Two new Cu^I compounds with zwitterionic tetrazolate ligand: In situ synthesis, crystal structures, luminescence and photocatalytic properties

Two 2D new Cu(I) coordination polymers, namely [Cu₂(mpTZ)₂Br₂]·H₂O (1), and [Cu₂(mpTZ)₂N₃]ClO₄ (2) (mpTZ=N-methyl-4-pyridinium tetrazolate) have been synthesized under solvothermal conditions, in which the mpTZ ligands and Cu^I ions were obtained through in situ [2+3] cycloaddition reaction and reduction reaction of Cu^II salts, respectively. Both compounds have been structural characterized by single crystal X-ray diffraction, FT-IR, PXRD and EA. Compound 1 exhibits a 2D neutral coordination network, in which the Cu^I ions are bridged by η₃-1, 2, 4-tetrazolate into 2D sheet. In compound 2, the Cu^I ions are linked by azide (in μ₃-1, 1, 3 bridging mode) and tetrazolate (in η₃-1, 2, 3 bridging mode) anions into 2D positively charged sheet, extended along the bc plane. Both compounds 1 and 2 exhibit intense bluish green luminescence in the solid state. Photocatalytic performances of the two compounds for the degradation of methylene blue (MB) under visible light were also investigated and the MB degradation in the presence of 1 was nearly complete (99%) after 150 min.