Theoretical analysis of a pyrrole-based compound: Insights into electronic properties and spectroscopic behavior via DFT and TD-DFT

A comprehensive density functional theory (DFT) and time-dependent DFT (TD-DFT) investigation was conducted to elucidate the structural, electronic, and spectroscopic properties of a pyrrole-based heterocyclic compound, namely ۳-(۵-phenyl-۱-(pyridin-۳-yl)-۱H-pyrrol-۲-yl)propanoic acid. The optimized geometry at the B۳LYP/۶-۳۱۱G(d.p) level confirmed the stability of the molecular structure, supported by the absence of imaginary frequencies. The calculated HOMO–LUMO energy gap (۴.۲۸ eV) indicates significant kinetic stability and low chemical reactivity. Molecular electrostatic potential (MEP) analysis revealed that oxygen and nitrogen atoms constitute the most nucleophilic regions. TD-DFT calculations, including solvent effects, predicted a dominant π→π* transition at ۲۸۱ nm, characteristic of conjugated systems. Furthermore, NMR chemical shifts calculated using the GIAO method showed excellent agreement with experimental data (R² ≈ ۰.۹۹), outperforming other approaches. These findings highlight the reliability of the computational protocol and provide valuable insights into the physicochemical behavior of pyrrole-based systems.

کلیدواژه ها:

Density functional theory ، ۳-(۵-phenyl-۱-(pyridin-۳-yl)-۱H-pyrrol-۲-yl)propanoic acid ، Electronic structure UV&ndash ، Vis spectroscopy ، NMR Prediction