Host-guest chemistry and chemical sensors: FT-IR-analysis and spectra simulation of CDCl3 inclusion

Host-guest principles are put into action advantageously by cyclodextrins t hat give remarkable sensor responses to halogenated hydrocarbons on mass-se nsitive devices such as QMB (quartz micro balance) and SAW (surface acousti c wave) resonators. Modifications of the structure can tune the compound to different analytes and molecular modeling allows us to understand and pred ict specific host-guest interactions. The FT-IR analysis of CDCl3, incorpor ated into a partially methylated cyclodextrine, yields an astonishingly str ong band shift of about 50 cm(-1) to lower wave numbers, in contrast to the permethylated product that shows a displaced band of 10 cm(-1) for the C-D stretching vibration. The explanation can be given by semiempirical method s and force field calculations. Two CDCl3 binding sites are revealed, one b eing a multicentered inclusion (<(nu)over tilde> similar to 2195 cm(-1)) of CDCl3 at the upper rim of the beta-cyclodextrine cone, whereas the other i s incorporated within the cavity (<(nu)over tilde> similar to 2240 cm(-1)).