Calorimetric and molecular modeling studies of N-alkoxycarbonylmethyl-N-alkyl-piperidinium chlorides

The micellization processes of N-alkoxycarbonylmethyl-N-alkyl-piperidinium chlorides were studied by means of isothermal titration calorimetry (ITC). The critical micelle concentrations (cmc) and enthalpies of micellization ( Δ H m ) were measured and presented in comparison with those for similar surfactants. The molecular modeling studies including the conformational analysis and hydration energy calculations were done to elucidate the experimental results on the atomic level. The results show, that the piperidinium ring in single-chain compounds gives almost negligible effect on cmc compared to analogous surfactants with methyl groups instead, but the effect is stronger on Δ H m . The presence of the second chain in double-chain compounds influences both the cmc and Δ H m compared to single-chained analogs. Numerical simulations show that the part of the short chain containing ester group is involved in the Stern region, and the terminal ethyl group partakes in the intramicellar interactions. The results may also contribute to the elucidation of microbial activity of the studied compounds.