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Determination of Real Composition of 3‐Mercaptopropionic Acid and 1‐Octadecanethiol Mixed Self‐Assembled Monolayers by Using Electrochemical and Electrochemical Quartz Crystal Microbalance Measurements
Author(s) -
Sato Yukari,
Mizutani Fumio
Publication year - 1998
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/(sici)1521-4109(199807)10:9<633::aid-elan633>3.0.co;2-a
Subject(s) - monolayer , quartz crystal microbalance , electrochemistry , chemistry , desorption , adsorption , inorganic chemistry , electrode , molecule , self assembled monolayer , organic chemistry , biochemistry
In order to clarify the electrochemical response of cytochrome c at the gold electrode modified with mixed monolayers of carboxylic acid terminated alkanethiol (promoter molecule) and n ‐alkanethiol (barrier molecule), electrochemical and electrochemical quartz crystal microbalance (EQCM) measurements were carried out during the reductive desorption of the mixed monolayer of 3‐mercaptopropionic acid and 1‐octadecanethiol (C 18 SH) in alkaline solution. The ratio of mercaptopropionic acid in the mixed monolayer was found to be smaller than that in the modifying solution, showing that C 18 SH adsorbed more preferentially than mercaptopropionic acid. The peak potentials for the reductive desorption of mercaptopropionic acid became more negative upon increasing the C 18 SH content in the monolayer. This means mercaptopropionic acid and C 18 SH did not form patched domains but were mixed well with each other. The mercaptopropionic acid molecules in a well‐mixed monolayer should be stabilized through the affinity between the mercaptopropionic acid and C 18 SH and becomes difficult to be desorbed from the electrode.