Vibrational and UV spectra, first order hyperpolarizability, NBO and HOMO-LUMO analysis of 4-chloro-N-(2-methyl-2,3-dihydroindol-1-yl)-3-sulfamoyl-benzamide

Structural, vibrational, electronic properties, hirshfeld surface analysis topological and molecular docking studies of N-[2-(diethylamino)ethyl]-2-methoxy-5-methylsulfonylbenzamide

The theoretical (Freebase, Cationic species) and experimental investigations on the molecular structural, spectroscopic characterization, and electronic properties of N2M5MB are reported. The most stable structure of the N2M5MB was analysed by employing Density Functional Theory (DFT) at different functional such as B3LYP, PBEPBE, TPSSTPSS and IEF-PCM (Freebase) and Cationic (B3LYP, IEF-PCM)/ 6-311++G (d,p) basis set level. The Potential Energy Scan (PES) analysis has been employed to investigate the conformational preference of the title molecule. The optimized molecular geometry, vibrational assignments (FT-IR, FT-Raman) of wavenumbers have been performed for freebase, cationic species (Gas, PCM) for the individual modes of vibration. The experimental UV-Vis absorption spectrum was obtained and compared with the simulated (Freebase, Cationic species) Time-Dependent (TD-DFT-M062X) method. The FMO's, electron-hole distributions, HOMA, FLU, Hirshfeld surface analysis, Electrostatic potential surface (ESP), Fukui functions, and topological parameters were discussed. Molecular docking studies were performed for the N2M5MB (ligand) into the active site of targeted proteins (1H22, 4DTL, 5OV9) which belong to AChE inhibitors with the minimum binding energy was detected.

Quantum mechanical, spectroscopic and docking studies of (2E)-1-(4-aminophenyl)-3-(4-benzyloxyphenyl)-prop-2-en-1-one Chalcone derivative by density functional theory - A prospective respiratory drug

Theoretical investigations on the molecular geometry, vibrational and electronic environment of (2E)-1-(4-aminophenyl)-3-(4-benzyloxyphenyl)-prop-2-en-1-one (APBPP) are presented for the first time. The vibration frequencies simulated were thoroughly analysed employing DFT/B3LYP using 6-311++G(d,p) basis set and compared with experimental FT- Raman and FT- IR data which showed good agreement vice-versa. Optimised molecular equilibrium geometry of the title compound was carried out. Vibrational assignments of wave numbers with PED (potential energy distribution) was done using VEDA software and the quantum chemical calculations of the molecular geometry were scaled using quantum mechanics. The title molecule showcased excellent results on HOMO - LUMO energies, NMR chemical shifts, 3.73 eV band gap, electronegativity (χ), chemical potential (μ), softness (S), global hardness (η). The low softness value (0.261) and thehigh value of electrophilicity index (4.0323) explains the biological activity of the title molecule. The reactive sites of APBPP were thoroughly investigated by Mulliken charges, MEP (Molecular electrostatic Potential) and Fukui functions. Thermo dynamical environment of the title compound for different temperatures were studied which reveals the correlations between entropy (S), heat capacity (C) and enthalpy changes (H) with temperatures. The title compound was docked into the reactive sites of antiviral (SARS-CoV-1,2) and anticancer protein using molecular docking tool and it showed excellent results compared to the ongoing clinical trials. The paper explains the experimental analysis which are in line with the quantum calculations and presents an optimistic evidence via Molecular docking studies. The synthesized compound against various panels of microorganism projects its ability to be the most potential drug to treat various pathologies in pharmacy Industry.

Quantum chemical determination of molecular geometries and spectral investigation of 4-ethoxy-2, 3-difluoro benzamide

The present work reports the application of density functional theory (DFT) at B3LYP with various basis sets which provide the relationship between the structural and spectral properties of 4-ethoxy-2, 3-difluoro benzamide (4EDFB). A Complete vibrational analysis has been performed at the density functional theory (DFT) method with various basis sets in the ground state. The results of vibrational wave numbers are in good agreement with the experimental spectra (Infrared and Raman). Energy gap of the molecule is evaluated using frontier molecular orbital energies (HOMO-LUMO). The frontier energy gap value reveals the chemical reactivity and intermolecular charge transfer occur within the molecule. Global chemical descriptors provide the local and global softness and local reactivity parameters used to identify the nucleophilic and electrophilic behavior of a specific site within the compound. The dimer structure is performed to evaluate the intermolecular hydrogen bond (O-H-O). The title molecule is capable of receiving second harmonic generation (SHG) is due to high value of hyperpolarizability indicates the NLO activity of the molecule. Apart from NLO entities, aromaticity and the molecular electrostatic potential surface (MEP) explain the hydrogen bonding and provide the reactive behavior of the molecule. The Mulliken population analysis leads to redistribution of electron density in the ring.

