Guang Hua Cui

Two metal–organic frameworks with unique high-connected binodal network topologies: synthesis, structures, and catalytic properties

{[Cd3(btec)(btx)0.5(μ3-OH)(H2O)]·H2O}n (1) and [Cu2(btec)(btx)1.5]n (2), two novel cadmium(II) and copper(II)-based high-connected metal–organic frameworks, with both 1,2,4,5-benzenetetracarboxylate (btec) and 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (btx) as mixed ligands were hydrothermally synthesized and structurally characterized. Both MOFs have three-dimensional (3D) structures, but different framework topologies and ligand linkage modes. 1 possesses an unprecedented binodal (4,12)-connected topology structure, in which the ligand btec serves as a rare dodecadentate and ordinary octadentate in two types of coordination modes. Meanwhile, 2 exhibits a binodal (4,7)-connected topological network with an enneadentate coordination geometry of the btec ligand. Both MOFs provide novel examples of designing and synthesizing novel binodal MOFs, and demonstrate that the 1,2,4,5-benzenetetracarboxylic acid ligand with rich coordination chemistry information is useful in the construction of binodal highly-connected nets. In addition, the catalytic performance of 2 has also been checked. 2 is active as a catalyst for the degradation of methyl orange.

A series of d10 metal coordination polymers based on a flexible bis(2-methylbenzimidazole) ligand and different carboxylates: synthesis, structures, photoluminescence and catalytic properties

To explore the influence of different aromatic polycarboxylates on the self-assembly and properties of d10 metal coordination frameworks, six coordination compounds containing a flexible bis(2-methylbenzimidazole) (pbmb) ligand, formulated as [Ag2(pbmb)(2,6-napdc)]n (1), {[Zn(pbmb)(tbta)]·H2O}n (2), {[Cd(pbmb)(tbta)]·H2O}n (3), [Zn2(pbmb)(btec)(H2O)]n (4), {[Zn2(OH)(pbmb)(bpdc)1.5]·H2O}n (5), and [Cd(pbmb)(3-npa)(H2O)]n (6), have been synthesized under hydrothermal conditions and characterized by physicochemical and spectroscopic methods as well as single-crystal X-ray diffraction analysis (2,6-H2napdc = 2,6-naphthalenedicarboxylic acid, H2tbta = tetrabromoterephthalic acid, H4btec = 1,2,4,5-benzenetetracarboxylic acid, H2bpdc = biphenyl-4,4′-dicarboxylic acid and H23-npa = 3-nitrophthalic acid). Complex 1 possesses an 8-connected 3D coordination framework with sqc3 topology based on rare tetranuclear Ag(I)-cluster secondary building units (SBUs). 2 and 3 possess 2D (4,4) grid structures. 4 shows a novel (3,4,5)-connected 2D network with the Schlafli symbol of {3·4·5}{3·42·52·6}{3·43·53·6·72}. 5 features a uninodal (4,4)-connected net containing binuclear {Zn2(OH)} SBUs and a 2-fold interpenetrating (3,6)-connected supramolecular framework with {42·6}{44·610·8}-3,6T24 topology that is formed via hydrogen bond interactions. Complex 6 is a 1D double-chain structure, which is finally extended to a 3D (4,5,5)-connected supramolecular network via hydrogen bonding interactions. Complexes 1–6 indicate high thermal stabilities and different photoluminescence behavior in the solid state. Moreover, all of these polymer materials manifest excellent photocatalytic activities for the degradation of methyl orange in the photo-Fenton-like process after 120 min (1: 99%, 2: 66%, 3: 91%, 4: 83%, 5: 91% and 6: 93%, respectively).

