Density functional theory study and vibrational analysis of FT‐IR and FT‐Raman spectra of N‐hydroxyphthalimide

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 C_s 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.     

FT‐IR and FT‐Raman investigations of the chemosensing material para‐hexafluoroisopropanol aniline

As an important chemosensing material involving hexafluoroisopropanol (HFIP) for detecting nerve agents, para‐HFIP aniline (p‐HFIPA) has been firstly synthesized through a new reaction approach and then characterized by nuclear magnetic resonance and mass spectrometry experiments. Fourier transform infrared absorption spectroscopy (FT‐IR) and FT‐Raman spectra of p‐HFIPA have been obtained in the regions of 4000–500 and 4000–200 cm⁻¹, respectively. Detailed identifications of its fundamental vibrational bands have been given for the first time. Moreover, p‐HFIPA has been optimized and vibrational wavenumber analysis can be subsequently performed via density functional theory (DFT) approach in order to assist these identifications in the experimental FT‐IR and FT‐Raman spectra. The present experimental FT‐IR and FT‐Raman spectra of p‐HFIPA are in good agreement with theoretical FT‐IR and FT‐Raman spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Food additives characterization by infrared,Raman, and surface‐enhanced Raman spectroscopies

Fourier‐transform infrared (FT‐IR), Raman (RS), and surface‐enhanced Raman scattering (SERS) spectra of β‐hydroxy‐β‐methylobutanoic acid (HMB), L ‐carnitine, and N‐methylglycocyamine (creatine) have been measured. The SERS spectra have been taken from species adsorbed on a colloidal silver surface. The respective FT‐IR and RS band assignments (solid‐state samples) based on the literature data have been proposed. The strongest absorptions in the FT‐IR spectrum of creatine are observed at 1398, 1615, and 1699 cm⁻¹, which are due to ν_s(COOH) + ν(CN) + δ(CN), ρ_s(NH₂), and ν(C O) modes, respectively, whereas those of L ‐carnitine (at 1396/1586 cm⁻¹ and 1480 cm⁻¹) and HMB (at 1405/1555/1585 cm⁻¹ and 1437–1473 cm⁻¹) are associated with carboxyl and methyl/methylene group vibrations, respectively. On the other hand, the strongest bands in the RS spectrum of HMB observed at 748/1442/1462 cm⁻¹ and 1408 cm⁻¹ are due to methyl/methylene deformations and carboxyl group vibrations, respectively. The strongest Raman band of creatine at 831 cm⁻¹ (ρ_w(R NH₂)) is accompanied by two weaker bands at 1054 and 1397 cm⁻¹ due to ν(CN) + ν(R NH₂) and ν_s(COOH) + ν(CN) + δ(CN) modes, respectively. In the case of L ‐carnitine, its RS spectrum is dominated by bands at 772 and 1461 cm⁻¹ assigned to ρ_r(CH₂) and δ(CH₃), respectively. The analysis of the SERS spectra shows that HMB interacts with the silver surface mainly through the  COO⁻, hydroxyl, and  CH₂ groups, whereas L ‐carnitine binds to the surface via  COO⁻ and  N⁺(CH₃)₃ which is rarely enhanced at pH = 8.3. On the other hand, it seems that creatine binds weakly to the silver surface mainly by  NH₂, and C O from the  COO⁻ group. Copyright © 2006 John Wiley & Sons, Ltd.     

A joint FTIR,FT‐Raman and scaled quantum mechanical study of 1,3‐dibromo‐2,4,5,6‐tetra‐fluoro benzene (DTB) and 1,2,3,4,5‐pentafluoro benzene (PB)

The liquid phase FTIR and FT‐Raman spectra of 1,3‐dibromo‐2,4,5,6‐tetrafluoro benzene (DTB) and 1,2,3,4,5‐pentafluoro benzene (PB) were recorded in the regions 4000–400 cm⁻¹ and 4000–50 cm⁻¹, respectively. The spectra were interpreted with the aid of normal coordinate analysis following full structure opti1mization and force field calculations based on the density functional theory using the standard B3LYP/6‐31G* method and basis set combination. The scaled force field reproduced the experimental wavenumbers of the molecule for DTFB and PFB, respectively. The effects of halogen substituents on the structure and vibrational wavenumbers have been investigated. Assignments of fundamental modes were made based on the comparison between calculated and experimental results. Copyright © 2009 John Wiley & Sons, Ltd.     

