The phosphorylation of imidazole by two activated phosphate diesters and a triester gives phosphorylimidazole derivatives that are stable enough in aqueous solution to be observed and identified by ESI-MS/MS and NMR. Half-lives ranging from hours to days (in the case of the monoethyl ester) show that it is possible to design molecules with variable half-lives with potential to be used for biological intervention experiments as possible inhibitors of biosignaling processes or as haptens for the generation of antibodies.

Phosphate diester hydrolysis is strongly accelerated, by a factor of 104, in the presence of artificial enzymes especially designed in the light of spatiotemporal concepts, anchoring imidazoles in a pillar[5]­arene matrix. Host:guest complexes cleave the aryl phosphodiesters via nucleophilic attack of the properly placed imidazole moieties with the release of 2,4-dinitrophenolate and the formation of unstable phosphoroamidates that regenerate the catalyst and 2,4-dinitrophenyl phosphate. Comparison of the reactivity of P5IMD with that of imidazole shows a 270-fold increase. Asymmetrical diesters allow the formation of two different docking structures of the host:guest complex, with just one being reactive and allowing selectivity increases of 102-fold, compared with the reaction in bulk water of the same asymmetrical diesters.

The high rate of spontaneous hydrolysis of tris-2-pyridyl phosphate (TPP) is explained by the activating effects of the non-leaving ("spectator") groups on P-OAr cleavage, and not by intramolecular catalysis. Previous work on phosphate-transfer reactions has concentrated on the contributions to reactivity of the nucleophile and the leaving group, but our results make clear that the effects of the non-leaving groups on phosphorus can be equally significant. Rate measurements for three series of phosphate triesters showed that sensitivities to the non-leaving groups are substantial for spontaneous hydrolysis reactions, although significantly smaller for reactions with good nucleophiles. There are clear differences between triaryl and dialkyl aryl triesters in sensitivities to leaving and non-leaving groups with the more reactive triaryl systems showing lower values for both β(LG) and β(NLG). Intramolecular catalysis of the hydrolysis of TPP by the neighbouring pyridine nitrogens is insignificant, primarily because of their low basicity.

Designing artificial enzymes with tailored molecular interactions between the substrate and active site is of major intellectual and practical significance. We report the improved catalytic efficiency of a supramolecular polymer/surfactant complex comprised of PAIM − , a poly(acrylic acid) derivative with imidazole groups attached to the polymer by amide bonds, and the cationic surfactant cetyltrimethylammonium bromide (CTAB). Supramolecular complex formation, at concentrations below the respective CMC values, provides convenient hydrophobic pockets for the reactants close to the multiple catalytic centers, where imidazole and carboxylate groups act as nucleophiles for the degradation of a model phosphate triester, delivering the highly efficient performance of the supramolecular catalysts. Catalytic effects are on the order of thousands for nucleophilic catalysis and are higher by 2 orders of magnitude for the supramolecular polymer/surfactant complex at pH 9. The reported supramolecular catalytic complexes allow important changes in polarity and, given the presence of functional groups common to a variety of hydrolytic enzymes, could be of general applicability in such reactions.

Aspartic proteinases, which include HIV-1 proteinase, function with two aspartate carboxy groups at the active site. This relationship has been modeled in a system possessing an otherwise unactivated amide positioned between two carboxy groups. The model amide is cleaved at an enzyme-like rate that renders the amide nonisolable at 35 °C and pH 4 owing to the joint presence of carboxy and carboxylate groups. A currently advanced theory attributing almost the entire catalytic power of enzymes to electrostatic reorganization is shown to be superfluous when suitable interatomic interactions are present. Our kinetic results are consistent with spatiotemporal concepts where embedding the amide group between two carboxylic moieties in proper geometries, at distances less than the diameter of water, leads to enzyme-like rate enhancements. Space and time are the essence of enzyme catalysis.