Search

Two highly porous metal–organic frameworks are successfully constructed through the assembling of Co/Ni ions and mixed ligands. From the contribution of the uncoordinated tetrazolate N atoms of the ligand the two complexes show high CO2 adsorption capacities, serving as potential CO2 adsorption materials. [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]

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]

A new lanthanide metal–organic framework was constructed using a tripodal flexible zwitterion ligand (H3LBr3) which takes a chair-shaped configuration. The luminescence of the compound displays highly selective sensing of the Fe3+ ion and nitrobenzene. [ABSTRACT FROM AUTHOR]

Abstract: This work presents two pairs of Ag(I) and Cd(II) supramolecular complexes assembled based on two versatile tripyridyltriazole ligands 3,5-bis(2-pyridyl)-4-(4-pyridyl)-1,2,4-triazole (L242) and 3-(2-pyridyl)-4,5-bis(4-pyridyl)-1,2,4-triazole (L244), respectively. All four complexes have been prepared under similar conditions and characterized by elemental analysis, IR, and powder X-ray diffraction techniques. Single-crystal X-ray diffraction indicates that these complexes display the infinite 1-D and 2-D arrays for {[Ag(L242)(CF3COO)](CH3OH)} n (1) and {[Ag2(L242)(CF3COO)2](CH3CN)0.75(H2O)0.25} n (2) as well as discrete dinuclear and tetranuclear coordination patterns for [Cd(L244)I2]2 (3) and [Cd2(L244)2I4(DMF)2]2(DMF)2 (4). In 1 and 3, extended supramolecular architectures are further constructed via aromatic stacking interactions. Structural difference for each pair of complexes can be properly assigned to the significant solvent effect on assembled reactions (CH3OH–H2O vs. CHCl3–CH3CN for 1 and 2 as well as CH3OH–H2O vs. H2O–DMF for 3 and 4). Thermal stability and fluorescence of these complexes have also been investigated. [Copyright &y& Elsevier]

Abstract: To investigate the effect of positional isomerism of ligands on the construction of coordination polymers, three Cd(II) complexes with tripyridyltriazole tectons and thiocyanate anions have been prepared and characterized, namely, [Cd(L 4 )(μ-SCN)(SCN)] n (1), [Cd(L 5 )(SCN)2] n (2), and [Cd(L 6 )(μ-SCN)2] n (3) (L 4 =3,4-bis(2-pyridyl)-5-(3-pyridyl)-1,2,4-triazole, L 5 =3-(2-pyridyl)-4,5-bis(3-pyridyl)-1,2,4-triazole, and L 6 =3-(2-pyridyl)-4-(4-pyridyl)-5-(3-pyridyl)-1,2,4-triazole. Crystal structure analysis indicates that the isomeric effect of ligands plays a crucial role in regulating the distinct 1D coordination patterns for 1–3, with the aid of the versatility of thiocyanate anion. The solid-state properties such as thermal stability and fluorescence of 1–3 have also been studied. [Copyright &y& Elsevier]

The novel ligand 4′-diferrocenylalkyne-2,2′:6′,2′′-terpyridine (7; Fc-CC-Fc-tpy; tpy = terpyridyl; Fc = ferrocenyl) and its Ru2+complexes 8–10have been synthesized and characterized by single-crystal X-ray diffraction, cyclic voltammetry, and UV–vis and luminescence spectroscopy. Electrochemical data and UV absorption and emission spectra indicate that the insertion of an ethynyl group causes delocalization of electrons in the extended π* orbitals. Cyclic voltammetric measurements of 7show two successive reversible one-electron-oxidation processes with half-wave potentials of 0.53 and 0.78 V. The small variations of the E1/2values for the Fe2+/Fe3+redox couples after the coordination of the Ru2+ion suggest a weak interaction between the Ru2+and Fe2+centers. After insertion of an ethynyl group, UV–vis absorption spectra show a red shift of the absorption peak of the 1[(d(π)Fe)6] → 1[(d(π)Fe)5(π*tpyRu)1] MMLCT of the Ru2+complexes. The Ru2+complex 8exhibits the strongest luminescence intensity (λmaxem712 nm, Φem= 2.63 × 10–4, τ = 323 ns) relative to analogous ferrocene-based terpyridine Ru(II) complexes in H2O/CH3CN (4/1 v/v) solution. [ABSTRACT FROM AUTHOR]

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]

A new 3D luminescence metal–organic framework with open channels was constructed by the assembling of the zwitterionic H 3 L Cl ligand and Zn(II) ions under solvothermal conditions. The compound exhibits relatively high luminescence selective sensing for Fe 3 + ions with surprisingly excellent recyclability, making it a promising candidate for sensing metal ions in practical. [ABSTRACT FROM AUTHOR]

Abstract: The reactions between the silyl-linked bis(amidinate) ligand [SiMe2{NC(Ph)N(Ph)Li(thf)2}2] and ZrCl4 in different stoichiometric chemistry, 2:1, 1:1, and 1:2, were explored. The resulting zirconium compounds, 1, 2, and 3, showed different molecular structural features which were confirmed by X-ray crystallographic analysis. The metal center in 1 was located in a highly saturated coordination environment with four amidinate moieties. Compound 2 exhibited an unprecedented linked tris(amidinate) N–C–N–Si–N–C–N–Si–N–C–N skeleton formed after the intermolecular rearrangement. In compound 3, a novel silyl-linked imino-amidinate ligand via the intramolecular rearrangement was involved. The mechanism for the formation of compounds 2 and 3 was proposed. Compound 2 was found to be a highly active catalyst for ethylene polymerization in the presence of methylalumoxane (MAO). [Copyright &y& Elsevier]

