A series of M–M′ heterometallic coordination polymers: syntheses, structures and surface photoelectric properties (M=Ni/Co, M′=Cd/Zn)

Four new heterometallic polymers, [NiCd(mal)2(H2O)2]n·2nH2O 1, [NiZn2(Hcit)2(H2O)2]n 2, [CoCd2(Hcit)2(H2O)2]n 3, [CoZn2(Hcit)2(H2O)2]n 4 (H2mal=malonic acid, H4cit=citric acid) were synthesized and characterized. The photoelectric properties of the polymers were discussed by the surface photovoltage spectroscopy (SPS). The structural analyses indicate 1 is a Ni–Cd heterometallic polymer with 3D structure bridged by the mal2– group. 2–4 are all heterometallic polymers with 2D structures bridged by the Hcit3– group. The results of SPS for the four polymers reveal that there are wide photovoltage response bands in the range of 300–800 nm, which indicates that they all possess photoelectric conversion properties. By the introduction of the other metals, the SPS of heterometallic polymers are broadened obviously than the SPS of monometallic complexes. Moreover, the relationships between SPS and UV–Vis absorption spectra have been discussed.