Search

Abstract: In our efforts to investigate the influence of the backbone of different triazole-based bridging ligands on the structure of their metal complexes, four new coordination polymers, {[Cu(L1 )2(H2O)2]Cl2} n (1), [Cu(L2 )2Cl2] n (2), [Co(L2 )2(SCN)2] n (3), and [Cu(L3 )2(NO3)2] n (4), (L1  = 1,2-bis(triazol-1-ylmethyl)benzene, L2  = 1,3-bis(triazol-1-ylmethyl)benzene, L3  = 1,4-bis(triazol-1-ylmethyl)benzene), have been synthesized. All the complexes have been structurally characterized by IR, elemental analysis and single-crystal X-ray diffraction. Structural analyses show that 1 and 4 possess 2D coordination networks with (4,4) topology, and 1 shows a diagonal–diagonal inclined interpenetration. 2 and 3 are isostructural and feature 1D double chain, which further connected by C–H···Cl or π···π weak interactions to form 2D supramolecular frameworks. The results show that the structures of ligands (with different non-coordination backbone spacers) play important roles in the formation of such coordination architectures. Furthermore, EPR (Electron Paramagnetic Resonance) spectra of CuII complexes (1, 2, and 4) have been investigated in the solid state at room temperature. [Copyright &y& Elsevier]

Solvothermal reactions of mixed ligands H3BTC and macrocyclic oxamide complexes (ML, M = Cu, Ni) with M(ClO4)2·6H2O (M = Co, Zn, Ni and Cd) afford six new complexes, including [M′4(BTC)2(ML)2(OH)2(H2O)2]·2H2O (M′ = Co, M = Ni, for (1); M′ = Zn, M = Ni, for (2); M′ = Zn, M = Cu, for (3)), [Ni3(BTC)2(NiL)2(H2O)6]·2CH3OH·2H2O (4), [Cd4(BTC)2(HBTC)(NiL)4(H2O)]·3H2O (5) and [Cd(HBTC)(CuL)]·H2O (6) (ML, H2L = 2, 3-dioxo-5, 6, 14, 15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,13-dien; H3BTC = 1,3,5-benzenetricarboxylic acid). Complexes 1–3consist of a 2D layer framework formed by the linkage of M(ii)(M = Ni, Cu) and M′4(M′ = Co, Zn) cluster viathe oxamide and BTC3−bridges and display a (3,6)-connected network with a (43)2(46.66.83) topology. The structure of 4consists of pentanuclear [NiII5] units and arranges in a 1D cluster chain. Complex 5exhibits a 2D layered structure characterized by 3,4,3-connected (4.62)3(4.63.82)(42.63.8)(42.6) topology. Complex 6possesses a 3D network with sratopology. The magnetic properties of complexes 1and 4were investigated. [ABSTRACT FROM AUTHOR]

Abstract: Five new complexes [Cu2(L1 )I2]∞ (1), [Cu(L2 )I]2 (2), {[Cu2(L2 )I2](CH3CN)3}∞ (3), [Cu2(L3 )I2]∞ (4) and {[Cu(L3 )I](CH3CN)}2 (5) have been obtained by reacting three structurally related ligands, 2,3-bis(n-propylthiomethyl)quinoxaline (L1 ), 2,3-bis(tert-butylthiomethyl)quinoxaline (L2 ) and 2,3-bis[(o-aminophenyl)thiomethyl]quinoxaline (L3 ) with CuI, respectively, at different temperatures. Single crystal X-ray analyses show that 1, 3, 4 possess 1D chain structures, while 2 and 5 are discrete dinuclear molecules. It is interesting that the reactions of CuI with L1 at room temperature and 0°C, respectively, only afforded same structure of 1 (1a and 1b), while using L2 (or L3 ) instead, two different frameworks 2 and 3 (or 4 and 5) have been obtained. The structural changes mainly resulted from the different conformations that L2 or L3 adopted at different temperatures. Our research indicates that terminal groups of ligands take an essential role in the framework formation, and the reaction temperature also has important effect on the construction of such Cu(I) coordination architectures. Furthermore, the influence of hydrogen bonds on the conformation of ligands and the supramolecular structures of these complexes have also been explored. The luminescence properties of complexes 1, 2, and 4 have been studied in solid state at room temperature. [Copyright &y& Elsevier]

