Cobalt(III) dithiocarbamates for anion sensing and preparation of cobalt sulfide and cobalt-iron sulfide nanoparticles: Photocatalytic degradation of dyes with as-prepared nanoparticles

Abstract

Five homoleptic complexes of general formula [Co(S2CNRR′)3] [where R=furfuryl; R′=cyclohexyl (1), benzyl (2), furfuryl (3), methylferrocenyl (4), 2-phenylethyl (5)] were prepared and studied by FT-IR, UV–vis and NMR (1H and 13C) spectroscopy. A single crystal X-ray structural analysis was carried out for complex 3. Electronic spectral studies suggest octahedral geometry for all the complexes. In the molecular structure of 3, cobalt atom coordinates to three N,N-difurfuryldithiocarbamate ligands in the S,S′-bidentate mode, forming an octahedral polygon [CoS6]. DFT calculations were carried out for 3. The ability of complex 4 containing redox-active ferrocene moiety to sense anions (benzoate, F−, Br− and I−) was examined by cyclic voltammetric titration studies. This study reveals that complex 4 prefer to bind with Br− Complexes 3, 4 and 5 were utilized for the preparation of cobalt sulfide (3 and 5) and cobalt-iron sulfide (4) nanoparticles. The as-prepared nanoparticles were characterized by PXRD, TEM, EDS, UV–vis and FT-IR spectroscopy. TEM image of cobalt-iron sulfide nanoparticles reveals that the particles are cuboid. The blue shift in the absorption maxima in the UV–vis spectra of cobalt sulfide and cobalt-iron sulfide is attributed to the consequence of the quantum confinement effect. Photocatalytic activities of as-prepared nanoparticles were studied by decolourization of methylene green and rhodamine-B under ultraviolet light. It was found that the cobalt-iron sulfide degrades methylene green and rhodamine-B much faster than cobalt sulfide.