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(S 2 CNRR′) 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 [CoS 6 ]. 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.