Search

Abstract: This work presents six CuII, CoII, and NiII supramolecular complexes assembled from a bent dipyridyl ligand 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (3-bpo) and R-isophthalic acids (R =–CH3 for 5-methylisophthalic acid or R =–OCH3 for 5-methoxyisophthalic acid), which have been prepared using the layer-separation diffusion method and fully characterized by IR, elemental analysis, and powder X-ray diffraction (PXRD) techniques. Single-crystal X-ray diffraction indicates that these complexes show 1-D tube-like (for CuII complexes 1 and 2) or discrete cage-like dinuclear (for CoII and NiII complexes 3–6) coordination patterns. Furthermore, extended 3-D supramolecular architectures are constructed via secondary interactions between the coordination arrays, and three types of packing fashions are observed for the dinuclear species 3–6. Structural diversification for these complexes can be properly attributed to the inherent discrepancy of metal ions and the substituent effect of R-isophthalate tectons. [Copyright &y& Elsevier]

A new supramolecular compound [Zn(H2EDTA)(H2O)](Q)2(H2O)2 (1), where H4EDTA=ethylenediaminetetraacetic acid and Q=4-(carboxylate)pyridinium, has been prepared by mild hydrothermal reaction and characterized by elemental analysis, IR spectrum and thermogravimetric analysis. Single-crystal X-ray diffraction of 1 [monoclinic, space group C2/c, a=11.310(4) Å, b=9.704(4) Å, c=23.798(10) Å, β=97.401(10)°, Z=4] revealed that the ZnII ion coordinates to the chelating tetradentate ligand H2EDTA and a water molecule, taking a distorted trigonal-bipyramid geometry. The mononuclear [Zn(H2EDTA)(H2O)] subunits are linked to form two-dimensional layered architectures by the lattice water moieties through O–H⋯O hydrogen bonds, which are further extended to a three-dimensional (3D) supramolecular network by 4-(carboxylate)pyridinium guests (resulting from the ring-opening hydrolysis of 2,5-bis(4-pyridyl)-1,3,4-oxadiazole) through extensive hydrogen-bonding interactions. The 3D supramolecular framework is also stabilized by significant face-to-face π–π stacking interactions between the aromatic pyridinium systems. [Copyright &y& Elsevier]

The crystal structure of the title complex, trans-dichloridotetrakis[1-phenyl-3-(1 H-1,2,4-triazol-1-yl-κ N4)propan-1-one]copper(II) hexahydrate, [CuCl2(C11H11N3O)4]·6H2O, is isomorphous with that of the corresponding nickel and cobalt compounds. The complex has crystallographic inversion symmetry with the CuII atom on an inversion centre. Each CuII atom is six-coordinated by one N atom from each of the four 1-phenyl-3-(1 H-1,2,4-triazol-1-yl)propan-1-one ligands in the equatorial plane and by two chloride ligands in axial positions. The structure includes a centrosymmetric irregular up-up-down-down (uudd) water tetramer cluster and O-H...Cl hydrogen bonds. Intermolecular C-H...Cl hydrogen bonds exist between adjacent molecules, resulting in a three-dimensional supramolecular network. [ABSTRACT FROM AUTHOR]

Two binuclear lanthanide complexes [Ln 2 (hfac) 6 (HL) 2 ] (Ln III = Dy( 1 ), Tb( 2 ); hfac = hexafluoroacetylacetonate, HL = (R)-2-amino-2-phenylethanol) have been successfully obtained by using amino alcoholate ligand. In two complexes, the Ln(III) ions are bridged by two alkoxido groups from HL ligands, resulting in binuclear complexes. The variable-temperature magnetic susceptibility studies indicate that there exists ferromagnetic interaction between two Ln(III) ions. Frequency dependent out-of-phase signals are observed for complex 1 , suggesting SMM type behavior. Complexes 1 and 2 display intensely characteristic luminescent properties. [ABSTRACT FROM AUTHOR]

