High pressure Raman study of the CO stretching mode in liquid <i>N</i>,<i>N</i>-dimethylacetamide

Thomas, H. D.; Jonáš, J.

doi:10.1063/1.455772

Cited by 39 publications

(20 citation statements)

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“…This suggests that the dipole interaction among NdMA is weakened and the transition dipole coupling disappears by dilution with cyclohexane. This observation is in good agreement with the result reported previously [15].…”

Section: Resultssupporting

confidence: 94%

“…On the other hand, the first moments of the aniso-and isotropic components are estimated to be 1648.3 and 1637.5 cm −1 , indicating δν = 10.8 cm −1 . These values are in good agreement with that those reported previously [15,22]. For NdMF, the δν value determined to be 14.7 cm −1 in the neat liquid [29,30], indicating that the noncoincidence effect observed in NdMA is smaller than that in NdMF.…”

Section: Resultssupporting

confidence: 92%

“…For NdMF-CCl 4 mixture, for example, it was reported that the asymmetry of the isotropic ν C=O profile moves from the higher to the lower wavenumber side by dilution [29,37]. It is generally expected that the IR and both Raman bands coincide at infinite dilution [15,22]. At χ = 0.048, the peak wavenumber and shape of the ν C=O envelope in the Raman spectrum are almost identical with those in the IR spectrum.…”

Section: Resultsmentioning

confidence: 88%

“…They revealed that the wavenumber difference (δν = ν aniso − ν iso ) decreases with decreasing the concentration of NdMA in C 6 H 6 , CHCl 3 , CH 3 CN, and CCl 4 , indicating that the interaction between solvent and NdMA is larger than that among NdMA molecules in a dilute solution (the mole fraction of NdMA is around 0.05). Thomas and Jones [15] investigated the effects of density on δν and examined theoretical models of the noncoincidence effect proposed by McHale [23,24] and Logan [25]. They clarified that the δν value marginally increases with increasing density of the neat liquid.…”

Section: Introductionmentioning

confidence: 99%

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Effects of dipole interaction and solvation on the C O stretching band of N,N-dimethylacetamide in nonpolar solutions: Infrared, isotropic and anisotropic Raman measurements

Katsumoto¹,

Tanaka²,

Ozaki³

et al. 2009

Vibrational Spectroscopy

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The concentration dependence of the C=O stretching (ν C=O) band of N,N'-dimethylacetamide (NdMA) in cyclohexane, n-hexane, and CCl 4 has been investigated by infrared (IR) and polarized Raman spectroscopy. For the neat liquid of NdMA, the noncoincidence of the aniso-and isotropic Raman wavenumbers is evident. In the 0.47 M cyclohexane solution of NdMA, the noncoincidence effect almost disappears and the ν C=O envelopes in both the Raman and IR spectra are asymmetric to the low-wavenumber side. When the concentration of NdMA decreases from 0.33 to 0.023 M, the peak of these bands slightly shift to a higher wavenumber and the band shape becomes symmetric. The shape of the ν C=O envelope does not show any significant change below 0.023 M. These results suggest that the asymmetric shape of the ν C=O band observed for the 0.33 M cyclohexane solution is associated with the intermolecular interaction among NdMA molecules, which vanishes at around 0.02 M. Spectral changes for the CCl 4 solution of NdMA show a similar tendency. However, the shape and peak wavenumber of the ν C=O band observed in a highly diluted CCl 4 solution (≤ 0.023 M) indicated that the solvation effect of CCl 4 is more complicated than those of cyclohexane and n-hexane. The analyses of the ν C=O band, which is sensitive to the intermolecular interactions between solutes and between solute and solvent for NdMA dissolved in nonpolar solvents, would serve to clarify the electronic property of the molecule in a solution.

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Section: Resultssupporting

confidence: 94%

Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of dipole interaction and solvation on the C O stretching band of N,N-dimethylacetamide in nonpolar solutions: Infrared, isotropic and anisotropic Raman measurements

Katsumoto¹,

Tanaka²,

Ozaki³

et al. 2009

Vibrational Spectroscopy

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“…While multiple peaks are occasionally observed with certain solutes and solvents, in the case of DMA the observed shoulder at ca. 1655 cm −1 may be attributed to either Fermi resonances 83 (previously observed with 19-nortestosterone, 1 where shoulders appear at the same frequency across different solvents) or the noncoincidence effect, 84–85 though we observe no appreciable concentration dependence between 1–100mM for the shoulder. We do not observe two separate peaks each with their own solvatochromic shifts and the simulations exhibit single populations based on the electric field distributions.…”

