A 2D bitriazole-bridging copper(II) polymer: Hydro thermal synthesis, crystal structure, and fluorescence

A new 2D metal-organic coordination polymer Cu(trtr)₂]_n (1) (Htrtr = 3-(1,2,4-triazolyl-4-yl)-1H-1,2,4-triazole) is synthesized through the hydrothermal reaction of Cu(ClO₄)₂ with Htrtr. The crystal structure of 1 is determined by a direct method from X-ray diffraction data (Rigaku Mercury CCD, MoK _α radiation). 1 crystallizes in the monoclinic C2/c space group with unit cell parameters: a = 14.158(2) ?, b = 9.8050(14) ?, c = 11.413(3) ?, β = 127.9870(10)°, V = 1248.7(4) ?³, Z = 4, D _calc = 1.775 g/cm³. 1 features a 2D grid based on the propagation of 28-membered rings, which is further fabricated into a 3D supramolecular framework via the hydrogen bond linkage. The fluorescence of 1 shows a blue emission at 441 nm with a 14 nm red-shift compared to that of free Htrtr, which can be assigned to LMCT.