Asian Journal of Physics Vol. 34, Nos 1 & 2 (2025) 23-46

A comparison between 5-fluorouracil and 5-fluorocytosine: Structure, tautomerism, vibrational spectra, and WC pairs

M Alcolea Palafox1, I Pavel2, J K Vats3, Kaushal Rani4, V S Jayakumar4, M K Gandhi4 and V K Rastogi4
1Departamento de Química-Física, Facultad de Ciencias Químicas, Universidad Complutense, Madrid-28040, Spain.
2Department of Physical and Environmental Sciences, Texas A&M University Corpus Christi,6300 Ocean Dr., Corpus Christi, TX 78412, U.S.A
3Department of Physics, Ram Jaipal College (A Constituent Unit of Jai Prakash University), Chapra-841 301, Bihar, India
4 Indian Spectroscopy Society, KC-68/1, Old Kavinagar, Ghaziabad-201 002, India

Two important compounds, 5-fluorouracil (5-FU) and 5-fluorocytosine (5-FC) are widely used today for cancer treatment. In this study, the two biomolecules were compared with respect to their molecular structure, tautomerism, relative stability, NBO atomic charge, dipole moment, solid state arrangement, and spectroscopic properties. The ketonic form is the most stable tautomeric form of 5-FU but it does not occur in 5-FC. The experimental FT-IR and Raman spectra of 5-FU in solid state were compared to the theoretical scaled ones in the 400-4000 cm–1 range. The observed spectral signatures were assigned to different normal modes of vibration through a detailed comparison with the theoretical ones determined by different DFT methods. The theoretical values were improved with scaling and dimer simulations. The WC stability of both molecules was also analyzed. © Anita Publications. All rights reserved.
Doi: 10.54955/AJP.34.1-2.2025.23-46
Keywords: Halogenated pyrimidines, 5-fluorouracil, 5-fluorocytosine, FT-IR spectra, FT-Raman spectra, WC pairs.

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A comparison between 5-fluorouracil and 5-fluorocytosine-Structure,tautomerism, vibrational spectra, and WC pairsDownload

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