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.     

Single‐crystal Raman spectroscopy of natural leiteite (ZnAs2O4) and comparison with the synthesised mineral

The oriented single‐crystal Raman spectrum of leiteite has been obtained and the spectra related to the structure of the mineral. The intensities of the observed bands vary according to orientation, allowing them to be assigned to either A_g or B_g modes. A_g bands are generally the most intense in the CAAC spectrum, followed by ACCA, CBBC, and ABBA whereas B_g bands are generally the most intense in the CBAC followed by ABCA. The CAAC and ACCA spectra are identical, as are those obtained in the CBBC and ABBA orientations. Both cross‐polarised spectra are identical. Band assignments were made with respect to bridging and non‐bridging As O bonds. Copyright © 2010 John Wiley & Sons, Ltd.     

Raman imaging and stress quantification in self‐assembled graphene oxide fiber ‘Latin Letters’

To probe the intrinsic stress distribution in terms of spatial Raman shift (ω) and change in the phonon linewidth (Γ), here we analyze self‐assembled graphene oxide fibers (GOF) ‘Latin letters’ by confocal Raman spectroscopy. The self‐assembly of GOF ‘Latin letters’ has been explained through surface tension, π–π stacking, van der Waals interaction at the air–water interface and by systematic time‐dependent investigation using field emission scanning electron microscopy analysis. Intrinsic residual stress due to structural joints and bending is playing a distinct role affecting the E_2g mode (G band) at and away from the physical interface of GOF segments with broadening of phonon linewidth, indicating prominent phonon softening. Linescan across an interface of the GOF ‘letters’ reveals Raman shift to lower wavenumber in all cases but more so in ‘Z’ fiber exhibiting a broader region. Furthermore, intrinsic stress homogeneity is observed for ‘G’ fiber distributed throughout its curvature with negligible shift corresponding to E_2g mode vibration. This article demonstrates the significance of morphology in stress distribution across the self‐assembled and ‘smart‐integrable’ GOF ‘Latin letters’. Copyright © 2016 John Wiley & Sons, Ltd.     

High‐pressure studies of the micro‐Raman spectra of iron cyanide complexes: Prussian blue (Fe4[Fe(CN)6]3), potassium ferricyanide (K3[Fe(CN)6]), and sodium nitroprusside (Na2[Fe(CN)5(NO)]·2H2O)

The pressure dependences of the peaks observed in the micro‐Raman spectra of Prussian blue (Fe₄[Fe(CN)₆]₃), potassium ferricyanide (K₃[Fe(CN)₆]), and sodium nitroprusside (Na₂[Fe(CN)₅(NO)]·2H₂O) have been measured up to 5.0 GPa. The vibrational modes of Prussian blue appearing at 201 and 365 cm⁻¹ show negative dν/dP values and Grüneisen parameters and are assigned to the transverse bending modes of the Fe C N Fe linkage which can contribute to a negative thermal expansion behavior. A phase transition occurring between 2.0 and 2.8 GPa in potassium ferricyanide is shown by changes in the spectral region 150–700 cm⁻¹. In the spectra of the nitroprusside ion, there are strong interactions between the FeN stretching mode and the FeNO bending and the axial CN stretching modes. The pressure dependence of the NO stretching vibration is positive, 5.6 cm⁻¹ GPa⁻¹, in contrast to the negative behavior in the iron(II)‐meso‐tetraphenyl porphyrinate complex. Copyright © 2011 John Wiley & Sons, Ltd.     

Raman and infrared spectroscopic study of the molybdate‐containing uranyl mineral calcurmolite

Raman and infrared spectra of calcurmolite were recorded and interpreted from the uranium and molybdenum polyhedra, water molecules and hydroxyls point of view. U O bond lengths in uranyl and Mo O bond lengths in MoO₆ octahedra were calculated and O H…O bond lengths were inferred from the spectra. The mineral calcurmolite is characterised by bands assigned to the vibrations of the UO₂ units. These units provide intense Raman bands at 930, 900 and 868 and 823 cm⁻¹. These bands are attributed to the anti‐symmetric and symmetric stretching modes of the UO₂ units, respectively. Raman bands at 794, 700, 644, 378 and 354 cm⁻¹ are attributed to vibrations of the MoO₄ units. The bands at 693 and 668 cm⁻¹ are assigned to the anti‐symmetric and symmetric A_g modes of the terminal MO₂ units. Similar bands are observed at 797 and 773 cm⁻¹ for koechlinite and 798 and 775 cm⁻¹ for lindgrenite. It is probable that some of the bands in the low wavenumber region are attributable to the bending modes of MO₂ units. Copyright © 2008 John Wiley & Sons, Ltd.     

