ThDione: A Powerful Electron-Withdrawing Moiety for Push-Pull Molecules

Abstract

A series of new push-pull chromophores based on a combined cyclopenta[c]thiophene-4,6-dione (ThDione) acceptor,N,N-dimethylaniline,N-piperidinylthiophene or ferrocene donors, and ethylene or buta-1,3-dienylene pi-linkers has been designed and synthesized. Utilizing one or two ThDione acceptors afforded linear or branched push-pull molecules. Experimental and theoretical study of their fundamental properties revealed thermal robustness up to 260 degrees C, a electrochemical/optical HOMO-LUMO gap that is tunable within the range of 1.47-2.19/1.99-2.39 eV, and thorough elucidation of structure-property relationships. Compared to currently available portfolio of heterocyclic electron-withdrawing units, ThDione proved to be a powerful and versatile acceptor unit. It imparts significant intramolecular charge transfer and polarizes the pi-system, which results in enhanced (non)linear optical response.