Synthesis of conjugated polymers with pendant metal complexes and study of their photophysical properties

Abstract

A series of copolymers based on poly(phenylene thienylene) mainchain that contains pendent bisterpyridine ruthenium(II) complexes was synthesized by palladium catalyzed Suzuki coupling reaction. The polymers contain different proportion of metal complexes. The copolymers exhibit broad absorption band in the visible region due to the conjugated backbone and the bisterpyridine ruthenium complexes. The relative intensity of each absorption band depends on the metal complex contents. There is a significant spectral overlap between the emission of the conjugated polymer mainchain and the absorption of the ruthenium complexes. It was found that there is a quenching of polymer emission by the complexes. Based on the results obtained by spectroscopic studies, it is proposed to be Förster type energy transfer process between the polymer mainchain as the donor and the complexes as the acceptors.

Two donor-acceptor molecules with pyrazinopyrazine bridge units were synthesized. They exhibit intramolecular charge transfer character and were characterized by 1 H NMR, FTIR, UV-visible absorption and mass spectrometry. The two compounds have absorption band in the near IR region and exhibit narrow band gap. Through structural modification, their optical and electronic properties can be fine tuned. They have potential applications in organic photovoltaic cells and organic field effect transistors.