Novel vic-dioxime ligand containing calix[4]pyrrole moiety: synthesis,characterization, anion binding studies and complexation with Ni(II)

A new vic-dioxime functionalized calix[4]pyrrole was synthesized from anti-chloroglyoxime and 4-aminophenyl-calix[4]pyrrole at room temperature. The Ni(II) complex has been prepared by reacting the ligand with NiCl₂·6H₂O in ethanol. These receptors were characterized by elemental analyses, ¹H and ¹³C NMR spectra, IR and mass spectra. Electrochemical properties of the ligand, and its Ni(II) complex were investigated in CH₂Cl₂ solution by cyclic voltammetry at 100 mV s^?1 scan rate. Anion-binding studies were carried out using UV–Vis, and ¹H NMR titrations, revealed that the Ni(II) complex exhibits selective recognition toward F^? over other anions. The selectivity for F^– among the halides is attributed mainly to the hydrogen-bond interaction of the receptor with F^–. Receptor showed colour change from red to brown in the presence of tetrabutylammonium fluoride (TBAF) with 1:2 stoichiometry.