The revision of intermolecular interactions in 1,3‐dinitrobenzene crystal—the role of nitro groups in optical nonlinearity

Abstract

Polarized Fourier transform-infrared (FT-IR) reflectance spectra and powder Raman spectra have been measured for 1,3-dinitrobenzene crystal in order to revise the assignments of bands by means of the oriented gas model reinforced with quantum chemical [density functional theory (DFT)] calculations. Longitudinal optical/transverse optical (LO-TO) splitting of some bands is observed indicating medium strong, long-range, dipole-dipole interactions. The analysis of overtones in the polarized FT-NIR spectra has allowed us to estimate the anharmonicity of vibrations in the crystal. The molecular motions of the nitro groups are analyzed on the basis of temperature-dependent polycrystalline IR spectra. Based on the values of the energy difference ( ν el ) between the forbidden A 1g →B 2u transition in the benzene molecule in the gas phase and the first electronic transition in 1,3-dinitrobenzene, it has been concluded that the intermolecular interactions are medium strong. The nitro group interactions are proposed to play the main role in the optical nonlinearity.

Recent advances in linear and nonlinear Raman spectroscopy. Part V

“…Polarized FT‐IR reflectance spectra and powder Raman spectra have been measured by Trzebiatowska‐Gusowska et al . for the 1,3‐dinitrobenzene crystal in order to revise the vibrational assignments of bands by means of the oriented gas model reinforced with quantum chemistry DFT calculations . Polarized micro‐Raman spectroscopy was carried out by Yang et al .…”

“…[156] Polarized FT-IR reflectance spectra and powder Raman spectra have been measured by Trzebiatowska-Gusowska et al for the 1,3-dinitrobenzene crystal in order to revise the vibrational assignments of bands by means of the oriented gas model reinforced with quantum chemistry DFT calculations. [157] Polarized micro-Raman spectroscopy was carried out by Yang et al on the (001) face of a 0.67PbMg 1/3 Nb 2/3 O 3 -0.33PbTiO 3 (PMN-33%PT) single crystal. [158] The Raman images revealed the spatial variations of the intensity of the Raman bands suggesting that the structure in the PMN-33%PT single crystal varied from one micro-area to another.…”

Vibrational signatures in the THz spectrum of 1,3-DNB: A first-principles and experimental study

“…The largest mode in the single-molecule DFPT calculation is 94.5 THz and compares favorably with the measured IR mode at 93.3 THz. We also successfully reproduce the large measured spectral gap [22] between 51 and 86 THz (vs. 50 and 93 THz) without adjustable parameters. The offset seen in Re ǫ between the experimental IR curve and theory stems from different parameters ǫ ∞ used at room temperature and 7.5 K, due to its strong temperature dependence.…”

Molecular motions contributions to optical nonlinearity of N-benzyl-2-methyl-4-nitroaniline studied by temperature-dependent FT-IR, 1H NMR spectroscopy and DFT calculations

“…The activation energy estimated from the Carabatos-Nédelec and Becker model [22] amounts to 11.09 ± 0.12 and 10.68 ± 0.08 kJ/mol for the -CH 2 and -NH stretching vibration bands (Table 1) while for the -NO 2 symmetric and antisymmetric stretching vibrations is equal to 9.07 ± 0.24 and 9.61 ± 0.18 kJ/mol, respectively. These activation energy values are typical though usually depend on compound and the type of motion and/or libration [15,[36][37][38].…”