Engineering the Hydrophobic Microenvironment in Polystyrene-Supported Artificial Catalytic Triad Nanocatalysts: An Effective Strategy for Improving Catalytic Performance

Abstract

Hydrophobic environments have been identified as one of the main parameters affecting the catalytic performance of artificial catalytic triads but are often ignored as an approach to engineering these catalysts. Here, we have developed a simple yet powerful strategy to engineer the hydrophobic environment in polystyrene-supported artificial catalytic triad (PSACT) nanocatalysts. Hydrophobic copolymers containing either oligo(ethylene glycol) side chains or hydrocarbon side chains were synthesized and used for the preparation of nanocatalysts through nanoprecipitation in aqueous media. By using the hydrolysis of 4-nitrophenyl acetate (4NA) as a model reaction, we studied the influence of chemical structures and effective constituent ratios of hydrophobic copolymers on the catalytic performance of PSACT nanocatalysts. Additionally, PSACT nanocatalysts could catalyze the hydrolysis of a few carboxylic esters, even polymers, and be reused for five consecutive runs without significant loss of catalytic activity. This strategy may open an avenue for engineering other artificial enzymes, and these PSACT nanocatalysts have potential applications for the hydrolysis of carboxylic esters.

Micelle-modulated reactivity of novel copper(ii) complexes with reduced l-histidine Schiff bases as mimic carboxylesterases

“…To overcome their intrinsic drawbacks, over the years, chemists have been attempting to develop some artificial hydrolases to mimic catalytic functions of natural carboxylesterases. [9][10][11][12][13][14][15][16][17] Histidine residues within the structures of natural hydrolase not only act as nucleophilic groups but also serve as general acid-base catalytic groups, and take part in some enzyme reactions through acid-base catalysis and covalent catalysis. 18,19 Imidazole derivatives with extensive conjugated systems facilitate electron transfer.…”

“…To overcome their intrinsic drawbacks, over the years, chemists have been attempting to develop some artificial hydrolases to mimic catalytic functions of natural carboxylesterases. 9–17…”

Colloidal polystyrene-supported cooperative imidazolidinone/thiourea catalysts for efficient aldol reaction and substrate-selective Knoevenagel condensation in water

“…28 Catechol-containing polystyrene and benzylamine-containing polystyrene were used as acid and base components for the formation of colloidal polystyrene in water by nanoprecipitation, 29 in which process the collapse of the hydrophobic polystyrene chains not only brought the acid and base in close proximity but also built hydrophobic microenvironments. 30 However, mutual deactivation between acid and base, the oxidation of catechol groups, and the poisoning of benzylamine groups through the formation of Schiff bases caused a significant loss of catalytic components, leading to moderate activities and recycling performance in the aldol reaction of 4-nitrobenzaldehyde with acetone in water.…”