Thiocarbonyl Substitution in 1,4-Dithioketopyrrolopyrrole and Thienopyrroledithione Derivatives: An Experimental and Theoretical Study

A series of new 1,4-dithioketopyrrolopyrrole and thienopyrrolodithione derivatives have been synthesized and characterized by spectroscopy and electrochemistry measurements. The replacement of carbonyl by thiocarbonyl has a direct effect on the optical gap and on the ionization potential and electron affinity energies. For example, the optical gaps have been lowered by 0.5 eV, a fact that has been correctly predicted by density functional theory and time-dependent density functional theory calculations. A theoretical analysis on the stability of the new molecules is also presented.