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Updated: May 7, 2026

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
Published on: October 18, 2019
Proton-bound dimers of 1-methylcytosine and its derivatives: vibrational and NMR spectroscopy
Hou U Ung1, Aaron R Moehlig, Ryan A Kudla
1Department of Chemistry, University of California, Riverside, CA 92521-0403, USA. morton@citrus.ucr.edu.
Abstract:
Vibrational spectroscopy and NMR demonstrate that the proton-bound dimer of 1-methylcytosine, 1, has an unsymmetrical structure at room temperature. In the gas phase, investigation of isolated homodimer 1 reveals five fundamental NH vibrations by IR Multiple Photon Dissociation (IRMPD) action spectroscopy. The NH···N stretching vibration between the two ring nitrogens exhibits a frequency of 1570 cm(-1), as confirmed by examination of the proton-bound homodimers of 5-fluoro-1-methycytosine, 2, and of 1,5-dimethylcytosine, 3, which display absorptions in the same region that disappear upon deuterium substitution. (13)C, and (15)N NMR of the solid iodide salt of 1 confirm the nonequivalence of the two rings in the anhydrous proton-bound homodimer at room temperature. IRMPD spectra of the three possible heterodimers also show NH···N stretches in the same domain, and at least one of the heterodimers, the proton-bound dimer of 1,5-dimethylcytosine with 1-methylcytosine, exhibits two bands suggestive of the presence of two tautomers close in energy.
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