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Abstract: Four Ln3+ coordination complexes with the formulas [Ln(p-toluylate)2(Ac)(H2O)] n (Ln=Ho 1, Yb 2) and {[Ln2(OOCCH2CH2COO)3(H2O)4]·6H2O} n (Ln=Ho 3, Yb 4) were synthesized hydrothermally. Their structures were determined by single-crystal X-ray diffraction. Complexes 1 and 2 are isomorphic and form infinite 2D network structures comprising p-toluylate and acetate (Ac–) moieties. Complexes 3 and 4 are also isomorphic and possess infinite 2D structures in which succinate acts as bridging ligands that are connected to a 3D hydrogen bonding network by O–H…O hydrogen bonds. Solid-state IR and UV-Vis-NIR spectra, excitation and emission spectra were determined for the four complexes at room temperature. Complexes 1 and 2 exhibit characteristic NIR emission bands of Ln3+ ions but these are shifted and split relative to the theoretical positions. This is also evident for their UV-Vis-NIR spectra. The influence of ligands on enhancing the NIR luminescence of Ln3+ ions in complexes is discussed. [Copyright &y& Elsevier]

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 1–3are isomorphous and structure 4has a similar molecular structure. In the near-infrared (NIR) region or in the visible region, complexes 1–4show 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, 2and 4exhibit 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. [ABSTRACT FROM AUTHOR]

Six Zn-Ln coordination complexes, [Nd 2 Zn 2 (C 6 H 5 COO) 10 (Imh) 2 (H 2 O) 2 ] ( 1 ), [Pr 2 Zn 2 (C 6 H 5 COO) 10 (Imh) 2 (H 2 O) 2 ] ( 2 ), [ErZn 2 (C 6 H 5 COO) 7 (Imh) 2 ] ( 3) , [HoZn 2 (C 6 H 5 COO) 7 (Imh) 2 ] ( 4 ), [EuZn 2 (C 6 H 5 COO) 7 (Imh) 2 ] ( 5 ), [TbZn 2 (C 6 H 5 COO) 7 (Imh) 2 ] ( 6 ) (C 6 H 5 COOH=benzoic acid, Imh=imidazole) have been synthesized under hydrothermal conditions and their crystal structures have been characterized by single crystal X-ray diffraction. All complexes are crystallized in triclinic system, with space group P ī. Complexes 1 and 2 are isomorphous with tetranuclear molecular structure and complexes 3–6 are isomorphous and trinuclear molecular complexes. All complexes are characterized by IR, UV–Vis–NIR and luminescent spectra in the visible and near-infrared (NIR) regions at room temperature. The study of luminescent properties indicates that all complexes exhibit the characteristic emission bands of corresponding Ln(III) ions, which should be attributed to sensitization from d-block and ligands after introducing Zn(II) ion and ligands into the system of Ln(III) complexes. Moreover, the NIR emission bands of complexes 1–4 exhibit shift and split, which can be evidenced in their UV–Vis–NIR absorption spectra. [ABSTRACT FROM AUTHOR]

Abstract: A novel cobalt(II) complex [Co3(oba)3(phen)2]n(H2oba=4,4′-oxybis benzoic acid, phen=1,10-phenanthroline) has been synthesized by hydrothermal method and characterized by single crystal X-ray diffraction, IR, UV–vis, thermal stability and Surface Photovoltage Spectroscopy (SPS). Structural analysis indicated that the complex is a 3D structure with the trinuclear building unit of [Co3(oba)3(phen)2] bridged by the oba ligands. The SPS of complex indicates that there are positive response bands in the range of 300–600nm showing photo-electric conversion properties. There are good relationships between SPS and UV–vis spectra. [Copyright &y& Elsevier]

