S. Yokokawa, K. Tamada, E. Ito
Mar 20, 2003
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0
Influential Citations
19
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Journal
Journal of Physical Chemistry B
Abstract
Cationic self-assembled monolayers (SAMs) composed of quaternary ammonium (QA) sulfur derivatives have been synthesized to control the distance between charged headgroups on gold substrates. Two molecules bearing resembling molecular structures, “gemini”-structured didodecyl dithiol (HS-gQA-SH) and didodecyl disulfide (QA-SS-QA), were utilized in this study, and the formation and structure of the SAMs were characterized by surface plasmon resonance spectroscopy (SPR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared-reflection adsorption spectroscopy (FTIR−RAS). In the HS-gQA-SH SAM, the orientation and distance between QA groups are specified by the covalent bonding with ethylene spacer, while those of the QA-SS-QA SAM are determined by the electric repulsion between charged headgroups, that is, QA groups in the QA-SS-QA SAM are more randomly located, being more distant than with those in the HS-gQA-SH SAM. We found that l-tartaric acid, a probe molecule with two carboxyl groups hav...