Synthesis, crystal structure and blue photoluminescence of a metal-organic framework constructed from triangular [Zn₃(μ₃-OH)] clusters with bis(tetrazole)amine ligands

A new metal-organic framework, {Zn[Zn₃(BTA)₃(μ ₃-OH)(H₂O)₃]₂}_n 1, has been synthesized under hydrothermal reaction of ZnCI₂ and bis(5-tetrazolyl)amine (H₂BTA), and characterized by elemental analysis, FT-IR, Raman spectrum, X-ray single-crystal diffraction, TGA and photoluminescence measurements. Compound 1 crystallizes in the trigonal system, space group P-3cl, a = 13.667(3), c = 12.981(3) Å,V= 2099.6(8) Å₃ and Z = 2. The BTA^2- ligand in 1 assumes the μ₃ tetradentate mode with both 1,2- and 1,4-tetrazole bridges, generating an unusual 2-D layer, in which the [Zn₃(μ₃- OH)] triangular motifs act as three-connecting nodes and the mononuclear Zn atoms as six-connecting nodes that are inter-linked by organic ligands. Adjacent 2-D metal-organic layers are linked by strong hydrogen bonds to form a novel 3-D supramolecular framework. Complex 1 exhibits blue fluorescence emission in the solid state at ambient temperature.