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Abstract: Four heteronuclear Zn–Ln coordination complexes, [Nd2Zn2(p-toluylate)10(phen)2] (1), [Ln2Zn2(p-toluylate)10(phen)2]·2(HAc)1/2 (Ln=Tb 2, Ho 3) and [PrZn2(p-toluylate)5(Ac)2(phen)2] (4) (phen=1, 10-phenanthroline), are synthesized by the hydrothermal method and their structures are measured by single-crystal X-ray diffraction. The IR and UV–vis–NIR absorption spectra and the emission spectra in the visible and near-infrared (NIR) regions of the four complexes are determined at room temperature. In the NIR region (or in the visible region), the complexes show the characteristic emission bands of Ln3+ ions, which may be attributed to sensitization from the ligands (the ligand directly-coordinated to Ln3+ ions and d-block) to Ln3+ ions after forming the Zn–Ln complexes. It is reported for the first time in this paper that the Zn–Pr complex 4 can exhibit the broad emission band in the NIR region. In addition, the shift, split or broadness of the ff emission bands in the NIR region of complexes 1, 3 and 4 are 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]

Abstract: Six novel heterometallic Zn–Ln coordination polymers {[ZnLnCl(pydc)2(H2O)6]·3H2O} n (Ln=Nd 1, Pr 2, Sm 3, Eu 4, Tb 5, Dy 6; pydc=pyridine-2,5-dicarboxylate) were synthesized by the hydrothermal method, and their structures were measured by the single-crystal X-ray diffraction. The IR and UV–Vis–NIR absorption spectra, and the luminescence spectra in the visible and near-infrared (NIR) regions of the six complexes were determined at room temperature. They possess the same crystal structure, and the Zn(II) and Ln(III) ions in each complex are bridged into 1D infinite chain by pyridine-2,5-dicarboxylates. Meanwhile, there are numerous hydrogen bonds which result in the 3D hydrogen bonding network in the crystal. In the visible and NIR regions, the emission spectra of the complexes show the characteristic bands of the corresponding Ln(III) ions, which are mainly attributed to the sensitization from the d-L-moiety to f-L-moiety after forming the Zn–Ln complexes. In this paper, we first report the Zn–Sm complex which can exhibit the emission bands of Sm(III) in the NIR region, and discuss the sensitization from the d-L-moiety to f-L-moiety on the basis of the different characteristics of levels for different Ln(III) ions. [Copyright &y& Elsevier]

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: 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: Three Ni(II) coordination complexes [NaNi(NTA)(H2O)] n (1), [Ni(pdc)2(Hppz)2]·H2O (2), [Ni(HL)2] (3) (H3NTA=nitrilotriacetic acid; ppz=piperazine; H2pdc=2,5-pyridinedicarboxylic acid; H2L=2-(1-piperazinl)-succinic acid) were obtained by hydrothermal synthesis method. The structures of the three complexes were determined by single crystal X-ray diffraction. Complex (1) is a 3D coordination polymer bridged by NTA3− groups; complex (2) is a mononuclear complex with ligands of pdc2− and Hppz+, forming a 3D supramolecule via hydrogen bonds; complex (3) is also a mononuclear complex with ligand of HL−, connected into a 3D supramolecule through hydrogen bonds. The photo-electric properties of complexes were investigated by surface photovoltage spectroscopy (SPS). The results of SPS show that the three complexes exhibit obvious photovoltage responses in the range of 300–800nm, which indicates that they all possess certain photo-electric conversion properties. Comparing and analyzing the SPS results of three complexes, it can be found that the component, structure and dimensionality of complex, the category of ligand, the species and number of the direct coordination atoms as well as change of the coordination microenvironment of central metal Ni(II) ion all affect obviously the SPS responses. The SPS and UV–Vis spectra of the complexes were interrelated. [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]