Synthesis, spectroscopic and electrochemical studies of novel transition metal complexes with quadridentate Schiff base

A novel quadridentate, N2O2 type Schiff base, synthesized from 1,4-bis-(o-aminophenoxy)butane and 2-hydroxynaphthalin-1-carbaldehyde, forms stable complexes with transition metal ions such as Co(II), Cu(II) and Ni(II) in DMF. Microanalytical data, elemental analysis, magnetic measurements, UV-visible and IR-spectra as well as conductance measurements were used to confirm the structures: Electrochemical measurements show that metal complexes undergo quasi-reversible one-electron redox processes. The voltammetric results also revealed that the CuL complex has the highest electron transfer rate indicating that both the Cu(II) and Cu(I) forms appear in a similar planar configuration, so the electron transfer does not require larger reorganization of the complex.