الدراسة التركيبية والطاقية لأيونات الليثيوم مع الأحماض الدهنية ميثيل استر [[FAME (9Z-18:1) + Li+ باستخدام الطريقة الكيميائية الكمومية (PM3)

Abstract

Lithium (Li) ions are being used in a variety of fields ranging from energy storage to the treatment of mental illnesses including bipolar disorder and schizophrenia. Lithium caton (Li+) is able to form cationic adducts with various compounds and they can stabilize the biomacromolecules that interact with. Here, the interaction of lithium ions with fatty acid methyl ester [FAME (9Z-18:1)] has been theoretically investigated to gain insight into the structure and energetics of [FAME (9Z-18:1) + Li+]. All theoretical calculations were performed using Gaussian09 software via a graphic user interface. Geometry optimisations with harmonic vibrational analysis of conformations for chelated and extended forms of [FAME (9Z-18:1) + Li+] were carried out using semi-empirical method PM3. To obtain accurate energetic, zero-point energy (ZPE) corrections were included in all optimized energies and relative energies between conformers. The calculations indicated that the chelated form is relatively more stable than extended forms by 25 and 118 kJmol-1 when lithium is bound to the carbonyl oxygen (O-Li+) or olefin (C=C-Li+), respectively. The comparison between the relative stabilization energies of extended (O-Li+) versus extended (C=C-Li+) reveals that the lithium cation energetically prefers to bind to with carbonyl oxygen over the carbon-carbon double bond. Keywords: lithium ions, geometry optimization, sim-empirical method, Gaussian 09.