Conformational analysis, molecular structure, spectroscopic, NBO, reactivity descriptors, wavefunction and molecular docking investigations of 5,6-dimethoxy-1-indanone: A potential anti Alzheimer's agent

The objective of the present study is focused to elucidate the structure of potential anti-Alzheimer's compound 5,6-Dimethoxy-1-indanone (5,6-DMI) and study its binding interaction towards the active site by molecular docking studies. The structural and various spectroscopic tools are used to understand the various interaction behaviors of the title compound. The theoretical calculation of 5,6-DMI molecule is computed by Gaussian 09W software with Density functional B3LYP and CAM-B3LYP method utilizing 6-311G(d,p) as basis set. The Natural Bond Orbital (NBO) analysis has been performed to find all possible transition was correlate with electronic transition. The Non covalent interaction of 5,6-DMI molecule was examined by adopt Reduced Density Gradient (RDG) analysis and colour filled ELF diagram. Molecular docking results suggest that 5,6-DMI may exhibit inhibitory activity against apoE protein and may act as potential against Alzheimer's disease.

Synthesis and spectroscopic characterization on 4-(2,5-di-2-thienyl-1H-pyrrol-1-yl) benzoic acid: A DFT approach

A complete structural and vibrational analysis of the 4-(2,5-di-2-thienyl-1H-pyrrol-1-yl) benzoic acid (TPBA), was carried out by ab initio calculations, at the density functional theory (DFT) method. Molecular geometry, vibrational wavenumbers and gauge including atomic orbital (GIAO) (13)C NMR and (1)H NMR chemical shift values of (TPBA), in the ground state have been calculated by using ab initio density functional theory (DFT/B3LYP) method with 6-311G(d,p) as basis set for the first time. Comparison of the observed fundamental vibrational modes of (TPBA) and calculated results by DFT/B3LYP method indicates that B3LYP level of theory giving yield good results for quantum chemical studies. Vibrational wavenumbers obtained by the DFT/B3LYP method are in good agreement with the experimental data. The study was complemented with a natural bond orbital (NBO) analysis, to evaluate the significance of hyperconjugative interactions and electrostatic effects on such molecular structure. By using TD-DFT method, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD-DFT method and the experimental one is determined. In addition, the molecular electrostatic potential (MEP), frontier molecular orbitals analysis and thermodynamic properties of TPBA were investigated using theoretical calculations.

Spectroscopic and molecular structure investigations of 9-vinylcarbazole by DFT and ab initio method

Fourier transform infrared (FT-IR) and FT-Raman spectra have been recorded and widespread spectroscopic investigations have been carried out on 9-vinylcarbazole (9VC). The optimized geometries, vibrational wavenumbers, intensity of vibrational bands and various atomic charges of 9VC have been investigated using Hartree-Fock (HF) and density functional theory (DFT-B3LYP) method using 6-31G(d,p) as basis set. Experimental fundamental vibrational modes are scrutinized and compared with the calculated results. (13)C and (1)H NMR spectra were recorded and the chemical shifts of the molecule have been computed using GIAO method. The nonlinear property of the title compound was confirmed by hyperpolarizability. Molecular stability and bond strength was analyzed by Natural Bond Orbital analysis. Electronic structure properties such as UV and frontier molecular orbital examination have been reported.

Synthesis, structural and spectral analysis of (E)-N'-(4-Methoxybenzylidene)pyridine-3-carbohydrazide dihydrate by density functional theory

New nonlinear optical crystal, (E)-N'-(4-Methoxybenzylidene)pyridine-3-carbohydrazide dihydrate (MBP3CD 2H2O) has been synthesized and grown as a single crystal by the slow evaporation solution growth technique. The compound was characterized by FTIR (4000-400 cm(-1)), FT-Raman (3500-50 cm(-1)) and UV-Vis (800-200 nm) spectroscopy. The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of MBP3CD 2H2O have been investigated experimentally and theoretically using Gaussian03 software package were performed using B3LYP method with the 6-31G(d,p) basis set. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using Natural Bond Orbital (NBO) analysis. The calculated first hyperpolarizability is comparable with the reported values of similar derivatives and is an attractive object for future studies of nonlinear optics. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. In addition, molecular electrostatic potential (MEP), frontier molecular orbital (FMO) analysis were investigated using theoretical calculations. The chemical reactivity and thermodynamic properties (heat capacity, entropy and enthalpy) of MBP3CD 2H2O at different temperature are calculated.