Resonance Raman spectra and excited state structural dynamics of ethylene trithiocarbonate in the A‐ and B‐band absorptions

A‐ and B‐band resonance Raman spectra were acquired for ethylene trithiocarbonate in cyclohexane solution. The results indicate that the S₃ state structural dynamics is mostly along vibrational motions of the CS stretch υ₁₁, while the S₄ state one has motions mainly via the S C S symmetric stretch υ₁₈, CS stretch υ₁₁, and the H C H rock + S C S antisymmetric stretch υ14 reaction coordinates. The very different excited state structural dynamics were briefly discussed in terms of vibronic couplings using local symmetry point group. Copyright © 2009 John Wiley & Sons, Ltd.     

A vibrational spectroscopic investigation of rhodanine and its derivatives in the solid state

Raman and infrared spectra are reported for rhodanine, 3‐aminorhodanine and 3‐methylrhodanine in the solid state. Comparisons of the spectra of non‐deuterated/deuterated species facilitate discrimination of the bands associated with N H, NH₂, CH₂ and CH₃ vibrations. DFT calculations of structures and vibrational spectra of isolated gas‐phase molecules, at the B3‐LYP/cc‐pVTZ and B3‐PW91/cc‐pVTZ level, enable normal coordinate analyses in terms of potential energy distributions for each vibrational normal mode. The cis amide I mode of rhodanine is associated with bands at ∼1713 and 1779 cm⁻¹, whereas a Raman and IR band at ∼1457 cm⁻¹ is assigned to the amide II mode. The thioamide II and III modes of rhodanine, 3‐aminorhodanine and 3‐methylrhodanine are observed at 1176 and 1066/1078; 1158 and 1044; 1107 and 984 cm⁻¹ in the Raman and at 1187 and 1083; 1179 and 1074; 1116 and 983 cm⁻¹ in the IR spectra, respectively. Copyright © 2010 John Wiley & Sons, Ltd.     

Raman and surface‐enhanced Raman studies of α‐aminophosphinic inhibitors of metalloenzymes

Here, we report the nature of new di‐α‐amino (L¹–L³) and α‐amino‐α‐hydroxyphosphinic (L⁴–L⁶) acids, which are considered potential inhibitors of the aminopeptidase N, adsorbed on a colloidal silver surface by means of surface‐enhanced Raman scattering (SERS) spectroscopy. In order to reveal the adsorption mechanism of these species from their SERS spectra, Fourier‐transform Raman (FT‐RS) spectra of these nonadsorbed molecules were measured. By examining the enhancement, shift in wavenumbers, and changes in breadth of the SERS bands due to the adsorption process, we revealed that the tilted compounds interact with the colloidal silver substrate mainly through the benzene ring, amino group, and phosphinic moiety in the following way. The benzene ring of L² and L³ is ‘standing up’ on the colloidal silver surface, and the C N bond is almost vertical to it, while the tilt angle between the O PO bond and this surface is greater than 45°. On the other hand, for L¹, L⁴, and L⁵, the aromatic ring and C N bond are arranged more or less tilted, and the tilt angle between the O PO bond and the silver substrate is smaller than 45°. The elongation of the bond to the benzene ring, the L⁶ case, produces an almost horizontal orientation of the benzene ring and the O PO bond on the silver nanoparticles. For these ligands, the complement inhibition IC₅₀ tested in vitro using porcine kidney leucine aminopeptidase was correlated mainly with the behavior of the O PO and C CH N fragments on the silver surface. Copyright © 2009 John Wiley & Sons, Ltd.     

Hydrogen bonding in different pyrimidine–methanol clusters probed by polarized Raman spectroscopy and DFT calculations

We report on the hydrogen bonding between pyrimidine (Pd) and methanol (M) as H‐donor in this study. Hydrogen bonds between pyrimidine and methanol molecules as well as those between different methanol molecules significantly influence the spectral features at high dilution. The ring‐breathing mode ν₁ of the reference system Pd was chosen as a marker band to probe the degree of hydrogen bonding. Polarized Raman spectra in the region 970–1020 cm⁻¹ for binary mixtures of (pyrimidine + methanol) at 28 different mole fractions were recorded. A Raman line shape analysis of the isotropic Raman line profiles at all concentrations revealed three distinct spectral components at mole fractions of Pd below 0.75. The three components are attributed to three distinct groups of species: ‘free Pd’ (pd), ‘Pd with low methanol content’ (pd1) and ‘Pd with high‐methanol content’ (pd2). The two latter species differ considerably in the pattern and the strengths of the hydrogen bonds. The results of density functional theory calculations on structures and vibrational spectra of neat Pd and eight Pd/M complexes with varying methanol content support our interpretations of the experimental results. A nice spectra–structure correlation for the different cluster subgroups was obtained, similar to earlier results obtained for Pd and water. Apart from N···H and O···H hydrogen bonds between pyrimidine and methanol, O···H hydrogen bonds formed among the methanol molecules in the cluster at high methanol content also play a crucial role in the interpretation of the experimental results. Copyright © 2010 John Wiley & Sons, Ltd.     

