Solvatochromism in diketopyrrolopyrrole derivatives: Experimental and computational studies

Abstract

A series of seven thiophen-substituted diketopyrrolopyrrole derivatives were synthesised and their solution absorption spectra characterised in a range of solvents of varying polarity. The absorption spectra of these diketopyrrolopyrrole derivatives exhibited significant negative solvatochromism. The behaviour is consistent with results of time-dependent density-functional theory calculations of excitation energies. Calculated electronic structures suggest that there is significant charge transfer between the electron-donating thiophen substituents and the diketopyrrolopyrrole core but that the magnitude of this charge shift is reduced in the excited state compared with the ground state. The..