Supramolecular complexes of spin-labeled and luminescent molecules with cyclodextrins

Abstract

Studies on the structure, molecular dynamics, and spectral-luminescent properties of the guesthost cyclodextrin (CD) complexes which were carried out in the Photochemistry Center and the Institute of Chemical Problems, Russian Academy of Sciences (RAS), in the period of 2000–2011 are reviewed. In a series of studies, the binary and ternary CD complexes in aqueous solutions, in the solid phase, and on silicawater and silica-gas interfaces were investigated. The spin-labeled analogs of the biologically active molecules (indoles, fatty acids, and cholesterol) were used as models of the functional guest molecules in these complexes. The use of various EPR approaches made it possible to determine the character of rotational motion and its quantitative parameters (rotational frequencies and angular amplitudes) for guest molecules in the CD cavities and to reveal the effects of the second and third guest molecules and of the covalent binding of CDs to silica microspheres on molecular dynamics, as well as the hydrophobicity of the environment for the spin-labeled molecules. The properties of the β-CD and γ-CD complexes of naphthalene and its derivatives were studied by fluorescence and phosphorescence methods; the effects of the cage compounds (adamantane, carborane, and cyclohexane (CH)), the low-molecular-mass compounds (acetone), and the adsorption on silica of the polymer CD on the appearance and the line shape of the naphthalene excimer fluorescence (EF) and the long-lived phosphorescence were analyzed.