A supramolecular assembly of sulfobutyl ether-β-cyclodextrin and viologen calix[4]resorcinol as the master key to sustainable and eco-friendly catalyst for paraoxon hydrolysis

Abstract

The search for effective ways of paraoxon (POX) degradation becomes an extremely urgent problem, which can be solved by creating effective bioscavengers in the form of three-dimensional macrocycles. In this work, supramolecular interactions in an aqueous medium were studied between (4-sulfobutyl)-β-cyclodextrin, the hydrophobic cavity of which is capable of binding POX, and viologen calix[4]resorcinol, the cationic groups of which are able to facilitate the nucleophilic attack on the phosphorus atom of the pesticide. A complex of physicochemical methods revealed the nature of the interactions between these cyclodextrin and calix[4]resorcinol, as a result of which the spontaneous formation of nanoparticles occurs. The kinetics of POX hydrolysis reaction using these nanoparticles was studied at room temperature in aqueous Tris-buffer medium by spectrophotometric method. Pure cyclodextrin does not exhibit catalytic activity in the POX hydrolysis, but its presence in a mixture with calix[4]resorcinol leads to a fivefold increase in the hydrolysis rate constant compared to pure calix[4]resorcinol.