A series of dn transition metal coordination complexes: Structures and comparative study of surface electron behaviors (n = 9, 8, 7, 6, 5)

Ten transition metal coordination complexes [Cu2(phen)(p-tpha)(μ-O)]n 1, [Cu(m-tpha)(imH)2]n 2, [Ni(5-Haipa)2(H2O)2]n 3, [Ni(phen)2(H2O)2]·btc·[Ni(H2O)6]0.5·9H2O 4, [Co(2,5-pdc)(H2O)2]n·nH2O 5, [Co2(2,5-pdc)2(H2O)6]n·2nH2O 6, [Fe(2,5-Hpdc)2(H2O)2]·H2O 7, [Co(C6H4NO2)3]·H2O 8, [Fe2(μ2-btec)(μ2-H2btec)(bipy)2(H2O)2]n 9, [Mn(phen)(2,5-pdc)(H2O)2]·H2O 10 (H4btec = 1,2,4,5-benzenetetracarboxylic acid, phen = 1,10-phenanthroline, 2,5-H2pdc = 2,5-pyridine-dicarboxylic acid, p-tpha = p-phthalic acid, m-tpha = m-phthalic acid, bipy = 2,2′-bipyridine, 5-H2aipa = 5-aminoisophthalic acid, imH = imidazole, H3btc = 1,3,5-benzenetricarboxylic acid) were synthesized through hydrothermal method. They were characterized by UV–Vis absorption spectra, single-crystal X-ray diffraction and surface photovoltage spectra (SPS). Structural analysis indicated that the complexes 1, 2, 3, 5, 6 and 9 were linked into infinite structures bridged by organic acid ligands. The other four complexes were molecular complexes and further connected to 2D or 3D structures by the hydrogen bonds. The SPS of complexes 1–10 indicate that there are positive response bands in the range of 300–800 nm showing different levels of photo-electric conversion properties. The intensity, position, shape and the number of the response bands in SPS are obviously different since the structure, species, valence, dn electrons configuration and coordinated environment of the center metals are different. There are good relationships between SPS and UV–Vis spectra.