Theoretical and experimental spectroscopic studies of the first highly luminescent binuclear hydrocinnamate of Eu(III), Tb(III) and Gd(III) with bidentate 2,2 '-bipyridine ligand

In this paper, the synthesis of three new binuclear lanthanide (III) complexes [Ln(2)(cin)(6)(bpy)(2)] (Ln=Eu (1), Tb (2), Gd (3), cin=hydrocinnamate anion; bpy=2,2'-bipyridine), and their complete characterization, including single crystal X-ray diffraction, FTIR spectroscopy and thermal analysis (TGA/DTA) are reported. In especial, photophysical properties of Eu(III) complex have been studied in detail via both theoretical and experimental approaches. Crystal structures of 1-3 reveal that all compounds are isostructural and that each lanthanide ion is nine-coordinated by oxygen and nitrogen atoms in an overall distorted tricapped trigonal-prismatic geometry. Eu(III) complex structure was also calculated using the Sparkle model for lanthanide complexes and the intensity parameters (Omega(2), Omega(4), and Omega(6)), calculated from the experimental data and from Sparkle/PM3 model. The theoretical emission quantum efficiencies obtained for Sparkle/PM3 structures are in excellent agreement with the experimental values, clearly attesting to the efficacy of the theoretical models. The theoretical procedure applied here shows that the europium binuclear compound displays a quantum yield about 65% suggesting that the system can be excellent for the development of efficient luminescent devices. (C) 2013 Elsevier By. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Synthesis, structural characterization, luminescent properties and theoretical study of three novel lanthanide metal-organic frameworks of Ho(III), Gd(III) and Eu(III) with 2,5-thiophenedicarboxylate anion

In this paper, the synthesis of three new metal-organic frameworks of lanthanides (LnMOFs) {[Ln(2)(2,5-tdc)(3)(dmso)(2)]center dot H2O}(n) (Ln=Ho (1); Gd (2); Eu (3); 2,5-tdc=2,5-thiophenedicarboxylate anion; dmso=dimethylsulfoxide), and their complete characterization, including single crystal X-ray diffraction, FTIR spectroscopy and thermogravimetric analysis are reported. In especial, photophysical properties of Eu(III) complex have been studied in detail via both theoretical and experimental approaches. Crystal structure of (1) reveals that each lanthanide ion is seven-coordinated by oxygen atoms in an overall distorted capped trigonal - prismatic geometry. The 2,5-tdc(2-) ligands connect four Ln(III) centers, adopting (kappa(1)-kappa(1))-(kappa(1)-kappa(1))-mu(4) coordination mode, generating an 8-connected uninodal 3D network. In addition, theoretical studies for Eu(III) complex were performed using the Sparkle model for lanthanide complexes. (C) 2015 Elsevier Inc. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Influence of Synthetic Methods in the Structure and Dimensionality of Coordination Polymers

Eight different coordination polymers (CPs) of Co²⁺ and Zn²⁺ ions with rigid polycarboxylate ligands (fumaric acid (<i>fum</i>) and 2,5-dihydroxyterephalic acid (<i>dhbdc</i>)) have been synthesized using the same solvents, stoichiometry, and counterion but two different synthetic methods: liquid–liquid diffusion method–method A and pH control method–method B. The synthesis using method A resulted in four novel CPs: <i>trans</i>-Co­(dmso)₂­(H₂O)₂­(fum)]_<i>n</i> (<b>1</b>), [<i>trans</i>-Zn­(dmso)₂­(H₂O)₂­(fum)]_<i>n</i> (<b>2</b>), <i>trans</i>-Co­(dmso)₂­(H₂O)₂­(dhbdc)]_<i>n</i> (<b>3</b>), and [<i>trans</i>-Zn­(dmso)₂­(H₂O)₂­(dhbdc)]_<i>n</i> (<b>4</b>). Synthesis using method B resulted in one new ([Zn­(fum)­(OH)₂] (<b>6</b>)) and three previously described CPs ([Co₃(H₂O)₄­(OH)₂­(fum)₂]­·2H₂O (<b>5</b>), [Co₂(dobdc)] (<b>7</b>), and [Zn₂(dobdc)] (<b>8</b>), where <i>dobdc</i> = 2,5-dioxyterephtalic acid). The new CPs (<b>1</b>–<b>4</b>) were also structurally investigated by single-crystal X-ray diffraction techniques, which showed that all of them form one-dimensional (1D) CPs with linear chain structure: it was evidenced that (<b>1</b>) and (<b>3</b>) are isomorphus crystals of (<b>2</b>) and (<b>4</b>), respectively. The crystal structures of <b>1</b>–<b>4</b> were compared with similar 1D, two- and three-dimensional (2D and 3D) CPs reported in the literature. Intra- and interchain H-bond networks and coordination (<i>fum</i>, <i>dhbdc</i>, DMSO, water) as well as linkage (<i>fum</i> and <i>dhbdc</i>) isomerism guide the chain configuration (linear or zigzag). It was also demonstrated that the new series of 1D CPs synthesized here (<b>1</b>–<b>4</b>) can work as precursors for CP with higher dimensionality. Our studies showed that the synthetic method plays a crucial role in the crystal growth of coordination polymers