Synthesis, crystal structure and DFT studies of a methylphenyl piperazinyl dithiocarbamato zinc(ii) precursor for zinc sulfide nanophotocatalysts used for the degradation of trypan blue and rhodamine 6G dyes

Abstract

A 1-(4-methylphenyl)piperazinyl dithiocarbamato-S,S′ Zn(II) complex was prepared, and its molecular structure was determined using single-crystal X-ray crystallography. The zinc(II) dithiocarbamate compound crystallized as a dimeric structure with two zinc(II) ions that are coordinated to two molecules of 1-(4-methylphenyl)piperazinyl dithiocarbamato anions as bidentate chelating ligands. In addition, the sulfur atom of the adjacent centrosymmetric molecule is coordinated to the adjacent Zn(II) ion. The geometry and electronic properties optimized using DFT and the HOMO–LUMO energies matched the experimental findings. The complex was thermolyzed in octadecylamine (ODA), dodecylamine (DDA), and hexadecylamine (HDA) to prepare zinc sulfide nanoparticles: ZnS-ODA, ZnS-DDA, and ZnS-HDA. The as-prepared zinc sulfide nanoparticles were used as photocatalysts for the degradation of trypan blue and rhodamine 6G dyes. The photocatalytic degradation of trypan blue by ZnS-ODA showed the highest photocatalytic efficiency of 95.71%, while ZnS-DDA degraded 83.21% of rhodamine 6G after 180 min. The degradation process followed pseudo-first-order kinetics with rate constants of 1.69 × 10⁻² min⁻¹, 5.18 × 10⁻³ min⁻¹, and 6.75 × 10⁻³ min⁻¹ for trypan blue dye and 3.54 × 10⁻³ min⁻¹, 7.44 × 10⁻³ min⁻¹, and 6.21 × 10⁻³ min⁻¹ for rhodamine 6G dye by ZnS-ODA, ZnS-DDA, and ZnS-HDA, respectively. The results indicate the potential of the as-prepared ZnS nanoparticles as effective photocatalysts for trypan blue and rhodamine 6G dyes degradation.