New Supramolecular Coordination Polymers Based on Cd(II) and Co(II) with Ethyl Nicotinate and Thiocyanate Ligands as Effective Catalysts for Removal of Organic Dyes

Abstract

Two new 3D- supramolecular coordination polymers (SCP) were synthesized by the reactions of ethyl nicotinate (EN) ligand and SCN ion with Cd(II) and Co(II) ions. Two different structures, {[Cd(SCN)2(EN)2]}, SCP 1 and {[Co2(NCS)4(EN)8]}, SCP 2, were characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, and thermal analysis. The structure of the SCP 1 consists of cyclic (CdSCN)n building blocks exhibiting chair conformation creating 1D-chain decorated by the coordinated EN on both sides while Cd atom exhibits octahedral geometry. The structure of 2 consists of two chemically identical and crystallographically different coordination complexes containing two distinct cobalt atoms, Co1 and Co2 each exhibits octahedral geometry. The structures of 1 and 2 extend to 3D-network via H-bonds and π–π stacking. The catalytic behavior of the SCP 1 and 2 for the degradation of acid blue 92 dye (AB-92) was also studied. The reaction is first order with respect to AB-92 dye. The irradiation of the reaction with UV-light enhanced the rate of AB-92 mineralization. Mineralization of AB-92 was investigated by FT-IR spectra. Disodium salt of terephthalic acid photoluminescence probing technology was carried out to identify the reactive oxygen species. The efficiency of recycled the catalysts 1 and 2 and mechanism of degradation of AB-92 dye were also investigated. The kinetic data indicated that 1 and 2 are effective catalysts for degradation of AB-92.