Self-assembled monolayers of aromatic omega-aminothiols on gold: surface chemistry and reactivity.
Amino-terminated self-assembled monolayers on gold substrates were studied by X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS) measurements, and atomic force microscopy (AFM). Two different omega-amino-4,4'-terphenyl substituted alkanethiols of the general structure H(2)N-(C(6)H(4))(3)-(CH(2))(n)-SH (ATPn) were used: 2-(4''-amino-1,1':4',1''-terphenyl-4-yl)ethane-1-thiol (n = 2, ATP2) and 3-(4''-amino-1,1':4',1''-terphenyl-4-yl)propane-1-thiol (n = 3, ATP3). Moreover, the addressability of amino groups within the films was investigated by chemical derivatization of ATPn SAMs with 3,5-bis(trifluoromethyl)phenyl isothiocyanate (ITC) forming fluorinated thiourea ATPn-F films. Evaluation of high-resolution C 1s and N 1s XPS data revealed successful derivatization of at least 50% of surface amino species. Furthermore, it could be demonstrated by angle-resolved NEXAFS spectroscopy that chemical derivatization with ITC has no noticeable influence on the preferential upright orientation of the molecules in the SAMs.
Dietrich
Paul M
PM
BAM Bundesanstalt für Materialforschung und -prüfung, D-12203 Berlin, Germany.
Graf
Nora
N
Gross
Thomas
T
Lippitz
Andreas
A
Schüpbach
Björn
B
Bashir
Asif
A
Wöll
Christof
C
Terfort
Andreas
A
Unger
Wolfgang E S
WE
D006046:Gold / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D013057:Spectrum Analysis / Q000379:methods; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties
D013438:Sulfhydryl Compounds; D006046:Gold