Cu(II) complexes of monobasic bi- or tridentate (NO, NNO) azo dye ligands: Synthesis, characterization, and interaction with Cu-nanoparticles

A series of copper(II) azo complexes having the formula [CuL1–4(nH2O)]·OAc·xH2O where (n = 1–2) and (x = 0–1) have been synthesized using azo dyes containing the triazol and thiadiazole moieties. The azodyes and their metal complexes were characterized by elemental analysis, molar conductance, IR, electronic, mass, ESR spectra, magnetic moment measurements, and thermal analyses. IR spectra showed that the ligands having triazole moiety were coordinated with the copper(II) ion in a tridentate manner with ONN donor sites of the naphthyl OH, N-atoms of azo group, and triazole moiety while azodyes having thiadiazole moiety were coordinated with the copper(II) ion in a bidentate manner with ON donor sites of the naphthyl OH and the N-atom of the group. The thermodynamic activation parameters such as ΔE*, ΔH*, ΔS*, and ΔG* were calculated from the TG curves. Prepared spherical copper nanoparticles were characterized using UV–Vis spectroscopy and transition electron microscope (TEM). The spectral data showed the formation of surface complex between azo-dye ligands and colloidal copper nanoparticles through (OH) anchoring group. The stability constant of the prepared copper nanoparticles complexes is higher compared with the corresponding bulk ones due to the larger surface area of copper nanoparticles.

► Characterization of Cu(II) azo dyes containing the triazol and thiadiazole moieties.
► Prepared spherical copper nanoparticles were characterized using UV–Vis spectroscopy and TEM.
► Formation of surface complex between azo-dye ligands and colloidal copper nanoparticles.
► The stability constant of the copper nanoparticles complexes is higher compared with the corresponding bulk ones.