FT-IR, FT-Raman, NMR spectra and DFT simulations of 4-(4-fluoro-phenyl)-1H-imidazole

The FT-IR, FT-Raman and FT-NMR spectra of the compound 4-(4-Fluoro-phenyl)-1H-imidazole (4-FPI) were recorded and analyzed. Density functional method (B3LYP level with the 6–311G(d, p) and 6–311++G(d, p) and cc-pVQZ as basis sets) has been used to compute optimized geometry, vibrational wavenumbers of the 4-FPI. Only one tautomeric form was found most stable by using DFT/B3LYP. The detailed interpretation of the vibrational spectra was carried out with the aid of total energy distribution following the scaled quantum mechanical force field methodology. Potential Energy Surface scan studies has also been carried out by ab initio calculations with the same basis sets.     

Structural,Spectroscopic, Antimicrobial Activity and DFT Studies on 4-Methyl-<Emphasis Type="Italic">N</Emphasis>-(4-methylphenylsulfonyl)-<Emphasis Type="Italic">N</Emphasis>-phenylbenzenesulfonamide

This study reports the structural characterization of a disulfonimide derivative, 4-methyl-N-(4-methylphenylsulfonyl)-N-phenylbenzenesulfonamide (MPBSA), using spectroscopic and quantum chemical methods. The molecule was characterized with FT-IR, ¹H ¹³C NMR and UV-Vis spectroscopies. Quantum chemical calculations of molecular geometry, vibrational wavenumbers and gauge including atomic orbital (GIAO) ¹H and ¹³C-NMR chemical shifts of the compound were carried out by using density functional method (DFT) at B3LYP/6?311++G(d,p) level of theory. Electronic absorption spectra of the compound have been computed using the time-dependent density functional theory (TD-DFT) method at the same level. A satisfactory consistency between the experimental and theoretical findings was obtained. The antimicrobial activity screening of the compound was performed on some bacteria and fungus species using microdilution method. The results showed that the title molecule have noteworthy antibacterial and antifungal activities.     

Spectral behavior study of 3-(4-dimethylamino-phenyl)-1-{6-[3-(4-dimethylamino-phenyl)-acryloyl]-pyridin-2-yl}-propanone

The photophysical properties such as singlet absorption, molar absorptivity, fluorescence spectra, fluorescence quantum yield (?_f) and transition dipole moment (μ₁₂) of 3-(4-dimethylamino-phenyl)-1-{6-[3-(4-dimethylamino-phenyl)-acryloyl]-pyridin-2-yl}-propanone (DMAPAPP) have been studied in different media. DMAPAPP exhibits a large red-shift in both absorption and emission spectra as the solvent polarity increases, indicating a large change in dipole moment of molecule upon excitation. The fluorescence quantum yield depends on the nature of the solvent. The absorption and emission spectra of DMAPAPP in dioxane–water mixture are also studied. The effect of different type of surfactants to determine their critical micellar concentration (CMC) and the microemulsion effect on the electronic absorption and emission spectra of DMAPAPP are recorded. The effect of acidity on the electronic absorption and emission spectra of DMAPAPP is studied to determine the pK_a and pK_a^? values.     

Vibrational spectra of M3PCr4O16 (M = K,NH4)

The infrared and Raman spectra of the two phosphochromates M₃PCr₄O₁₆ (M = K, NH₄) have been recorded and analysed. The spectra could be interpreted on the basis of the vibrations of Cr-O-P, O-P-O and CrO₃ groups. A large number of vibrational bands have been observed for each mode due to the existence of different Cr-O bond lengths. The anion is more distorted in potassium phosphochromate. The three ammonium groups are distinct.     

Microwave spectrum,conformation, and dipole moment of 4-thiacyclohexanone

The microwave spectra of 4-thiacyclohexanone in the ground state and eight vibrationally excited states have been studied in the frequency region 18.0–40.0 GHz and the corresponding rotational constants have been determined. The following values of the ground-state rotational constants (MHz) were obtained from the analysis of the a-type transitions: A = 3935.149 (0.031), B = 1829.444 (0.001), and C = 1364.609 (0.001). Analysis of the Stark effect gives for the dipole components (in Debye units) μ_a = 1.409 (0.002), μ_c = 0.391 (0.064). These data are consistent with a chair conformation for the ring. A phisically reasonable set of structural parameters which reproduce the ground-state rotational constants has been derived. A qualitative estimate of the low-frequency vibrational modes was obtained from relative-intensity measurements. The lowest vibrational frequency is believed to be a ring-bending mode and it occurs at 77 ± 22 cm^?1 while the ring-twisting mode is at 204 ± 27 cm^?1.     

