The first example of calix[4]pyrrole functionalized vic-dioxime ligand: Synthesis, characterization, spectroscopic studies and redox properties of the mononuclear transition metal complexes

摘要

Novel calix[4]pyrrole bearing vic-dioxime ligand (LH_2) of the general formula, R_1R_2C_2N_2O _2H_2 (where, R_1 = C_6H_5- and R_2 = C_(39)H_(50)N_5-) has been synthesized by the reaction of anti-chlorophenylglyoxime with 3-aminophenylcalix[4]pyrrole at room temperature. The mononuclear Cu(II), Ni(II) and Co(II)complexes of this vic-dioxime ligand were prepared and their structures were confirmed by elemental analysis, FT-IR, TGA and magnetic susceptibility measurements; the HMBC, DEPT, ~1H and ~(13)C NMR spectra of the LH_2 ligand were also reported. The electrochemical property of the complexes was investigated in DMSO by cyclic voltammetry at 200 mV s~(-1) scan rate. The cyclic voltammetric measurements clearly indicated that Co(LH)_2·2H_2O complex differs from the Ni(LH)_2 and Cu(LH)_2 complexes upon the exhibition of quasi-reversible one-electron transfer reduction process in the negative region instead of an irreversible process.