Spectral analysis (FT-IR,FT-Raman,UV and NMR), molecular docking,ADMET properties and computational studies: 2-Hydroxy-5-nitrobenzaldehyde

The hybrid correlation method was used to examine the spectra of 2-Hydroxy-5-nitrobenzaldehyde (2H5NB) in the FT-IR, FT-Raman, UV–Vis and NMR ranges. For the best molecular shape, vibrational wavenumbers, infrared intensities, and Raman activity using density functional theory, B3LYP and the 6–311++G(d,p) basis set were used. The MOLVIB software was tasked with providing an in-depth interpretation of the vibrational spectra. Intermolecular charge transfer is a result of bonding orbitals participating as donors and acceptors in all phases of NBO analysis, which stabilizes molecules. High gastrointestinal absorption, but no brain-blood barrier penetration or cytochrome P450 inhibition, were observed despite the expected ADMET characteristics and expected gastrointestinal absorption (1A2, 2C19, 2C9, 2D6 and 3A4). Following CFN and EDE, the results of molecular docking showed that 2H5NB had the highest negative mean binding affinity of ?5.717 kcal/mol, followed by CFN and EDE. 2H5NB also had a more significant hydrogen bond with the amino acid residues of selected receptor proteins. As a result, the current compound may be described as a possible analeptic agent.     

Molecular structure, vibrational spectra and nonlinear optical properties of l-Valine Hydrobromide: DFT study

FT-IR and Raman spectra of the nonlinear optical material l-Valine Hydrobromide crystal have been recorded and analyzed. The equilibrium geometry, bonding features and the harmonic vibrational wavenumbers of LVB have been calculated with the help of density functional theory (DFT) calculation. The lowering of NH stretching wavenumber indicates the formation of NH?Br hydrogen bonding. The calculated First order hyperpolarizability value shows that LVB is the potential candidate for the NLO applications. The electronic effects and the hydrogen bonding were explained using natural bond orbital analysis.     

FT-Raman and FT-IR spectra, vibrational assignments and density functional studies of 5-bromo-2-nitropyridine

The Fourier transform Raman and Fourier transform infrared spectra of 5-bromo-2-nitropyridine were recorded in the solid phase. The equilibrium geometry, natural atomic charges, harmonic vibrational frequencies, infrared intensities and Raman scattering activities were calculated by density functional B3LYP method with the 6-311++G(d,p) basis set. The scaled theoretical wavenumbers showed very good agreement with the experimental values. A detailed interpretations of the infrared and Raman spectra of 5-bromo-2-nitropyridine is reported on the basis of the calculated potential energy distribution (PED). The theoretical spectrograms for the Raman and IR spectra of the title molecule have been constructed.     

FT-IR,FT-Raman,NMR spectra and DFT calculations on 4-chloro-N-methylaniline

In this work, the vibrational spectral analysis was carried out by using FT-IR and FT-Raman spectroscopy in the range 400–4000 and 50–3500 cm^?1 respectively, for the title molecule. The structural and spectroscopic data of the molecule in the ground state were calculated by using density functional method using 6-311++G(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. The complete assignments of all the vibrational mode were performed on the basis of the total energy distributions (TED). ¹³C and ¹H 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 coincides with experimental one.     

FT-IR, FT-Raman, ab initio and DFT structural, vibrational frequency and HOMO-LUMO analysis of 1-naphthaleneacetic acid methyl ester

In this work, the FT-IR and FT-Raman spectra of 1-naphthaleneacetic acid methyl ester (abbreviated as 1-NAAME, C₁₀H₇CH₂CO₂CH₃) have been recorded in the region 3600–10 cm⁻¹. The optimum molecular geometry, normal mode wavenumbers, infrared and Raman intensities, Raman scattering activities, corresponding vibrational assignments, Mullikan atomic charges and other thermo-dynamical parameters were investigated with the help of HF and B3LYP (DFT) method using 6-31G(d,p), 6-311G(d,p) basis sets. Reliable vibrational assignments were made on the basis of total energy distribution (TED) calculated with scaled quantum mechanical (SQM) method. From the calculations, the molecules are predicted to exist predominantly as the C1 conformer. The correlation equations between heat capacity, entropy, enthalpy changes and temperatures were fitted by quadratic formulae. Lower value in the HOMO and LUMO energy gap explains the eventual charge transfer interactions taking place within the molecule. UV–VIS spectral analyses of 1NAAME have been researched by theoretical calculations. In order to understand electronic transitions of the compound, TD-DFT calculations on electronic absorption spectra in gas phase and solvent (DMSO and chloroform) were performed. The calculated frontier orbital energies, absorption wavelengths (λ), oscillator strengths (f) and excitation energies (E) for gas phase and solvent (DMSO and chloroform) are also illustrated.     