Abstract: The synthesis and characterization of a class of group 4 metal derivatives based on the silyl-linked bis(amidinate) ligands [SiMe2{NC(Ph)N(2,6-R2Ph)Li}2] [L1 (R=H) and L2 (R=Me)] are described. The metal salts coordinated with cyclopentadienyl were used in order to increase the steric hindrance and lower the Lewis acidity of metal centers, which could prevent the N-ligands from rearranging. The tetradentate ligands L1 and L2 reacted with TiCl2(C5H5)2 to give compounds 1 and 2 in tridentate and bidentate bonding modes, respectively. Treatment of the ligand L1 with ZrCl3(C5H5) produced the half-sandwich zirconium complex 3. Reactions of the ligands with ZrCl2(C5H5)2 afforded zirconium compounds 4 and 5, demonstrating the same geometry as 1. Comparing these analogous molecular structures, it suggests that the coordination modes of the N-ligands are variable according to the properties of the metal centers as well as the bulky hindrance of the terminal groups on the seven-membered N–C–N–Si–N–C–N backbone. [Copyright &y& Elsevier]

Abstract: Under hydrothermal conditions using a triazole derivative ligand 3-carboxylic acid-4H-1,2,4-triazole (HL) and corresponding lead(II) salts, a novel two-dimensional(2D) lead(II) complex {[Pb(L)(μ2-Cl)(H2O)} n (1) has been isolated. In 1 Pb2Cl2(H2O)2 building blocks can be observed, which are extended by tetra-dentate coordinated L ligands to form a 2D corrugated layered structure. 1 also represents a novel example of luminescent lead(II) frameworks with triazole derivatives. Solid-state fluorescence spectrum of 1 exhibits the excited peak at 376nm while the emission peak at 604nm. [Copyright &y& Elsevier]

Highlights: [•] A novel three-dimensional porous luminescent silver(I) complex 1 has been isolated. [•] Anion exchange with NaNO3 was also monitored by FT-IR, PXRD and elemental analysis. [•] 1 can behave anion-responsive tunable luminescence properties. [ABSTRACT FROM AUTHOR]

Abstract: The alkyl chain-linked diimidazolium (or dibenzimidazolium) salts, 1,1′-diethyl-4,4′-tetramethylene-diimidazolium-diiodide (L1H2 ·I2 ) and 1,1′-diethyl-3,3′-trimethylene-dibenzimidazolium-diiodide (L2H2 ·I2 ), and their silver(I) and copper(II) coordination polymers, [L1AgI] n (1) and [L2Cu2I4] n (2), have been prepared and characterized. Complex 1 is a 1D helical polymer generated by bidentated carbene ligands (L1) and Ag(I) atoms. The 1D polymer of 2 is formed by bidentated carbene ligands (L2) and coplanar quadrilateral Cu2I2 units. 3D supramolecular frameworks in the crystal packings of 1 and 2 are formed via intermolecular weak interactions, including C–H···π contacts, π–π interactions and C–H···I hydrogen bonds. [Copyright &y& Elsevier]

Abstract: The two Cd(II) and Co(II) 2-D frameworks have been prepared by means of self-assemblies of Cd(II) or Co(II) salts and 1-substituted imidazole and terephthalic acid, and structurally characterized by X-ray diffraction analyses. In complex 1 2-D frameworks with rhombic cavity are formed, in which the each top point of rhombus contains one hexa and two heptacoordinated Cd(II). In complex 2 2-D networks with rectangular cavities are formed, and the opposite benzene rings from carboxyls in each rectangular cavity are parallel. [Copyright &y& Elsevier]

• 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]

• Two novel coordination polymers (CPs) were prepared. • Complex 2 can effectively degrade the methylene blue in the water solution under the irradiation of ultraviolet. • The inhibitory effect of compound against the production of intestinal butyrate was evaluated. Through utilizing a mixed-ligand method, two novel coordination polymers (CPs) containing Co(II) of [Co(L)(dcdps)] n (1) and {Co(L)(bdc)} n (2) [H 2 bdc = 1,4-dicarboxybenzene; H 2 dcdps = 4,4′-sulfonyldibenzoic acid and L = 4,4′-(2,5-bis(methylthio)-1,4-phenylene)dipyridine] have been prepared by the solvothermal method through Co(NO 3) 2 •6H 2 O reacting with the methylthio functionalized dipyridine ligand L in the existence of distinct carboxylic ligands. Compound 2 contains excellent water stability can effectively degrade the methylene blue in the water solution under the irradiation of ultraviolet, which is expected to become a potential photo active material. Furthermore, the inhibitory effect of compound against the production of intestinal butyrate, as well as the HDAC2 expression in colon cancer cells was evaluated. The ELISA test kit was conducted to detect the butyrate content in the intestinal tissue. The real time RT-PCR method was implemented, and the HDAC2 gene relative expression levels in colon cells was measured. Finally, our aim is to generate novel mechanism for the treatment of anti-colon cancer. [ABSTRACT FROM AUTHOR]

A practical synthetic pathway to alkyl-ended ansa-bis(amidinate) ligands was developed via linking the freshly prepared aliphatic group substituted lithium amidinate and the subsequent deprotonation. The lithium complexes prepared by this method were characterized by NMR spectroscopy, elemental analysis and single-crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]