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Self‐Assembled Monolayers of Cobalt and Iron Phthalocyanine Complexes on Gold Electrodes: Comparative Surface Electrochemistry and Electrocatalytic Interaction with Thiols and Thiocyanate
Author(s) -
Ozoemena Kenneth I.,
Nyokong Tebello,
Westbroek Philippe
Publication year - 2003
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200302753
Subject(s) - thiocyanate , chemistry , monolayer , electrochemistry , self assembled monolayer , redox , inorganic chemistry , electrocatalyst , electrode , phthalocyanine , cyclic voltammetry , organic chemistry , biochemistry
Abstract The self‐assembling of the octa(hydroxyethylthio)‐metallophthalocyanine {MOHETPc (M=Co and Fe)} complexes and their similar analogues, octabutylthiometallophthalocyanine {MOBTPc (M=Co and Fe)} complexes on gold electrodes are investigated. Comparative surface voltammetric insights into their distinct self‐assembling properties with respect to the passivation of Faradaic processes and surface coverages, including their solution electrochemistry, suggest different orientations and non‐cleavage of their CS bonds. In the pH 2−9 range, the reversible [M (III) Pc(−2)] + / [M (II) Pc(−2)] redox couples show potential shifts close to −59 mV / pH. The gold electrodes modified with the SAMs of these species show electrocatalytic activity towards the oxidation of thiols ( L ‐cysteine, homocysteine and penicillamine) and thiocyanate in acidic media with detection limits in the region of 10 −7 –10 −6 mol dm −3 . These monolayers are stable and easily reproducible.