Search

Abstract: Using aromatic carboxylic acids as main ligands, four Ln(III) coordination polymers, [Er(CH3C6H4COO)2(Ac)(H2O)] n (1), [Yb(β-C10H7COO)2(Ac)(H2O)] n (2), [Nd(C9H7O2)3] n (3) and [Ho(C9H7O2)3] n (4) (CH3C6H4COO= p-toluylate, Ac=acetate, β-C10H7COO= β-naphthoyloxy, C9H7O2 =cinnamate), were synthesized by hydrothermal method and their structures were studied by single-crystal X-ray diffraction. Polymers 1 and 2 possess 2D layer structures, and polymers 3 and 4 possess 1D chain structures. At room temperature in the solid state, the IR, UV–Vis–NIR spectra and the emission spectra in the visible and near-infrared (NIR) regions of the four polymers were determined. In the NIR region, polymers 1–4 show characteristic emission bands of the corresponding Ln(III) ions which exhibit shift, splitting or broadness in comparison with their theoretical emission bands. This can be confirmed by their UV–Vis–NIR spectra and discussed emphatically. [Copyright &y& Elsevier]

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]

A series of coordination polymers, {[LnZn(2,3-pydc)(1,3-bdc)(OH)(H 2 O) m ] · H 2 O} n , (Ln = Sm 1 , Eu 2 , Gd 3 , Tb 4 , Dy 5 , Er 6 , Yb 7 , Pr 8 , Nd 9 ), ( 1 – 7 , m = 1; 8 , 9 , m = 2), (2,3-H 2 pydc = pyridine-2,3-dicarboxylic acid, 1,3-H 2 bdc = isophthalic acid), are synthesized by the hydrothermal method and their crystal structures are determined by single-crystal X-ray diffraction. Structural analysis shows that coordination polymers 1 – 9 present two-dimensional layered structures and all of them are crystalized in triclinic system with space group P ī. Hereinto polymers 1 – 7 are isomorphous, while polymers 8 and 9 are also isomorphous and each of them includes one more coordinated water molecule than others. All coordination polymers are characterized by IR, UV–Vis–NIR and fluorescent spectra, and the luminescent properties are the research emphasis. In addition, except for polymer 3 , the other eight Zn-Ln polymers exhibit the characteristic luminescence of corresponding Ln(III) ions, which should be owing to the sensitization of the Zn-Ligand moiety. With the influence of the crystal field and the introduction of Zn(II) ion, the internal energy levels of the system are tuned, which is reflected by shift and split of the partial characteristic bands of Ln(III) ions in their UV–Vis–NIR absorption spectra and NIR emission spectra, and both can corroborate each other. [ABSTRACT FROM AUTHOR]

Fourteen Ni/Co-Ln heterometallic coordination polymers were successfully synthesized. All CPs are bridged into the 3D network structure by 2,3-pydc2- and ox2- and exhibit characteristic emission bands of the corresponding Ln(III) ion. [Display omitted] • A series of heterometallic NiII/CoII-LnIII coordination polymers have been synthesized by using pyridine-2,3-dicarboxylic acid as main ligand. • They exhibit characteristic luminescence of Ln(III) ions. • NIR emission bands of Ln(III) ions in some polymers present shift, split and broad under the double influence from the crystal field and Ni(II) or Co(II) ions. Fourteen isomorphic heterometallic coordination polymers (CPs) with general formulas of {[LnM(2,3-pydc) 2 (ox) 0.5 (H 2 O) 3 ]·3H 2 O} n (M = Ni, Ln = Pr 1 , Nd 2 , Sm 3 , Eu 4 , Gd 5 , Tb 6 , Dy 7 ; M = Co, Ln = Pr 8 , Nd 9 , Sm 10 , Eu 11 , Gd 12 , Tb 13 , Dy 14 ; 2,3-pydc2– = fully deprotonated pyridine-2,3-dicarboxylic acid, ox2– = fully deprotonated oxalic acid) have been synthesized by hydrothermal methods. All the CPs crystallize in triclinic P -1 space group and exhibit a 3D network formed by 2,3-pydc2– and ox2– bridging Ln(III) and Ni(II)/Co(II) ions. Meamwhile the room temperature photoluminescent properties have been explored. Except for CPs 5 and 12 , the other CPs exhibit characteristic luminescence of Ln(III) ions. [ABSTRACT FROM AUTHOR]

Abstract: Three titanium coordination polymers, {[Ti(SO4)2(H2O)]·0.5bipy·2H2O} n 1, {[Ti1(SO4)2(H2O)]·[Ti2(SO4)2(H2O)]·bipy·5H2O} n 2 and [Ti(tea)] n 3 (bipy=4,4′-bipyridine, H3tea=triethanolamine) were synthesized and characterized by IR, UV–Vis absorption spectra, TG analysis, X-ray single crystal diffraction and surface photovoltage spectroscopy (SPS). The surface photoelectric properties of titanium coordination polymers were discussed emphatically by the SPS. The results of single crystal diffraction indicate that polymers 1 and 2 possess 1D infinite structure bridged by SO4 2− groups and coordinated water molecules and further connected into supramolecular structures by hydrogen bonds. Polymer 3 possesses 2D infinite structure bridged by weak sub-coordinated Ti–O bonds. The results of SPS show that there are obvious photovoltage responses in the range of 300–500nm, which indicates that they possess photoelectric conversion ability. The SPS of three titanium polymers were analyzed comparatively. It is found that the valence of central metal ions, coordination micro-environment and kinds of coordination atoms influence the results of the SPS. The SPS is associated with UV–Vis absorption spectra. [Copyright &y& Elsevier]

Abstract: Two new Fe(II) coordination polymers, [Fe(dcbp)(H2O)2]n 1 and [Fe(pdc)(H2O)2]n∙nH2O 2 (H2dcbp=4,4′-dicarboxy-2,2′-bipyridine, H2pdc=pyridine-2,5-dicarboxylic acid), were synthesized by hydrothermal method and characterized by IR, UV–Vis absorption spectra, elemental analysis, electron paramagnetic resonance spectra and X-ray single crystal diffraction. The surface photoelectric properties of Fe(II) coordination polymers were discussed emphatically by surface photovoltage spectroscopy (SPS). The structural analyses indicate that 1 is 3D coordination polymer bridged by dcbp2− groups and 2 is 2D layer structure bridged by pdc2− groups. The results of SPS show that there are photoelectric responses in the range of 300–550nm, which reveals that they all possess photoelectric conversion properties. By the comparison and analysis, it is found that the dimension, species of ligands and coordination micro-environment of the Fe(II) ions should affect the results of the SPS. The SPS were associated with the UV–Vis absorption spectra. [Copyright &y& Elsevier]