Neutral guest capture by a cationic water-soluble pillar[5]arene in water

A cationic water-soluble pillar[5]arene offering a well-defined cavity with hydrophobic inner surface can capture neutral guests, even water-insoluble guests, into its cavity via hydrophobic forces. The binding ability depends upon guest hydrophobicity. The higher guest hydrophobicity contributes to the higher host affinity. Methanol and ethanol do not show any affinity for the host at all, because they are too hydrophilic for the host to compete with water.