Abstract: Mono(2-phenylseleno-2-deoxy)-β-cyclodextrin(2) and mono[2-(p-methoxyphenylseleno)-2-deoxy]-β-cyclodextrin(4), were newly synthesized and characterized by combustion analyses, IR, ¹H NMRand ¹³C NMR. Spectrofluorometric titrations have been performed in aqueous phosphate buffer solution(pH7.20, 0.1 mol/L) at 25 ℃ to give the complex K_Sand -ΔG° for the stoichiometric 1∶1 inclusion complexation of mono(6-phenylseleno-6-deoxy)-β-cyclodextrin(1), mono[6-(p-methoxyphenylseleno)-6-deoxy]-β-cyclodextrin(3) and the novel cyclodextrin derivatives 2 and 4 with L- and D-tryptophan. The molecular binding ability and selectivity for L- and D-tryptophan of modified β-cyclodextrins(1_4) are discussed from the size/shape-fit and geometrical complement relationships between the host cavity and the guest molecule. The results obtained indicate that van der Waals force and hydrophobic interactions dominate the complexation of 1-4 and the aromatic substituents introduced extend the original hydrophobicity of cavity and the molecular binding ability, but reduce the enantioselectivity for L/D-tryptophan guests.

Key words: Modified cyclodextrin, Supramolecular complex, Chiral recognition, Tryptophan