Synthesis, structural, spectral (FTIR, FT-Raman, UV, NMR), NBO and first order hyperpolarizability analysis of N-phenylbenzenesulfonamide by density functional theory

In this study sulfonamide compound, N-phenylbenzenesulfonamide (NPBS) has been synthesized and grown as a high quality single crystal by the slow evaporation solution growth technique. The grown crystals were characterized by the Fourier transform infrared (4000-400cm(-1)), Fourier transform Raman (3500-500cm(-1)), UV-Vis (200-800nm) and NMR spectroscopy. Density functional (DFT) calculations have been carried out for the compound NPBS by utilizing DFT level of theory using B3LYP/6-31G(d,p) as basis set. The theoretical vibrational frequencies and optimized geometric parameters such as bond lengths and bond angles have been calculated by using quantum chemical methods. The stability of the molecule arising from hyper conjugative interaction and charge delocalization has been analyzed using NBO analysis. The dipole moment, linear polarizability and first order hyperpolarizability values were also computed. The chemical reactivity and ionization potential of NPBS were also calculated. In addition, Molecular Electrostatic Potential (MEP), Frontier Molecular Orbital (FMO) analysis was investigated using theoretical calculations. The thermodynamic properties of the compound were calculated at different temperatures and corresponding relations between the properties and temperature were also studied. Finally, geometric parameters, vibrational bands were compared with available experimental data of the molecules.

Spectral analysis, vibrational assignments, NBO analysis, NMR, UV-Vis, hyperpolarizability analysis of 2-aminofluorene by density functional theory

In this present investigation, the collective experimental and theoretical study on molecular structure, vibrational analysis and NBO analysis has been reported for 2-aminofluorene. FT-IR spectrum was recorded in the range 4000-400 cm(-1). FT-Raman spectrum was recorded in the range 4000-50 cm(-1). The molecular geometry, vibrational spectra, and natural bond orbital analysis (NBO) were calculated for 2-aminofluorene using Density Functional Theory (DFT) based on B3LYP/6-31G(d,p) model chemistry. (13)C and (1)H NMR chemical shifts of 2-aminofluorene were calculated using GIAO method. The computed vibrational and NMR spectra were compared with the experimental results. The total energy distribution (TED) was derived to deepen the understanding of different modes of vibrations contributed by respective wavenumber. The experimental UV-Vis spectra was recorded in the region of 400-200 nm and correlated with simulated spectra by suitably solvated B3LYP/6-31G(d,p) model. The HOMO-LUMO energies were measured with time dependent DFT approach. The nonlinearity of the title compound was confirmed by hyperpolarizabilty examination. Using theoretical calculation Molecular Electrostatic Potential (MEP) was investigated.

Molecular structure, vibrational spectra, NMR and UV spectral analysis of sulfamethoxazole

Fourier transform infrared (FTIR) and FT-Raman spectra have been recorded and extensive spectroscopic investigations have been carried out on Sulfamethoxazole (SMX). The structural and spectroscopic data of the molecule in the ground state were calculated by using density functional method (DFT) using 6-31G(d,p) basis set. The vibrational frequencies were calculated and scaled values were compared with experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. (13)C and (1)H NMR chemical shifts results were given and are in agreement with the corresponding experimental values. The theoretically constructed FT-IR and FT-Raman spectra exactly coincide with experimental one. Besides, NBO, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations.

