirradiation especially for that bearing a 1,3,5-tri- tert-butylphenyl ring. This survey exemplifies that sufficient electronic and steric modification is key to construct photostable D-π-A type triarylborane-based fluorophores.
已开发出一种两步合成法来制备带有三个不同芳基的三配位有机硼化合物。在芳基硼酸酯发生首次芳基取代后，中间体物种，即双（二芳基硼酸酯）物种，被分离为一种对空气和湿气稳定的固体，这使得第二次芳基取代能够以选择性方式进行。随后，合成了一系列具有空间位阻大的芳基、三芳基胺部分和对位官能化苯环的不对称三芳基硼烷。这些三芳基硼烷不仅如供体-π-受体（D-π-A）体系所预期的那样表现出显著的溶剂依赖性荧光，而且它们还具有很强的抗光照射持久性，特别是对于带有1,3,5-三叔丁基苯环的三芳基硼烷。这项研究表明，充分的电子和空间修饰是构建光稳定的基于D-π-A型三芳基硼烷的荧光团的关键。
