Designs of Singlet Fission Chromophores with a Diazadiborinine Framework**

Abstract

Abstract In 2016, a diazadiborinine molecule was synthesized ( Nature Commun . 2016 , 7 , 11871). The core structure of this molecule is a 6‐membered π system with a trans stitching up of two NCB fragments. This core structure is identical to a model singlet fission chromophore that one of us (T.Z.) proposed in 2014 ( J. Am. Chem. Soc . 2014 , 136 , 12638–12647.) Inspired by this resemblance, we performed quantum chemistry calculations to design a series of singlet fission chromophores based on the diazadiborinine framework. The essence is to impair the aromaticity of the diazadiborinine framework by substitutions and/or additions so that diradical resonance structures gain higher weight in the ground states of the designed chromophores.