Spectral and structural studies of the anti-cancer drug Flutamide by density functional theoretical method

A comprehensive screening of the more recent DFT theoretical approach to structural analysis is presented in this section of theoretical structural analysis. The chemical name of 2-methyl-N-[4-nitro-3-(trifluoromethyl)phenyl]-propanamide is usually called as Flutamide (In the present study it is abbreviated as FLT) and is an important and efficacious drug in the treatment of anti-cancer resistant. The molecular geometry, vibrational spectra, electronic and NMR spectral interpretation of Flutamide have been studied with the aid of density functional theory method (DFT). The vibrational assignments of the normal modes were performed on the basis of the PED calculations using the VEDA 4 program. Comparison of computational results with X-ray diffraction results of Flutamide allowed the evaluation of structure predictions and confirmed B3LYP/6-31G(d,p) as accurate for structure determination. Application of scaling factors for IR and Raman frequency predictions showed good agreement with experimental values. This is supported the assignment of the major contributors of the vibration modes of the title compound. Stability of the molecule arising from hyperconjugative interactions leading to its bioactivity, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. NMR chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. The comparison of measured FTIR, FT-Raman, and UV-Visible data to calculated values allowed assignment of major spectral features of the title molecule. Besides, Frontier molecular orbital analyze was also investigated using theoretical calculations.

The spectroscopic (FT-IR, FT-Raman, UV and NMR) first order hyperpolarizability and HOMO-LUMO analysis of dansyl chloride

The solid phase FT-IR and FT-Raman spectra of dansyl chloride (DC) have been recorded in the regions 400-4000 and 50-4000 cm(-1), respectively. The spectra have been interpreted in terms of fundamentals modes, combination and overtone bands. The structure of the molecule has been optimized and the structural characteristics have been determined by density functional theory (B3LYP) method with 6-311++G(d,p) as basis set. The vibrational frequencies were calculated for most stable conformer and were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. The infrared and Raman spectra have also been predicted from the calculated intensities. (1)H and (13)CNMR spectra were recorded and (1)H and (13)C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV-Visible spectrum of the compound was recorded in the region 200-600 nm and the electronic properties HOMO and LUMO energies were measured by time-dependent TD-DFT approach. Nonlinear optical and thermodynamic properties were interpreted. All the calculated results were compared with the available experimental data of the title molecule.

The infrared, Raman, NMR and UV spectra, ab initio calculations and spectral assignments of 2-amino-4-chloro-6-methoxypyrimidine

The 2-amino-4-chloro-6-methoxypyrimidine abbreviated as ACMP have been investigated by both the experimental and theoretical methods; through this work we provide the essential fact about the structural and vibrational insights. The optimized molecular structure, atomic charges, vibrational frequencies and ultraviolet spectral interpretation of ACMP have been studied by performing DFT/B3LYP/6-311++G(df,pd) level of theory. The FT-IR, FT-Raman spectra were recorded in the region 4000-400 cm(-1) and 4000-50 cm(-1) respectively. The UV absorption spectrum of the compound that dissolved in ethanol and water solution were recorded in the range of 200-400 nm. The scaled wavenumbers are compared with the experimental values. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. Based on the UV spectrum and TD-DFT calculations, the electronic structure and the assignments of the absorption bands were carried out. The (1)H, (13)C and DEPT 135 nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated using with the Gauge Including Atomic Orbital (GIAO) method and compared with experimental results. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations.

Experimental and theoretical FTIR and FT-Raman spectroscopic analysis of 1-pyrenecarboxylic acid

The title molecule 1-pyrenecarboxylic acid (1PCA) has been characterized by FTIR, FT-Raman, NMR and UV-Vis spectral analyses. The molecular geometry, harmonic vibrational modes, the corresponding wavenumbers and IR intensities of 1PCA were calculated by DFT method with 6-311G(d,p) basis set. The assignments of the fundamentals were proposed on the basis of total energy distribution (TED) calculations. The calculated (13)C and (1)H NMR chemical shifts using gauge including atomic orbitals (GIAOs) approach are in good agreement with the observed chemical shifts. The polarizability and first order hyperpolarizability of the title molecule were calculated and interpreted. Using TD-DFT method, the electronic transitions have been compared with the experimental wavelengths. The molecular electrostatic potential map was used for prediction of possible hydrogen and oxygen bonding sites 1PCA molecule.