FT-IR and FT-Raman spectroscopy study of di-urethanesil hybrids doped with Mg(CF3SO3)2

In the present work di-urethane cross-linked poly(oxyethylene) (POE)/siloxane hybrids (di-urethanesils) incorporating magnesium triflate (Mg(CF₃SO₃)₂) with 100 ≥ n ≥ 2 (where n, composition, is the molar ratio of oxyethylene repeat units per Mg²⁺ ion) have been characterized by Fourier transform infrared and Raman spectroscopy to elucidate the Mg²⁺/POE, Mg²⁺/urethane, Mg²⁺/CF₃SO₃⁻ and hydrogen bonding interactions. The Mg²⁺ ions bond to POE chains and to the carbonyl oxygen atoms of the urethane linkages over the whole range of salt content studied. A crystalline POE/Mg(CF₃SO₃)₂ complex of unknown stoichiometry is formed at n = 5. “Free” and weakly coordinated CF₃SO₃⁻ ions are present in all the materials examined. Contact ion pairs emerge at n ≤ 20 and higher ionic aggregates appear at n ≤ 5.     

The spectroscopic (FT-IR, FT-Raman), NCA, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of L-cysteine by ab inito HF and density functional method

In this work, we report a combined experimental and theoretical study on molecular structure (monomer, dimer), vibrational spectra, and Natural Bond Orbital (NBO) analysis of non-ionized L-cysteine (LCY). The FT-IR solid phase (4000-400 cm(-1)) and FT-Raman spectra (3500-50 cm(-1)) of LCY was recorded at room temperature. The molecular geometry, harmonic and anharmonic vibrational frequencies and bonding features of LCY in the ground state have been calculated by using the density functional method (B3LYP) with 6-311G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the Scaled Quantum Mechanical Force Field (SQMFF) methodology. The first order hyperpolarizability (β(0)) of this novel molecular system and related properties (β, α(0) and Δα) of LCY are calculated using HF/6-311G(d,p) method on the finite-field approach. Stability of the molecule has been analyzed using NBO analysis. The calculated first hyperpolarizability shows that the molecule is an attractive molecule for future applications in non-linear optics. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally the calculations results were applied to stimulate infrared and Raman spectra of the title compound which show good agreement with observed spectra.     

Experimental (FT-IR, FT-Raman, H, C NMR) and theoretical study of alkali metal 2-aminonicotinates

The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of 2-aminonicotinic acid (2-ANA) was studied by the methods of molecular spectroscopy. The vibrational (FT-IR, FT-Raman) and NMR (¹H and ¹³C) spectra of 2-aminonicotinic acid and its alkali metal salts were recorded. Characteristic shifts and changes in intensities of bands along the metal series were observed. The changes of chemical shifts of protons (¹H NMR) and carbons (¹³C NMR) in the series of studied alkali metal 2-aminonicotinates (2-AN) were observed too.Optimized geometrical structures of the studied compounds were calculated by the B3LYP method using the 6-311++G** basis set. Aromaticity indices, atomic charges, dipole moments and energies were also calculated. The theoretical chemical shifts in ¹H and ¹³C NMR spectra and theoretical wavenumbers and intensities of IR and Raman spectra were determined. The calculated parameters were compared to the experimental characteristics of the studied compounds.     

利用付立叶红外光谱与付立叶拉曼光谱初探超细羊毛粉的光谱行为

采用付立叶红外(FT-IR)和付立叶拉曼(FT-Raman)光谱仪,对美利奴原毛、机械磨碎羊毛粉、氯化或氧化预处理后经酶水解的超细羊毛粉进行分析。研究结果表明:机械磨碎羊毛粉,其化学结构与原毛相比无明显变化;氯化或氧化预处理后经酶水解的超细羊毛粉的IR谱图发生了较大的变化,羊毛大分子中胱氨酸最终氧化为磺基丙氨酸,且原胱氨酸二硫键发生了断裂,生成新的半胱氨酸磺酸盐;同时预处理时间越长,羊毛粉的平均直经越小,新产生的1 044 cm-1、1 026 cm-1吸收信号也越强。     

FT-IR, FT-Raman spectra and ab initio HF and DFT calculations of 4-N,N'-dimethylamino pyridine

In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of 4-N,N'-dimethylamino pyridine (4NN'DMAP). The Fourier transform infrared and Fourier transform Raman spectra of 4NN'DMAP was recorded in the solid phase. The optimized geometry was calculated by HF and B3LYP methods with 6-31G(d,p) and 6-311++G(d,p) basis sets. The harmonic vibrational frequencies, infrared intensities and Raman scattering activities of the title compound were performed at same level of theories. The scaled theoretical wavenumber showed very good agreement with the experimental values. The thermodynamic functions of the title compound was also performed at HF/6-31G(d,p) and B3LYP/6-311++G(d,p) level of theories. A detailed interpretation of the infrared and Raman spectra of 4NN'DMAP was reported. The theoretical spectrograms for FT-IR and FT-Raman spectra of the title molecule have been constructed.     

FT-IR, FT-Raman spectra and ab initio DFT vibrational analysis of p-bromophenoxyacetic acid

The Fourier transform Raman and Fourier transform infrared spectra of p-bromophenoxyacetic acid were recorded in the solid phase. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities were calculated by HF and DFT (B3LYP) method with the 6-31G(d,p) basis set. The scaled theoretical wavenumbers showed very good agreement with the experimental ones. A detailed interpretation of the infrared and Raman spectra of p-bromophenoxyacetic acid is reported on the basis of the calculated potential energy distribution. The theoretical spectrograms for the IR spectrum of the title molecule have been constructed.     

