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Vibrational spectro...
Vibrational spectroscopic and theoretical studies of urea derivatives with biochemical interest: N,N’-dimethylurea, N,N,N’,N’-tetramethylurea and N,N’-dimethylpropyleneurea
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- Sandström, Magnus, 1945- (author)
- Stockholms universitet,Institutionen för material- och miljökemi (MMK)
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- Mink, János, 1938- (author)
- Stockholms universitet,Institutionen för material- och miljökemi (MMK)
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- Papai, Imre (author)
- Chemical Research Center of the Hungarian Academy of Sciences, P.O. Box 77, H-1525, Budapest, Hungary
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- Skripkin, Mikhail, 1965- (author)
- Department of Chemistry, St. Petersburg State University, Universitetski pr., 26, 198504 St. Petersburg, Russia
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- Hajba, László (author)
- Stockholms universitet,Institutionen för material- och miljökemi (MMK)
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- Mihály, Judith (author)
- Chemical Research Center of the Hungarian Academy of Sciences, Budapest
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- Neméth, Csaba (author)
- Chemical Research Center of the Hungarian Academy of Sciences, Budapest
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(creator_code:org_t)
- Taylor and Francis, 2010
- 2010
- English.
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In: Applied spectroscopy reviews (Softcover ed.). - : Taylor and Francis. - 0570-4928 .- 1520-569X. ; 45, s. 274-326
- Related links:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Subject headings
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- Mid-infrared, far-infrared and Raman vibrational spectroscopic studies were combined with DFT calculations and normal coordinate force field analyses for N,N’-dimethylurea (DMU), N,N,N’,N’-tetramethylurea (TMU) and N,N'-dimethylpropyleneurea (DMPU, IUPAC name 1,3-dimethyltetrahydropyrimidin-2(1H)-one). The equilibrium molecular geometry of DMU (all three conformers), TMU and DMPU, and the frequencies, intensities and depolarization ratios of their fundamental IR and Raman vibrational transitions were obtained by DFT calculations. The vibrational spectra were fully analysed by normal coordinate methods as well. A starting force field for DMPU was obtained by adapting corresponding force constants for DMU and TMU, resulting after refinements in the stretching force constants: C=O (7.69, 7.30, 7.68 N×cm -1), C-N (5.16, 5.55, 5.05 N×cm -1) and C-Me (5.93, 4.00, 4.22 N×cm-1) for DMU, TMU and DMPU, respectively. The dominating conformer of liquid DMU was identified as trans-trans, strong intermolecular hydrogen bonding was verified in solid DMU, and weak dipole-dipole association was found in liquid TMU and in DMPU. Special attention was paid to analysing the methyl group frequencies, which revealed deviations from local C3v symmetry. A linear correlation was found between the CH stretching force constants and the inverse of the CH bond lengths (1/r2). The averaged NH stretching frequencies of gaseous, dissolved and solid urea and of DMU, with variations for hydrogen bonding of different strength, are linearly correlated to the NH stretching force constants. Characteristic skeletal vibrations were assigned for a broad variety of urea derivatives and also for pyrimidine derivatives, which all contain the N2C=O entity. The very strong IR bands of C=O stretching (1676 ± 40 cm-1) and asymmetric CN2 stretching (1478 ± 60 cm-1), and the very intense Raman feature of symmetric CN2 stretching or ring breathing (757 ± 80 cm-1), can be recognized as fingerprint bands also for the pyrimidine derivatives cytosine, thymine and uracil, which all are nucleobases in DNA and RNA nucleotides.
Subject headings
- NATURVETENSKAP -- Kemi -- Analytisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Analytical Chemistry (hsv//eng)
Keyword
- Vibrational spectra
- theoretical calculations
- equilibrium geometry
- urea
- N
- N’-dimethylurea
- N
- N
- N’
- N’-tetramethylurea
- N
- N’-dimethylpropyleneurea
- hydrogen bonding
- Spectroscopy
- Spektroskopi
- Structural Chemistry
- strukturkemi
Publication and Content Type
- ref (subject category)
- art (subject category)
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