Synthesis, structure and comparison of photo-electric properties of Co(II) complexes with benzoic derivatives ligand

Four Co(II) complexes [Co(btec)(0.5)(pz)(2)](n) (1), [Co(btec)(0.5)(pz)(3)](n) (2), [Co(phen)(Hbtc)(H(3)btc) (H2O)(2)] center dot 3H(2)O (3), [Co(Imh)(2)(anis)(2)(H2O)] (4), (H(4)btec=1,2,4,5-benzenetetracarboxylic acid, pz =pyrazole, H(3)btc =1,3,5-benzenetricarboxylic acid, phen =1,10-phenanthroline, Imh =imidazole, Hanis =p-anisic acid) were synthesized by hydrothermal method. They were characterized by X-ray single crystal diffraction, IR, elemental analysis, UV-Vis-NIR diffuse reflection spectrum and surface photovoltage spectroscopy (SPS). The structural analyses indicate that 1 is a Co(II) polymer with 2D structure. The Co(II) ion is four-coordinate in 1; the ones in 2 similar to 4 are both six-coordinate. 2 possesses 1D structure, connected by hydrogen bonds into 2D layer. 3 and 4 are molecular complexes, which are networked into 3D and 2D structures by hydrogen bonds, respectively. Four complexes all exhibit obvious surface photovoltage responses within 300 similar to 600 nm in SPS, which indicates that they possess certain photo-electric conversion properties. The influences of structure, dimension of complex and coordination micro-environment of center metal ion on the SPS were discussed emphatically. The energy band theory of semiconductor and crystal field theory are combined to analyze and assign SPS response bands. CCDC: 883535, 1; 883536, 2; 883537, 3; 883538, 4.