Experimental and theoretical FT‐IR and FT‐Raman spectroscopic analysis of N1‐methyl‐2‐chloroaniline

In this work, the experimental and theoretical vibrational spectra of N1‐methyl‐2‐chloroaniline (C₇H₈NCl) were studied. FT‐IR and FT‐Raman spectra of the title molecule in the liquid phase were recorded in the region 4000–400 cm^?1 and 3500–50 cm^?1, respectively. The structural and spectroscopic data of the molecule in the ground state were calculated by using density functional method (B3LYP) with the 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 were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. ¹³C and ¹H NMR chemical shifts results were compared with the experimental values. The optimized geometric parameters (bond lengths and bond angles) were given and are in agreement with the corresponding experimental values of aniline and p‐methyl aniline. Copyright © 2008 John Wiley & Sons, Ltd.     

Molecular structure,spectroscopic (FTIR,FTIR gas phase,FT‐Raman) first‐order hyperpolarizability and HOMO–LUMO analysis of 4‐methoxy‐2‐methyl benzoic acid

Vibrational spectral analysis was carried out for 4‐methoxy‐2‐methyl benzoic acid (4M2MBA) by using Fourier transform infrared (FT‐IR) (solid, gas phase) and FT‐Raman spectroscopy in the range of 400–4000 and 10–3500 cm⁻¹ respectively. The effects of molecular association through O H···O hydrogen bonding have been described by the single dimer structure. The theoretical computational density functional theory (DFT) and Hatree‐Fock (HF) method were performed at 6–311++G(d,p) levels to derive the equilibrium geometry, vibrational wavenumbers, infrared intensities and Raman scattering activities. The scaled theoretical wavenumbers were also shown to be in good agreement with experimental data. The first‐order hyperpolarizability (β₀) of this novel molecular system and related properties (β, α₀ and Δα) of 4M2MBA are calculated using the B3LYP/cc‐pvdz basis set, based on the finite‐field approach. A detailed interpretation of the infrared and Raman spectra of 4M2MBA is reported. The theoretical spectrograms for FT‐IR and FT‐Raman spectra of the title molecule were also constructed and compared with the experimental one. Copyright © 2010 John Wiley & Sons, Ltd.     

Identification of epidermal L‐tryptophan and its oxidation products by in vivo FT‐Raman Spectroscopy further supports oxidative stress in patients with vitiligo

In the past, non‐invasive in vivo FT‐Raman spectroscopy has been used to detect H₂O₂‐mediated oxidation of methionine to methionine sulfoxide and methionine sulfone, as well as cysteine to cysteic acid, in the sequence of proteins in the epidermis of patients with vitiligo. L ‐tryptophan (Trp) is another potential target for this oxidation. Owing to the presence of 10⁻³M epidermal albumin which contains one Trp residue, it was tempting to follow the oxidation of this amino acid. Using in vivo and in vitro FT‐Raman spectroscopy, we show for the first time that epidermal Trp is oxidised in patients with vitiligo, yielding 5‐OH‐Trp at 930 cm⁻¹ and other oxidation products (i.e. N‐formyl kynurenine and kynurenine) from indole ring oxidation peaking at 1050 cm⁻¹. On the basis of detailed in vitro results, we could conclude that 5‐OH‐Trp as well as formyl kynurenine and kynurenine are formed via H₂O₂‐mediated Fenton chemistry. These results once again bring out the strength of non‐invasive in vivo FT‐Raman Spectroscopy in dermatology to follow the effect of oxidative stress in the skin of patients with vitiligo. Copyright © 2008 John Wiley & Sons, Ltd.     

