Document Detail

Formation of Self-Assembled Monolayers with Homogeneously Mixed, Loosely Packed Alkyl Groups Using Unsymmetrical Dialkyldithiophosphinic Acids.
MedLine Citation:
PMID:  23199153     Owner:  NLM     Status:  Publisher    
We report the formation and characterization of self-assembled monolayers (SAMs) based on dialkyldithiophosphinic acid adsorbates {[CH3(CH2)n]2P(S)SH (n = 5, 9, 11, 13, 15)} on gold substrates. The SAMs were characterized using x-ray photoelectron spectroscopy, reflection-absorption infrared spectroscopy, contact angle measurements, and electrochemical impedance spectroscopy. The data show that there is a roughly 60:40 mixture of bidentate and monodentate adsorbates in each of these SAMs. The presence of monodentate adsorbates is due to the numerous and deep grain boundaries of the underlying gold substrate, which disrupt chelation. Comparing the characterization data of dialkyldithiophosphinic acid SAMs with those of analogous n-alkanethiolate SAMs shows that both SAMs follow a similar trend: The alkyl chains become increasingly organized and crystalline with increasing alkyl chain length. The alkyl groups of R2DTPA SAMs, however, are generally less densely packed than those of RSH SAMs. For short alkyl chains (hexyl, decyl, and dodecyl), the significantly lower packing densities cause the alkyl chains to be liquid-like and disorganized. Long-chain dialkyldithiophosphinic acid SAMs are only slightly less crystalline than analogous n-alkanethiolate SAMs.
Tricia Carmichael; Ronan R San Juan
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-11-30
Journal Detail:
Title:  Langmuir : the ACS journal of surfaces and colloids     Volume:  -     ISSN:  1520-5827     ISO Abbreviation:  Langmuir     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-12-3     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9882736     Medline TA:  Langmuir     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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