Binding or aggregation? Hazards of interpretation in studies of molecular recognition by porphyrins in water

Reports suggest that polar porphyrins can serve as carbohydrate receptors in water. Addition of glucose to TPPS (shown) does cause changes in UV-visible absorption. However, these are best explained by altered aggregation states and not by formation of a closely-bound complex.</p

Affinity enhancement by dendritic side chains in synthetic carbohydrate receptors

Dendritic side chains have been used to modify the binding environment in anthracene-based synthetic carbohydrate receptors. Control of length, charge, and branching enabled the positioning of side-chain carboxylate groups in such a way that they assisted in binding substrates rather than blocking the cavity. Conformational degeneracy in the dendrimers resulted in effective preorganization despite the flexibility of the system. Strong binding was observed to glucosammonium ions in water, with K(a) values up to 7000 m(−1). Affinities for uncharged substrates (glucose and N-acetylglucosamine) were also enhanced, despite competition from solvent and the absence of electrostatic interactions