Structural, vibrational, electronic and NMR spectral analysis of 3-chloro-6-methoxypyridazine by DFT calculations

In this work, the FT-Raman and FT-Infrared spectra of 3-chloro-6-methoxypyridazine sample were measured to elucidate the spectroscopic properties of title molecule in the spectral range of 3500-50 cm(-1) and 4000-400 cm(-1), respectively. The molecular geometry and vibrational frequencies of 3-chloro-6-methoxypyridazine in the ground state were calculated using the DFT/B3LYP/6-31G(d),6-311G(d,p) level. The recorded FT-IR and FT-Raman spectral measurements favor the calculated structural parameters which are further supported by spectral simulation. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The UV-Visible absorption spectrum of the compound that dissolved in methanol was recorded in the range of 800-200 nm. The formation of hydrogen bond and the most possible interaction are explained using natural bond orbital (NBO) analysis. The isotropic chemical shift computed by (13)C and (1)H NMR analysis also shows good agreement with experimental observations. In addition, the molecular electrostatic potential (MEP) and frontier molecular orbitals (FMOs) analysis of the title compound were investigated using theoretical calculations.

Structural, vibrational, electronic and NMR spectral analysis of benzyl phenyl carbonate

In the present work, we reported the combined experimental and theoretical study on molecular structure, vibrational spectra of Benzyl Phenyl Carbonate (BPC). The optimized molecular structure, natural atomic charges, vibrational frequencies and UV-Vis spectral interpretation of Benzyl phenyl carbonate have been studied by performing DFT/B3LYP level of theory with 6-31G(d,p) as basis set. The FT-IR, FT-Raman spectra were recorded in the region 400-4000 cm(-1) and 50-3500 cm(-1) respectively. UV-Vis spectrum of the compound was recorded in the region 200-800 nm and the electronic properties HOMO and LUMO energies were measured by time dependent DFT approach. (1)H and (13)C NMR spectra were recorded and (1)H and (13)C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations.

Vibrational spectra, molecular structure, natural bond orbital, first order hyperpolarizability, TD-DFT and thermodynamic analysis of 4-amino-3-hydroxy-1-naphthalenesulfonic acid by DFT approach

Vibrational spectral analysis of 4-amino-3-hydroxy-1-naphthalenesulfonicacid (4A3HNSA) molecule were carried out using FT-IR and FT-Raman spectroscopic techniques. The equilibrium geometry, harmonic vibrational wavenumbers, various bonding features have been computed using density functional B3LYP method with 6-31G(d,p) as basis set. The Non-Linear Optical (NLO) behavior of 4A3HNSA has been studied by determination of the electric dipole moment (μ) and hyperpolarizability β using HF/6-31G(d,p) method. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in σ(*) and π(*) antibonding orbitals and second order delocalization energies (E2) confirms the occurrence of Intramolecular Charge Transfer (ICT) within the molecule. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincide with the experimental spectra.

Molecular structure and vibrational spectra of Irinotecan: a density functional theoretical study

The solid phase FTIR and FT-Raman spectra of Irinotecan have been recorded in the regions 400-4000 and 50-4000 cm(-1), respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (DFT) using B3LYP method with 6-31G(d) as basis set. The vibrational frequencies were calculated for Irinotecan by DFT method and were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. The infrared spectrum was also simulated from the calculated intensities. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations.

Vibrational spectra, UV and NMR, first order hyperpolarizability and HOMO-LUMO analysis of 2-amino-4-chloro-6-methylpyrimidine

The solid phase FTIR and FT-Raman spectra of 2-amino-4-chloro-6-methylpyrimidine (2A4Cl6MP) have been recorded in the regions 400-4000 and 50-4,000 cm(-1), respectively. The spectra have been interpreted interms of fundamentals modes, combination and overtone bands. The structure of the molecule has been optimized and the structural characteristics have been determined by density functional theory (B3LYP) method with 6-311++G(d,p) as basis set. The vibrational frequencies were calculated and were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. The infrared and Raman spectra have also been predicted from the calculated intensities. (1)H and (13)C NMR spectra were recorded and (1)H and (13)C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV-Vis spectrum of the compound was recorded in the region 200-400 nm and the electronic properties HOMO and LUMO energies were measured by time-dependent TD-DFT approach. Nonlinear optical and thermodynamic properties were interpreted. All the calculated results were compared with the available experimental data of the title molecule.

