QUANTUM CHEMICAL SCREENING OF HYDROPHOBIC DEEP EUTECTIC SOLVENTS BASED ON MONOTERPENOIDS

Abstract

In this article, quantum chemical calculations were performed in the HyperChem software to select the 10 most stable hydrophobic deep eutectic solvents based on 6 monoterpenoids as mandatory components of the mixture and 4 fatty acids. This involved two-stage optimization of the geometry of the molecules of the substances and determination of their quantum chemical descriptors: electrostatic potential, energies of the lowest unoccupied and highest occupied molecular orbitals, dipole moment. The MM+ molecular mechanical method (primary geometry optimization) and the PM3 semiempirical quantum chemical method (secondary geometry optimization, construction of isosurfaces, energy profiles) were used for calculations. To rank solvents according to the stability of intermolecular interactions, two quantitative evaluation criteria were introduced – K1 and K2 – corresponding to the electrostatic and chemical components of the formation of “hydrogen bond acceptor – hydrogen bond donor” complexes, respectively. Based on the integral indicator K1 + K 2, it was established that the most stable deep eutectic solvents are “(±)-menthol – thymol” (1,690), “(±)-camphor – thymol” (1,686), “(+)-borneol – thymol” (1,833), “1,8-cineol – thymol” (1,814), “capric acid – thymol” (1,677), “lauric acid – thymol” (1,684), “myristic acid – thymol” (1,657), “oleic acid – thymol” (1,667), “(+)-borneol – lauric acid” (1,731), “1,8-cineole – lauric acid” (1,712). The obtained data correlates with the calculated values of dipole moments. The results of the work can be used for molecular design of deep eutectic solvents.