Poly-CPDT films decorated with dinuclear Re(I) complex chromophore pendants : electrochemical and spectroscopic properties

In our current development of new classes of luminescent dinuclear Re(I) complexes, looking for innovative hybrid materials for solid-state devices, we have synthesized and electrochemically characterized the compound Re2(CO)6(μ-H)(μ-3Me-pydz)(μ-OOC- cpdt), a novel conjugate between a luminescent complex and a cyclopentabithiophene (cpdt) unit. By comparison with the corresponding free dinuclear Re complex and with the free HOOCcpdt ligand the CV peaks of the new conjugate have been assigned to the different redox centers. Efficient and very regular electrochemical polymerization has been obtained on GC, Pt, and ITO electrodes as a consequence of the high polymerization ability and regioselectivity of the terminal α-thiophene positions of cpdt. The resulting films have been characterized by CV, EQCM, EIS and UV-vis spectroelectrochemistry. They are stable even upon repeated cycling, exhibiting two subsequent reversible oxidation peaks, whose relative charge ratio is regularly depending on the potential scan rate (possibly, on account of different rates of the counter ion ingress/egress). They also exhibit conspicuous charge trapping features, in terms of both quantity and stability, and excellent electrochromic properties.