The spectroscopic (FT-IR, UV-vis), Fukui function, NLO, NBO, NPA and tautomerism effect analysis of (E)-2-[(2-hydroxy-6-methoxybenzylidene)amino]benzonitrile

A new o-hydroxy Schiff base, (E)-2-[(2-hydroxy-6-methoxybenzylidene)amino]benzonitrile was isolated and investigated by experimental and theoretical methodologies. The solid state molecular structure was determined by X-ray diffraction method. The vibrational spectral analysis was carried out by using FT-IR spectroscopy in the range of 4000-400cm(-)(1). Theoretical calculations were performed by density functional theory (DFT) method using 6-31G(d,p) basis set. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The UV-vis spectrum of the compound was recorded in the region 200-800 nm in several solvents and electronic properties such as excitation energies, and wavelengths were calculated by TD-DFT/B3LYP method. The most prominent transitions were corresponds to π→π∗. Hybrid density functional theory (DFT) was used to investigate the enol-imine and keto-amine tautomers of titled compound. The titled compound showed the preference of enol form, as supported by X-ray and spectroscopic analysis results. The geometric and molecular properties were compaired for both enol-imine and keto-amine forms. Additionally, geometry optimizations in solvent media were performed with the same level of theory by the integral equation formalism polarizable continuum (IEF-PCM). Stability of the molecule arises from hyperconjugative interactions, charge delocalization and intramolecular hydrogen bond has been analyzed using natural bond orbital (NBO) analysis. Mulliken population method and natural population analysis (NPA) have been studied. Also, condensed Fukui function and relative nucleophilicity indices calculated from charges obtained with orbital charge calculation methods (NPA). Molecular electrostatic potential (MEP) and non linear optical (NLO) properties are also examined.

Experimental and theoretical studies on the vibrational spectra of trans-3-phenylacryloyl chloride

The infrared and Raman spectra of trans-3-phenylacryloyl chloride (TPC) were reported and compared with the theoretical results calculating at B3LYP/6-311++G (d, p) level. Both wavenumbers and intensities obtained from the experimental and theoretical spectra were in good agreement. A complete spectral assignment was made with the aid of potential energy distribution (PED) based on the scaled quantum mechanical (SQM) force field method. This study provided valuable insight for understanding the observed spectral features of TPC. Additionally, the HOMO-LUMO gap, molecular electrostatic potential (MEP) atomic charge distribution, and natural bond orbitals (NBO) were studied theoretically on the same basis set.

Experimental and theoretical studies on IR, Raman, and UV-Vis spectra of quinoline-7-carboxaldehyde

Spectroscopic properties of quinoline-7-carboxaldehyde (Q7C) have been studied in detail both experimentally and theoretically. The FT-IR (4000-50 cm(-1)), FT-Raman (4000-50 cm(-1)), dispersive-Raman (3500-50 cm(-1)), and UV-Vis (200-400 nm) spectra of Q7C were recorded at room temperature (25 °C). Geometry parameters, potential energy surface about CCH(O) bond, harmonic vibrational frequencies, IR and Raman intensities, UV-Vis spectrum, and thermodynamic characteristics (at 298.15K) of Q7C were computed at Hartree-Fock (HF) and density functional B3LYP levels employing the 6-311++G(d,p) basis set. Frontier molecular orbitals, molecular electrostatic potential, and Mulliken charge analyses of Q7C have also been performed. Q7C has two stable conformers that are energetically very close to each other with slight preference to the conformer that has oxygen atom of the aldehyde away from the nitrogen atom of the quinoline.

Vibrational frequency analysis, FT-IR, DFT and M06-2X studies on tert-Butyl N-(thiophen-2yl)carbamate

In this study, the experimental and theoretical vibrational frequencies of a newly synthesized tert-Butyl N-(thiophen-2yl)carbamate have been investigated. The experimental FT-IR (4000-400 cm(-1)) spectrum of the molecule in the solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters (bond lengths and bond angles) have been calculated by using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr) and DFT/M06-2X (the highly parametrized, empirical exchange correlation function) quantum chemical methods with the 6-311++G(d,p) basis set by Gaussian 09W software, for the first time. The vibrational frequencies have been assigned using potential energy distribution (PED) analysis by using VEDA 4 software. The computational optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data, and with related literature results. In addition, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies and the other related molecular energy values have been calculated and are depicted.