Research Information System
Journal of Molecular Structure, vol.1356, 2026 (SCI-Expanded, Scopus)
Herein study, new cyclotriphosphazenes (1a and 2a) were synthesized and their structures were characterized using elemental analysis, spectroscopy and crystallography techniques. Subsequently, a series of quantum chemical calculations based on density functional theory (DFT) were performed to explore the structural, electronic, and nonlinear optical properties of the tetrachloro (1 and 2) and fully substituted (1a and 2a) derivatives. Initially, bond lengths and angles were calculated at the DFT/B3LYP/6-31G(d,p) level to evaluate the consistency between the experimental and optimized geometries. A satisfactory correlation was observed between the theoretically optimized geometry and the corresponding experimental data. The nonlinear optical (NLO) properties of phosphazenes were calculated. The dipole moments range from 1.7380 to 2.7804 Debye, the polarizability values range from 4.01732 to 8.03846 esu, and the hyperpolarizability ranges from 6.7120 to 10.6333 esu. These results are in good agreement with experimental data reported for structurally related systems. Additionally, frontier molecular orbitals (FMOs) were computed. The energy difference between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) (Egap) was calculated to be 1.69–1.77 eV. The results reveal an inverse correlation between Egap and NLO properties. Based on the calculated orbital energies, reactivity descriptors such as chemical hardness (η), chemical potential (µ), electronegativity (χ), electrophilicity index (ω) and chemical softness (S) were determined. These findings highlight the potential applicability of the studied cyclotriphosphazenes in optoelectronic and photonic device technologies. In addition, the intermolecular interactions in the crystal structure of 1a were clarified by Hirshfeld surface (HS) analysis.