Density functional and experimental studies on the FT‐IR and FT‐Raman spectra and structure of benzoic acid and 3,5‐dichloro salicylic acid

FT‐IR and FT‐Raman spectra of benzoic acid (BA) and 3,5‐dichloro salicylic acid (SA) have been recorded in the regions of 4000–400 and 4000–50 cm⁻¹ respectively. The spectra were interpreted with the aid of normal coordinate analysis following the full structure optimizations and force field calculations based on density functional theory (DFT) using standard B3LYP6‐31G** method and basis set combinations. The DFT force field transformed to natural internal coordinates was corrected by a well‐established set of scale factors that were found to be transferable to the title compounds. The infrared and Raman spectra were also predicted from the calculated intensities. Comparison of the simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes. Copyright © 2008 John Wiley & Sons, Ltd.     

Density functional theory calculations and vibrational spectra of p‐bromonitrobenzene

FT‐IR and FT‐Raman spectra of p‐bromonitrobenzene (p‐BNB) have been recorded in the region 4000–400 cm⁻¹ and 4000–50 cm⁻¹, respectively. The molecular structure, geometry optimization, vibrational wavenumbers have been investigated. The spectra were interpreted with the aid of normal coordinate analysis based on the density functional theory (DFT) using the standard B3LYP/6‐31G method and basis set combination and was scaled using multiple scale factors yielding good agreement between observed and calculated wavenumbers. The results of the calculations are applied to simulate infrared and Raman spectra of the title compound which showed reasonable agreement with the observed spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Density functional theory calculation and vibrational spectral analysis of 4‐hydroxy‐3‐(3‐oxo‐1‐phenylbutyl)‐2H‐1‐benzopyran‐2‐one

The Fourier transform infrared (4000–400 cm⁻¹) and Fourier transform Raman (3500–500 cm⁻¹) spectra of 4‐hydroxy‐3‐(3‐oxo‐1‐phenylbutyl)‐2H‐1‐benzopyran‐2‐one (Warfarin) have been measured and calculated. The structure optimization has been made using density functional theory (DFT) calculations. Complete vibrational assignments of the observed spectra have been compared with theoretical wavenumbers. The wavenumber increasing in the methyl group shows the electronic hyperconjugation effect. The natural bond orbital (NBO) analysis reveals the hyperconjugation interaction and the intramolecular hydrogen bonding. The first‐order hyperpolarizability has been calculated. Copyright © 2009 John Wiley & Sons, Ltd.     

FT‐Raman and FT‐IR spectral and quantum chemical studies on some flavonoid derivatives: Baicalein and Naringenin

In this study, the experimental and theoretical results on the molecular structures of some flavonoid derivatives (Baicalein and Naringenin) are presented. The FT‐IR and FT‐Raman spectra of the compounds have been recorded together for the first time between 4000–400 cm⁻¹ and 3500–5 cm⁻¹ regions, respectively. The molecular geometry and vibrational wavenumbers of the compounds have been also calculated in their ground states by using ab initio HF and DFT/B3LYP functional with 6‐31G(d,p) basis set used in calculations. The calculations were utilized to the C₁ symmetries of the molecules. All calculations were performed with Gaussian 98 software. The obtained vibrational wavenumbers and optimized geometric parameters were seen to be in good agreement with the experimental data. Scale factors have been used in order to compare how the calculated and experimental data are in agreement. Theoretical infrared intensities were also reported. Copyright © 2008 John Wiley & Sons, Ltd.     

FTIR and FT‐Raman spectra and density functional computations of the vibrational spectra,molecular geometry and atomic charges of the biomolecule: 5‐bromouracil

