What does this research mean for the field?

The E isomer of 2-furaldehyde semicarbazone derivatives is generally more thermodynamically stable and chemically reactive than the Z isomer, and M-polynomial-derived topological indices can accurately predict these properties, establishing a unified bridge between molecular topology and chemical reactivity. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

May 8, 2026Open Access

Unveiling the electronic and thermodynamic properties of 2-furaldehyde semicarbazone derivatives: combined DFT and M-polynomial topological indices analysis

Puntos clave

This research aims to investigate the electronic and thermodynamic properties of 2-furaldehyde semicarbazone derivatives using DFT and topological indices analysis.
Performed quantum chemical calculations using DFT on FSC derivatives
Calculated relative thermodynamic stabilities of isomers and conformers
Analyzed global chemical reactivity descriptors and M-polynomial topological indices
E isomer is more stable than Z isomer by 1.1 kcal/mol; rotation barrier ~ 97 kcal/mol
Topological indices indicate the E isomer has the highest stability and reactivity characteristics
Global descriptors suggest the E isomer exhibits a lower energy gap and higher chemical reactivity.

Resumen

In the current research, quantum chemical calculations in terms of Density Functional Theory, DFT, were performed on 2-furaldehydesemicarbazone (FSC) and its derivatives, including 5MFSC, 5AFSC, 5DFSC, 5CFSC and 5NFSC, where M, A, D, C and N correspond, respectively, to -CH3, -NH2, N (CH3) 2, -CN and -NO2 groups. The relative thermodynamic stabilities of the envisaged isomers (E and Z) and conformers (E1 and Z1) were calculated at the B3LYP/6-311 + + G (3df, 2p) //6-311 + G (d, p) level of theory in the gas phase. Results revealed that the relative stability trend is E > Z > E1 > Z1. The rotation barrier of the E→Z isomerization process was calculated by performing the scan coordinate of the restricted C = N. Unexpectedly, the Z isomer of the FSC molecule is slightly more stable than the E isomer by 1. 1 kcal/mol with a rotation barrier of ~ 97 kcal/mol. On the other hand, the E isomer of the other FSC derivatives, regardless of the nature of the substituents, is slightly more stable than the Z isomer, with a rotation barrier ranging from ~ 45–94 kcal/mol. Quantum theory of atoms in molecules (QTAIM) and the noncovalent interactions (NCIs) were used to confirm the stability of the E and Z isomers. The geometrical structure and the vibrational frequency analysis were also investigated and discussed. The global chemical reactivity descriptors, such as EHOMO, ELUMO, energy gap, hardness, electronegativity, and electrophilicity were also computed and discussed. The results revealed that the energy gap of the E isomer is lower than that of the Z isomer, reflecting its higher chemical reactivity and lower kinetic stability. To complement the quantum-chemical analysis, \: M-polynomial–derived topological indices were computed to quantify molecular connectivity and electronic symmetry. The E isomer shows the highest index values, the smoothest M-polynomial surface, the lowest Gibbs free energy, and the widest HOMO–LUMO gap, confirming its thermodynamic superiority. The stability trend E> Z> E₁ Z₁ aligns closely with DFT results. Overall, higher topological indices correspond to smoother \: M-polynomial surfaces, lower Gibbs energies, and greater stability, establishing the \: M-polynomial framework as a unified, predictive bridge between molecular topology and chemical reactivity.

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