Synthesis, Structure and Surface Photovoltage of a Series of NiII Coordination Polymers

Three novel NiII coordination polymers [Ni2(HCOO)4(H2O)4]n (1), [Na2Ni(btec)(H2O)8]n (2; H4btec = 1,2,4,5-benzenetetracarboxylic acid) and [{Ni(pdc)(H2O)2}·H2O]n (3; H2pdc = pyridine-2,5-dicarboxylic acid) have been hydrothermally synthesized and their structures determined by single-crystal X-ray diffraction. The formate groups in complex 1 bridge the NiII ions to form a infinite 3D structure. Complex 2 also possesses a infinite 3D structure and the coordination environment of the NiII ion is a perfect octahedron. Complex 3 is a 2D infinite coordination polymer. The surface photovoltage spectra of complexes 1–3 indicate that they all show three positive surface photovoltage (SPV) responses in the range of 300–800 nm and all show p-type semiconductor characteristics. Although the intensities of the SPV responses are obviously different, this can mainly be attributed to the difference of their structures. The field-induced surface photovoltage spectra (FISPS) of complexes 1–3 confirm their p-type semiconductor characteristics. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)