FTIR and FT‐Raman spectra of 5‐bromouracil in the powder form were recorded in the region 400–4000 cm⁻¹ and 50–4000 cm⁻¹, respectively. The observed wavenumbers were analysed and assigned to different normal modes of vibration of the molecule. Quantum chemical calculations were performed to support the assignments of the observed wavenumbers. The performance of the B3LYP hybrid density functional (DFT) method was compared with other methods. With the 6–31 G** and 6–311 + G(2d,p) basis sets, the calculated geometry, dipole moments and harmonic vibrations were determined. A comparison with the uracil molecule was made, and specific scale factors were deduced and employed in the predicted wavenumbers of 5‐bromouracil. The total atomic charges and thermodynamic parameters were calculated, and are discussed briefly. Structure and harmonic vibrations of 5‐bromouracil were also calculated in the presence of water within a simple model with one molecule. It is observed that the bromine atom at position 5 exhibits smaller inductive effects than the fluorine atom, producing a small distortion of the electrostatic potential around the ring and a reduction of the molecular dipole moment. Copyright © 2007 John Wiley & Sons, Ltd.     

FT‐Raman and FTIR spectroscopic characterization of biogenic carbonates from Philippine venus seashell and Porites sp. coral

Some seashells of the Philippine venus species and sea coral of Porites sp. were studied by means of FT‐Raman, Fourier transform infrared spectroscopy (FTIR) and Far‐FTIR spectroscopic methods. The Raman spectra show that both Porites sp. and P. venus are of aragonite‐structured CaCO₃. Detailed spectral analysis, however, reveals some small differences, due to differences in the crystallite size or habit and to different minor element contents. IR spectra show that Porites sp. contains also some small quantities of calcite‐structured carbonates. The ν₂ band (shoulder) of calcite at 875.7 cm⁻¹ is present in the IR spectrum. The separation of the two ν₂ bands (856.4 cm⁻¹ for aragonite and 875.7 cm⁻¹ for calcite) suggests the absence of solid solution of the two polymorphic phases of CaCO₃. Spectroscopic results were confirmed also by X‐ray powder diffraction measurements. Copyright © 2008 John Wiley & Sons, Ltd.     

FT‐Raman,FT‐IR spectral and DFT studies on 6, 8‐dichloroflavone and 6, 8‐dibromoflavone

In this study, experimental and theoretical vibrational spectral results of the molecular structures of 6,8‐dichloroflavone (6,8‐dcf) and 6,8‐dibromoflavone (6,8‐dbf) are presented. The FT‐IR and FT‐Raman spectra of the compounds have been recorded together between 4000 and 400 cm⁻¹ and 3500–5 cm⁻¹ regions, respectively. The molecular geometry and vibrational wavenumbers of 6,8‐dcf and 6,8‐dbf in their ground state have been calculated by using DFT/B3LYP functional, with 6‐31 + + G(d,p) basis set used in calculations. All calculations were performed with Gaussian03 software. The obtained vibrational wavenumbers and optimized geometric parameters were seen to be in good agreement with the experimental data. Scale factors have been used in order to compare how the calculated and experimental data are in agreement. Theoretical infrared intensities are also reported. Copyright © 2009 John Wiley & Sons, Ltd.     

Molecular structure,vibrational spectroscopic,first‐order hyperpolarizability and HOMO,LUMO studies of 3‐hydroxy‐2‐naphthoic acid hydrazide

The Fourier‐transform infrared spectrum of 3‐hydroxy‐2‐naphthoic acid hydrazide (3H2NAH) was recorded in the region 4000–400 cm⁻¹. The Fourier‐transform Raman spectrum of 3H2NAH was also recorded in the region 3500–10 cm⁻¹. Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of 3H2NAH were carried out by density functional theory (DFT/B3LYP) method with 6‐31G(d,p) as basis set. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The values of the electric dipole moment (µ) and the first‐order hyperpolarizability (β) of the investigated molecule were computed using ab initio quantum mechanical calculations. The UV spectrum was measured in ethanol solution. The calculation results also show that the 3H2NAH molecule might have microscopic nonlinear optical (NLO) behavior with non‐zero values. A detailed interpretation of the infrared and Raman spectra of 3H2NAH is also reported based on total energy distribution (TED). The calculated HOMO and LUMO energies shows that charge transfer occur within the molecule. The theoretical FT‐IR and FT‐Raman spectra for the title molecule have also been constructed. Copyright © 2009 John Wiley & Sons, Ltd.     