FTIR and FT-Raman spectra, assignments, ab initio HF and DFT analysis of xanthine

The molecular vibrations of xanthine were investigated in polycrystalline sample, at room temperature by Fourier transform infrared (FTIR) and FT-Raman spectroscopies. The spectra of the molecule have been recorded in the regions 4000-50 cm(-1) and 3500-100 cm(-1), respectively. Theoretical information on the optimized geometry, harmonic vibrational frequencies, infrared and Raman intensities were obtained by means of ab initio Hartree-Fock (HF) and density functional theory (DFT) gradient calculations with complete relaxation in the potential energy surface using 6-311++G(d,p) basis set. The vibrational frequencies which were determined experimentally from the spectral data are compared with those obtained theoretically from ab initio and DFT calculations. A close agreement was achieved between the observed and calculated frequencies by refinement of the scale factors. The infrared and Raman spectra were also predicted from the calculated intensities. Thermodynamic properties like entropy, heat capacity, zero point energy have been calculated for the molecule. Unambiguous vibrational assignment of all the fundamentals was made using the potential energy distribution (PED).     

Vibrational (FT-IR and FT-Raman) and NMR studies on selected metal (Ca, Mn, Zn) complexes with ortho-, meta-, and para-iodobenzoic acids

The vibrational (FT-IR and FT-Raman) and NMR (¹H and ¹³C) spectra of Ca, Mn, and Zn complexes with ortho-, meta-, and para-iodobenzoic acids have been studied. The solid state samples of all complexes have been measured within the range 4000–400 cm⁻¹, while water solutions of ortho-iodobenzoates within the range 4000–800 cm⁻¹. Based on previous experimental data and normal mode calculations for simpler complexes the assignment of bands observed in vibrational spectra of studied compounds has been done. Some significant differences in vibrational structure (frequency and intensity of selected bands) have been observed and discussed. The effect of metal on ring vibrations and carboxylic anion stretching and deformation has been investigated. Also, influence of iodine substitution on the aromatic ring and carboxylic anion, depending on iodine ring position, has been discussed. In case of soluble compounds, wavenumbers of characteristic bands of water solution samples have been compared with wavenumbers of corresponding bands of solid state samples.     

FT-IR, NIR-FT-Raman and gas phase infrared spectra of 3-aminoacetophenone by density functional theory and ab initio Hartree-Fock calculations

The gas phase infrared spectrum of 3-aminoacetophenone (3AAP) was measured in the range 5000-500cm(-1) and with a resolution of 0.5cm(-1). The Fourier transform Raman (FT-Raman) and Fourier transform infrared (FT-IR) spectra of 3AAP were recorded in the solid phase. Geometry optimizations were done without any constraint and several thermodynamic parameters were calculated for the minimum energy conformer at ab initio and density functional theory (DFT) levels invoking 6-311G(2df 2p) basis set and the results are compared with the experimental values. Harmonic-vibrational wavenumber was also calculated for the minimum energy conformer at ab initio and DFT levels using 6-31G(d,p) basis set and the results are compared with related molecules. With the help of specific scaling procedures, the observed vibrational wavenumbers in gas phase, FT-IR and FT-Raman spectra were analyzed and assigned to different normal modes of the molecule. Most of the modes have wavenumbers in the expected range, the error obtained was in general very low. The appropriate theoretical spectrogram for the FT-IR spectra of the title molecule is also constructed.     

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.     

FTIR, FT-Raman spectra and ab initio DFT vibrational analysis of 2,4-dichloro-6-nitrophenol

The FTIR and FT-Raman spectra of 2,4-dichloro-6-nitrophenol (2,4-DC6NP) has been recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The optimized geometry, frequency and intensity of the vibrational bands of (2,4-DC6NP) were obtained by the ab initio and DFT levels of theory with complete relaxation in the potential energy surface using 6-31G(d,p) and 6-311+G(d,p) basis sets. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar type spectrograms.     

FT-IR, FT-Raman spectra and ab initio HF, DFT vibrational analysis of p-chlorobenzoic acid

The infrared, the Fourier transform infrared and Fourier transform Raman spectra of p-chlorobenzoic acid (p-CBA) has been recorded in the region 4000-600 cm(-1), 4000-400 cm(-1) and 4000-100 cm(-1), respectively. The optimized geometry, frequency and intensity of the vibrational bands of p-CBA were obtained by the ab initio HF and DFT (B3LYP) methods with complete relaxation in the potential energy surface using 6-311+G(d,p) basis set. The harmonic-vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar type spectrograms.     

FT-IR, FT-Raman and SERS spectra of pyridine-3-sulfonic acid

FT-IR and FT-Raman spectra of pyridine-3-sulfonic acid are recorded and analysed. Surface enhanced Raman scattering (SERS) spectrum is recorded in a silver colloid. The bands due to upsilonCH, upsilonSO are enhanced in the SERS spectrum. A likely 'perpendicular orientation' of the molecule on the silver surface is suggested.