Synthesis and self-assembly of a novel cobalt(II) porphyrin lipoic acid derivative on gold

Abstract

A novel Co(II) porphyrin lipoic acid derivative was synthesized starting from the commerically available red blood pigment hemin. The disulfi de functionalities of the lipoic acid moieties allowed its immobilization on gold by a self-assembly method. The Co(II) porphyrin self-assembled monolayer (SAMs) on gold (111) surfaces were characterized electrochemically through monolayer reductive desorption and evaluation of the redox properties of the immobilized molecules in organic medium, and by scanning tunneling microscopy (STM). It was found that after assembly the Co(II) porphyrin is electroactive exhibiting the typical redox processes observed for its precursor without the appended lipoic acid in solution. A coverage of 2.7 × 10 -10 mol.cm -2 has been estimated assuming that four electrons (one per each sulfur atom) are involved in the process. The porphyrin-modifi ed gold electrodes exhibit catalytic acitivity demonstrated towards the reduction of molecular oxygen in acidic solution.

Regulation of a Porphyrin Derivative Containing Two Symmetric Benzoic Acids by Different Pyridines

“…It is important for us to know that porphyrin and porphyrin derivatives are famous for their optical and electrical performances, − which play a key role in photocatalytic , and electroluminescent materials, molecular sensors, solar cells, , etc. Besides, porphyrin derivatives have been considered seriously for their thermal stability and rigidity in molecular functional design and device assembly .…”

Optical and electrochemical behavior of new nano-sized complexes based on gold-colloid and Co-porphyrin derivative in the presence of H 2 O 2

“…Another complex between Co(II) porphyrin and lipoic acid, deposited on gold electrodes, exhibited catalytic activity towards the reduction of molecular oxygen, this time in acidic solution [7]. The same catalytic performance for oxygen reduction in high acidic media, at room temperature, was obtained by grafting a Co(II) porphyrin onto multiwalled carbon nanotubes [8] and onto the network of three-dimensionally distributed gold (polyoxometallate-modified) nanoparticles producing cobalt porphyrin-hybrid multi-layered film with high activity toward electroreduction of hydrogen peroxide [9].…”