AB INITIO AND DENSITY FUNCTIONAL THEORY STUDY ON IONIZATION OF BETAHISTINE AND CIMETIDINE NANO DRUG IN AQUEOUS SOLUTION
FARHOUSH KIANI*, BAHAREH KHANLARZADEH, HASAN TAHERMANSOURI
Department of Chemistry, Faculty of Science, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran
*corresponding author: farhoush_kiani@yahoo.com
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Abstract:
In this paper, pKa values of the drugs betahistine and cimetidine were determined in aqueous solution. We used ab initio and density functional theory (DFT) methods with the B3LYP 6-31+G(d) functional and basis sets and polarizable continuum solvation model (PCM) to include the effects of aqueous solvation. Also, we have calculated the free energies for determining the pKa values, and intermolecular hydrogen bonds (IHBs) in aqueous solution by Tomasi’s model. In the present work, there is comparable agreement between the experimentally determined pKa values for the acid-base reactions selected by potentiometric and spectrophotometric methods and those reported in the literature, demonstrating the theoretically calculated pKa values.






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