Supramolecular complexes based on calixarenes: force field calculations and applications for chemical sensors

The inclusion of organic molecules to different calixarenes was investigated both experimentally and theoretically. Experimental data were obtained for various calixarenes of different thicknesses interacting with perchloroethylene, chloroform, benzene and toluene at different partial pressures and temperatures. The amount of included molecules was monitored by frequency responses of mass-sensitive bulk acoustic wave devices. To estimate ‘key-lock’ binding energies, the activation energy of desorption was determined experimentally from thermodesorption spectroscopy. The host/guest interaction energies were calculated theoretically with the TRIPOS force field approach which, in contrast to current quantum chemical approaches (MOPAC/AM1, MOPAC/PM3), gave satisfactory distance-dependent energy minima. Experimentally observed changes in the binding energies for the inclusion of C₂Cl₄, CHCl₃, CH₃C₅H₆ and C₆H₆ molecules in calixarenes agree surprisingly well with results with theoretical calculations.