Metal-Ligand Ratio-Controlled Assembly of Two Cadmium(II) Complexes with 1,4-Bis(1,2,4-Triazol-1-Ylmethyl)Benzene Ligand: Syntheses, Structures, and Fluorescence Properties

Two Cd(II) coordination polymers, {[Cd(3-NPA)(btmb)(H2O)]·H2O}n (1) {[Cd(3-NPA)(btmb)(H2O)]·1.75H2O}n (2) (H23-NPA is 3-nitrophthalic acid, btmb is 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene) were synthesized by the hydrothermal reaction and characterized by single crystal X-ray diffraction. The structures of two complexes are adjusted by metal-ligand ratio. Complex 1 is a 3D metal organic framework by 3-NPA and btmb ligand linkers at the Cd/btmb ligand ratio of 1 : 2. The Cd(II) is was hepta-coordinate and adopted a slightly distorted [CdO5N2] pentagonal-bipyramid geometry. Complex 2 exhibits a two-dimensional layered structure containing a 1D Cd-carboxylate chain in the presence of Cd/btmb ligand ratio of 1 : 1. The Cd(II) is six-coordinated with a slightly distorted [CdO4N2] octahedral geometry. In addition, powder X-ray diffraction, thermogravimetric analysis and fluorescence spectroscopies of both complexes were investigated. Both complexes show similar emission characteristics with the H23-NPA ligand, which may be used as potentially useful photoactive materials.