Monomeric and dimeric cadmium(II) complexes of S-alkyl/aryl dithiocarbazate as single-source precursors for cadmium sulfide nanoparticles: An experimental, theoretical interpretation in the stability of precursor and visible light dye degradation study

Abstract

The reaction of S-alkyl/aryl dithiocarbazate functionalized with 2-acetyl pyridine ligands and cadmium chloride in ethanol leads to the formation of a mono nuclear cadmium(II) complex, [Cd(L1)2] (SP1), (HL1 is S-methyl-2-(1-(pyridine-2-yl)ethylidene)hydrazine-1-carbodithioate) and a dinuclear dichloro bridged complex, [(L2)Cd(μ-Cl)2Cd(L2)] (SP2), (L2 is S-benzyl-2-(1-(pyridine-2-yl)ethylidene)hydrazine-1-carbodithioate). The complexes are characterized by FTIR, single X-ray crystallography and thermogravimetry analysis. Density functional calculations indicate that different coordination patterns of the complexes with HL1 and HL2 ligands relate with the available space of the dissociation of CdCl2 in their solutions. Thermochemical destruction of the precursor complexes at the molecular level fabricated hexagonal CdS nanoparticles where the morphology is guided by the precursor. In situ generated thiols e.g., CH3SH in case of SP1, and PhCH2SH in case of SP2, internally stabilized the flower-like and rod shaped CdS structures, respectively. The synthesized nanoparticles were characterized by powder X-ray diffraction (XRD), scanning electronic microscope (SEM) and energy-dispersive X-ray spectroscopy (EDAX). The UV–Vis spectroscopic study shows a prominent quantum confinement effect in CdS with a band gap energy of 2.4 eV and 2.5 eV for SP1 and SP2, respectively. The CdS nanocrystals under investigation degrade Rose Bengal (RB) dye (96%) under visible light irradiation. A reusability study shows that the CdC nanoparticles retain their catalytic activity (86%).