Luminescent properties of activated forms of rigid ligand Cd(II)-coordination polymers sustained by hydrogen bond

Abstract

Two new Cd(II) coordination polymers namely {[Cd(BTC)(H2O)]∙0.5HBimb·2H2O}n(1) and{[Cd2(CH3COO)4(4,4′-dpy)2]∙H2O}n(2) were synthesized using an extremely versatile imidazole-based N-donor ligand,1,4-bis[(1H-imidazol-1-yl)methyl]benzene (Bimb), rigid 1,3,5-Benzenetricarboxylic acid (H3BTC) and 4,4′-dipyridyl (4,4′-dpy) with different metal salt at different temperatures. Elemental analysis, Variable Temperature Photoluminescence, and thermal stability were used to characterize both coordination polymers. The single crystal analysis reveals that (1) is an anionic framework in which charge neutrality is compansated by H2Bimb+2 ions, where as (2) is a neutral complex. The OH⋯O hydrogen bonding helps in elevation of dimensionality from 1D coordination chain to 2D architectures in both the complexes. The solid-state luminescence spectra of as synthesized and activated forms (90 °C, 180 °C and 300 °C) for complexes (1) and (2) were recorded at 350 nm and 330 nm as excitation wavelength respectively. The activated forms reflect strong blue luminescence with the peak maximum in the range of 391–390 nm (3.1710–3.1791 eV) for complex (1) and for complex (2) it is at396-399 nm (3.1309–3.1074 eV). Thermogravimetric analysis reveals that both are contented with good thermal stability.