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

Abstract

Three new isostructural coordination polymers, {Cd_1.33L(Cl)_0.67(H₂O)_0.67}_n (1), {Cd_1.33L(Br)_0.67(H₂O)_0.67}_n (2), and {Cd_1.33L(I)_0.67(H₂O)_0.67}_n (3), have been synthesized using a semiflexible in situ generated tetrazole ligand. All the complexes crystallize in cubic space group P4₁32. In complex 1, three Cd²⁺ 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.