Chang-Kun Xia

Syntheses, crystal structures, and properties of complexes constructed with polybenzoate and 2,2′-bibenzimidazole

Six new complexes constructed with polybenzoate and 2,2′-bibenzimidazole, namely, [Co(H2bibzim)(1,4-bdc)] (1), [Ni(H2bibzim)(1,4-bdc)] (2), [Co(H2bibzim)2(1,3-bdc)]·H2O (3), [Co4(H2bibzim)3(Hbibzim)2(1,3,5-btc)2·2H2O]·5H2O (4), [Co2(H2bibzim)4(1,2,4,5-btec)] (5), and [Ni(H2bibzim)3](1,4-bdc)·3H2O (6) (bdc = benzenedicarboxylate, H2bibzim = 2,2′-bibenzimidazole, btc = benzenetricarboxylate, btec = benzenetetracarboxylate) have been synthesized by hydrothermal methods and characterized by single crystal X-ray diffraction. Complexes 1 and 2 are isomorphous. Both crystallize in the monoclinic space group P21/c and feature 1-D “zigzag” chains, which can be further arranged into undulating sheets in a zipper-like fashion through π-π and hydrogen bonding interactions. Complex 3 belongs to the P21/c space group. Each Co(II) atom coordinates to one 1,3-bdc and two H2bibzim ligands. With the help of strong N–H⋯O hydrogen bonding interactions between H2bibzim and neighboring 1,3-bdc, a 2-D network with windows of about 14.8 × 18.2 A can be formed with [Co(H2bibzim)2(1,3-bdc)] dimers as building blocks. Complex 4 belongs to the Cc space group and features a 3-D framework. Interestingly, two of the five H2bibzim are deprotonated into Hbibzim− and act as bridging ligands. Complex 5 crystallizes in P-1, the dinuclear units are connected into a 2-D sheet through π–π and hydrogen bonding interactions, forming a molecular zipper synchronously. Complex 6 crystallizes in P21/n, the nickel atom is six coordinated by three H2bibzim ligands, and the terephthalate (tp) groups act as counterions, connecting the coordination cations into a 3-D framework through N–H⋯O hydrogen bonding interactions. The thermal stabilities of complexes 1–6 were examined. The temperature-dependent magnetic susceptibilities of complexes 1, 2 and 4 were also studied.

Synthesis of Isoindolinones by Pd-Catalyzed Coupling between N-Methoxybenzamide and Styrene Derivatives

An atom-economical protocol for a tandem process involving Fujiwara-Moritani-aza-Wacker reactions has been developed for the Pd-catalyzed coupling between N-methoxy benzamide and styrene derivatives. The generality of the methodology was demonstrated by the synthesis of a library of 25 3-benzylidene isoindolinones in moderate to good yields. A further 40 3-benzyl derivatives were obtained by telescoping the process with a catalytic hydrogenation reaction.

Cage-like pores of a metal–organic framework for separations and encapsulation of Pd nanoparticles for efficient catalysis

A porous metal–organic framework, {[Zn(BDC)1/2(trz)]·DMAC}n (Zn-BDC), was synthesized hydrothermally with the decomposition of 2,3-di(1,2,4-triazole)quinoxaline ligand (H2BDC = 1,4-benzenedicarboxylic acid; Htrz = 1,2,4-1H-triazole). Structural analysis indicates the porosity of Zn-BDC with distorted oblong cages. Gas adsorption studies of N2 and Ar on activated Zn-BDC reveal the BET surface areas of 587.3 and 519.5 m2 g−1, respectively. Considering the certain size of the cages, Zn-BDC can separate organic compounds with different sizes through a MOF-column chromatographic method and deliver 5-fluorouracil, which can act as an anticancer drug. Zn-BDC has also been employed as a support for Pd nanoparticles. The results of catalytic hydrogenation of 4-nitrophenol demonstrate that the catalytic activity of Pd@Zn-BDC is superior enough compared to most Pd catalysts reported.

Bis[2-(3-pyridinio)benzimidazolium] di-μ-chloro-bis­[trichloro­cadmium(II)]

The title compound, (C12H11N3)2[Cd2Cl8], consists of two discrete 2-(3-pyridinio)benzimidazolium cations and one [Cd2Cl8]4- anion. The dimeric [Cd2Cl8]4- anion lies about an inversion centre and consists of two distorted [CdCl5] trigonal bipyramids which share a common edge. The two Cd atoms are each coordinated by two mu-Cl atoms and three terminal Cl atoms, with a Cd...Cd separation of 3.9853 (6) A. The packing displays two-dimensional hydrogen-bonded sheets, which are further linked by C-H...Cl contacts and pi-pi stacking interactions to yield a three-dimensional network.

