Messenger Tagging Vibrational Spectroscopy of Protonated Nicotinamide
Maddie K Klumb1, Lane M Terry1, Deacon Nemchick2
1JILA and Department of Chemistry, University of Colorado, 440 UCB, Boulder, Colorado 80309-0440, United States.
The Journal of Physical Chemistry. A
|December 29, 2025
Summary
Protonated nicotinamide complexes with N2 show specific vibrational spectra. The N2 tag attaches to the charged site, causing a red-shift in NH+ stretching frequency.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Quantum Chemistry
Background:
- Nicotinamide is a vital biomolecule.
- Understanding protonation sites is crucial for its function.
- Cryogenic spectroscopy provides insights into molecular interactions.
Purpose of the Study:
- To investigate the vibrational photodissociation spectrum of protonated nicotinamide-N2 complexes.
- To determine the protonation site and N2 tagging effects.
- To analyze anharmonic effects in the NH stretching region.
Main Methods:
- Cryogenic preparation of molecular complexes.
- Vibrational photodissociation spectroscopy.
- Quantum chemical calculations.
- Vibrational perturbation theory.
Main Results:
- The vibrational spectrum was recorded in the NH stretching region (3250-3600 cm-1).
- Only the pyridine ring protonation site was significantly populated.
- Quantum chemical methods confirmed N2 tag attachment to the charged site.
- A significant red-shift in NH+ stretching frequency was observed due to the N2 tag.
Conclusions:
- Protonation predominantly occurs on the pyridine ring of nicotinamide.
- The N2 tag localizes at the protonation site.
- The N2 tag induces a measurable red-shift in the NH+ stretching frequency, providing a spectroscopic marker.
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