Fourier‐transform infrared and Raman spectra,vibrational assignment and density functional theory calculations of 1,4,5‐triazanaphthalene

The Fourier‐transform infrared (FT‐IR) (4000–50 cm⁻¹) and Raman spectra (3500–100 cm⁻¹) of 1,4,5‐triazanaphthalene in polycrystalline state were measured. Comparison between the spectra by two techniques, a series of density functional theory (DFT) calculations and the spectral behaviour upon deuteration were used for the assignment of the vibrational spectra of the title compound. The calculated vibrational wavenumbers by the B3LYP density functionals are generally consistent with the observed spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Density functional theory calculations and vibrational spectra of 3,5 dichloro hydroxy benzaldehyde and 2,4 dichloro benzaldehyde

The solid‐phase Fourier transform infrared (FT‐IR) and FT‐Raman spectra of 3,5 dichloro hydroxy benzaldehyde (DHB) and 2,4 dichloro benzaldehyde (DB) have been recorded in the regions 4000–400 and 4000–0 cm⁻¹, respectively. Theoretical information on the optimized geometry, harmonic vibrational wavenumbers as well as infrared and Raman intensities were obtained by means of density functional theory (DFT) using standard B3LYP/6–31G** level. This information was used in the assignment of the various fundamentals. Comparison of the simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes. Copyright © 2008 John Wiley & Sons, Ltd.     

Vibrational spectroscopy investigation using ab initio and density functional theory on flucytosine

The FT Raman and FTIR spectra of flucytosine were recorded in the region 3500–100 cm⁻¹ and 4000–400 cm⁻¹, respectively. The optimized geometry, wavenumber and intensity of the vibrational bands of flucytosine were obtained by ab initio and density functional theory (DFT) levels with complete relaxation in the potential energy surface using the 6‐31G(d,p) and 6‐311G(d,p) basis sets. A complete vibrational assignment aided by the theoretical harmonic frequency analysis is proposed. The harmonic vibrational wavenumbers calculated are compared with experimental FTIR and FT Raman spectra. The observed and the calculated wavenumbers are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar‐type spectrograms. Copyright © 2007 John Wiley & Sons, Ltd.     

Density functional theory calculations and vibrational spectra of 2‐bromo‐4‐chloro phenol and 2‐chloro‐4‐nitro phenol

FTIR and FT Raman spectra of 2‐bromo‐4‐chloro phenol (BCP) and 2‐chloro‐4‐nitro phenol (CNP) were recorded in the region 4000–400 and 4000–50 cm⁻¹, respectively. The molecular structure, geometry optimization, and vibrational wavenumbers were investigated. The spectra were interpreted with the aid of normal coordinate analysis based on density functional theory (DFT) using the standard B3LYP/6‐31G** method and basis set combination and was scaled using multiple scale factors, which yield good agreement between the observed and calculated wavenumbers. The results of the calculations are applied to simulate the infrared and Raman spectra of the title compounds, which showed excellent agreement with the observed spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Minerals from Macedonia. XXII. Laser‐induced fluorescence bands in the FT‐Raman spectrum of almandine mineral

Two strong bands centered at 446 and 607 cm⁻¹ have been observed in the FT‐Raman spectrum of almandine [Fe₃Al₂(SiO₄)₃] excited with 1064 nm, which were completely absent in the corresponding dispersive Raman spectra obtained using 488, 514.5 and 532 nm excitation. Furthermore, the mentioned strong bands have not been registered in the anti‐Stokes side of the FT‐Raman spectrum, and were therefore assigned to laser‐induced fluorescence bands. Their appearance is related to the presence of rare‐earth element traces as impurities in the almandine sample. Additionally, the FT‐Raman (and dispersive Raman) spectrum of the isomorphous spessartine [Mn₃Al₂(SiO₄)₃] mineral has been introduced, which did not show the presence of these fluorescence emission bands. The purity of the minerals was confirmed by study of their powder X‐ray diffraction (PXRD) patterns. Copyright © 2008 John Wiley & Sons, Ltd.