1,4-Bis(aryl)-[1,2,4,5]-tetrazines prepared by light-driven ring-expansion skeletal editing

Abstract

Nitrogen-containing heterocycles are essential components in the medicine–agriculture–materials continuum and beyond. Recently, functional N-heterocycles have been facilely prepared by light-driven skeletal editing, starting with easily accessible compounds. In this work, three 1,4-bis(aryl)-1,2,4,5-tetrazine compounds, PTn (n = 1, 2, 3), which were difficult to attain via previously reported synthetic strategies, were successfully synthesized through light-driven ring-expansion skeletal editing of 2,5-disubstituted tetrazoles. Spectroscopic analyses and density functional theory (DFT/TD-DFT) calculations confirmed that the unique multiple emission of PTn in solution and powdered forms exhibits anti-Kasha-like characteristics. Additionally, the compact, twisted π-systems based on a tetrazine core demonstrated attractive cubic nonlinear optical (NLO) capabilities.