Oxime-Based Receptors for Mono- and Disaccharides

Representatives of a new series of acyclic oxime-based receptors were prepared and their binding properties toward neutral sugar molecules studied. 1H NMR and fluorescence titrations revealed that receptors 2a and 2b, incorporating suitable positioned amine and oxime moieties, are able to form strong 1:1 complexes (Ka1 approximately 10(5) M-1) with dodecyl alpha- and beta-maltoside in chloroform solutions. Furthermore, the binding studies with beta-glucopyranoside indicated the formation of complexes with 1:1 and 1:2 receptor-monosaccharide binding stoichiometry (with overall binding constant beta2 approximately 10(5) M-2). Both hydrogen bonding and interactions of the sugar CH's with the phenyl rings of the receptor contribute to the stabilization of the receptor-sugar complexes. Molecular modeling calculations, synthesis, and binding studies are described.