First and second‐order Raman scattering of B6O

First and second‐order Raman spectra of B₆O and their dependence on the wavelength of the excitation line from IR (infrared) to deep UV (ultraviolet) has been studied. The first‐order Raman spectra contain 11 well‐resolved lines of the 12 expected modes 5 A_1g + 7 E_g (space group R‐3m, point group D_3d). The second‐order Raman spectra contains eight lines that are resolved only in the case of the 244‐nm excitation line. Copyright © 2009 John Wiley & Sons, Ltd.     

Vibrational studies of hexagonal bronze systems: phonon calculation and high pressure induced phase transformation

Hexagonal bronzes and valence‐balanced hexatungstates (VBHT) have attracted great attention for presenting rich polymorphism and displaying superconductor or ferroelectric properties. In the present work, structural and vibrational properties of RbBi_1/3W_8/3O₉ (RBW) crystal (VBHT type) were investigated by high‐pressure Raman scattering experiments. The results suggest the existence of a reversible pressure‐induced structural phase transition at about 4 GPa. This transformation is most likely related to rotations of octahedral units along the c‐axis with no abrupt changes of apical O W O bonds length. In order to get further understanding of RBW vibrational properties, we performed phonon calculations, by using classical lattice dynamics, in the related hexagonal structure of the K_0.26WO₆ system. These calculations revealed that most of vibrational properties of K_0.26WO₆ are governed by tubular ‘like’ vibrations of the hexagonal cavity, which resemble similar vibrations of tubular nanostructures. The pressure dependence of Raman modes is understood in terms of calculated phonon eigenvectors at ambient pressure. Copyright © 2009 John Wiley & Sons, Ltd.     

CARS spectral fitting with multiple resonant species using sparse libraries

The coherent anti‐Stokes Raman spectroscopy (CARS) technique is often used in the study of turbulent flames. Fast and accurate algorithms are needed for fitting CARS spectra for temperature and multiple chemical species. This paper describes the development of such an algorithm. The algorithm employs sparse libraries whose size grows more slowly with number of species than a regular library. It was demonstrated by fitting synthetic ‘experimental’ dual‐pump CARS spectra containing four resonant species (N₂, O₂, H₂ and CO₂), both with added noise and without it, and by fitting experimental spectra from a H₂ air flat flame produced by a Hencken burner. In the four‐species example, the library was nearly an order of magnitude smaller than the equivalent regular library (fitting times are correspondingly faster), and the fitting errors in the absence of added noise were negligible compared to the random errors associated with fitting noisy spectra. When fitting noisy spectra, weighted least squares fitting to signal intensity, as opposed to least squares fitting or least squares fitting to square root of intensity, minimized random and bias errors in fit parameters. Copyright © 2011 John Wiley & Sons, Ltd.     

Single‐crystal Raman spectroscopy of brandholzite Mg[Sb(OH)6]2•6H2O and bottinoite Ni[Sb(OH)6]2• 6H2O and the polycrystalline Raman spectrum of mopungite Na[Sb(OH)6]

The single‐crystal Raman spectra of minerals brandholzite and bottinoite, formula M[Sb(OH)₆]₂•6H₂O, where M is Mg⁺² and Ni⁺², respectively, and the non‐aligned Raman spectrum of mopungite, formula Na[Sb(OH)₆], are presented for the first time. The mixed metal minerals comprise alternating layers of [Sb(OH)₆]⁻¹ octahedra and mixed [M(H₂O)₆]⁺²/[Sb(OH)₆]⁻¹ octahedra. Mopungite comprises hydrogen‐bonded layers of [Sb(OH)₆]⁻¹ octahedra linked within the layer by Na⁺ ions. The spectra of the three minerals were dominated by the Sb O symmetric stretch of the [Sb(OH)₆]⁻¹ octahedron, which occurs at approximately 620 cm⁻¹. The Raman spectrum of mopungite showed many similarities to spectra of the di‐octahedral minerals, supporting the view that the Sb octahedra give rise to most of the Raman bands observed, particularly below 1200 cm⁻¹. Assignments have been proposed on the basis of the spectral comparison between the minerals, prior literature and density functional theory (DFT) calculations of the vibrational spectra of the free [Sb(OH)₆]⁻¹ and [M(H₂O)₆]⁺² octahedra by a model chemistry of B3LYP/6‐31G(d) and lanl2dz for the Sb atom. The single‐crystal spectra showed good mode separation, allowing most of the bands to be assigned to the symmetry species A or E. Copyright © 2010 John Wiley & Sons, Ltd.     