IR active phonons in single crystals RFe3(BO3)4 (R = Pr,Nd, and Sm)

We have studied the reflection and transmission spectra of multiferroics RFe₃(BO₃)₄ (R = Pr, Nd, and Sm) at room temperature. Simulation of reflection spectra by the dispersion-analysis method have allowed us to determine the frequencies and oscillator strengths of the majority of IR active A ₂ and E vibrational modes.     

Synthesis,experimental and theoretical analysis,and antiproliferative activity of 2-(4-methoxyphenylamino)-2-oxoethyl methacrylate

In this study 2-(4-methoxyphenylamino)-2-oxoethyl methacrylate (MPAEMA) has been synthesized and characterized experimentally (FTIR, NMR). Theoretically, physical, electronic and vibrational properties of MPAEMA molecule have been investigated using density functional theory (DFT) calculations at B3LYP/6-311++G(d,p) basis set. Bond distance, FTIR spectrum, NMR spectra and vibrational frequencies have been carried out. The calculated FTIR and NMR spectra of the headline molecule from the DFT have been compared with the measured ones, and good results have been obtained. UV spectrum characteristics and the electronic properties, like frontier orbitals, and band gap energy of MPAEMA have also been recorded by time-dependent (TD-DFT) method based on optimized structure with different solvent. The experimental results have been compared with theoretical values. Both experimental and theoretical methods have shown that the compound has successfully been synthesized. Cytotoxicity of MPAEMA has been investigated by XTT cell proliferation assay. IC50 values of MPAEMA have been identified as 1.8 mM on HeLa cell line.     

Electronic photodissociation spectra of the Arn-C4H2 (n=1-4) weakly bound cationic complexes

Electronic spectra of a series of weakly bound clusters consisting of argon (Ar_n, n=1-4) bound to the butadiyne cation, C₄H₂⁺, have been recorded in the visible range from 440 to 520 nm by photodissociation. The C₄H₂⁺ fragment signal was recorded as a function of the laser wavelength during excitation of the A←X electronic transition. The observed transitions were assigned to the band origin of the cationic complexes and to vibronic bands involving excitation of the ν₃ and ν₇ vibrational modes of the C₄H₂⁺ moiety, as well as combination bands of these modes. Comparison of the photodissociation spectra of the various clusters reveals a small blue shift, 25 cm⁻¹ of the band maxima relative to the corresponding transitions reported from gas phase spectra of the bare C₄H₂⁺ cation. The magnitude of the blue shift of each band increases with successive Ar solvation up to n=3. Furthermore, each band becomes increasingly broadened towards the red with the addition of Ar atoms due to an increasing number of unresolved transitions involving excited intermolecular modes.     

Molecular structure,vibrational spectral investigation and the confirmation analysis of 4-Methylesculetin molecule

In this work, FT-IR, FT-Raman, and FT-NMR spectra of 4-Methylesculetin molecule are presented for the first time. FT-IR, FT-Raman, and FT-NMR spectra of 4MEC have been recorded and analyzed. The FT-IR and FT-Raman spectra of this molecule are recorded at 4000-400 cm^?1 and 50–3500 cm^?1, respectively. The infrared vibrational frequencies, absolute intensities, potential energy profile, HOMO-LUMO plot and NBO analysis of the molecule have been also predicted using Becke’s three-parameter hybrid B3LYP method in the density functional theory DFT method. Calculated and experimental data are in good agreement.     

Fourier transform infrared study of perchlorate (ClO4 and ClO4) anions isomorphously isolated in potassium permanganate matrix. Vibrational anharmonicity and pseudo-symmetry effects

Fourier transform infrared spectra of isotopomeric ³⁵ClO₄⁻ and ³⁷ClO₄⁻ anions isomorphously isolated in potassium permanganate matrix were recorded at room and low temperature (LT, ∼100 K). On the basis of the detected second-order vibrational transitions involving the dopant species ν₃ mode components, anharmonicity constants and harmonic eigenvalues for these modes were calculated. Although the overall appearance of the region of fundamental vibrational transitions in the spectra of dopant perchlorate anions may be better explained in terms of a pseudo-symmetry (the so-called ‘latent’ symmetry) site group C_2v, corresponding to the pseudo-symmetry space group Imma, instead of the (rigorous) crystallographic C_s one (corresponding to the crystallographic Pnma space group), an opposite statement seems to be valid for the region of the second-order vibrational transitions. The vibrational mode mixing (a ‘Fermi-like’ resonance) of the ClO₄⁻ ν₁ mode with the ν_3a site group component is almost negligible.     

