Chemical properties of hydrogen-bonded organic bilayers fabricated via self-assembly of COOH-functionalised oligophenylthiols on Au substrates

Here we present an investigation of chemical reactions induced by exposing organic, hydrogen-bonded films prepared from COOH-tenninated oligophenylthi ol molecules on Au to solutions of different reactants. Our study includes reactions with acids (trifluoroacetic acid, TFA) and metal ions (potassium (K+)- and copper (Cu2+)-ions). On the basis of XPS measurements the film th ickness and the elemental ratios of the elements involved in the process ha ve been quantified. Our results reveal that treatment of the bilayers with trifluoroacetic acid results in the removal of the second layer and the for mation of highly oriented, COOH-terminated monolayers, While the immersion of the bilayers in solutions containing Cu2+ ions leads to the removal of t he second layer and the formation of a Cu2+-terminnted monolayer-surface, p otassium ions are incorporated in the bilayers by immersion into an ethanol ic solution of potassium hydroxide, The reasons of these differences are re lated to the different coordination spheres of the ions and their compatibi lity with the structure of the self-assembled film. (C) 1999 Elsevier Scien ce B.V. All rights reserved.