Four cobalt(II) coordination polymers with diverse topologies derived from flexible bis(benzimidazole) and aromatic dicarboxylic acids: syntheses, crystal structures and catalytic properties

Four mixed ligand coordination polymers based on the flexible bis(5,6-dimethybenzimidazole) and aromatic dicarboxylic acids, namely, [Co(L1)(bpdc)]n (1), {[Co(L1)(npht)]·0.5H2O}n (2), [Co(L2)(bpdc)]n (3), and [Co(L3)(bpdc)(H2O)]n (4) (L1 = 1,4-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, H2bpdc = 4,4′-biphenyldicarboxylic acid, L2 = 1,3-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, H2npht = 3-nitrophthalic acid, L3 = 1,1′-bis(5,6-dimethylbenzimidazole)methane) have been hydrothermally synthesized and structurally characterized. Polymer 1 features a 3D three-fold interpenetrating dia array with a 4-connected 66 network, while 2 exhibits a 3D noninterpenetrated 3-connected framework with a 103-ThSi2 architecture. 3 and 4 have two-dimensional 3-connected (63) and 4-connected (44.62) topologies, respectively. Complex 4 ultimately is extended into an unusual 3D (3,5)-connected seh-3,5-P21/c supramolecular network via O–H⋯O hydrogen bonding interactions. The fluorescence and catalytic properties of the complexes for the degradation of the Congo red azo dye in a Fenton-like process are reported.

Synthesis, crystal structures, luminescence and catalytic properties of two d10 metal coordination polymers constructed from mixed ligands

Two new coordination polymers [Cd(bmb)(hmph)]n (1), {[Ag(bmb)]·H2btc}n (2) (bmb=1,4-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H2hmph=homophthalic acid, H3btc=1,3,5-benzenetetracarboxylic acid) were synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction methods, IR spectroscopy, TGA, XRPD and elemental analysis. Complex 1 features a 3D threefold interpenetrating dia array with a 4-connected 6(6) topology. Complex 2 shows a 1D helix chain structure connected by L1 ligands, which is finally extended into a rarely 2D 4L2 supramolecular network via C-H⋯O hydrogen bond interactions. In addition, the luminescence and catalytic properties of the two complexes for the degradation of the methyl orange azo dye in a Fenton-like process were presented. The degradation efficiency of the methyl orange azo dye for 1 and 2 are 56% and 96%, respectively.

Syntheses, structures, and photoluminescence of three cadmium(II) coordination polymers with flexible bis(benzimidazole) ligands

Three cadmium(II) coordination polymers, [CdBr2(L1)] n (1), [CdI2(L2)] n (2), and Cd2Br4(L3)2 (3), where L1 = 1,3-bis(5,6-dimethylbenzimidazole)propane, L2 = 1,4-bis(5,6-dimethylbenzimidazole)butane, and L3 = 1,6-bis(5,6-dimethylbenzimidazole)hexane, have been synthesized by hydrothermal methods and characterized by elemental analyses, IR spectra, TGA, PXRD, and X-ray crystallographic diffraction. Complex 1 contains a 1-D helical chain in which CdBr2 units are linked by L1. For 2, each CdI2 is connected by two different conformations of L2 to form a 1-D zigzag chain. For 3, each CdBr2 is linked by L3 bridges to afford a binuclear structure. These results indicate that the spacer length of the ligands play important roles in assembly of Cd(II) coordination polymers. Thermogravimetric analyses and solid-state luminescent properties of the complexes have also been investigated.

Synthesis, crystal structures, and fluorescence properties of two 1-D zinc(II) coordination polymers constructed from a bis(benzimidazole) ligand

[Zn(L)(HCOO)Cl]n (1) and {[Zn2(L)2(OH)(HCOO)Cl]·I}n (2) have been obtained by hydrothermal methods of zinc chloride with 1,3-bis(5,6-dimethylbenzimidazole-1-ylmethyl)benzene (L) and potassium bromide (or potassium iodide), and are characterized by elemental analysis, IR spectra, X-ray powder diffraction, and single-crystal X-ray diffraction. The zinc(II) centers display tetrahedral coordination in 1 and 2. Solid 1 forms a one-dimensional (1-D) helical chain bridged by L, which is further arranged into a two-dimensional supramolecular structure through intermolecular π–π stacking interactions. A 1-D ladder-like chain of 2 connected by hydroxyl and L is presented. Solid-state fluorescent properties of 1 and 2 have been investigated.

