A Tris-Macrocycle with Proton Sponge Characteristics as Efficient Receptor for Inorganic Phosphate and Nucleotide Anions
Résumé
Synthesis, characterisation and proton-sponge behaviour of a new linear constrained tris-macrocycle (L), containing three cyclen (cyclen = 1,4,7,10-tetraazacyclododecane) reinforced macrocycles connected by two 2,6-pyridinediylbis(methylene) linkers, is reported. Protonated forms of L are efficient receptors for inorganic phosphate and nucleotide anions (ATP and ADP). The binding properties of L toward these substrates have been investigated in aqueous solution by means of potentiometric titrations, determining the stability constants of the adducts. The interaction mode was clarified by using 1H and 31P NMR measurements in aqueous solution and by means of molecular modelling calculations carried out on differently protonated species of L as well as on several nucleotide-receptor adducts. The stability of the adducts is mainly due to charge-charge and hydrogen bonding interactions between the polyphosphate chain of nucleotides and the ammonium groups of L.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)