Aryl-substituted symmetrical and unsymmetrical benzothiadiazoles

Abstract

A set of benzothiadiazoles (BTD) of the type D–π–A–π–D and D₁–π–A–π–D₂ were designed and synthesized by the Pd-catalyzed Sonogashira cross-coupling reaction. Their photophysical and electrochemical properties were studied. The substitution of anthracene on BTD improves its thermal stability, and lowers the HOMO–LUMO gap, which results in a red shift of the electronic absorption. The experimental optical gap values show good agreement with the calculated HOMO–LUMO gap.