Surfactant monolayers on electrode surfaces: Self-assembly of a viologen derivative having a cholesteryl hydrophobic residue

Jing Li, Angel Kaifer

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Abstract

The self-assembly properties of N-[(cholesteryloxy)carbonyl]-N′-ethylviologen (12+) and N-ethyl-N′-octadecylviologen (22+) at the electrode surface were compared on Au in order to assess the effects of the two different hydrophobic tails. Voltammetric data indicated that both compounds self-assemble from aqueous solution forming compact monolayers with the following saturation surface coverages: 3.7 × 10-10 mol/cm2 for 12+ and 4.2 × 10-10 mol/cm2 for 22+. The formal potential for viologen reduction is more positive in 12+ monolayers (-0.345 V vs SSCE) than in 22+ monolayers (-0.458 V vs SSCE). The voltammetric reduction wave for interfacial 12+ is much broader than that for reduction of 22+. However, the monolayers of the cholesteryl derivative seem to be less organized than those made from the octadecyl analog, as judged from the blocking properties of the two monolayers for the reduction of the water-soluble complex Ru-(NH3)63+. These results suggest that the cholesteryl-based monolayers are less organized due to the difficulties associated with the packing of the rigid and sterically bulky cholesteryl subunits.

Original languageEnglish
Pages (from-to)591-596
Number of pages6
JournalLangmuir
Volume9
Issue number2
StatePublished - Dec 1 1993

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry

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