Experimental and theoretical spectroscopic studies of anticancer drug rosmarinic acid using HF and density functional theory

In this work, we reported a combined experimental and theoretical study on molecular structure, vibrational spectra and NBO analysis of anticancer drug of rosmarinic acid. The optimized molecular structure, atomic charges, vibrational frequencies, natural bond orbital analysis and ultraviolet-visible spectral interpretation of rosmarinic acid have been studied by performing HF and DFT/B3LYP/6-31G(d,p) level of theory. The FT-IR (solid and solution phase), FT-Raman (solid phase) spectra were recorded in the region 4000-400 and 3500-50 cm(-1), respectively. The UV-Visible absorption spectra of the compound that dissolved in ethanol were recorded in the range of 200-800 nm. The scaled wavenumbers are compared with the experimental values. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The formation of hydrogen bond was investigated in terms of the charge density by the NBO calculations. Based on the UV spectra and TD-DFT calculations, the electronic structure and the assignments of the absorption bands were carried out. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations.

Experimental (FT-IR, FT-Raman and UV-Vis) spectra and theoretical DFT investigations of 2,3-diaminophenazine

Vibrational analysis of the planar electron-rich heterocyclic 2,3-diaminophenazine (DAP) molecule was carried out using FT-IR and FT-Raman spectroscopic techniques. The equilibrium geometry, harmonic vibrational wavenumbers, various bonding features have been computed using density functional method. The calculated molecular geometry parameters have been compared with XRD data. The detailed interpretation of the vibrational spectra has been carried out. The first order hyperpolarizability (β(0)) of the molecular system and related properties (β, α(0) and Δα) of DAP are calculated using HF/6-31G(d,p) method on the basis of finite-field approach. Vibrational analysis reveals that the simultaneous IR and Raman activation of the C-C stretching mode in the molecule provide the evidence for the charge transfer interaction takes place from electron donating group to the ring. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. The simulated spectra satisfactorily coincide with the experimental spectra.

The spectroscopic properties of anticancer drug Apigenin investigated by using DFT calculations, FT-IR, FT-Raman and NMR analysis

The FT-Raman and FT-Infrared spectra of solid Apigenin sample were measured in order to elucidate the spectroscopic properties of title molecule in the spectral range of 3500-50 cm(-1) and 4000-400 cm(-1), respectively. The recorded FT-IR and FT-Raman spectral measurements favor the calculated (by B3LYP/6-31G(d,p) method) structural parameters which are further supported by spectral simulation. Additional support is given by the collected (1)H and (13)C NMR spectra recorded with the sample dissolved in DMSO. The predicted chemical shifts at the B3LYP/6-31G(d) level obtained using the Gauge-Invariant Atomic Orbitals (GIAO) method with and without inclusion of solvent using the Polarizable Continuum Model (PCM). By using TD-DFT method, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD-DFT method and the experimental one is determined. The UV-visible absorption spectra of the compound that dissolved in Ethanol, Methanol and DMSO were recorded in the range of 800-200 nm. The formation of hydrogen bond and the most possible interaction are explained using natural bond orbital (NBO) analysis. In addition, the molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis and atomic charges of the title compound were investigated using theoretical calculations. The results are discussed herein and compared with similar molecules whenever appropriate.

