Binding of Small Guest Molecules to Multivalent Receptors

The complexation of phenol derivatives, aromatic carboxylic acids, and n-octylgalactopyranoside by hydrogen-bonded exo-receptors is described. The receptors are formed by self-assembly of differently functionalized calix[4]arene dimelamines with 5,5-diethyl barbiturate or butyl cyanurate. The multivalent complementary recognition site of the receptors is used very efficiently to complex multiple guests. A 1:6 binding mode was observed for phenol derivatives forming single hydrogen bonds with all six recognition sites of an ureido functionalized receptor assembly, while 1:3 complexation was observed for phenol derivatives which form two hydrogen bonds with two different ureido recognition sites of the same receptor. Aromatic carboxylic acids are complexed in a 1:6 ratio by receptors having six amino recognition sites. The complexation of n-octylgalactopyranoside by Gly-L-Ser functionalized receptors is also described, indicating that it is possible to use small peptidic fragments to complex biologically important molecules.