Bioinspired Catalysts Based on Poly(acrylic acid) and Surfactant Aggregates: Effect of the Organization on Nucleophilic Catalysis by Carboxylate AITranslate

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DOI：https://doi.org/10.1021/acsapm.2c01558

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Bioinspired catalysts were obtained by assembling poly(acrylic acid) (PAA) of different molecular weights and cetyltrimethylammonium bromide. For PAA, the proximity between the carboxylate groups led to the appearance of two distinct mean pKa values of 4.6 and 6.8. The increase in pKa is a consequence of the destabilization of the conjugate base due to the proximity of the negative charges, mimicking the catalytic carboxylate–carboxylate dyads of aspartic proteases and glycosidases. The nanostructured polymer/surfactant complexes accelerated the hydrolysis reaction of the diethyl 2,4-dinitrophenyl phosphate by four orders of magnitude compared to the spontaneous hydrolysis. In the absence of a surfactant, the polymer containing the carboxylate–carboxylate dyad did not show a significant catalytic effect. This demonstrates the importance of structural organization and the formation of hydrophobic microenvironments for the approach of the substrate to the active site. Mechanistic studies have shown that the phosphate transfer reaction occurred through a carboxylate nucleophilic attack. It is worth mentioning that the enzyme-like patterns observed in this work open the way for fundamental studies in the understanding of natural enzymes. Moreover, the application of polymer-based nanostructured supramolecular complexes with bioinspired functional groups enables the development of environmentally friendly methodologies for the catalysis of phosphate transfer reactions.