Structural, vibrational (FT-IR and FT-Raman) and UV-Vis spectral analysis of 1-phenyl-3-(1,2,3-thiadiazol-5-yl)urea by DFT method

The Fourier Transform Infrared (FT-IR) and FT-Raman spectra of 1-phenyl-3-(1,2,3-thiadiazol-5-yl)urea (TDZ) have been recorded and analyzed. The molecular structure and vibrational spectra (harmonic and anharmonic) of TDZ were calculated by the Density Functional Theory (DFT) method using the B3LYP function with 6-31G(d,p) as the basis set. A detailed interpretation of the Infrared and Raman spectra of TDZ was reported based on Potential Energy Distribution (PED). The first order hyperpolarizability (β(0)) of this novel molecular system and related properties (β, α(0) and Δα) were calculated using HF/6-31G(d,p) method on the finite-field approach. Stability of the molecule arising from hyperconjugative interactions and charge delocalization have been analyzed using Natural Bond Orbital analysis. The results show that charge in electron density in the σ(∗) and π(∗) antibonding orbitals and second order delocalization energies E(2) confirm the occurrence of Intramolecular Charge Transfer (ICT) within the molecule. UV-Vis spectrum of the title molecule was recorded and the electronic properties such as HOMO and LUMO energies were determined by Time-Dependent Density Functional Theory approach.

Synthesis, FT-IR, FT-Raman, dispersive Raman and NMR spectroscopic study of a host molecule which potential applications in sensor devices

The solid phase FT-IR, FT-Raman and dispersive Raman spectra of the host molecule which potential applications in sensor devices have been recorded in the region 400-4000 and 50-3500cm(-1), respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (DFT) using B3LYP method with 6-31G(d) basis set. The vibrational frequencies were calculated for the studied molecule by DFT method, and compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. Finally the calculation results were applied to simulate infrared and Raman spectra of the compound. Obtained these spectra also showed good agreement with observed spectra. The dipole moment, linear polarizability and first hyperpolarizability values were also computed. The linear polarizability and first hyperpolarizability of the studied molecule indicate that the compound is a good candidate of nonlinear optical materials.

The spectroscopic (FT-IR, FT-Raman, UV) and first order hyperpolarizability, HOMO and LUMO analysis of 3-aminobenzophenone by density functional method

In this work, experimental and theoretical study on the molecular structure and the vibrational spectra of 3-aminobenzophenone (3-ABP) is presented. The vibrational frequencies of the title compound were obtained theoretically by DFT/B3LYP calculations employing the standard 6-311++G(d,p) basis set for optimized geometry and were compared with Fourier transform infrared spectrum (FTIR) in the region of 400-4000 cm(-1) and with Fourier Transform Raman spectrum in the region of 50-4000 cm(-1). Complete vibrational assignments, analysis and correlation of the fundamental modes for the title compound were carried out. The vibrational harmonic frequencies were scaled using scale factor, yielding a good agreement between the experimentally recorded and the theoretically calculated values.

The spectroscopic (FTIR, FT-Raman, NMR and UV), first-order hyperpolarizability and HOMO-LUMO analysis of methylboronic acid

The solid phase FTIR and FT-Raman spectra of methylboronic acid (MBA) have been recorded in the regions 400-4000 and 50-4000 cm(-1), respectively. The spectra were interpreted interms of fundamentals modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (B3LYP) and HF method with 6-311++G(d,p) as basis set. The vibrational frequencies were calculated for most stable conformer and were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. The infrared and Raman spectra were also predicted from the calculated intensities. (1)H and (13)C NMR spectra were recorded and (1)H and (13)C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compound was recorded in the region 200-400 nm and the electronic properties HOMO and LUMO energies were calculated by time-dependent TD-DFT approach. Mulliken charges of the MBA molecule was also calculated and interpreted. The geometric parameters, energies, harmonic vibrational frequencies, IR intensities, Raman intensities and absorption wavelengths were compared with the available experimental data of the molecule.

