β-Cyclodextrin Supramolecular Recognition of <i>bis</i>-Cationic Dithienylethenes

Abstract

The supramolecular interactions in water between β-cyclodextrin and the open and closed photochromic forms of two bis-cationic dithienylethenes, characterized by different electronic properties, were investigated aiming at underlying the key aspects of the recognition process. The dithienylethene equipped with the cyclopentenyl unit showed a difference in binding free energies to the β-cyclodextrin between the open and closed photochromic forms of about 1 kJ/mol. Conversely, the dithienylethene equipped with the perfluorinated cyclopentenyl unit not only was a better guest but showed a three times higher difference in the binding of free energies between the open and closed isomers.

Keywords

• photochromic compounds
• dithienylethenes
• <i>β</i>-cyclodextrin
• host–guest complex
• water