Theoretical study of the force field and vibrational assignments of acetamide and deuterated analogues

Hase, Yoshiyuki

doi:10.1016/0584-8539(95)01496-9

Cited by 20 publications

(18 citation statements)

References 16 publications

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“…The region above 2200 cm - 1 (2700−3100 cm -1 for the protonated and 2200−3100 cm -1 for the deuterated form) is characteristic for different types of CH and NH (ND) stretching vibrations. The observed spectral changes in this envelope show a good correspondence to those reported in the literature for different amides. − , …”

Section: Resultssupporting

confidence: 88%

“…It is clearly seen that the considered band also displays a multicomponent structure. In accordance with results of ab initio calculations, the low-frequency part is mostly due to CO stretch, while the high-frequency component includes essential contributions from the CN stretching vibration. , The sharp peak in the center of the band was tentatively ascribed as an evidence of the hydrogen bonding 10 Raman spectra of the different systems indicated in the frequency region of amide I. …”

Section: Resultssupporting

confidence: 84%

“…Figure compares Raman spectra of dry PAAA in hydrated and deuterated forms, and it is immediately seen that spectra are quite different, although the only difference between two compounds is the NH → ND substitution. Below we will analyze the whole spectral interval on the basis of known (reported) theoretical and experimental data on different amine/amide systems. −

2 Raman spectra of solid PAAA in protonated (solid line) and deuterated (dashed line) forms. …”

Section: Resultsmentioning

confidence: 99%

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Raman Spectroscopic Characterization of Association and Thermoreversible Gelation in Aqueous Systems of Poly(N-acetamidoacrylamide)

et al. 1999

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Polymer self-association and thermoreversible gelation in aqueous solutions of poly(N-acetamidoacrylamide) (PAAA) have been investigated by Raman spectroscopy. We found that aqueous solutions of PAAA, even at low concentrations, revealed the presence of polymer−polymer coordination, suggesting formation of polymer clusters. The effect of denaturant (sodium thiocyanate) on the inter- and intramolecular interactions in the system has been also studied. It is shown that the SCN ions destroy the macroscopic hydrogen-bond network of water, as well as reduce the polymer's ability for self-association by occupying the NH groups. The changes observed in the Raman spectra upon the gel transition show that in the gel state the equilibrium of the system is shifted toward polymer−polymer coordination, whereas in the solution it is mostly polymer−water coordination. The influence of the different factors such as polymer concentration, level of denaturant addition, and type of solvent on the gel formation is discussed.

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Section: Resultssupporting

confidence: 88%

Section: Resultssupporting

confidence: 84%

2 Raman spectra of solid PAAA in protonated (solid line) and deuterated (dashed line) forms. …”

Section: Resultsmentioning

confidence: 99%

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Raman Spectroscopic Characterization of Association and Thermoreversible Gelation in Aqueous Systems of Poly(N-acetamidoacrylamide)

et al. 1999

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“…Calculation using HF/4-31G* provides values for the acetamide fundamental vibrations, which are in agreement with the experimental values yielded by the matrix-isolation technique [6,7]. Despite the much higher flexibility of the atenolol molecule, in the present work, a more robust basis set was used at a reasonable computational cost.…”

Section: Calculated Infrared Spectrasupporting

confidence: 77%

Infrared spectroscopy of racemic and enantiomeric forms of atenolol

Castro

Canotilho

Barbosa

et al. 2007

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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The molecular structure of conformational isomorphs given by X-ray diffraction for racemic and enantiomeric atenolol were optimized at the HF/6-31G* level of theory and the infrared spectra of the structure were calculated. These spectra are used to characterize the differences between the various atenolol conformers.The spectra of the (R,S)-and S-atenolol solid forms were recorded and the bands corresponding to the functional groups identified with the aid of the calculated spectra, fitting analysis, temperature effect and H/D isotopic exchange. Particular attention was paid to the stretch vibration modes of the functional groups present in the atenolol.

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“…As mentioned above, these species are, with all probability, ethanolamine and acetamide, respectively. However, identification in the spectra of the irradiated matrices of bands originated in these compounds could not be made unequivocally because of the low intensity of their infrared spectra [24,25] and extensive overlap with bands due to the serine (for example, in the high-frequency nOH stretching region, the most stable conformer of ethanolamine isolated in an argon matrix absorbs at 3555 cm K1 [24], which coincides exactly with the frequency of the most intense group of bands of serine observed in this spectral region). In addition, for ethanolamine, there is also the possibility of photoproduction of different conformers, which leads also to reduce the intensities of bands due to individual conformers, while the total amount of photoproduced acetamide is certainly very low, since this species is produced in the substantially less important reaction channel.…”

Section: Resultsmentioning

confidence: 99%

Entropy effects in conformational distribution and conformationally dependent UV-induced photolysis of serine monomer isolated in solid argon

Jarmelo

Fausto

2006

Journal of Molecular Structure

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Monomeric serine can be trapped in low temperature argon matrices in different conformers, which can be classified in three groups (A, B, C) accordingly to the main intramolecular interaction they exhibit: A (OH A /N hydrogen bond), B (OH C /N) and C (OH A /Oa) (subscripts A and C stand for alcohol and carboxylic group, respectively). The OH C /N intramolecular interaction found in B-type conformers is considerably stronger than both the OH A /N and OH A /Oa hydrogen bonds, and leads to reduce the abundance of B-type form relatively to A and C forms at high temperatures due to entropy effects. When submitted to UV irradiation (lO200 nm), the main observed photoprocess is decarboxylation, leading to production of CO 2 and ethanolamine. A less important photochemical process is also observed, where the compound undergoes decarbonylation, with formation of CO, H 2 O and acetamide. The two observed photoprocesses were found to be dependent on the conformation assumed by the reactant molecule, with Aand C-type conformers of serine undergoing decarboxylation and B-type conformers decarbonylation.

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Theoretical study of the force field and vibrational assignments of acetamide and deuterated analogues

Cited by 20 publications

References 16 publications

Raman Spectroscopic Characterization of Association and Thermoreversible Gelation in Aqueous Systems of Poly(N-acetamidoacrylamide)

Raman Spectroscopic Characterization of Association and Thermoreversible Gelation in Aqueous Systems of Poly(N-acetamidoacrylamide)

Infrared spectroscopy of racemic and enantiomeric forms of atenolol

Entropy effects in conformational distribution and conformationally dependent UV-induced photolysis of serine monomer isolated in solid argon

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