Abstract: Aiming at exploring the effect of substituting groups of three structurally related ligands, 5,6-diethyl-pyrazine-2,3-dicarboxylic acid (H2 L 1 ), 5,6-diphenyl-pyrazine-2,3-dicarboxylic acid (H2 L 2 ), and dibenzo[f,h]quinoxaline-2,3-dicarboxylic acid (H2 L 3 ), seven new coordination polymers constructed from these three substituted dicarboxylate ligands, {[Zn(L1)(H2O)3]·2H2O}∞ (1), {[Cd2(L2ʹ)4(H2O)]·3H2O}∞ (2), [Zn(L2)(CH3OH)]∞ (3), {[Zn(L2)(H2O)2]·H2O}∞ (4), {[Zn(L2ʹ)]·H2O}∞ (5), [Zn 2 (L 3 )(DMF) 4 ] ∞ (6), [Zn(L 3 )(2,2ʹ-bipy)(H 2 O)] ∞ (7), have been prepared and structurally characterized. 1 is a 1D chain structure in which ZnII ion is six-coordinated with octahedron geometry. 2 is also a 1D chain structure in which there are two crystallographically independent CdII ions in the asymmetric unit and exist transformative L 2ʹ ligands in the resulting complex. 3 and 4 both possess 2D layer network with the same (4, 82) topology, while the two complexes take different coordination modes during the forming of the compounds. 5 has a 1D chain structure based on the transformative L 2ʹ ligand in which ZnII ion is five-coordinated with bipyramidal geometry. 6 and 7 both have 1D chain structure constructed from L 3 ligand. Thereinto, ZnII ion in 6 is five-coordinated by three oxygen atoms from two individual L 3 ligands and two oxygen atoms from two DMF molecules. While in 7 there are also five coordination sites occupied by two carboxylate oxygen atoms from two L 3 ligands. In addition, the compounds are characterized by elemental analysis, IR spectra. The luminescent properties of the compounds are also discussed and exhibit strong fluorescent emissions in the solid state. [Copyright &y& Elsevier]

Abstract: Two new coordination polymers, namely, [Cd(HL)2]∞ (1) and [La2(L)3(DMAC)6]∞ (2) (L =anthracene-9,10-dicarboxylate and DMAC=N,N-dimethylacetamide), were synthesized. Their structures were characterized by elemental analyses, infrared spectra, and single crystal X-ray diffraction analysis. Complex 1 is found to assume a three-dimensional (3D) twofold interpenetrating diamond network, showing one-dimensional channels running along the [111] direction. On the other hand, 2 has a two-dimensional 63 honeycomb network, which is further linked into 3D supramolecular networks by C–H···π interactions. The results indicate that the different synthesis methods play important roles in controlling the formation of the final frameworks of 1 and 2. The luminescent properties of the corresponding complexes were also briefly investigated. [Copyright &y& Elsevier]

Abstract: Four Ag(I) coordination complexes formulated as {[Ag(L1 )(ClO4)]}n (1), {[Ag(L1 )(NO3)]}n (2), {[Ag(L1 )(PF6)]}2 (3) and {[Ag(L2 )](ClO4)·CH3OH}n (4), (L1 = 3,6-bis(1-pyrazolyl)pyridazine, L2 = 3,6-bis(3,5-dimethyl-1-pyrazolyl)pyridazine) have been synthesized in the presence of different anions [ClO4 − (1) and (4), NO3 − (2), PF6 − (3)] and structurally characterized by FT-IR spectra, elemental analysis and X-ray diffraction. Studies of X-ray diffraction reveal that complexes 1, 2 and 4 show infinite helical chains, which are the alternate left- and right-handed helical chains. Furthermore, helical chains are arranged to 2D sheet via C–H⋯O (from anion O atoms) hydrogen bonds. As the anion changed to PF6 −, a dinuclear molecule is formed in complex 3, further constructing a 2D sheets by C–H⋯F hydrogen bonds. The photoluminescence properties of all the complexes 1–4 have been investigated in the solid state at room temperature. [Copyright &y& Elsevier]

A polynuclear manganesecomplex composed of alternating cyclictetramer and monomer has been solvothermally prepared and magneticallycharacterized. Magnetic analyses indicate that the title compoundshows spin-canting behavior. [ABSTRACT FROM AUTHOR]

Hydrothermalsynthesis of Gd2O3and iminodiaceticacid (H2IDA) yields a three-dimensional (3D) complex {[Gd2(IDA)3]·2H2O}n(1) including Gd16macrocycles. Magneticinvestigation indicates the presence of weak antiferromagnetic interactionbetween GdIIIions and a large magnetocaloric effect with−ΔSmmax= 40.6J kg–1K–1. [ABSTRACT FROM AUTHOR]

Two series of lanthanide metal–organic frameworks,[Ln(FDA)(OX)0.5(H2O)2]·(H2O) (1Ln) (Ln = Pr 1, Nd 2, Eu 3, Gd 4,Tb 5), [Ln(FDA)(OX)0.5(H2O)2]·(H2O) (2Ln) (Ln = Sm 6, Tb 7, Dy 8, Ho 9, Yb 10) (OX = oxalate),have been prepared by reacting Ln(NO3)3·6H2O with furan-2,5-dicarboxylic acid (H2FDA) at differenttemperatures under hydrothermal conditions. All the complexes arecharacterized by elemental analysis, IR, X-ray powder diffraction,and single-crystal X-ray diffraction. Structure analyses show that 1Lnand 2Lnare supramolecular isomerisms. 1Lnpossesses a three-dimensional network with monoclinicspace group P21/c, whereas 2Lnexhibits a three-dimensional framework with monoclinicspace group C2/c. The distinct architecturesof these two series of ten complexes indicated that the reaction temperatureplays an important role in the formation of such coordination structures.Meanwhile, the photoluminescent properties of 4, 5, 7, and 8are also investigatedin the solid state at room temperature. [ABSTRACT FROM AUTHOR]

