Crystal growth, structural scrutiny, optical properties, Hirshfeld surface examination and DFT calculations of an organic NLO material −2,4,6-trinitrophenyl benzoate

Abstract

Excellent grade mono crystals of 2,4,6-Trinitrophenyl Benzoate (TNPB), a nonlinear optical (NLO) material, were successfully synthesized using acetonitrile as solvent through a slow evaporation technique. Single crystal X-ray diffraction confirmed that the titled material crystallizes in the non-centrosymmetric space group P 2 1 2 1 2 1 . Crystal morphology was simulated to highlight growth rates along various facets and to provide insight into the anticipated crystal habit. UV–Vis absorption analysis was performed to determine the optical characteristics of the crystal, revealing a cut-off wavelength of 297 nm. Hirshfeld surface study showed that molecular packing is strongly influenced by intermolecular H…O, C…H, and H…H interactions. Density Functional Theory (DFT) calculations at the B3LYP/6–31 G (d,p) level were employed to investigate the molecular structure at the ground state. Natural Bond Orbital (NBO) and Mulliken charge analyses were carried out using the optimized geometry. Density of States (DoS) and Frontier Molecular Orbitals (FMOs) were analyzed to determine the energy gap. Non-Covalent Interaction via Reduced Density Gradient (NCI-RDG) analysis was performed to confirm intermolecular interactions. Atoms in Molecules (AIM) analysis provided further topological insights. Second Harmonic Generation (SHG) was verified by the Kurtz–Perry powder method, revealing efficiency 3.5 times greater than potassium dihydrogen phosphate (KDP). • TNPB crystallizes in non-centrosymmetric space group P 2 1 2 1 2 1. • Crystal morphology reveals facet-specific growth behavior. • UV-Vis cut-off wavelength observed at 297 nm. • H⋯O, C⋯H, and H⋯H interactions dominate molecular packing. • SHG output is 3.5 times higher than standard KDP reference.