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.

A kinetic study on dinitrophenylphosphate monoester hydrolysis in the presence of a cationic pillararene, P5A, has been carried out. Formation of the supramolecular complex between phosphate ester and P5A has been studied by NMR showing complexation-induced upfield proton shifts indicative of aromatic ring inclusion in the pillararene cavity. Molecular dynamic calculations allow structure characterization for the 1 : 1 and 1 : 2 complexes. As a result of the supramolecular interaction both the acidity of DNPP and its hydrolysis rate constants are increased. Catalysis results from combination of both electrostatic stabilization reducing the negative electron density on the PO3(=) oxygens and monoester dianion destabilization by the steric effects of close NMe3(+) groups hindering the hydrogen-bonding with water and destabilising the monoester dianion.

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Synthesis of Alkynyl Chalcogenides (Selenides and Tellurides) from Terminal Acetylenes and Diorganyl Dichalcogenides. -(GODOI, M.; LIZ, D. G.; RICARDO, E. W.; ROCHA, M. S. T.; AZEREDO, J. B.; BRAGA*, A. L.; Tetrahedron 70 (2014) 20, 3349-3354, http://dx.