Three new isostructural coordination polymers with Cd(II) clusters as the SBU: Synthesis, structural characterization, and luminescence properties

摘要

Three new isostructural coordination polymers, {Cd_(1.33)L(Cl) _(0.67)(H_2O)_(0.67)}_n (1), {Cd _(1.33)L(Br)_(0.67)(H_2O)_(0.67)}_n (2), and {Cd_(1.33)L(I)_(0.67)(H_2O) _(0.67)}_n (3), have been synthesized using a semiflexible in situ generated tetrazole ligand. All the complexes crystallize in cubic space group P4_132. In complex 1, three Cd~(2+) ions along with two N atoms each from three tetrazole units form a trinuclear unit where each metal ion is additionally bridged by carboxylate O and μ_3-Cl units. This Cd(II) cluster along with the ligand form a trigonal arrangement that extends to form a two-dimensional sheet that further undergoes extensive interpenetration to generate an overall three-dimensional coordination polymer. All complexes exhibit thermal stability up to ～330 °C losing coordinated water molecules at ～140 °C. Upon excitation at 340 nm, the complexes exhibit solid-state luminescence with an emission peak at ～415 nm that shows slight red shift with broadening of the band with changing the halide anion from chloride to bromide to iodide.