Syntheses, Crystal Structures, Luminescent Properties, and Electrochemical Synthesis of Group 12 Element Coordination Polymers with 4-Substituted 1,2,4-Triazole Ligands

The self-assembly of Zn(II), Cd(II), or Hg(II) salts with long flexible 1,2,4-triazole-based ligands resulted in coordination polymers and mononuclear complexes of diverse topology. Indeed, the 1D chain [ZnCl2(btpm)] (1) (P1̅), the 2D square grid [Zn(btpm)2(H2O)](BF4)2·2btpm·8H2O (2) (P21212), and the 1D chain [Cd3Cl6(btpm)2]·8H2O (3) (P1̅) with btpm = bis(4-(1,2,4-triazol-4-yl)phenyl)methane were crystallized. In addition, the mononuclear complexes [ZnCl2(ppt)2] (4) (I2) and [HgBr2(ppt)2] (5) (C2) were obtained along with the 1D polymer [Cd2Cl2(ppt)4](CdCl4)·4DMF (6) (P1) with ppt = (4-phenoxyphenyl)-1,2,4-triazole. 1D chains of the formula [ZnCl2(tpca)] (7) (P21/c) and [HgBr2(tpca)] (8) (P21/c) along with the 2D net [Cd(tpca)2(H2O)2]·2H2O (C2/c) (9) with tpca = N-(1,2,4-triazol-4-yl)pyridine-3-carboxamide were obtained. In addition, the X-ray structures of tpca and ppt are described. All compounds display solid-state blue luminescence, which has been investigated in detail. Electrochemical synthesis of 2, which has been rarely applied for MOF synthesis, revealed hollow particles.