Molecular dynamics simulations of the oil spill-treating phase-selective organogelator N-acetyl-l-isoleucine-N'-n-octyl amide

Phase-selective organogelators that can solidify hydrocarbons are being investigated as oil spill treating agents for emergency response to accidental discharges of crude oil or petroleum products in inland or marine environments. We employ molecular dynamics simulations to study and understand the behaviour of the natural product-based organogelator, N-acetyl-l-isoleucine-N'-n-octyl amide, Ac-Ile-C8. Forty molecules of the Ac-Ile-C8 organogelator are placed in the simulation box and then solvated with either pure or with mixtures of solvents consisting of heptane, toluene and water. Molecular dynamics simulations are performed on the solvated organogelators at temperatures ranging from 278 K to 358 K. The degree of molecular aggregation of the Ac-Ile-C8 molecules in different solvents is evaluated by calculating the radius of gyration. The results show increasing organogelator compactness in the order from toluene to heptane and water. Molecular interactions among the Ac-Ile-C8 molecules and between the Ac-Ile-C8 and solvent molecules are also evaluated by calculating the number of hydrogen bonding interactions as well as the nonpolar interactions. In hydrocarbon-water mixtures, the number of water-Ac-Ile-C8 hydrogen bonds is higher in those containing heptane compared to those with toluene. The number of nonpolar contacts of the organogelator with heptane is lower than that with toluene. The intermolecular interaction analysis results are valuable for understanding the mechanism of action of organogelators and the discovery of improved gelators. More effective natural product-based organogelators are needed to improve oil spill response outcomes. © His Majesty the King in Right of Canada, as represented by the Minister of Natural Resources, 2023.