Self-assembled monolayers of heptapodant b-cyclodextrins on gold

M.W.J. Beulen, H.J. Bugler, Ben Lammerink, Frank A.J. Geurts, Ed M.E.F. Biemond, Kees G.C. Leerdam, F.C.J.M. van Veggel, Johannes F.J. Engbersen, David Reinhoudt

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Abstract

A route was developed for the synthesis of three different cyclodextrin adsorbates: heptakis{6-O-[3-(thiomethyl)propionyl)]-2,3-di-O-methyl}-ß -cyclodextrin, heptakis{6-O-[12-(thiododecyl)dodecanoyl)]-2,3-di-O-methyl}-ß -cyclodextrin (a short and long alkyl chain sulfide cyclodextrin adsorbate, respectively), and heptakis[6-deoxy-6-(3-mercaptopropionamidyl)-2,3-di-O-methyl]-ß-cyclodextrin (a short alkyl chain thiol adsorbate). Self-assembled monolayers on gold of these three cyclodextrin adsorbates with seven sulfur moieties were fully characterized by electrochemistry, wettability studies, X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The electrochemical capacitance measurements show the differences between the thicknesses of the ß-cyclodextrin monolayers, and the XPS-(S2p) measurements show the different effectivenesses of the sulfur moieties of the three monolayers in their binding to the gold surface. Sulfide-based -cyclodextrin monolayers use on average 4.5 of the 7 attachment points whereas the thiol-based cyclodextrin monolayer only uses 3.2 of the 7 sulfurs. These experiments show that, for adsorbates with multiple attachment points, sulfides may be more effective than thiols. TOF-SIMS measurements confirm the robust attachment of these adsorbates on gold obtained by XPS.
Original languageUndefined
Pages (from-to)6424-6429
JournalLangmuir
Volume14
Issue number14
DOIs
Publication statusPublished - 1998

Keywords

  • METIS-105983
  • IR-11079

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