The template co-crystallization of β-cyclodextrin with polymeric inclusion complex

Abstract

The study of the crystal formation in aqueous solution of β-cyclodextrin in the presence of the additives of polypropylene oxide in a wide range of macrocycle:polymer molar ratios was carried out. The cyclodextrin separation from the mixture was made by 1) the isothermal crystallization; 2) the rapid crystallization via the precipitation in acetone. The influence of thermodynamic and kinetic factors on the mechanism of crystallization of unbound macrocycles was demonstrated for the first time. It was shown that the isothermal crystallization led to the formation of the mixture of two solids: the channel polymer inclusion complex and unbound β-cyclodextrin in the cage form. The precipitation method at polypropylene oxide content in the initial solutions corresponded to the range of 0,03–92% from stoichiometry of the complex resulted in the formation of the structures with the channel organization of macrocycles. Thus, the ability of β-cyclodextrin for the template co-crystallization with the polymeric inclusion complex was demonstrated. These data enable to develop the novel method of creation of the channel nanoporous structure of β-cyclodextrin. The obtained products represent lamellar structures possessing cylindrical nanopores with the diameter of ∼0,65 nm.