Influence of phonon confinement,surface stress,and zirconium doping on the Raman vibrational properties of anatase TiO2 nanoparticles

We present a comprehensive analysis of the Raman spectra of pure and zirconium‐doped anatase TiO₂ nanoparticles. To account for the wavenumber shifts of the E_g(ν₆) mode as a function of particle size (L) and dopant concentration (x), a modification of the standard phonon confinement model (PCM) is introduced, which takes into account the contribution of surface stress by means of the Laplace–Young equation. Together with X‐ray diffraction (XRD) and transmission electron microscopy data, our analysis shows that the surface stress contribution to the observed blue shift of the Raman wavenumber is of the same magnitude as the spatial phonon confinement effect. Annealing experiments show that Zr‐doped nanoparticles exhibit retarded grain growth and delayed anatase‐to‐rutile phase transition by up to 200 K compared to pure anatase TiO₂. XRD shows that Zr doping leads to a unit cell expansion of the anatase structure. Applying the modified PCM to the x‐dependent variations of the E_g(ν₆) Raman mode, the mode‐Grüneisen parameter is found to increase abruptly at x > 0.07 with a concomitant mode softening. This coincides with the x range over which the Zr cations are reported to be displaced from their position in the tetrahedral lattice, and where Zr precipitation occurs upon annealing. The results have implications for the interpretation of Raman spectra of ionic metal oxide nanoparticles and how these are modified upon cation doping. Copyright © 2011 John Wiley & Sons, Ltd.     

Adsorption of 4,4′‐thiobisbenzenethiol on silver surfaces: surface‐enhanced Raman scattering study

Adsorption of 4,4′‐thiobisbenzenethiol (4,4′‐TBBT) on a colloidal silver surface and a roughened silver electrode surface was investigated by means of surface‐enhanced Raman scattering (SERS) for the first time, which indicates that 4,4′‐TBBT is chemisorbed on the colloidal silver surface as dithiolates by losing two H‐atoms of the S H bond, while as monothiolates on the roughened silver electrode. The different orientations of the molecules on both silver surfaces indicate the different adsorption behaviors of 4,4′‐TBBT in the two systems. It is inferred from the SERS signal that the two aromatic rings in 4,4′‐TBBT molecule are parallel to the colloidal silver surface as seen from the disappearance of ν_{C H} band (3054 cm⁻¹), which is a vibrational mode to be used to determine the orientation of a molecule on metals according to the surface selection rule, while on the roughened silver electrode surface they are tilted to the surface as seen from the enhanced signal of ν_{C H}. The orientation of the C‐S bond is tilted with respect to the silver surface in both cases as inferred from the strong enhancement of the ν_{C S}. SERS spectra of 4,4′‐TBBT on the roughened silver electrode with different applied potentials reveal that the enhancement of 4,4′‐TBBT on the roughened silver electrode surface may be related to the chemical mechanism (CM). More importantly, the adsorption of 4,4′‐TBBT on the silver electrode is expected to be useful to covalently adsorb metal nanoparticles through the free S H bond to form two‐ or three‐ dimensional nanostructures. Copyright © 2007 John Wiley & Sons, Ltd.     

Solvent‐dependent structural dynamics of 2(1H)‐pyridinone in light absorbing S4(ππ*) state

