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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)

Four novel hetero-tetranuclear d-f coordination complexes, [Ln2Cd2(p-toluylate)10(phen)2] (Nd, 1; Pr, 2; Sm, 3) and [Ho2Cd2(p-chloro-benzoate)10(phen)2](4) (phen = 1, 10-phenanthroline), are synthesized by the hydrothermal method, and their structures are studied by single-crystal X-ray diffraction. Structures 1-3 are isomorphous and structure 4 has a similar molecular structure. In the near-infrared (NIR) region or in the visible region, complexes 1-4 show the characteristic emission bands of Ln(III) ions, which are attributed to the sensitization from the ligands and d-block (cadmium-ligand section) to f-block (lanthanide-ligand section). Moreover, in the Cd-Ln complexes, the CdLn separation is very close, so the d-orbital of the Cd(II) ion and the f-orbital of the Ln(III) ion may influence each other, which probably cause the intra-levels to be adjusted. This can have a significant effect on the emission bands in the NIR region, hence the corresponding emission bands of complexes 1, 2 and 4 exhibit shift or splitting compared with isolated Ln(III) ions. At the same time in the UV-Vis-NIR absorption spectra of the complexes, the corresponding absorption bands also show shift or splitting. The shift or splitting of bands in the NIR emission spectra and in the absorption spectra can evidence each other.

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