Abstract: In our continuing efforts to explore the effects of substituent groups of ligands in the formation of supramolecular coordination structures, seven new CuII complexes formulated as [Cu2(L1 )4(DMF)2] (1), {[Cu2(L1 )4(Hmta)](H2O)0.75} ∞ (2), [Cu2(L2 )4(2,2′-bipy)2] (3), [Cu2(L3 )4(H2O)2] (4), [Cu2(L3 )4(Hmta)] ∞ (5), [Cu2(L3 )4(Dabco)] ∞ (6) and [Cu2(L3 )4(Pz)] ∞ (7) with three monocarboxylate ligands bearing different substituent groups HL1 –HL3 (HL1 =phenanthrene-9-carboxylic acid, HL2 =2-phenylquinoline-4-carboxylic acid, HL3 =adamantane-1-carboxylic acid, Hmta=hexamethylenetetramine, 2,2′-bipy = 2,2′-bipyridine, Dabco = 1,4-diazabicyclo[2.2.2] octane and Pz = pyrazine), have been prepared and characterized by X-ray diffraction. In 1, 2 and 4–7, each CuII ion is octahedrally coordinated, and carboxylate acid acts as a syn–syn bridging bidentate ligand. While each CuII ion in 3 is penta-coordinated in a distorted square-pyramidal geometry. 1 and 4 both show a dinuclear paddle-wheel block, while 2, 5, 6 and 7 all exhibit an alternated 1D chain structure between dinuclear paddle-wheel units of the tetracarboxylate type Cu2-(RCO2)4 and the bridging auxiliary ligands Hmta, Dabco and Pz. Furthermore, 3 has a carboxylic unidentate and μ1,1-oxo bridging dinuclear structure with the chelating auxiliary ligand 2,2′-bipy. Moreover, complexes 1–6 were characterized by electron paramagnetic resonance (EPR) spectroscopy. [Copyright &y& Elsevier]

Abstract: Two new Silver(I) complexes, {[AgL]·(H2O)2} n (1, HL =acridine-9-carboxylic acid) and {[Ag(L)(4,4′-bipy)]·(H2O)5} n (2), has been synthesized and characterized by elemental analysis, IR, and single-crystal X-ray diffraction analysis. Ag(I) ion in complex 1 is coordinated by L as a bridging ligand with its acridine N donor and bidentate chelating carboxylate group forming a 1D chain. Different from 1, complex 2 adopts a 1D chain structure with 4,4′-bipy as a bridging ligand. In 2, L coordinates to Ag(I) ion as a terminal ligand by its carboxylate group in a bidentate chelating mode similar to that in 1, leaving N donor as a H-bond acceptor. It is worth noting that in 1 C–H⋯Ag weak interactions are observed, and these weak interactions are also elucidated by theoretical investigation of TD-DFT (B3LYP) methods and NBO analysis. Furthermore, the photoluminescence properties of 1 and 2 are also investigated in the solid state at room temperature, and the theoretical calculations of the absorption and emission spectra of 1 were carried out with B3LYP method on the basis of the experimental structure. [Copyright &y& Elsevier]

Abstract: In our efforts to investigate the relationships between the structures of ligands and their complexes, two structurally related ligands, 1-(2-pyridylmethyl)-1H-benzimidazole (L1 ) and 1-(4-pyridylmethyl)-1H-benzimidazole (L2 ), and their four complexes, [Zn(L1 )2Cl2] (1), [Hg(L1 )Br2]∞ (2), {[Zn(L2 )Cl2](CH3CN)}∞ (3) and [Hg(L2 )Br2]2(CH3CN)2 (4) were synthesized and structurally characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction analysis. Structural analyses show that 1 has a mononuclear structure, and 2 and 3 both take 1D structure. While 4 takes a dinuclear structure. 1, 2 and 4 were further linked into higher-dimensional supramolecular networks by weak interactions, such as C–H⋯Cl and C–H⋯Br H-bonding, C–H⋯π, and π⋯π stacking interactions. The structural differences of 1–4 may be attributed to the difference of the spatial positions of the terminal N donor atoms in the pendant pyridyl groups in L1 and L2 , in which the pyridine rings may act as the directing group for coordination and the benzimidazole rings act as the directing group for π⋯π stacking and C–H⋯π interactions. The luminescent properties of the corresponding complexes and ligands have been further investigated. [Copyright &y& Elsevier]