Erkang Fan

Molecular recognition: directed hydrogen bonding receptors for acylamino acid carboxylates

Abstract A new series of receptors for acylamino acid carboxylates has been synthesized and shown to have increased binding affinity for the substrate as the number of hydrogen bonding groups in the cavity increases.

Hydrogen-bonding control of molecular aggregation: self-complementary subunits lead to rod-shaped structures in the solid state

Simple cyclohexane-1,3,5-triamide derivatives are shown to form linear, rod-shaped structures in the solid state; a triple hydrogen-bonding interaction directs formation of the aggregate and leads to non-centrosysmmetric packing arrangement with modest non-linear optical properties.

Molecular recognition. Design of new receptors for complexation and catalysis

Abstract In recent years there has been intense activity in the design of synthetic molecules capable of enzyme-like recognition and binding of small substrates.1 Two fundamental approaches have been taken. The first has generally involved non-directional binding forces (such as solvophobic, π-stacking and dispersion interactions) in water-soluble cyclophane frameworks.2 This approach led to extremely important quantitative insights into the hydrophobic effect and the enthalpic and entropic contributions of solvent reorganization to binding.3 However, the weakly oriented nature of the binding interactions has resulted in only moderate substrate selectivity beyond the shape recognition permitted by the cavity. In nature such selectivity is a prerequisite for the chiral recognition and catalytic activity of enzymes and is achieved by hydrogen bonding and electrostatic interactions. The second major approach to artificial receptors makes use of these more directional interactions by incorporating several hyd...

The Design of Artificial Receptors for Complexation and Controlled Aggregation

Simple synthetic receptors have been developed that function via directed hydrogen bonding interactions in highly competitive solvents. Strong binding of this type in polar solvents may be due to a number of factors including favourable secondary hydrogen bonding interactions between the carboxylate and urea, the use of charged H-bond acceptors, an inefficient solvation of the closely spaced H-bond donor sites in the urea, and an entropically favourable release of solvent and/or counterion molecules on complex formation. We also demonstrate that these types of interactions can be used to induce, both in solution and the solid state, discrete 2 + 2 aggregates stabilized by a network of hydrogen bonds.

Intra- and Intermolecular Hydrogen Bonding Control of Supramolecular Structure

Hydrogen bonding is used to control supramolecular structure in two distinct ways. The first involves intramolecular hydrogen bonds to stabilize linear and helical conformations in synthetic oligomers. The second uses intermolecular hydrogen bonding to direct the self-assembly of several interacting subunits.