Zn(II)-containing metallo-supramolecular polymers: synthesis, photophysical and electrochemical properties

Two novel building blocks M1, M2 with different electronic structures, were synthesized based on 2,2 ':6 ',2 ''-terpyridine modified with cyano-p-phenylenevinylene (CN-PV) and carbazole moieties through Knoevenagel condensation and Suzuki coupling, respectively. Directed by transition metal ion Zn2+, the metallo-homopolymers P1, P2 and metallo-copolymer P3 were obtained via self-assembly polymerization. The structures of the monomers and metallo-supramolecular polymers were fully characterized by MS, H-1-NMR and C-13-NMR. Meanwhile, the UV-vis absorption, photoluminescence (PL) and electrochemical properties of these compounds were systematically investigated. With respect to that of the monomers, both the UV-vis absorption and PL spectra of the polymers are significantly red-shifted. The resulting metallo-supramolecular polymers show similar double absorption peaks (342, 418nm for P1, 339, 410nm for P2, and 332, 412nm for P3), which is caused by the pi-pi* transition and intramolecular charge transfer (ICT). Further, all the polymers display red-orange emission in toluene and narrow electrochemical energy gaps of 1.46, 1.65 and 1.48eV for P1, P2, and P3, respectively.