Synthesis and Structure of 3D Bis[5-(2-pyridyl)tetrazolato]diquacopper(II) Framework: One-pot Facile Fabrication of a Series of Catalysts Towards Dye Degradation in Sunlight

A copper-based metal-organic framework (MOF) Bis[5-(2-pyridyl)tetrazolato]diaquacopper(II) [{CuP}(n)], has been designed and structurally characterized by single-crystal X-ray crystallography. The three-dimensional crystal structure belongs to the monoclinic space group P2(1)/c with Z=4. Further a series of isostructural complexes [{Cu1-xZnxP}(n)] (x=1, 0.75, 0.5, 0.25, 0), {P=(5-(2-pyridyl)tetrazolato)(2).2H(2)O} have been synthesized via a facile one-pot microwave irradiated solvothermal method. The optical and photocatalytic properties of the synthesized bimetallic complexes were investigated and compared with those of monometallic complexes. The effects of metal substitutions in the ligand backbone were investigated. A striking variation in the bandgap i. e., from 4.1 eV (x=1) to 2.79 eV (x=0) was observed among the catalysts with a minimum value of 1.93 eV (x=0.25). The optimized catalyst Cu0.75Zn0.25P exhibits the highest degradation activity and reached up to 99 % for RhB (rhodamine B) and 96 % for MB (methylene blue) in 120 min of Sunlight, corresponding to the respective photocatalytic degradation rates of 0.0328 min(-1) and 0.0301 min(-1). The kinetics of the degradation processes were best statistically described by pseudo-first-order. The catalyst was also found to have sufficient stability and recyclability with promising applications in removal of organic dye pollutants.

Automated summary

A copper-based metal-organic framework was designed and synthesized, and its bimetallic complexes showed excellent photocatalytic properties for removing organic dye pollutants.