Scanning tunneling microscopy investigation of an inclusion complex between the beta-cyclodextrin and the sodium salt of the trisulfonated triphenylphosphine

Scanning tunneling microscopy has been used to image on a highly orientated pyrolytic graphite substrate an inclusion complex between the sodium salt of the trisulfonated triphenylphosphine (TPPTS) and the beta -cyclodextrin (CyD). The images were in very good agreement with the structure that has been reported for this inclusion complex and it is postulated that beta -CyD/TPPTS inclusion complex lies on the apolar graphite substrate by its primary face. A correlation of image contrast with the frontier orbitals of the inclusion complex is also clearly established for the first time in the case of CyD-based supramolecular assemblies. The self-assembly of the inclusion complexes on the graphic surface is also discussed. (C) 2001 Elsevier Science B.V. All rights reserved.