Molecular structure and vibrational spectroscopic studies of Chrysin using HF and Density Functional Theory

In the present study, the molecular confirmation, vibrational and electronic transition analysis of 5,7-dihyroxyflavone (Chrysin) were investigated using experimental techniques (FT-IR, FT-Raman and UV) and quantum chemical calculations by HF and DFT/B3LYP method with 6-31G(d,p) as basis set. The FT-IR and FT-Raman spectra in solid phase were recorded in the region 4000-400cm(-1) and 3500-50cm(-1) respectively. The UV absorption spectra of the title compound dissolved in water, methanol and ethanol were recorded in the range of 200-400nm. The complete vibrational assignments were performed on the basis of total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanic (SQM) method. By using TD-DFT calculation, electronic absorption spectra of the title compound have been predicted and a good agreement with experimental one is established. In addition, the molecular electrostatic potential (MEP), natural bond orbital (NBO) analysis have been investigated using theoretical calculations. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule.

FT-IR, FT-Raman, NMR and UV-vis spectra, vibrational assignments and DFT calculations of 4-butyl benzoic acid

The solid phase FTIR and FT-Raman spectra of 4-butyl benzoic acid (4-BBA) have been recorded in the regions 400-4000 and 50-4000cm(-1), respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (DFT) using B3LYP method with 6-311++G(d,p) as basis set. The vibrational frequencies were calculated for monomer and dimer by DFT method and were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. The infrared and Raman spectra were also predicted from the calculated intensities. (13)C and (1)H NMR spectra were recorded and (13)C and (1)H nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compound was recorded in the region 200-400nm and the electronic properties HOMO and LUMO energies were measured by time-dependent TD-DFT approach. The geometric parameters, energies, harmonic vibrational frequencies, IR intensities, Raman intensities, chemical shifts and absorption wavelengths were compared with the available experimental data of the molecule.

Experimental, theoretical calculations of the vibrational spectra and conformational analysis of 2,4-di-tert-butylphenol

In the present work, we reported a combined experimental and theoretical study on conformational stability, molecular structure and vibrational spectra of 2,4-di-tert-butylphenol (2,4-DTBP). The FT-IR (400-4000cm(-1)) and FT-Raman spectra (50-3500cm(-1)) of 2,4-DTBP were recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of 2,4-DTBP in the ground-state have been calculated by using the density functional BLYP/B3LYP methods. The energy calculated by time-dependent density functional theory (TD-DFT) result complements with the experimental findings. The calculated highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies show that charge transfer occurs within the molecule. Finally the calculation results were compared with measured infrared and Raman spectra of the title compound which showed good agreement with observed spectra.

Molecular structure, vibrational spectroscopic, first-order hyperpolarizability and HOMO, LUMO studies of 2-aminobenzimidazole

In the present work, we reported a combined experimental and theoretical study on molecular structure, vibrational spectra and HOMO-LUMO analysis of 2-aminobenzimidazole (2-ABD). The FTIR (400-4000 cm(-1)) and FT-Raman spectra (50-3500 cm(-1)) of 2-ABD were recorded. The molecular geometry, harmonic vibrational wavenumbers and bonding features of 2-ABD in the ground-state have been calculated by using the density functional B3LYP method with 6-311++G(d,p) and 6-31G(d) as basis sets. The energy and oscillator strength were calculated by time-dependent density functional theory (TD-DFT) result complements with the experimental findings. The calculated HOMO and LUMO energies showed that charge transfer occurs within the molecule. Finally, the calculation results were applied to simulate infrared and Raman spectra of the title compound which showed good agreement with the observed spectra.

FT-IR, FT-Raman spectra, density functional computations of the vibrational spectra and molecular conformational analysis of 2,5-di-tert-butyl-hydroquinone

The purpose of finding conformer among six different possible conformers of 2,5-di-tert-butyl-hydroquinone (DTBHQ), its equilibrium geometry and harmonic wavenumbers were calculated by the B3LYP/6-31G(d,p) method. The infrared and Raman spectra of DTBHQ were recorded in the region 400-4000 cm(-1) and 50-3500 cm(-1), respectively. In addition, the IR spectra in CCl(4) at various concentrations of DTBHQ are also recorded. The computed vibrational wavenumbers were compared with the IR and Raman experimental data. Computational calculations at B3LYP level with two different basis sets 6-31G(d,p) and 6-311++G(d,p) are also employed in the study of the possible conformer of DTBHQ. The complete assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated using VEDA 4 program. The general agreement between the observed and calculated frequencies was established.

