Cd(II) and Cu(II) coordination polymers based on a multidentate N-donor ligand: syntheses, crystal structures, optical band gaps, and photoluminescence

Four Cd(II)- and Cu(II)-containing coordination polymers (CPs) based on a multidentate N-donor ligand and varied dicarboxylate anions, [Cd(3,3′-tmbpt)(p-bdc)]·2.5H₂O (1), [Cd(3,3′-tmbpt)(m-bdc)]·2H₂O (2), [Cu(3,3′-tmbpt)(m-bdc)]·H₂O (3), and [Cu(3,3′-tmbpt)(p-bdc)]·2H₂O (4), where 3,3′-tmbpt = 1 − ((1H-1,2,4-triazol-1-yl)methyl)-3,5-bis(3-pyridyl)-1,2,4-triazole, p-H₂bdc = 1,4-benzenedicarboxylic acid, and m-H₂bdc = 1,3-benzenedicarboxylic acid, have been prepared hydrothermally. The structures of the compounds were determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra and elemental analyses. Compound 1 exhibits a 3-D twofold interpenetrating framework with a 6⁵·8 CdSO₄ topology. Compound 2 is a 2-D layer containing meso-helical chains with a 4⁴·6² sql topology. Compound 3 shows a 1-D → 3-D interdigitated architecture while 4 displays a 2-D → 3-D interdigitated architecture. The structural differences of the compounds indicate that the dicarboxylate anions and the central metal ions play important roles in the resulting structures of CPs. Optical band gaps and solid-state photoluminescent properties have also been studied.