Theoretical Insights into the Effects of Positional Isomerism: DFT/TD-DFT Approach

Authors : Sümeyya Serin, Öznur Doğan Ulu

Pages : 122-135

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Publication Date : 2023-12-15

Article Type : Research Paper

Abstract :The phenomenon of positional isomerism arises when functional groups or substituents occupy different positions in the same carbon skeleton. Although the molecular formula remains the same, the arrangement of atoms in the molecule is different. This leads to differences in physical and chemical properties. In this context, the present study aims to investigate the properties of the three isomers (1-3) obtained from the interaction of 3-formylacetylacetone with ortho-, meta- and para-aminobenzoic acids using computational chemistry methods. Density Functional Theory (DFT) study was carried out to explore the effects of positional isomerism on thermodynamic parameters, physicochemical quantities, reactivity indices, electrostatic surface properties and intramolecular interactions. Also, the TD-DFT method was used in order to examine ground and excited state characteristics. No significant changes were observed in the computed ∆E (total energy), ∆H (enthalpy), and ∆G (Gibbs free energy) values of all three isomers. On the other hand, as a result of the frontier molecular orbital analysis, it was determined that the quantum chemical reactivity descriptors differed.
Keywords : Konumsal İzomerizm, Aminobenzoik Asit, YFT, Reaktivite