Molecular organization and electrochemical reduction of a Ni(II)Porphyrin complex in LB films

Abstract

In this work, mixed films of a tetra-cationic porphyrin, Ni(II)TMPyP, and an anionic phospholipid, DMPA, in molar ratio of 1:4, were formed at the air–water interface and transferred onto glass and optically transparent indium tin oxide (ITO) electrodes. Transmission spectroscopy (on glass and ITO) and cyclic voltammetry (on ITO) were used to infer the molecular organization and the electrochemical reduction of these LB films. Likewise, we compare the electrochemical reduction of the Ni(II)TMPyP in water solution with that in LB films. The porphyrin molecules in water solution show three two-electron reduction waves, which are related to the two-electron reduction of the central ring of the porphyrin and to the one-electron reductions of the four methyl–pyridyl groups of the molecule, respectively, while only two reversible one-electron reduction waves are observed in LB films corresponding to the reduction of the central ring of the porphyrin and to the Ni(II) to Ni(I) reduction, respectively.