1-(4-Chlorophenyl) piperazine: FT-IR, Raman, NMR and Theoretical studies

The structure of 1-(2-nitrophenyl)piperazine (NPP, C 10 H 13 N 3 O 2 ) was characterized by nuclear magnetic resonance (NMR), Fourier Transform infrared (FTIR) and Raman techniques. The conformational analysis, nuclear magnetic shielding tensors, normal mode frequencies and corresponding vibrational assignments of NPP were examined using the density functional theory (DFT), with the Becke-3-Lee-Yang-Parr (B3LYP) functional and the 6-31G(d) and 6-311++G(d,p) basis sets. Reliable vibrational assignments were investigated by the total energy distributions (TED) obtained with scaled quantum mechanical (SQM) method. The hydrogen of NH group in piperazine and the phenyl fragment of NPP equatorially oriented relative to piperazine. There is a good agreement between the experimentally determined nuclear magnetic shielding tensors and vibrational frequencies of NPP and those predicted theoretically.

N-(2,4-dichlorobenzylidene)-3-methylbenzenamine ( L6 ) was synthesized as single crystal and characterized by FT-IR, Raman, 1 H NMR, 13 C NMR and UV-VIS spectroscopy. The thermal stability of the title compound was also studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) analyses. The optimized geometric parameters, conformational analysis, normal mode frequencies and corresponding vibrational assignments of L6 was theoretically examined by means of density functional theory (DFT) method using the Becke-3-Lee-Yang-Parr (B3LYP) exchange-correlation functional and the 6-311G++(d, p) basis sets. The DFT based nuclear magnetic resonance (NMR) calculations was also performed to use for assigning the 1 H and 13 C NMR chemical shifts of L6 . Reliable vibrational assignments were investigated by the potential energy distribution analysis and the highest occupied and the lowest unoccupied molecular orbitals (HOMO and LUMO) of L6 was predicted. A good consistency was obtained between the theoretically predicted structural parameters, vibrational frequencies and those obtained experimentally.

Quantum mechanical and spectroscopic (FT-IR, FT-Raman) study, NBO analysis, HOMO-LUMO, first order hyperpolarizability and molecular docking study of methyl[(3R)-3-(2-methylphenoxy)-3-phenylpropyl]amine by density functional method

Molecular Mechanism of SSR128129E, an Extracellularly Acting, Small-Molecule, Allosteric Inhibitor of FGF Receptor Signaling

Vibrational spectra, molecular structure, NBO, NMR, UV, first order hyperpolarizability, analysis of (S)-(−)-N-(5-Nitro-2-pyridyl) alaninol by Density functional theory

In the present work, structural and spectroscopic investigations were carried out on a borreverine derivative. Borreverine is a class of alkaloid as well a natural antimalarial drug extracted from Borreria verticillata. With the aim of finding possible conformers, a detailed conformational analysis of a borreverine derivative was conducted utilizing density functional theory employing the B3LYP/6-31G(d,p) method. The crystallographic geometry was used for full geometry optimization, followed by a conformational analysis. The conformational investigation predicted the most stable conformer (conformer I), which was further compared with the initial crystallographic geometry (conformer V). The geometry optimization, vibrational frequency, and intensity of these two conformers (I and V) were calculated in the ground state using density functional theory with the B3LYP functional and 6-31G(d,p) basis set. The spectroscopic investigation was conducted using Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) techniques. Tentative vibrational assignments of some selective modes were presented utilizing the observed FT-IR, FT-Raman, and calculated spectra. The scaled and observed wavenumbers were found to be in good agreement. The molecular electrostatic potential was computed and plotted so as to elucidate the reactive sites of the molecule. Natural bond orbital studies were performed to investigate the intramolecular charge transfer that results in molecular stability.

A joint theoretical and experimental study of 1-acetylpiperazine: Conformational stability, infrared and Raman spectra

Experimental and theoretical FT-IR, Raman and XRD study of 2-acetyl-5-chlorothiophene

In situ NMR Investigation of the Photoresponse of Perovskite Crystal

Synthesis, molecular structure, FT-IR and XRD investigations of 2-(4-chlorophenyl)-2-oxoethyl 2-chlorobenzoate: A comparative DFT study

Infrared and Raman spectra, conformational stability and vibrational assignment of 1-formylpiperazine

FT-IR and Raman spectra of methacrylamidoantipyrine (MAAP) have been reported in the region of 4000–10 cm−1 and 4000–100 cm−1, respectively. The optimized geometric parameters, conformational analysis, normal mode frequencies, and corresponding vibrational assignments of MAAP (C15H17N3O2) have been examined by means of density functional theory (DFT) method using the Becke-3-Lee-Yang-Parr (B3LYP) exchange-correlation functional and the 6-31G++(d,p) basis sets. Vibrational assignments have been made on the basis of potential energy distribution (PED) and the thermodynamics functions, and the highest occupied and the lowest unoccupied molecular orbitals (HOMO and LUMO) of MAAP have been predicted. Calculations are carried out with the possible seven (amide-1–5 and imide-1-2) conformational isomers of MAAP. Comparison between the experimental and theoretical results indicates that the B3LYP method provides satisfactory evidence for the prediction of vibrational wavenumbers, and the amide-1 conformational isomer is supposed to be the most stable form of MAAP.

Molecular structure, vibrational spectra and 13C and 1H NMR spectral analysis of 1-methylnaphthalene by ab initio HF and DFT methods

Molecular structure, vibrational spectral assignments (FT-IR and FT-RAMAN), NMR, NBO, HOMO-LUMO and NLO properties of O-methoxybenzaldehyde based on DFT calculations

The Fourier transform infrared (FT‐IR) spectrum of N‐hydroxyphthalimide has been recorded in the range of 4000–400 cm−1, and the Fourier transform Raman (FT‐Raman) spectrum of N‐hydroxyphthalimide has been recorded in the range of 4000–50 cm−1. With the hope of providing more and effective information on the fundamental vibrations, the Density Functional Theory (DFT)‐Becke3‐Lee‐Yang‐Parr (B3LYP) level with 6‐31G* basis set has been employed in quantum chemical analysis, and normal coordinate analysis has been performed on N‐hydroxyphthalimide by assuming Cs symmetry. The computational wavenumbers are in good agreement with the observed results. The theoretical spectra obtained along with intensity data agree well with the observed spectra. Copyright © 2009 John Wiley & Sons, Ltd.