Volume 14, Issue 34, July - December, 2020

The comparative study of basicities, Li+ and Na+ affinities of a series of heterocyclic molecules (Pyrrole, Furan, Thiophene and Pyridine) in the ground state - A DFT Study

Biswarup Mandal^1♦, Bikash Kumar Panda², Suman Sengupta³

¹Assistant Professor, Dept. of Chemistry, Sitananda College, Pin-721631, Nandigram, Purba medinipur, W.B., India
²Assistant Professor, Dept. of Chemistry, Jangipur College, Pin-742213, Murshidabad, W.B., India
³Assistant Professor, Dept. of Chemistry, Ananda Chandra College, Jalpaiguri, PIN-735101, W.B., India

^♦Corresponding author
Assistant Professor, Dept. of Chemistry, Sitananda College, PIN-721631, Nandigram, Purba medinipur, W.B., India; Email: biswarupmandal75@gmail.com (Biswarup Mandal).

ABSTRACT

A comparative study of the proton affinities (PA), Li+ affinities and Na+ affinities of a series of heterocyclic molecules Pyrrole, Furan, Thiophene and pyridine and their protonated, lithium and sodium complexes in the gas phase have been performed theoretically by B3LYP (DFT) method using 6-311G(d,p) basis set with complete geometry optimization both before and after protonation, Li+ complex formation and Na+ complex formation. The gas phase protonation, Li+ complex formation and Na+ complex formation turns out to be exothermic and the local stereochemical disposition of proton, Li+, and Na+ is found almost same in each case. Computed proton, lithium and sodium affinities are sought to be correlated with a number of computed system parameters like the net computed charge on the hetero atom (X) of the free molecules and the net charge on the hetero atom (X) and on proton, Li+, and Na+ of the protonated, lithium and sodium complexes. The energetics structural and electronic properties of the complexes indicate that the interaction between proton–free molecule, lithium-free molecule and sodium-free molecule is predominantly an ion-dipole attraction and the ion– induced dipole interaction as well rather than a covalent interaction. The overall reactivity is explained by distant atom contribution in addition to the contribution from free base

Keywords: B3LYP, DFT, Gaussian, Gas phase, PA, Li-A, Na-A, drug discovery

Drug Discovery, 2020, 14(34), 212-216

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