Redox potential of [Fe₄S₄(SPh)₄]^2−/13—, a model of the active centre of ferredoxin, in DMF solution shows a 90-mV positive shift, when the charged microenvironment provided by the surfactant is changed from negative to positive. Inside the positive surfactant film on GC electrode there is a 235-mV positive shift in redox potential compared to that in neutral DMF solution. Diffusion coefficient of the reduced cluster onto the electrode surface is also found to be 10²times greater in the presence of negative surfactant compared to that in positive surfactant.

Although cysteine is the preferred ligand for [Fe-S] core in case of iron-sulphur proteins, presence of other ligands together with cysteine is not uncommon. Being basically electron transfer proteins, redox potential of [Fe-S] core in these proteins in crucial to their functioning. Among other factors, charged nature of the microenvironment is believed to tune the redox potential. The iron-sulphur cluster, [Fe₂S₂(OC₆H₅)₄]²⁻, has been investigated electrochemically in positive and negative microenvironments, both in solution and in film. Charge nature around the active centre has been found to affect its redox potential and diffusion coefficient significantly. In a film, where charges are more localized compared to solution, the effect on redox potential was more prominent.

A new binuclear copper(II) complex, bridged by the ligand phthalicacid[bis(benzyloxy)ethyl]ester, where each copper(II) is coordinated to one carboxylate (from ligand) and one acetate in square planar mode is reported. The ligand synthesized by the reaction of phthalic anhydride and ethylene glycol, has been characterized by FT-IR, ¹HNMR and LCMS. The binuclear Copper(II) complex has been characterized by UV/visible spectra, FTIR spectra, EPR spectra, ESI-MS spectra, magnetic moment measurement and thermogravimetric analysis. DFT calculation has shown a Z type structure for the complex. Excellent superoxide dismutase activity with IC₅₀ value 8.6 × 10⁻⁶ M for the complex has been observed.

Coordination polymer of Cu(II) bridged by o-phthalic acid alone is not known. The reaction of$CuCl_{2}.2H_{2}O$ with (2-butoxycarbonyl)benzoic acid yielded three dimensional coordination polymer bridged byo-phthalic acid. X-ray crystal structure shows structure with monoclinic P21/c space group. o-Phthalic acidmolecules act as bridge between two Cu(II), one carboxylate binds to one Cu(II) as bidentate while the othercarboxylate binds to another Cu(II) as monodentate. The four planar co-ordination positions of Cu(II) aresatisfied by two chelated carboxylates while fifth and sixth co-ordination positions are satisfied by monodentatecarboxylates. EPR and TGA of the coordination polymer are also reported.