Synthesis, Spectral Characterization, and DFT Studies on Co(II), Ni(II), and Cu(II) Complexes Possessing Naphthoquinone Signaling Unit for their Use as Selective Colorimetric Fluoride ion Sensor

Co(II), Ni(II), and Cu(II) complexes of a new Schiff base have been prepared and characterized by elemental analyses, FT-IR, UV-Vis, ESR, conductivity, magnetic susceptibility measurements, and thermal analyses. The results indicated a square planar geometry around the metal ion in these complexes. The applicability of the ligand and the complexes toward colorimetric sensing of fluoride ions was also been screened by employing UV-Vis, H-1 NMR, and fluorescence studies. H-1 NMR studies indicated that the fluoride ion sensing by the receptors is due to the formation of H-bonds between F(-)ions and the -NH moiety of the receptors.