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Zheng Z.-P.,South China Normal University | Zhang X.-X.,South China Normal University | Li T.,South China Normal University | Yang J.,South China Normal University | And 5 more authors.
Dalton Transactions | Year: 2014

Four low-dimensional ytterbium(iii)-organic compounds through hydrothermal reactions of quinoline-2,3-dicarboxylic acid (2,3-H2qldc) and oxalic acid (H2ox) with Yb2O3, namely, [Yb(2,3-qldc)(ox)1/2(H2O)3·(H 2O)4]n (1), [Yb(2,3-qldc)(ox) 1/2(H2O)2·(H2O) 2]n (2), [Yb(2,3-Hqldc)(ox)(H2O) 2·(H2O)]n (3) and [Yb(2,3-Hqldc)(ox) (H2O)·(H2O)2]n (4), were first synthesized and characterized by elemental analysis (EA), infrared spectroscopy (IR), thermogravimetric analysis (TG), and single-crystal X-ray diffraction. When the reactant ratio of 2,3-H2qldc:H 2ox:Yb2O3 is 2:1:1, 1-D chain-like complex 1 with three coordinated water molecules around the Yb(iii) ion was obtained in mixed solvents of H2O and CH3OH (v:v = 10:1) at 70 °C, and with the increase of temperature to 100 °C, the same reactants gave 2-D 63 topological layer-like complex 2 with two coordinated water molecules in the coordination sphere of the Yb(iii) ion. However, when the reactant ratio was changed to 1:1:1, two 2-D 63 topological layer-like complexes 3 (70 °C) and 4 (100 °C) were obtained at different temperatures, in which the coordination water molecules in 3 and 4 are two and one, respectively. Obviously, these results reveal that the reaction temperature and reactant ratios play critical roles in the structural direction of these low-dimensional compounds. Interestingly, with the gradual loss of coordination water molecules to the Yb(iii) ion, the near infrared (NIR) emission of four Yb(iii)-based compounds 1-4 can be gradually strengthened with increasing order of 1 < 3 < 2 < 4, indicating that these ytterbium(iii) complexes have tunable near infrared luminescence. © 2014 the Partner Organisations. Source

Zheng Z.-P.,South China Normal University | Wei Q.,South China Normal University | Yin W.-X.,South China Normal University | Wan L.-T.,South China Normal University | And 4 more authors.
RSC Advances | Year: 2015

Two Schiff base ligands (HL1, HL2) were conveniently synthesised by one-step condensation between pyridine 2-ylmethanamine and 3-ethoxy-2-hydroxybenzenaldhyde (for HL1) or salicylaldehyde (for HL2) as fluorescent sensors for distinguishing sensing of Zn2+ or Cd2+. Both of the two fluorescent sensors present very weak emission at 463 nm (for HL1) or 453 nm (for HL2). For HL1, upon addition of Zn2+, the fluorescence intensity of HL1 enhanced and gradually red shifted to 493 nm with a green emission while addition of Cd2+ only induced enhancement of fluorescent intensity at 463 nm. For HL2, only addition of Zn2+ induced enhancement of fluorescence intensity, presenting a high Zn2+/Cd2+ selectivity. A Zn2+-induced red shift in fluorescent spectra of HL1 could be attributed to twisted intramolecular charge transfer (TICT) from the interaction between the Zn2+ ion and in situ formed ligand L1′ with the twisted structure in compound 1, which is absent in compound 2. The Zn2+/Cd2+ selectivity of fluorescent response for HL2 correlates with the Cd-HL2 and Zn-HL2 coordination bond distances. Obviously, introduction of ethoxyl groups onto the benzene ring as an electron-donating group facilitates the Zn-induced in situ dimerization of HL1 into new ligand L1′ with a twisted molecular structure, further resulting in a red shift of the fluorescence spectra. This journal is © The Royal Society of Chemistry 2015. Source

Hong X.-J.,South China Normal University | Zhan Q.-G.,South China Normal University | Zhan Q.-G.,State Key Laboratory of Structure Chemistry | Huang Z.-P.,South China Normal University | And 6 more authors.
Inorganic Chemistry Communications | Year: 2014

