Association of Naphthalene and Its Methyl Derivatives with Cyclodextrins in Aqueous Medium

Abstract

Formation constants of naphthalene and its (1- and 2-)methyl and (1,4-, 1,5-, and 1,8-)dimethyl derivatives with α-, β-, and γ-cyclodextrins (CyD) were determined in the aqueous medium in the presence of excess CyD. The technique used to study associations between host (CyD) and guest(hydrocarbon) is based on the facts that the guest molecules can be driven out to gaseous phase by introducing an inert gas at a constant flow rate into the aqueous solution and that the volatilization rate of guest decreases with increasing association with the host in aqueous solution. The 1:1 and 2:1 (host:guest) formation constants were evaluated at 25 °C. From the formation constant estimated, a host–guest spatial-fitting model for each association complex is presented.