Self-assembly of three d10 metal coordination polymers based on a flexible bis(2-methylbenzimidazole) and dicarboxylate co-ligands

Properties of Aliphatic Ligand-Based Metal-Organic Frameworks

Ligands with a purely aliphatic backbone are receiving rising attention in the chemistry of coordination polymers and metal-organic frameworks. Such unique features inherent to the aliphatic bridges as increased conformational freedom, non-polarizable core, and low light absorption provide rare and valuable properties for their derived MOFs. Applications of such compounds in stimuli-responsive materials, gas, and vapor adsorbents with high and unusual selectivity, light-emitting, and optical materials have extensively emerged in recent years. These properties, as well as other specific features of aliphatic-based metal-organic frameworks are summarized and analyzed in this short critical review. Advanced characterization techniques, which have been applied in the reported works to obtain important data on the crystal and molecular structures, dynamics, and functionalities, are also reviewed within a general discussion. In total, 132 references are included.

A new three-dimensional bis(benzimidazole)-based cadmium(II) coordination polymer

A new coordination polymer (CP), formulated as [Cd(L)(DCTP)]_n (1) (L=1,1'-(1,4-butanediyl)bis(2-methylbenzimidazole), H₂DCTP=2,5-dichloroterephthalic acid), was synthesized under hydrothermal conditions and the performance as luminescent probe was also investigated. Single-crystal X-ray diffraction reveals CP 1 is a 3D 3-fold interpenetrated dia network with large well-defined pores. It is found that CP 1 revealed highly sensitive luminescence sensing for Fe³⁺ ions in acetonitrile solution with a high quenching efficiency of K_SV=2541.238L·mol^-1 and a low detection limit of 3.2μM (S/N=3). Moreover, the photocatalytic efficiency of 1 for degradation of methylene blue could reach 82.8% after 135min. Therefore, this coordination polymer could be viewed as multifunctional material for selectively sensing Fe³⁺ ions and effectively degrading dyes.

A novel two-dimensional cadmium(II) complex: poly[diaquatris(μ4-cyclohexane-1,4-dicarboxylato)bis[2-(pyridin-4-yl)-1H-benzimidazole]tricadmium(II)

The title compound, [Cd3(C8H10O4)3(C12H9N3)2(H2O)2]nor [Cd3(chdc)3(4-PyBIm)2(H2O)2]n, was synthesized hydrothermally from the reaction of Cd(CH3COO)2·2H2O with 2-(pyridin-4-yl)-1H-benzimidazole (4-PyBIm) and cyclohexane-1,4-dicarboxylic acid (1,4-chdcH2). The asymmetric unit consists of one and a half CdIIcations, one 4-PyBIm ligand, one and a half 1,4-chdc2−ligands and one coordinated water molecule. The central CdIIcation, located on an inversion centre, is coordinated by six carboxylate O atoms from six 1,4-chdc2−ligands to complete an elongated octahedral coordination geometry. The two terminal rotationally symmetric CdIIcations each exhibits a distorted pentagonal–bipyramidal geometry, coordinated by one N atom from 4-PyBIm, five O atoms from three 1,4-chdc2−ligands and one O atom from an aqua ligand. The 1,4-chdc2−ligands possess two conformations,i.e.e,e-trans-chdc2−ande,a-cis-chdc2−. Thecis-1,4-chdc2−ligands bridge the CdIIcations to form a trinuclear {Cd3}-based chain along thebaxis, while thetrans-1,4-chdc2−ligands further link adjacent one-dimensional chains to construct an interesting two-dimensional network.

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.

A series of d10metal coordination polymers based on a flexible bis(2-methylbenzimidazole) ligand and different carboxylates: synthesis, structures, photoluminescence and catalytic properties

Six d¹⁰metal coordination polymers have been prepared and characterized. Complexes possess structural diversities with interesting topologies and high catalytic activities for the degradation of methyl orange.