Supramolecular systems based on polyethyleneimines and octa-2-hydroxyethylated calix[4]resorcinarenes. Aggregation and catalytic activity

Resumo

The aggregation of octa-2-hydroxyethylated calix[₄]resorcines (CR) with different alkyl chain length (R = Et, n-C₅H₁₁, n-C₁₁H₂₃), hydrophobically modified polyethyleneimine (HPEI) and their mixed systems was investigated by the tensiometry and dynamic light scattering in water and water-organic solvents at different temperatures. The critical aggregation concentration (CAC) and the size of aggregates were determined. It was established that the temperature affects significantly the surface and aggregation properties of the CR. The hydrolysis of 4-nitrophenyl-О-butylchloromethyl phosphonate was investigated in the presence of CR, HPEI, and their mixed systems by spectrophotometry. The parameters of the reaction (rate constant in the micellar phase, binding constant of the substrate with aggregates, and CAC) testify that the catalytic activity of the HPEI system in the presence of СR with undecyl radicals is the highest.