Quantum-chemical study of structural, spectral, and electrooptical parameters of fluorosilanes SiH4− x Fx(x=0–4)

The possibility of calculating the molecular structure, vibrational frequencies, and electrooptical parameters of the silane molecule SiH₄ and the silicon tetrafluoride molecule SiF₄ is analyzed by using the ab initio quantum-chemical method (the MP2 perturbation theory) and the density functional theory (the B3LYP functional) with a wide variation of basis sets up to the cc-pV5Z set. The results obtained are used as reference values for studing mixed fluorosilanes SiH_4?x F_x (x=1–3) and for refining their geometry, the vibrational frequencies, and the absolute intensities of absorption bands. Based on the results of high-level quantum-chemical calculation corrected against the experimental data for SiH₄ and SiF₄, the structural parameters of mixed flouro-silanes are estimated and their vibrational frequencies are calculated and assigned for the first time. The quantum-chemical estimates of the absolute intensities of IR spectra are for the first time presented for all mixed fluorosilanes.     

Calculation of frequencies of normal vibrations and interpretation of IR spectra for 2,3-dihydro-3-O-(1,4-naphthoquinon-2-yl)-2-oxo-1,4-naphthoquinone derivatives

We have used B3LYP/6-31(d) density functional theory to calculate the frequencies and modes of the normal vibrations of 2-oxo-2,3-dihydro-and 2-methoxy-1,4-naphthoquinones. Based on these calculations within an additive model, we have assigned the carbonyl bands in the IR spectra of 2,3-dihydro-3-O-(1,4-naphthoquinon-2-yl)-2-oxo-1,4-naphthoquinones (diquinones 1–4). We have carried out a direct calculation of the vibrational spectra for diquinones 1–4 using PBE and B3LYP correlation functionals. We have shown that the calculation of the vibrational spectra of the diquinones based on an additive model on the whole is quite consistent with the results of direct calculations and the experimental spectra. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 713–720, November–December, 2006.     

Fourier Transform Infrared and Raman Spectra of 4-Vinylpyridine and its Transition Metal(II) Tetracyanonickelate Complexes

Abstract

Infrared and Raman spectra (4000-200 cm^?1) were recorded for 4-vinylpyridine and vibrational assignments made for fundamental modes on the basis of frequency shifts of the coordinated ligand, of the group vibrational concept and comparison with the assignments for related molecules. the infrared spectra of M(4-vinylpyridine)₂Ni(CN)₄ (M=Mn, Cd, Fe, Co, Ni or Cu) are reported.     

Near-Infrared Spectrum (3000-10 000 cm) of 4-Chlorophenol in Solution

The near-infrared spectra (3000-10 000 cm⁻¹) of 4-chlorophenol-OH and 4-chlorophenol-OD are studied at room temperature in carbon tetrachloride. Some data are also reported for 4-bromophenol-OH and 4-bromophenol-OD. The observed absorptions are assigned to overtones or combinations involving the fundamental transitions which have been recently calculated at the B3LYP/6-311++G(df,pd) level (J. Phys. Chem. A104, 11 685 (2000)). The anharmonicities and the harmonic frequencies of the local ν(OH) and ν(CH) modes and the coupling constants for the binary or ternary combinations are obtained. The extinction coefficients of these transitions are discussed. The half-band width of the ν(OH) and ν(CH) vibrations increases with the absorption frequencies. The experimental harmonic frequencies are obtained from the anharmonicity constants. Comparison with the theoretical frequencies indicates that the low scaling factors ranging from 0.950 to 0.960 characterizing the ν(OH) and ν(CH) vibrations can be accounted for by the large anharmonicity of these vibrations. For these vibrations, the ratio of the experimental harmonic frequencies to the computed frequencies is 0.993. This value does not significantly differ from the average scaling factors of 0.987-0.989 obtained for all the other vibrational modes.     

Infrared Spectroscopy of the ν1 Band of Sulfur Tetrafluoride, SF4

Infrared absorption spectra of the ν₁ axial S-F stretching vibrational bands of sulfur tetrafluoride, SF₄, have been recorded and analyzed. A diode-laser jet spectrometer was used to record high-resolution spectra of ³²SF₄, with 87 vibration-rotation lines of the ν₁ fundamental being assigned. Least-squares fitting of the data yielded a precise vibrational band origin, as well as rotational parameters for the upper state. In addition, lower-resolution spectra of a static sample of SF₄ held at room temperature were recorded using a Fourier transform (FTIR) spectrometer. The progressions of prominent features observed in the room-temperature FTIR spectra are attributed to summation bands arising from ν₁ transitions from excited vibrational levels of the low-frequency ν₄ manifold of both ³²SF₄ and ³⁴SF₄.     

