Host—guest complexation of 6-deoxy-6-(1-pyridinio) derivatives of α-cyclodextrin (cyclomaltohexaose) with inorganic anions in aqueous solution

Abstract

The anions I −1, SCN −, and Br − formed 1:1 charge-transfer complexes with the HCO 3 − salts of bis-, tris-, and hexakis-[6-deoxy-6-(1-pyridinio)]-α-cyclodextrins in aqueous solution. Increase in the number of the pyridinio groups resulted in a remarkable increase in the binding constant, K a . A maximum K a value of 9 × 10 5 mol −1.dm 3 was observed for the complex of the hexapyridinio derivative with I −. Acetylation of the mono- and di-pyridinio derivatives also resulted in a significant increase in the K a values.