Hydrothermal syntheses of a series of cluster-based micro-porous luminescent cadmium(ii) metal–organic frameworks with 4-amino-benzene-1,2,4-triazole: topological diversity, gas absorption and photo-luminescent characterization

Abstract

In this work the multi-dentate 4-amino-benzene-1,2,4-triazole (L 1 ) ligand is used. A series of novel clusterbased micro-porous luminescent cadmium(II) frameworks, namely [Cd 3 5H 2 O} n (3) have been isolated under hydrothermal conditions. 1 presents a 4-connected (4,4) topology using trinuclear Cd(II) clusters as basic nodes. For 1, two bridging m 2 -Cl À anions and two bridging m 3 -L 1 ligands connect three neighboring Cd II ions forming trinuclear Cd 3 clusters. Each Cd 3 cluster links four neighboring Cd 3 clusters forming a 2D (two-dimensional) neutral micro-porous framework. 1D rhombic channels with dimensions of 7.594(2) Å Â 21.250(6) Å can be observed along the c-axis. 2 presents a rare I 1 O 3 hybrid type micro-porous framework. In 2 these bridging m 3 -L 1 ligands link central Cd II ions forming a 3D Cd-L 1 organic connectivity. Two kinds of 1D Cd-Br-Cd inorganic connectivities further consolidate the 3D Cd-L 1 organic connectivity, which ultimately forms a rare I 1 O 3 type hybrid framework. 3 presents a novel 3D cluster-based micro-porous cation framework containing 1D channels, in which guest CdI 4 2À anions and water molecules are located. Topological analysis indicates that 3 presents a novel 4-connected dmp topology using binuclear Cd 2 I 2 clusters as basic nodes. PXRD, TGA and Gas absorption experiments for 1-3 have also been carried out. Solid state photo-luminescent spectra of 1-3 have been determined indicating strong emission bands. For 1 selective photo-luminescent quenching for NO 2 À anions can be observed. The result also reveals that L 1 can adopt various different coordinated modes and flexible spatial distortion dihedral angles (between aromatic benzene and triazole rings), which has great potential in the construction of these novel cluster-based micro-porous coordination frameworks.

An Interpenetrated Pillar-Layered Metal-Organic Framework with Novel Clusters: Reversible Structural Transformation and Selective Gate-Opening Adsorption

“…The cluster has a twofold symmetry of axis at the central Co atom, in which all Co atoms show the distorted octahedral coordination environments. Notably, the coordination polymers based on the metal-azolate-halide trinary building blocks were frequently reported; however, the corresponding clusters-based compounds were rarely recorded. − The cluster in 1 differs from some known trinuclear cluster containing azolates and halide anions, such as [Cu 3 (CN 4 ) 4 (Cl 2 )], [Cu 3 (C 2 N 3 ) 4 (Cl 2 )], , [Co 3 (C 2 N 3 ) 4 F 2 ], [Cd­(C 2 N 3 ) 2 (Cl) 4 ], [Cd­(C 2 N 3 ) 4 (Cl) 2 ]. , In the cluster of 1 , the outer Co atom is coordinated by one chelating carboxylate group and one tetrazolate N atom of two tzba, two pyridine N atoms of two bpy, and one F atom. The central Co atom is ligated by two tetrazolate N atoms of two tzba, two pyridine N atoms of two bpy, and two F atoms.…”