Abstract: Four Fe(II/III) supramolecules, {[Fe(Hpdc)2(H2O)2]·2H2O} (1), [Fe(HImbc)2(H2O)2] (2), [Fe(phen)2(CN)2]·CH3CH2OH·2H2O (3), K[Fe(tp)2]·SO4 (4) (H2pdc = 2,5-Pyridinedicarboxylic acid, H2Imbc = 4,5-Imidazoledicarboxylic acid, phen = 1,10-phenanthroline, tp− = poly(pyrazolyl)borate), were synthesized by hydrothermal and room temperature stirring methods. They were characterized by single crystal X-ray diffraction, surface photovoltage spectroscopy (SPS), field-induced surface photovoltage spectroscopy (FISPS), electron paramagnetic resonance (EPR), UV–Vis absorption spectra (UV–Vis), infrared spectra (IR) and element analysis. The structural analyses indicate that complex (1) is a supramolecule with 2D structure connected by hydrogen bonds. Complex (2) is a supramolecule with hydrogen-bonded 3D structure. Complexes (3) and (4) are both 1D supramolecules connected by hydrogen bonds. The electronic state of central metal Fe(II) ions in complexes (1) and (2) is d6 with FeN2O4 coordination mode, lying in weaker distorted octahedral field. The electronic state of Fe(II) ion in complex (3) is d6 with Fe(CN)2N4 mode in the strong distorted octahedral field. The electronic state of Fe(III) ion in complex (4) is d5 with FeN6 mode, lying in the strong octahedral field. The micro-environment of Fe(II/III) ions in the four complexes is further investigated by EPR. The SPS of four complexes all exhibit photovoltage responses in the range of 300–700 nm. This indicates that they all possess certain photoelectric conversion capability. The effects of component, structure, type of ligands of the complexes, valence state and coordination micro-environment of the central metal ions on the SPS were discussed. Furthermore, the SPS and UV–Vis absorption spectra were interrelated. [Copyright &y& Elsevier]

Abstract: Five Cd(II)/Zn(II) complexes [Cd(1,2-bdc)(pz)2(H2O)] n (1), [Cd1Cd2(btec)(H2O)6] n (2), [Cd(3,4-pdc) (H2O)] n (3), [Zn(2,5-pdc)(H2O)4]·2H2O (4) and {[Zn(2,5-pdc)(H2O)2]·H2O} n (5) (H2bdc=1,2-benzenedicarboxylic acid, pz=pyrazole, H4btec=1,2,4,5-benzenetetracarboxylic acid, H2pdc=pyridine-dicarboxylic acid) were hydrothermally synthesized and characterized by single-crystal X-ray diffraction, surface photovoltage spectroscopy, XRD, TG analysis, IR and UV–vis spectra and elemental analysis. Structural analyses show that complexes 1–3 are 1D, 2D and 3D Cd(II) coordination polymers, respectively. Complex 4 is a mononuclear Zn(II) complex. Complex 5 is a 3D Zn(II) coordination polymer. The surface photoelectric properties of complexes were investigated by SPS. The results indicate that all complexes exhibit photoelectric responses in the range of 300–600nm, which reveals that they all possess certain photoelectric conversion properties. By the comparative analyses, it can be found that the species and coordination micro-environment of central metal ion, the species and property of ligands affect the intensity and scope of photoelectric response. [Copyright &y& Elsevier]

Abstract: Four new heterometallic polymers, [NiCd(mal)2(H2O)2]n·2nH2O 1, [NiZn2(Hcit)2(H2O)2]n 2, [CoCd2(Hcit)2(H2O)2]n 3, [CoZn2(Hcit)2(H2O)2]n 4 (H2mal=malonic acid, H4cit=citric acid) were synthesized and characterized. The photoelectric properties of the polymers were discussed by the surface photovoltage spectroscopy (SPS). The structural analyses indicate 1 is a Ni–Cd heterometallic polymer with 3D structure bridged by the mal2– group. 2–4 are all heterometallic polymers with 2D structures bridged by the Hcit3– group. The results of SPS for the four polymers reveal that there are wide photovoltage response bands in the range of 300–800nm, which indicates that they all possess photoelectric conversion properties. By the introduction of the other metals, the SPS of heterometallic polymers are broadened obviously than the SPS of monometallic complexes. Moreover, the relationships between SPS and UV–Vis absorption spectra have been discussed. [Copyright &y& Elsevier]

Abstract: Four oxo-vanadium coordination complexes, {[ P4O20(OH)]·2(H2en)·1.5H2O} n (1), {[ P4O22(H2O)]·(H2en)} n (2), {[ O5(SO4)2(phen)3(H2O)3]·6H2O} (3) and [VO(o-phta)(phen)(H2O)] (4) (en=1,2-ethanediamine, o-phta=o-phthalic group, and phen=1,10-phenanthroline), were synthesized hydrothermally and the structures were determined through single-crystal X-ray diffraction. The surface electron behaviors and photo-electric conversion properties of the complexes were studied emphatically by SPS and UV–Vis absorption spectra. Structural analysis indicates that 1 and 2 are both oxo-vanadium phosphate polymers with V+4/V+5 mixed valence states. Complexes 3 and 4 are vanadyl coordination supramolecules including organic ligands. There are all positive response bands within the range 300–800nm in the SPS of the four complexes, which indicates that they all possess photo-electric conversion properties. There are three species of O→V LMCT response bands in the SPS and UV–Vis spectra of the complexes, because the coordinated oxygen atoms are from different groups. The similarities and differences of the spectra are compared and discussed. [Copyright &y& Elsevier]