Coumarin-derivatized fluorescent <Emphasis Type="Italic">vic</Emphasis>-dioxime-type ligand and its complexes; the preparation,spectroscopy, and electrochemistry

A new vic-dioxime bearing coumarin functionality, N′¹,N′²-Dihydroxy-N ¹,N ²-bis(4-methyl-2-oxo-2H-chromen-7-yl)oxalimidamid (LH₂), N,N-bis-4-methylcoumarinyl]-diamino glyoxime (LH₂), and its mono- and dinuclear complexes {copper^II, cobalt^II, nickel^II and uranyl^II} have been reported. The fluorescence excitation and emission spectra of LH₂ and its complexes with metal ions were examined. It was observed that fluorescence and excitation emission intensity of LH₂ was quenched depending on complex formation with metal ions. The characterizations of all newly synthesized compounds were made by elemental analysis, ¹H-n.m.r, i.r., u.v.–vis., and l.c-m.s./m.s. data. Electrochemical behaviour of the ligand involving oxime and coumarine moieties, and its complexes with Ni^II, Cu^II, Co^II and UO ₂ ^II were investigated by cyclic voltammetry. The comparison of the electrochemical behaviour of the ligand with its complexes enabled us to identify metal-, oxime- and coumarine-based signals.