Resolution of d- and l-glucoses by chiral N-octyl-β-d-glycoside–Cu(II) complex adsorbed at the gas/liquid interface of small bubbles

A new technique of the jet drop method (JDM) was applied to a chiral molecular discrimination of optically active d- or l-glucose (guest) by chiral N-octyl-β-d-glycoside (OβDG)–Cu(II) complex (host) at the gas/liquid interface of small bubbles. The discrimination of glucoses as the guests is possible using OβDG adsorbed at the gas/liquid interface of bubbles where it acts as the host, either in the presence or the absence of Cu(II) ions. In order to make clear the host–guest interaction at the gas/liquid interface, the composition of 5000 top jet drops periodically collected onto a slide glass receiver was analyzed. The relative concentration (ηi − 1) and the surface excess amount, Γi0 of species i such as d- and l-glucoses, and OβDG were determined as a function of bubble size, db and bulk concentration Cb. The partition coefficient, Πi=Γi0/Cb was also evaluated for each component. The adsorption of these materials either in the presence or absence of Cu(II) ions, was assigned to the Freundlich type, and the discrimination of d- and l-glucoses with OβDG was evaluated in terms of the Freundlich constant, ki and 1/n. The discrimination ability of OβDG was also evaluated by determining the equilibrium constants, Kc of complex formations for the respective glucoses in the presence and absence of Cu(II) ions. It was found that l-glucose can form a more stable complex with OβDG–Cu(II).