Section: Resultssupporting

confidence: 49%

Vibrational Stark Effects of Carbonyl Probes Applied to Reinterpret IR and Raman Data for Enzyme Inhibitors in Terms of Electric Fields at the Active Site

2016

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IR and Raman frequency shifts have been reported for numerous probes of enzyme transition states, leading to diverse interpretations. In the case of the model enzyme ketosteroid isomerase (KSI), we have argued that IR spectral shifts for a carbonyl probe at the active site can provide a connection between the active site electric field and the activation free energy (Fried et al. Science, 2014, 346, 1510–1514). Here we generalize this approach to a much broader set of carbonyl probes (e.g. oxoesters, thioesters, and amides), first establishing the sensitivity of each probe to an electric field using vibrational Stark spectroscopy, vibrational solvatochromism, and MD simulations, and then applying these results to re-interpret data already in the literature for enzymes such as 4-chlorobenzoyl-CoA dehalogenase and serine proteases. These results demonstrate that the vibrational Stark effect provides a general framework for estimating the electrostatic contribution to the catalytic rate and may provide a metric for the design or modification of enzymes. Opportunities and limitations of the approach are also described.

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Vibrational relaxation processes in isotropic molecular liquids. A critical comparison

Morresi

Mariani

Distefano

et al. 1995

J Raman Spectroscopy

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Dynamic processes in the liquid state can be examined from different points of view; the rapid development of highly sophisticated time-resolved experiments and very complex computer simulation techniques have certainly improved the accuracy of some labratory results, but they are often not followed by an adequate attempt at interpretation. In any case, the extent of the subject and the enormous spread of experimental data do not help systematic analysis.This review attempts to contribute to a critical examination of a particular aspect of the dynamics of the liquid phase. Through a study of vibrational relaxation in isotropic molecular liquids it is possible to gain information about the molecular environment and the main intermolecular forces operative in this state of matter. It is therefore possible to formulate hypotheses about the force potentials and to describe the dynamic regime of the liquid system under consideration.(1) diatomic and/or highly symmetric molecules (e.g. HCl, 0, , CH,);(2) derivatives of hydrocarbons, especially methane (e.g. CH,NO, , CHCl, , CH,CI,);(3) aromatic and cyclic aliphatic molecules (e.g. benzene and its derivatives, cyclohexane, pyridine); (4) hydrogen bonded (with OH and/or HCO groups).This paper concerns the comparison between vibrational motions that have similar normal coordinate descrip tions; for this reason, we shall limit our considerations to the second and third groups in the above list. Hydrogenbonded and highly symmetrical systems are excluded because they need specific considerations.The currently used basic nomenclature of this field will be illustrated, in addition to the physical meaning of the dynamic parameters usually obtained by steady-state (continuous Raman and infrared), time-resolved spectroscopy and computer simulation techniques; these different experimental data will be compared, when available. We shall also outline and discuss current theoretical models, and attempt to emphasize their potential and limitations.At present, we may single out four groups of molecules that have been investigated by these methods: VIBRATIONAL RELAXATION IN LIQUIDS: THE PROBLEMSince the early 1960s, the study of vibrational relaxation in condensed phases has been considered a way of investigating dynamic processes,' but only with the advent of lasers as spectroscopic sources have frequency-and time-resolved experiments been performed; lineshape and coherent picosecond excitation studies allowed accurate information to be obtained on the dynamics in the solid and liquid states. Since that time, many papers2-14 have proved useful in the development of theoretical models and experimental results; for a detailed analysis of the whole question, one may refer to the above publications and references therein. For the purpose of this paper, the basic definitions of the main physical entities and variables involved in the subject must be clarified, avoiding the conflicts and ambiguities often present in the literature. DEPHASING: DEFINITIONSDephasing is important as probe of the...

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High pressure Raman study of the CO stretching mode in liquid N,N-dimethylacetamide

Cited by 39 publications

References 47 publications

Effects of dipole interaction and solvation on the C O stretching band of N,N-dimethylacetamide in nonpolar solutions: Infrared, isotropic and anisotropic Raman measurements

Effects of dipole interaction and solvation on the C O stretching band of N,N-dimethylacetamide in nonpolar solutions: Infrared, isotropic and anisotropic Raman measurements

Vibrational Stark Effects of Carbonyl Probes Applied to Reinterpret IR and Raman Data for Enzyme Inhibitors in Terms of Electric Fields at the Active Site

Vibrational relaxation processes in isotropic molecular liquids. A critical comparison

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