Two 1,2,4-triazole-based zinc(II) complexes with aromatic acid as coligand: Synthesis, structure and fluorescence properties

Two two-dimensional (2-D) trz-based coordination polymers, {[Zn(trz)(mb)]center dot H2O}(n) (1) and {[Zn(trz)(ca)]center dot H2O}(n) (2) (Htrz = 1,2,4-triazole, Hmb = 4-methylbenzoic acid, and Hca = trans-cinnamic acid), have been synthesized by diffusion method and fully Structural characterized by elemental analysis, FT-IR, single-crystal X-ray crystallography, TG and fluorescence spectra. Structural analysis reveals that both complexes exhibit the analogous 2-D Zn-II-trz layer motif with hydrophobic aromatic rings attached on both sides despite their different crystal system and space group (orthorhombic, Pbca for 1 and monoclinic, P2(1)/c for 2). Interestingly, the discrete water-dinier and infinite 1-D water-chain were observed to be entrapped in the 2-D layer of 1 and 2, respectively, resulted from the different orientation of lattice water molecules as well as the patterns of hydrogen bonds involved. In addition, their simliar thermal behaviors and fluorescence emissions originated from intraligand electronic transfer were also investigated and compared.