A combined experimental and computational studies of 3,3,6,6-Tetramethyl-9-(4-Methoxyphenyl)3,4,6,7,9,10 hexahydroacridine-1,8-dione

ABSTRACT

In this work, we have recorded the Fourier Transform Infrared (FTIR) and Ultra-Violet Visible (UV–Vis) spectra of 3,3,6,6-Tetramethyl-9-(4-Methoxyphenyl)3,4,6,7,9,10 hexahydroacridine-1,8-dione (C₂₄H₂₉NO₃) in the spectral range 4000–400?cm^?1 and 190–1400?nm, respectively. The thermo gravimetric (TG) analysis of the compound has been performed to check the thermal stability of the compound. The molecular geometry and complete vibrational spectra in the ground state are calculated by Hartree Fock (HF) and Density Functional Theory (DFT) using6-311G(d,p) basis set. The calculated vibrational harmonic frequencies are scaled using a proper scale factor, yielding a good agreement with the experimental data. Stability of the molecule arising from hyperconjugative interactions, charge delocalisation has been studied using natural bond orbital analysis (NBO). Mulliken charges, MEP mapping and temperature dependence on the thermodynamic properties in the optimised ground state have been calculated. UV–Visible spectrum of the molecule was calculated by using TD-DFT approach and the results were compared with the experimental one. We have calculated the several molecular parameters like ionisation potential, electron affinity, global hardness, electron chemical potential, electronegativity and global electrophilicity based on HOMO and LUMO energy values calculated at B3LYP/6-311G(d,p) level of theory. The calculated optimised structural parameters and vibrational wavenumbers are found to be in good agreement with the experimental results.     

Charging effects on the vibrational properties of Au and Au2 on MgO(100)

Vibrational spectra of charge-neutral and charged Au and Au₂ on MgO(100) were investigated using ab-initio density functional perturbation theory. The calculated vibrational spectra showed vibrational features associated with the charge states of Au and Au₂ on MgO(100). Further analyses of surface in-plane and normal phonon modes of Au and Au₂ on MgO(100) were performed to extract vibrational features involving the Au modes. These features provide important information for experimentally explaining the charge states of Au and Au₂ on MgO(100).     

Molecular structure of alkali metal 4‐nitrobenzoates

The influence of lithium, sodium, potassium, rubidium, and cesium on the electronic system of the 4‐nitrobenzoic acid molecule was studied. The vibrational (FT‐IR, FT‐Raman) and NMR (¹H and ¹³C) spectra for 4‐nitrobenzoic acid salts of alkali metals were recorded. The assignment of vibrational spectra was done. Characteristic shifts of band wavenumbers and change in band intensities along the metal series were observed. Good correlation between the wavenumbers of the vibrational bands in the IR and Raman spectra for 4‐nitrobenzoates and ionic potential, electronegativity, atomic mass, and affinity of metals were found. The chemical shifts of protons and carbons (¹H, ¹³C NMR) in the series of studied alkali metal 4‐nitrobenzoates were observed too. Optimized geometrical structures of studied compounds were calculated by HF, B3PW91, B3LYP methods using 6‐311++G** basis set. The theoretical IR, Raman, and NMR spectra were obtained. The theoretical vibrational spectra were interpreted by means of potential energy distributions (PEDs) using VEDA 3 program. The calculated parameters were compared to experimental characteristic of studied compounds. Copyright © 2007 John Wiley & Sons, Ltd.     

The fir-absorption of V2O5 single crystals doped with monovalent interstitial impurities: Li,Na, Cu

Absorption spectra are presented of α-M_xV₂O₅ single crystals (M = Li, Na, Cu) in the frequency range 15–105 cm^-1 and at temperatures between 4 and 78 K. Impurity-induced absorption bands are observed at 29 and 53 cm^-1 with E ∥ [010]. A discussion is made of assignments to electronic and vibrational mechanisms.     

The molecular structures, vibrational spectroscopies (FT-IR and Raman) and quantum chemical calculations of n-alkyltrimethylammonium bromides

The FT-IR and micro-Raman spectra of three n-alkyltrimethylammonium bromides (dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB) and hexadecyl(cetyl)trimethylammonium bromide (CTAB)) in powder form were recorded in the regions 4000–550 cm^?1 and 3200–300 cm^?1, respectively. The optimized geometries and vibrational frequencies of DTAB, TTAB and CTAB have been carried out with ab initio Hartree-Fock (HF) and density functional theory method B3LYP calculations with the 6–31 G (d, p) basis set in the ground state. The comparison of the observed fundamental vibrational frequencies and calculated results for the fundamental vibrational frequencies of DTAB, TTAB and CTAB indicate that the scaled B3LYP method is superior compared to the scaled HF method.