A bifunctional cationic metal–organic framework based on unprecedented nonanuclear copper(ii) cluster for high dichromate and chromate trapping and highly efficient photocatalytic degradation of organic dyes under visible light irradiation?

Dalton Transactions Pub Date: 2018-06-11 DOI: 10.1039/C8DT01685B

Abstract

A bifunctional cationic metal–organic framework {[Cu9(OH)6Cl2(itp)6(1,4-bdc)3](NO3)2(OH)2·20H2O}n (1-NO3-OH·20H2O) was synthesized and characterized (itp = 1-imidazol-1-yl-3-(1,2,4-triazol-4-yl)propane, 1,4-bdc = 1,4-benzenedicarboxylate). In 1-NO3-OH·20H2O, three [Cu3(μ3-OH)(μ2-OH)] trimeric clusters are bridged by two μ3-Cl and form a [Cu9(μ3-OH)3(μ2-OH)3(μ3-Cl)2] cluster. Such a nonanuclear copper(II) cluster [Cu9(μ3-OH)3(μ2-OH)3(μ3-Cl)2] has not been reported till now, at least to the best of our knowledge. 1-NO3-OH·20H2O showed a 6-connected 2D 36-hxl net based on a nonanuclear copper(II) cluster [Cu9(μ3-OH)3(μ2-OH)3(μ3-Cl)2]. 1-NO3-OH·20H2O is also the first 2D 36-hxl net-based nonanuclear cluster. 1-NO3-OH (guest-free phase) showed fast and highly efficient Cr2O72? and CrO42? trapping, and good recyclability for capturing Cr2O72? and CrO42?. The adsorption capacities of 1-NO3-OH to capture Cr2O72? and CrO42? were 1.762 mol mol?1 (154.8 mg g?1) and 1.896 mol mol?1 (89.5 mg g?1), respectively, at a molar ratio of 1?:?2 (1-NO3-OH to 2.5 × 10?3 mol L?1 Cr2O72? or CrO42?). 1-NO3-OH exhibited the selective sorption of Cr2O72? or CrO42? from a solution containing a mixture of Cr2O72? or CrO42? and a ten-fold molar amount of ClO4?, NO3?, Cl?, BF4? or a five-fold molar amount of mol L?1 SO42?. 1-NO3-OH could capture 87.9% dilute Cr2O72? or 91.8% dilute CrO42? at an equimolar 1-NO3-OH to 20 ppm Cr2O72? or CrO42?. 1-NO3-OH·20H2O exhibited a highly efficient photocatalytic degradation of the cationic organic dyes methylene blue (MB) and rhodamine B (RhB) under visible light irradiation, and was shown to be a good photocatalyst for photocatalytic degradation of the cationic organic dyes.

Graphical abstract: A bifunctional cationic metal–organic framework based on unprecedented nonanuclear copper(ii) cluster for high dichromate and chromate trapping and highly efficient photocatalytic degradation of organic dyes under visible light irradiation
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