Abstract

Introduction: Several molecular modelling techniques and quantum chemical methods have been performed to correlate the chemical structures of the compounds with their physical molecular properties.

Methods: Theoretical parameters were used to characterize the molecular structure of the investigated ligands and to study their equilibria mechanism. Molecular modelling data such as the bond length, bond order, bond angles and dihedral angles values were estimated for some pyrimidine compounds, where the data suggested the presence of tautomerism and dynamic equilibria were deduced between all the detected tautomers in the solid state.

Results: Four main tautomers were predicted for barbital and thiobarbituric acid, while three tautomers were for thiouracil. Quantum chemical parameters such as the highest occupied molecular orbital energy (EHOMO), the lowest unoccupied molecular orbital energy (ELUMO), energy gap (ΔE), dipole moment (μ), sum of the total negative charge (STNC), electronegativity (χ), chemical potential (Pi), global hardness (η) and softness (σ) were calculated.

Conclusion: These studies display a good correlation between the theoretical and experimental data.

Keywords: Molecular orbital energy, molecular modelling data, pyrimidines tautomers, quantum chemical parameters, artificial models, drug discovery.

Graphical Abstract