A Qualitative Measure of Diradical Character Based on Radical-Radical Coupling Reaction

We propose a relationship between the diradical character and the radical-radical coupling reaction rate of the lightinduced radical pair of the photochromic biimidazoles which photochemically generate a couple of imidazolyl radical with significant diradical character. We also found the diradical character can be altered by changing the aromaticity of the bridging unit connecting two imidazole rings. The large aromaticity of the bridging unit increases the diradical character, resulting in the acceleration of the radical-radical coupling reaction rate.

Automated summary

This study proposes a relationship between the diradical character and radical-radical coupling reaction rate of the light-induced radical pair of photochromic biimidazoles, and suggests that the aromaticity of the bridging unit connecting two imidazole rings can alter the diradical character and accelerate the reaction rate.