Syntheses and characterization of two new compounds based on versatile 1,2,3,5-benzenetetracarboxylic acid and 2,2′-bibenzimidazole

Abstract Two coordination complexes based on H4btec and H2bibzim (H4btec = 1,2,3,5-benzenetetracarboxylic acid, H2bibzim = 2,2′-bibenzimidazole), [Ni(H2bibzim)3]2(btec) (1) and [Zn(H2bibzim)(btec)0.5]n (2), have been synthesized by hydrothermal methods and characterized by single-crystal X-ray diffraction. Complex 1 is composed of [Ni(H2bibzim)3]2+ with free btec4− as counter anion. In 2, the btec4− ligands bridge the Zn(II) ions into a 1-D chain with H2bibzim as auxiliary chelating ligands. Interesting supramolecular structures were demonstrated due to the existence of hydrogen bonding as well as π⋯π interactions in the two different complexes. The H2bibzim ligands act as a 2-connected spacer in both complexes. However, in 1, the [Ni(H2bibzim)3]2+ cations act as 3-connected nodes, hydrogen bonded with the 6-connected btec4− ligands into a 3-D framework with (3,6)-connected topology Schläfli symbol as (4.6.8)(42.6)(43.64.87.10). As for 2, Zn serves as a 3-connected node with btec4− as a 6-connected node, leading to a 2D (3,6)-connected hydrogen bonding kgd topology sheet with Schläfli symbol of (43)2(46.66.83). Thermal stabilities and photoluminescent properties of 1 and 2 were also studied.

Silver(I), nickel(II) N-heterocyclic carbene complexes based on bidentate bis-imidazolium salt with a quinoxaline linker: syntheses, structures, and characterization

Abstract Quinoxaline-bridged bidentate bis-imidazolium dicarbene ligand 1,1′-(quinoxaline-2,3-diyl)bis(3-methyl-1H-imidazol-3-ium) hexafluorophosphate salt H2L·2PF6 (3) was prepared by a two-step reaction based on 2,3-bis(imidazol-1-yl)quinoxaline (1). First, the 2,3-bis(imidazol-1-yl)quinoxaline reacted with CH3I resulting in the 1,1′-(quinoxaline-2,3-diyl)bis(3-methyl-1H-imidazol-3-ium) iodide salt H2L·2I (2), then through anion exchange reactions with NH4PF6 in water produced the desired bis-imidazolium bidentate ligand H2L·2PF6 (3). Reaction of the bidentate bis-imidazolium ligands H2L·2PF6 (3) with Ag2O in acetonitrile gave the macrocyclic binuclear silver(I) carbene complex [Ag2(L)2]·2PF6·CH3CN (4). Nickel carbene complex [Ni(L)PPh3Cl]·PF6·2DMSO (5) was obtained via transmetalation of 4 with Ni(PPh3)2Cl2 in DMSO. The bidentate carbene ligand is a chelating ligand in 5, while bridging in 4. The imidazolium ligand H2L·2PF6 (3) and transition metal carbene complexes 4 and 5 have been fully characterized by elemental analysis, NMR, ESI-MS spectroscopy, and X-ray diffraction analyses. Furthermore, the UV and luminescent properties of 3–5 were also studied.

Syntheses, crystal structures, and properties of two dinuclear iron(III) complexes constructed with 1,2,3,5-benzenetetracarboxylic acid and chelating N-donor auxiliary coligands

Abstract Two dinuclear Fe(III) metal–organic complexes with tetracarboxylate and chelating N-donor ligands, [Fe(Hbtec)(phen)(H2O)]2·2H2O (1) and [Fe(Hbtec)(bpy)(H2O)]2·2H2O (2) (H4btec = 1,2,3,5-benzenetetracarboxylic acid, phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine) have been prepared and characterized by elemental analysis, IR spectroscopic, and X-ray diffraction methods. Both complexes crystallize in the monoclinic space group P21/c with two Fe(III) ions bridged by two Hbtec3− ligands into a dinuclear unit. Hydrogen bonding connects the dinuclear units into a 3-D framework. The dinuclear units are 10-connected nodes that produce a 3-D framework with topology Schläfli symbol as (312·428·55). Thermal stabilities and luminescent properties of the two complexes have also been investigated.

Three coordination compounds based on benzene tetracarboxylate ligand: syntheses, structures, thermal behaviors and luminescence properties

Using 1,2,3,5-benzenetetracarboxylic acid and different pyridyl ligands, three metal-organic coordination compounds, [

Syntheses, Structures, and Photoluminescent Properties of Three Silver(I) Coordination Polymers with 2-(4-Pyridyl)benzimidazole

\hbox {Co(H}_{3}\hbox {btec})(1{,}{10}\hbox {-phen})(\hbox {H}_{2}\hbox {O})_{3}