1-Adamantanethiolate monolayer displacement kinetics follow a universal form.
Alkanethiol molecules in solution displace 1-adamantanethiolate self-assembled monolayers on Au{111}, ultimately leading to complete molecular exchange. Specifically, here, fast insertion of n-dodecanethiolate at defects in the original 1-adamantanethiolate monolayer nucleates an island growth phase, which is followed by slow ordering of the n-dodecanethiolate domains into a denser and more crystalline form. Langmuir-based kinetics, which describe alkanethiolate adsorption on bare Au{111}, fail to model this displacement reaction. Instead, a Johnson-Mehl-Avrami-Kolmogorov model of perimeter-dependent island growth yields good agreement with kinetic data obtained by Fourier transform infrared spectrometry over 100-fold variation in n-dodecanethiol concentration. Rescaling the growth rate at each concentration collapses all the data onto a single universal curve, suggesting that displacement is a scale-free process. The rate of displacement varies as the square-root of the n-dodecanethiol concentration across the 0.01-1.0 mM range studied.
Department of Chemistry, The Pennsylvania State University, 104 Davey Laboratory, University Park, Pennsylvania 16802-6300, USA.
Héctor M
HM
Saavedra
Corina M
CM
Barbu
Arrelaine A
AA
Dameron
Thomas J
TJ
Mullen
Vincent H
VH
Crespi
Paul S
PS
Weiss
D000218:Adamantane / Q000031:analogs & derivatives* / Q000737:chemistry; D000473:Alkanes / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D007700:Kinetics; D017550:Spectroscopy, Fourier Transform Infrared; D013438:Sulfhydryl Compounds / Q000737:chemistry*
D000473:Alkanes; D013438:Sulfhydryl Compounds; C007548:n-dodecane; D006046:Gold; D000218:Adamantane