Molecular modeling of fatty acid triglyceride dimers and their aqueous complexes by DFT: thermodynamic association analysis
E. Yu. Stepanovich 1, K. V. Berezin 2 , K. N. Dvoretsky 3, E. M. Antonova 4, A. M. Likhter 1, I. Yu. Yanina 2.5
1 Astrakhan State University named after V.N. Tatishchev,Russia, 414056, Astrakhan, Tatishcheva St., 20a
2 Saratov State National Research University named after N.G. Chernyshevsky,Russia, 410012, Saratov, Astrakhanskaya St., 83
3 Saratov State Medical University named after V.I. Razumovsky,Russia, 410012, Saratov, Bolshaya Kazachya St., 112
4 Astrakhan State Medical University,Russia, 414000, Astrakhan, Bakinskaya St., 121
5 National Research Tomsk State University,Russia, 634050, Tomsk, Lenin Ave., 36
Abstract
In this work, we employed density functional theory (B3LYP/6-31+G(d) and wB97XD/6-311+(d,p)) to construct molecular models and calculate the association thermodynamics of dimers for three fatty acid triglycerides (triacetin, tributyrin, and tricaprylin), along with their most probable mono- and dihydrates. Our results confirm the hypothesis that while a single strong hydrogen bond forms between water molecules and triglyceride carbonyl groups, a weaker double hydrogen bond simultaneously emerges between water molecules and carbonyl groups of two different triglycerides.The enthalpy evaluation for each of these weaker hydrogen bonds reveals values approximately three times smaller than that of the strong single bond. The association enthalpies (ΔH) for triglyceride dimer formation increase with acyl chain length, ranging from -47.2 kJ/mol for triacetin to -65.9 kJ/mol for tricaprylin, reflecting enhanced van der Waals contributions. The observed increase in equilibrium constants (Ka) with longer acyl chains correlates with reduced entropic contribution
Speaker
Ekaterina Yu. Stepanovich
Astrakhan State University
Russia
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