Two zinc(II) complexes with NO- and N2O-set oxime-containing Schiff base ligand of 2-hydroxyimino-N′-[1-(2-pyridyl)ethylidene] propanohydrazone (Hpop), namely [Zn3(pop)2-(CH 3OH)2Cl4] (1) and [Zn(pop)Cl] 4·(H2O)2 (2), have been successfully synthesized from the reaction of Hpop with ZnCl2 in CH3OH under different temperatures and fully characterized by X-ray single-crystal diffraction, EA and IR as well as TG. At the low temperature, the linear M 3L2-type trinuclear Zn(II) compound 1 was obtained, however, the grid-like Zn4L4-type tetranuclear Zn(II) compound 2 was given at the high temperature from the same reactants. Interestingly, compound 1 may be irreversibly transformed into 2 via ring-closed coordination reaction under the high temperature, accompanied by the corresponding changes in fluorescent property. © 2014 Elsevier B.V. Source

Liu Y.-T.,South China Normal University | Du Y.-Q.,South China Normal University | Du Y.-Q.,State Key Laboratory of Structure Chemistry | Wu X.,South China Normal University | And 5 more authors.
CrystEngComm | Year: 2014

Two different types of microporous lanthanide metal-organic frameworks based on pyridine-3,5-dicarboxylic acid (H2pydc) and succinic acid (H2suc), namely [Ln(pydc)(suc)0.5·3H 2O]·2H2O (type I) [Ln = Pr (1), Eu (2), Tb (3), Er (4)] and [Ln(pydc)(suc)0.5·2H2O]·2H 2O (type II) [Ln = Yb (5) and Lu (6)], have been successfully synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction, infrared spectroscopy (IR), elemental analysis, thermogravimetric analyses (TGA) and powder X-ray diffraction (PXRD). Complexes 1-4 (type I structure) are isomorphous, crystallize in the monoclinic P2 1/c space group and present three-dimensional (3D) pillar-layered frameworks constructed from two-dimensional (2D) [Ln(pydc)]- layers and suc2- pillars with 1D rhombic channels. The isomorphous compounds 5-6 (type II structure) crystallize in the triclinic P1 space group and feature a 2D layer made up of 1D ladder-like [Ln(pydc)]- chains and suc 2- connectors with the water molecules occupying the interlayer spaces. The results show that structural variation from I to II may be attributed to the lanthanide contraction effect. Furthermore, the sorption ability of compound 2 and the luminescence properties of compounds 2-3 are also investigated. This journal is © the Partner Organisations 2014. Source

Hong X.-J.,South China Normal University | Hong X.-J.,State Key Laboratory of Structure Chemistry | Liu X.,South China Normal University | Zhang J.-B.,South China Normal University | And 7 more authors.
CrystEngComm | Year: 2014

Two low-dimensional oxime-containing Schiff base copper(i/ii) complexes with iodine-copper cluster [Cu2I4]2- bridges, namely, {[CuII 4I3(pop)4] 2(CuI 2I4)}·(CH 3CN)2·H2O (2) and [CuII 4I2(pop)4(CuI 2I 4)·(CH3CN)]n (3) (Hpop = 2-(hydroxyimino)-N′-[1-(2-yridyl)ethylidene]propanehydrazone), have been synthesized from the reaction of [2 × 2] grid-like compound {[Cu III(pop)]4}2·4H2O (1) with equivalent CuI 2I2 (iodine-copper clusters) under solvothermal conditions and characterized by elemental analysis (EA), infrared spectroscopy (IR), thermogravimetric analysis (TGA), and X-ray single-crystal/powder diffraction. The results show that 2 is a 0-D discrete structure from an assembly of one [Cu2I4]2- unit and two [2 × 2] molecular grids (1) via μ3-I atoms coordinating to CuI/CuII atoms. However, compound 3 presents a 1-D wave-like chain, which is constructed by coordination of μ2-I atoms from [CuI 2I4] 2- units with CuII atoms in [2 × 2] molecular grids (1). Moreover, catalytic experiments demonstrated that compounds 2 and 3 have promising visible-light-driven catalytic activity in degrading various organic dyes. This journal is © the Partner Organisations 2014. Source

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