Quantum mechanical and spectroscopic (FT-IR, FT-Raman, 13C, 1H and UV) investigations of antiepileptic drug Ethosuximide

The Fourier Transform Infrared (FT-IR) and Fourier Transform Raman (FT-Raman) spectra of antiepileptic drug Ethosuximide (ETX) have been recorded and analyzed. In addition, the IR spectra in CCl(4) at various concentrations of ETX are also recorded. The equilibrium geometry, bonding features and harmonic vibrational frequencies have been investigated with the help of Density Functional Theory (DFT) method. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge Including Atomic Orbital (GIAO) method. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ* and π* antibonding orbitals and second order delocalization energies E(2) confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. UV-vis spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies, were performed by Time-Dependent Density Functional Theory (TD-DFT) approach. Finally the calculation results were applied to simulate infrared and Raman spectra of the title compound which showed good agreement with observed spectra.

One-pot synthesis, FT-IR, NMR and density functional method (B3LYP) studies on 2-(cyclohexylamino)-2-oxo-1-(pyridin-2-yl)ethyl benzoate

2-(Cyclohexylamino)-2-oxo-1-(pyridin-2-yl)ethyl benzoate has been synthesized and characterized by elemental analysis, FT-IR, (1)H NMR and (13)C NMR. Geometrical structures, vibrational frequencies, (1)H and (13)C chemical shift values, molecular electrostatic potential maps and several thermodynamic parameters of title compound in the ground state have been calculated by using the density functional method with 6-31G(d) basis set. The IR spectrum of title compound was interpreted in terms of potential energy distribution (PED) analysis and NMR chemical shifts were also simulated using the GaussView program. Comparison of the theoretical vibrational spectra, (1)H and (13)C NMR chemical shifts of title compound showed a good agreement with the experimental data.

Molecular structure, vibrational, UV and NBO analysis of 4-chloro-7-nitrobenzofurazan by DFT calculations

In the present work, we reported a combined experimental and theoretical study on molecular structure, vibrational spectra and NBO analysis of 4-chloro-7-nitrobenzofurazan (NBD-Chloride). The FT-IR (400-4000 cm(-1)) and FT-Raman spectra (50-4000 cm(-1)) of NBD-Chloride were recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of NBD-Chloride in the ground-state have been calculated by using the density functional B3LYP method with 6-311++G (d, p) as higher basis set. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) result in DMSO and CDCl3 solvents complements with each other. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally the calculation results were applied to simulate infrared and Raman spectra of the title compound which show good agreement with observed spectra.

FT-IR, FT-Raman spectra, density functional computations of the vibrational spectra and molecular geometry of butylated hydroxy toluene

The FT-IR spectrum of 2,6-di-tert-butyl-4-methylphenol [butylated hydroxy toluene] was recorded in the region 4000-400 cm(-1). The FT-Raman spectrum of butylated hydroxy toluene was also recorded in the region 3500-50 cm(-1). The molecular structure and vibrational frequencies of butylated hydroxy toluene (BHT) have been investigated with combined experimental and theoretical study. Two stable conformers of the title compound were obtained from the result of geometry optimizations of these possible conformers. The conformer 1 is (approximately 2.6 kcal/mol) more stable than conformer 2. Geometry optimizations and vibrational frequency calculations were performed by BLYP and B3LYP methods using 6-31G(d), 6-31G(d,p) and 6-31+G(d,p) as basis sets. The scaled frequencies were compared with experimental spectrum and on the basis of this comparison; assignments of fundamental vibrational modes were examined. Comparison of the experimental spectra with harmonic vibrational wavenumbers indicates that B3LYP/6-31G(d) results are more accurate. Predicted electronic absorption spectra of BHT from TD-DFT calculation have been analyzed and compared with the experimental UV-vis spectrum. The calculated HOMO and LUMO energies show that the charge transfer occurs within the molecule.