Multi-colour and red emissions from a small donor–acceptor molecule by breaching Kasha's rule

Abstract

Reported herein is a small (MW 260 Da) organic molecule that emits multicolour and red lights, capitalising on simultaneous anti-Kasha and donor–acceptor effects. The molecule emits from two excited states, namely S₁ and S₃. Introduction of donor–acceptor substituents resulted in the large Stokes shifts (>5000 cm⁻¹) with negligible spectral overlap.