Impedimentric and microscopic probes of the integrities of selfassembled monolayers of organosulphur-metal complexes

Abstract

Electrical and structural integrities of Self-assembled Monolayers (SAMs) of some organosulphur-metal complexes, formed on polycrystalline gold disc electrode, were probed, using Electrochemical Impedance Spectroscopy (EIS) and Atomic Force Microscopy (AFM) respectively. Values of relevant circuit elements in the equivalent circuits, proposed to explain the physical electrochemistry of the cells, were a reflection of the electrical conductivity of the SAM-modified gold electrodes. Electrical integrity of SAMs was influenced by both the metal center and molecular identity of the substituent, attached to the ligand framework, in the chemical modifier of interest. AFM images of the SAMs were indicative of their structural integrity. SAM formed from organosulphur-metal complex containing diethylaminoethanethio substituent (4-SAM) was more compact than those formed from organosulphur-metal complexes containing benzylthio substituent (1-3- SAMs). This was typical of SAMs formed from alkanethio and alkylthio substituted metallophthalocyanine complexes.

Keywords: Electrochemical Impedance Spectroscopy, Atomic Force Microscopy, Self-assembled Monolayer, Organosulphur-metal Complex, Metallophthalocyanine