C38H34Ni2Cl2N4O12, monoclinic, C2/c (no. 15), a = 17.867(3) Å, b = 9.170(6) Å, c = 24.651(5) Å, β = 110.837(2)°, Z = 4, V = 3775(3) Å3, Rgt(F) = 0.0323, wRref(F2) = 0.1078, T = 293(2) K. [ABSTRACT FROM AUTHOR]

Based on the bis-triazole ligand 2, 6-bis(1, 2,4-triazole-4-yl)pyridine (L), the triazole-iron(II) complexes [Fe(L)2(dca)2(H2O)2] ·2H2O ( 1) (Nadca = sodium dicyanamide), {[Fe(μ2-L)2(H2O)2]Cl2} n ( 2), and {[Fe(μ2-L)2(H2O)2](ClO4)2 ·L ·H2O} n ( 3) were isolated by solvent diffusion methods. When iron(II) salts and Nadca were used, compound 1 was isolated, which contains mononuclear Fe(L)2(dca)2(H2O)2 units. When FeCl2 or FeClO4 were used, one-dimensional (1D) cation iron(II) chains ( 2) and two-dimensional (2D) cation iron(II) networks ( 3) were isolated indicating anion directing structural diversity. Moreover, variable-temperature magnetic susceptibility data of 1- 3 were recorded in the temperature range 2-300 K. The magnetic curve of complex 2 was fitted by using the classical spin Heisenberg chain model indicating anti-ferromagnetic interactions ( J = -5.31 cm-1). Obviously complexes 1- 3 show no detectable thermal spin crossover behaviors, the lack of spin-crossover behavior may be correlated with FeN4O2 coordination spheres in 1- 3. [ABSTRACT FROM AUTHOR]

• The Schiff base binuclear Zn(II) complex, [Zn 2 (L) 2 ∙(H 2 O) 2 ]∙2DMF (1) and its coordination polymer, [Zn 2 (L) 2 ∙(4,4′-bpy) 2 ] n (2) by introducing auxiliary ligand 4,4′-bpy. • The fluorescence spectrum showed the complex 2 containing 4,4′-bpy was substantially quenching of the fluorescence as compared with the complex 1. • The LUMO and HOMO orbits of the complex 2 were occupied by the 4,4′-bpy, which is different from complex 1 , resulting in 1 and 2 had different spectral properties. The Schiff base binuclear Zn(II) complexes, [Zn 2 (L) 2 ∙(H 2 O) 2 ]∙2DMF (1) and its coordination polymer [Zn 2 (L) 2 ∙(4,4′-bpy) 2 ] n (2) (H 2 L = 3-[(5-chloro-2-hydroxy-benzylidene)-amino]-4-hydroxy-chromen-2-one, 4,4′-bpy = 4,4′-bipyridine), were synthesized under the same experimental condition without or with the auxiliary ligand 4,4′-bpy, respectively. The structural analysis revealed that complexes 1 and 2 have different crystal structures. The complex 1 was a centrosymmetric binuclear structure. It is noteworthy that the linker 4,4′-bpy was introduced during the synthesis of complex 2 , so that two water molecules in complex 1 were replaced by two 4,4′-bpy linkers to form one-dimensional (1D) chain-like coordination polymer. The central Zn(II) ions in complex 1 were penta-coordinated distorted square pyramid geometry with τ = 0.42. However, the Zn(II) ions of complex 2 were hexa-coordinated distorted octahedral geometry. The fluorescence spectrum showed the complex 2 containing 4,4′-bpy was substantially quenching of the fluorescence as compared with the complex 1. In addition, it could be seen from the DFT calculation the energy gaps of the complexes 1 and 2 were both reduced compared to the ligand H 2 L. However, the LUMO and HOMO orbits of the complex 2 were occupied by the 4,4′-bpy, which is different from complex 1 , resulting in 1 and 2 had different spectral properties. [ABSTRACT FROM AUTHOR]