The B‐band resonance Raman spectra of 2(1H)‐pyridinone (NHP) in water and acetonitrile were obtained, and their intensity patterns were found to be significantly different. To explore the underlying excited state tautomeric reaction mechanisms of NHP in water and acetonitrile, the vibrational analysis was carried out for NHP, 2(1D)‐pyridinone (NDP), NHP–(H₂O)_n (n = 1, 2) clusters, and NDP–(D₂O)_n (n = 1, 2) clusters on the basis of the FT‐Raman experiments, the B3LYP/6‐311++G(d,p) computations using PCM solvent model, and the normal mode analysis. Good agreements between experimental and theoretically predicted frequencies and intensities in different surrounding environments enabled reliable assignments of Raman bands in both the FT‐Raman and the resonance Raman spectra. The results indicated that most of the B‐band resonance Raman spectra in H₂O was assignable to the fundamental, overtones, and combination bands of about ten vibration modes of ring‐type NHP–(H₂O)₂ cluster, while most of the B‐band resonance Raman spectra in CH₃CN was assigned to the fundamental, overtones, and combination bands of about eight vibration modes of linear‐type NHP–CH₃CN. The solvent effect of the excited state enol‐keto tautomeric reaction mechanisms was explored on the basis of the significant difference in the short‐time structural dynamics of NHP in H₂O and CH₃CN. The inter‐molecular and intra‐molecular ESPT reaction mechanisms were proposed respectively to explain the Franck–Condon region structural dynamics of NHP in H₂O and CH₃CN.Copyright © 2015 John Wiley & Sons, Ltd.     

Polarized Raman scattering and lattice eigenmodes of antiferromagnetic NdFeO3

The first‐ and second‐order Raman‐active phonons in the orthorhombic Pbnm NdFeO₃ single crystals were studied by means of polarized Raman scattering and lattice dynamics computations (LDC). The zone‐center phonons of A_g symmetry were distinguished from the B_1g eigenmodes by performing polarized Raman scattering experiments using two parallel polarization configurations, X′(ZZ)X′ and Z(X′X′)Z. With the help of LDC, we were able to assign most of the observed Raman‐active modes, including phonons of B_2g and B_3g symmetry. The LDC results indicated that among the 16 force constants employed, the one corresponding to the stretching vibration between the central Fe cation and the axial oxygen atom in a FeO₆ octahedron unit had the largest value. This suggests that the B‐site Fe cation is more tightly bound to the axial O1 ion than the other two equatorial O2 ions. It was further shown that at higher wavenumbers, the displacement of oxygen atoms contributed dominantly to the zone‐center vibrations. Copyright © 2008 John Wiley & Sons, Ltd.     

Raman and infrared study of phyllosilicates containing heavy metals (Sb,Bi): bismutoferrite and chapmanite

The kaolinite‐like phyllosilicate minerals bismutoferrite BiFe³⁺₂Si₂O₈(OH) and chapmanite SbFe³⁺₂Si₂O₈(OH) have been studied by Raman spectroscopy and complemented with infrared spectra. Tentatively interpreted spectra were related to their molecular structure. The antisymmetric and symmetric stretching vibrations of the Si O Si bridges, δ SiOSi and δ OSiO bending vibrations, ν (Si O_terminal)⁻ stretching vibrations, ν OH stretching vibrations of hydroxyl ions, and δ OH bending vibrations were attributed to the observed bands. Infrared bands in the range 3289–3470 cm⁻¹ and Raman bands in the range 1590–1667 cm⁻¹ were assigned to adsorbed water. O H···O hydrogen‐bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Vibrational characterization of L‐valine phosphonate dipeptides: FT‐IR,FT‐RS,and SERS spectroscopy studies and DFT calculations

Four L ‐valine (L ‐Val) phosphonate dipeptides that are potent inhibitors of zinc metalloproteases, namely, L ‐Val‐C(Me)₂‐PO₃H₂ (V1), L ‐Val‐CH(iP)‐PO₃H₂ (V2), L ‐Val‐CH(iB)‐PO₃H₂ (V3), and L ‐Val‐C(Me)(iP)‐PO₃H₂ (V4), are studied by Fourier‐transform infrared (FT‐IR) spectroscopy, Fourier‐transform Raman spectroscopy (FT‐RS), and surface‐enhanced Raman scattering (SERS). The band assignment (wavenumbers and intensities) is made based on (B3LYP/6‐311 + + G**) calculations. Comparison of theoretical FT‐IR and FT‐RS spectra with those of SERS allows to obtain information on the orientation of these dipeptides as well as specific‐competitive interactions of their functionalities with the silver substrate. More specifically, V1 and V4 appear to interact with the silver substrate mainly via a  C_sgCH₃ moiety localized at the  N_amideC_sg(CH₃)P molecular fragment. In addition, the  POH and isopropyl units of V4 assist in the adsorption process of this molecule. In contrast, the  C_αNH₂ and  PO₃H⁻ groups of V2 and V3 interact with the silver nanoparticles, whereas their isopropyl and isobutyl fragments seem to be repelled by the silver substrate (except for the  CH₂  of V3), similar to the  C_β(CH₃)₂ fragment of L ‐Val for all L ‐Val phosphonate dipeptides investigated in this work. The adsorption mechanism of these molecules onto the colloidal silver surface is also affected by amide bond behavior. Copyright © 2010 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.