DFT Study for the Spectroscopic and Structural Analysis of p-Dimethylaminoazobenzene

Abstract

The study under consideration represents the computational calculations of Azo-based direct dye named p-(dimethylamino)azobenzene (DMAB) under the effect of solvents with different relative permittivities. A density functional theory (DFT) method at the B3LYP level with 6-311G++ was applied for the spectroscopic and structural analysis of the title compound. Calculations of geometric parameters (bond orders, bond lengths, and dihedral angles), electron densities, thermodynamic parameters, and orbital energies were performed for the title compound. Mulliken population analysis (MPA) as well as natural population analysis (NPA) was also performed at the B3LYP level with different solvents for finding solvent effects. In order to predict the reactivity of DMAB, molecular electrostatic potential (MESP) calculations were carried out for it. For vibrational analysis, the infrared (IR) spectra were computed for the title compound at the B3LYP/6-311G++ level in the gas phase and in different solvents with good agreement to the experimental FT-IR spectrum. The different modes of vibrations were assigned using potential energy distribution (PED). The computed Raman spectra also showed appreciable agreement with the experimental recorded Raman spectrum. The electronic absorption spectra of the title compound have been computed employing DFT/B3LYP with the 6-311G++ basis set in the gas phase and in four different solvents, that is, DMSO, ethanol, acetonitrile, and water which were compared with the experimental spectra with appreciable agreement. NBO analysis was carried out for understanding the intramolecular and intermolecular bonding of the compound and the density transfer from completely filled to unfilled orbital was found. The HOMO-LUMO energies were determined for analyzing the mechanism of intramolecular charge transfer.

Efficient Synthesis of Novel Tricyclic Benzoxazine Derivative via Ring Opening of Epoxide Along the Mp and DFT Studies of Structural, Spectroscopic (Ir, Raman, Uv-Vis), Thermodynamic, Orbitals and Nlo Properties of Desired Tricyclic Benzoxazine Derivative

“…In the aromatic ring the stretching vibration of C -H is reported in range of 3100 cm -1 . The stretching of non-aromatic C -H is reported around 3000 cm -1 [25,41]. The aromatic C -H stretch have multiple weak bands.…”

“…This interaction is the measure of delocalization. The charge transfer interactions arising from the non-covalent bonding and anti-bonding is the quantitative measure of the second order perturbation interaction energy (E 2 ) [25][26][27]. The TD-DFT calculations in vacuo by using the polarized continuum model (PCM) were performed for the UV absorption spectra of S11 with the hybrid exchange function B3LYP [20,21], and the gradient based exchange and correction functions B3PW91 [28] and PBEPBE [29,30].…”

“…The second order perturbation energy (E 2 ) is the quantitative measure of interactions between donor and acceptors in NBO and is also known as stabilization energy. The higher value of E (2) is reflecting stronger interactions of donor and acceptor and the higher extend of conjugation [25]. The value of E (2) depends on occupancy of donor (i) and acceptor (j), the diagonal elements (orbital energies) and and the off-diagonal Fork matix element, ( , ) [54].…”

High-field and benchtop NMR spectroscopy for the characterization of new psychoactive substances

“…In order to achieve a faster structural elucidation, most of the above-mentioned techniques are combined with databases [8,9]. In addition, structural elucidation is sometimes supported by Density Functional Theory (DFT) calculations to predict spectroscopic values, e.g., vibrational frequencies in IR [10] or NMR chemical shifts and couplings [11] in order to help confirming the final structure. Finally, one of the most suitable techniques for a complete molecular structure elucidation is Nuclear Magnetic Resonance (NMR) spectroscopy.…”

“…NMR has great ability to identify and quantify small organic molecules, and is therefore essential for the structure elucidation of NPS. A first strategy consists in associating NMR spectra with databases [10]. This is particularly useful when a known molecule is suspected, but also to identify compounds in mixtures whose spectra are overlapped.…”