1H Fast MAS NMR studies of hydrogen-bonding interactions in self-assembled monolayers

Shane Pawsey, Mark McCormick, Susan De Paul, Robert Graf, Yoon Suk Lee, Linda Reven, Hans W. Spiess

Research output: Journal article publicationJournal articleAcademic researchpeer-review

114 Citations (Scopus)

Abstract

The structures formed by the adsorption of carboxyalkylphosphonic acids on metal oxides were investigated by1H fast magic angle spinning (MAS), heteronuclear correlation (HETCOR), and1H double-quantum (DQ) MAS solid-state NMR experiments. The diacids HO2C(CH2)nPO3H2(n = 2, 3, 11, and 15) were adsorbed on TiO2and two types of ZrO2powders having average particle sizes of 20, 30, and 5 nm, respectively. Carboxyalkylphosphonic acids bind selectively via the phosphonate group, forming monolayers with pendant carboxylic acid groups. Whereas dipolar coupled P-OH protons are detected on TiO2, there are only isolated residual P-OH groups on ZrO2, reflecting the relative binding strengths of phosphonic acids on these two substrates. From a comparative1H MAS NMR study with an analogous monolayer system, HO2C(CH2)7SH coated gold nanoparticles, the hydrogen-bonding network at the monolayer/air interface is found to be quite disordered, at least for SAMs deposited on nonplanar substrates. Whereas only hydrogen-bonded homodimers occur in the bulk diacids, hydrogen bonding between the carboxylic and phosphonic acid groups is present in multilayers of the diacids on the ZrO2nanopowder.
Original languageEnglish
Pages (from-to)4174-4184
Number of pages11
JournalJournal of the American Chemical Society
Volume125
Issue number14
DOIs
Publication statusPublished - 9 Apr 2003
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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