Versatile cavitands for small molecules: the entropically driven ethanol selectivity

Two new C2v cavitands based on resorcin[4]arene were synthesized and their binding properties for nine small molecules were studied. The alcohol selectivity was in the order of CH3OH∼CH3CHOHCH3<CH3CH2CH2OH≪CH3CH2OH with the highest Ka=260 M−1 at 23°C in CDCl3. Their carceroisomerism was observed by 1H NMR spectra and the quinone-capped cavitandʹs complexation of ethanol was driven entropically.