Methylation Mediated Anharmonic Vibrational Signature of Nucleobases: A Case Study of Uracil and Thymine. Issue 16 (24th April 2018)

• Record Type: Journal Article
• Authors: Wang, Guixiu; Li, Fenghai; Zhao, Juan; Wu, Yifang; Wang, Jianping
• Is Part Of: ChemistrySelect. Volume 3:Issue 16(2018)
• Page Start: 4374
• Page End: 4381
• Publication Date: 2018-04-24
• Subjects: Anharmonicities -- FTIR -- thymine -- uracil -- vibrational coupling; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.201800080
• Languages: English
• ISSNs: 2365-6549

Abstract

Abstract: The vibrational spectra of uracil and thymine in the frequency range of 1600 − 1800 cm −1, which mainly contains the C=C and C=O stretching vibration modes, are found to be distinct due to a simple insertion of a methyl group. The nature of these vibrational modes in both molecules was examined through linear infrared spectroscopy and DFT calculations. Anharmonic calculation reveals a generally stronger couplings between pair‐wise C=O modes and also between C=O and C=C modes in uracil than in thymine, agreeing reasonably with previously reported two‐dimensional infrared experimental results. Vibrational transition density cube and vibrational potential energy distributions analyses suggest that methylation causes more localization of the carbonyl stretching modes in thymine, which is the main reason of the observed spectral differences between the two molecules. Abstract : Vibrational spectral profiles of uracil and thymine, differed by a methyl group, are found to be different from each other in the frequency range of 1600 − 1800 cm −1 . A detailed analysis on the structural and vibrational properties of these nucleobases was carried out and how the vibrational modes are coupled in this region is discussed. The effect of a simple methylation in the vicinity of C=O bond is found to cause relatively more localization of the carbonyl stretching modes in thymine than in uracil, leading to the observed IR spectral differences.