Synthesis, structures, and fluorescence of two cadmium(II) coordination polymers with a semirigid bis-benzimidazole

Compounds [CdLCl2] n (1) and {[Cd(L)2(ClO4)]·ClO4} n (2), where L = 1,3-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, have been synthesized by hydrothermal method, and characterized by element analysis, IR spectra, Powder XRD, and X-ray crystallographic diffraction. Cd(II) in 1 and 2 are both trigonal bipyramidal. Different cadmium salts of chloride and perchlorate lead to different configurations of [Cd2L2]2+, trans-form in 1 but trans and cis-forms in 2. The 1-D beaded chains of 1 are further linked to generate a 3-D supramolecular architecture by strong π–π stacking interactions as well as intermolecular C–H ··· Cl hydrogen bonds. In 2, the 1-D beaded chains are further assembled by intermolecular C–H ··· O hydrogen bonds to form a 2-D layer. Solid-state fluorescent properties of 1 and 2 were investigated at room temperature.

Synthesis, crystal structures, luminescence properties of two metal coordination polymers derived from 5-substituted isophthalate and flexible bis (triazole) ligands.

Two new metal complexes, [Ni(btx)(nip)(H2O)]n (1), {[Cd(btx)(mip)(H2O)]·H2O}n (2) (btx=1,4-bis(1,2,4-triazol-1-ylmethyl)benzene, H2nip=5-nitroisophthalic acid, H2mip=5-methyisophthalic acid) were synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction methods, IR spectroscopy, TGA and elemental analysis. Complex 1 features a 3D metal-organic framework with three-fold interpenetrating CdSO4-type topology. Complex 2 exhibits a 2D network with square grid units, which is further extended into a rare 3,5T1 three-dimensional supramolecular network via three modes of classical OH⋯O hydrogen bonds. In addition, luminescence properties of 1 and 2 have also been investigated in the solid state.

Structural diversity of transition-metal coordination polymers derived from isophthalic acid and bent bis(imidazole) ligands

Four coordination polymers associated with bent bis(imidazole) 1,3-bis(imidazol-l-yl-methyl)benzene (mbix) and isophthalic acid (H2ip) or 5-methylisophthalic acid (H2mip) ligands, formulated as {[Cd(mbix)(mip)]·H2O}n (1), {[Co(mbix)(mip)]·0.4H2O}n (2) [Ni(mbix)(mip)H2O]n (3) and [Ni(mbix)(ip)]n (4), were synthesized under hydrothermal conditions and characterized by physico-chemical and spectroscopic methods. Complexes 1 and 2 are isomorphous and exhibit a 1D loop-like chain. Complex 3 features a 2D (4,4) layer, which further extends into an unusual 2D (3,5)-connected 3,5L2 double-layered supramolecular network via classical O–H···O hydrogen bonding interactions. Complex 4 is a 3D network, which shows a rare binodal (3,5)-connected 3,5T1 framework. Moreover, the luminescence and catalytic properties of the complexes for the degradation of methyl orange by sodium persulfate in a Fenton-like process are reported.

Sonochemical synthesis of two nanostructured silver(I) coordination polymers based on semi-rigid bis(benzimidazole) ligands

Nanoparticles of two silver(I) coordination polymers (CPs), [Ag2(L1)2(DCTP)]n (1) and [Ag2(L2)(DCTP)]n (2) (L1=1,3-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, L2=1,4-bis(benzimidazol-1-yl)-2-butene, H2DCTP=2,5-dichloroterephthalic acid), were synthesized by the sonochemical approach and hydrothermal method. Both CPs were characterized by elemental analysis, IR spectra, single-crystal X-ray diffraction, scanning electron microscopy (SEM), and thermogravimetric analyses (TGA). CP 1 exhibits a 2D 4-connected sql net with the point symbol {44.62}. While CP 2 displays a 2D 3,4-connected 3,4L13 net with the point symbol {4.62}2{42.62.82}. The structural diversity indicates that semi-rigid bis(benzimidazole) co-ligands play important roles in tuning the structures of the mixed Ag(I) CPs. The ultrasound irradiation time, temperature, and power showed significant effects on the morphology and growth process of the nanoparticles of two silver(I) CPs. The luminescence and photocatalytic properties of the nanoparticles of CPs 1-2 on the degradation of methyl blue (MB) were also investigated in detail.