Synthesis, structure and surface photo-electric property of Ni(II) complexes

Three Ni(II) coordination complexes [NaNi(NTA)(H2O)]n (1), [Ni(pdc)2(Hppz)2]·H2O (2), [Ni(HL)2] (3) (H3NTA = nitrilotriacetic acid; ppz = piperazine; H2pdc = 2,5-pyridinedicarboxylic acid; H2L = 2-(1-piperazinl)-succinic acid) were obtained by hydrothermal synthesis method. The structures of the three complexes were determined by single crystal X-ray diffraction. Complex (1) is a 3D coordination polymer bridged by NTA3− groups; complex (2) is a mononuclear complex with ligands of pdc2− and Hppz+, forming a 3D supramolecule via hydrogen bonds; complex (3) is also a mononuclear complex with ligand of HL−, connected into a 3D supramolecule through hydrogen bonds. The photo-electric properties of complexes were investigated by surface photovoltage spectroscopy (SPS). The results of SPS show that the three complexes exhibit obvious photovoltage responses in the range of 300–800 nm, which indicates that they all possess certain photo-electric conversion properties. Comparing and analyzing the SPS results of three complexes, it can be found that the component, structure and dimensionality of complex, the category of ligand, the species and number of the direct coordination atoms as well as change of the coordination microenvironment of central metal Ni(II) ion all affect obviously the SPS responses. The SPS and UV–Vis spectra of the complexes were interrelated.