Designs Of Singlet Fission Chromophores With A Diazadiborinine Framework

In 2016, a diazadiborinine molecule was synthesized (Nature Commun. 2016, 7, 11871). The core structure of this molecule is a 6-membered pi 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.