Related Experiment Video
Updated: Jun 23, 2026

Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
pH-dependent UV resonance Raman spectra of cytosine and uracil
Brant E Billinghurst1, Sulayman A Oladepo, Glen R Loppnow
1Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
Abstract:
Cytosine is a nucleobase found in both DNA and RNA, while uracil is found only in RNA. Uracil has abstractable protons at N3 and N1. Cytosine has only one abstractable proton at N1 but can also accept a proton at N3. The pKa values of these protons are well-known, but the effect of the change in protonation on the rest of the molecule is not well understood and is very important in base stacking, base pairing, and protein-nucleic acid interactions. In this paper, UV resonance Raman (UVRR) spectroscopy is used to probe the structures of both cytosine and uracil at varying pH to determine the structural changes that take place. The results show that cytosine has increased electronic delocalization when moving to either basic or acidic environments, whereas uracil shows no significant change in acidic environment but increases its electronic delocalization in basic environment.
Related Concept Videos
IR and UV–Vis Spectroscopy of Carboxylic Acids
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency, 1710 cm−1. The C=O bond of the...
Spectroscopy of Carboxylic Acid Derivatives
In the...
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
IR and UV–Vis Spectroscopy of Aldehydes and Ketones
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
Raman Spectroscopy: Overview
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and the...

