Two-dimensional infrared study of 3-azidopyridine as a potential spectroscopic reporter of protonation state

Journal Article · Thu Oct 07 00:00:00 EDT 2010 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3483688· OSTI ID:21559924

Nydegger, Michael W; Dutta, Samrat; Cheatum, Christopher M ^[1]

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1. Department of Chemistry, University of Iowa, Iowa City, Iowa 52242 (United States)

The lack of general spectroscopic probes that can be used in a range of systems to probe kinetics and dynamics is a major obstacle to the widespread application of two-dimensional infrared (2D IR) spectroscopy. We have studied 3-azidopyridine to characterize its potential as a probe of the protonation state of the pyridine ring. We find that the azido-stretching vibration is split by accidental Fermi resonance interactions with one or more overtones and combination states. Using 2D IR spectroscopy, we determine the state structure of the resulting eigenstates for complexes of 3-azidopyridine with formic acid and trifluoroacetic acid in which the pyridine ring is unprotonated and protonated, respectively. Based on the measurements, we develop a two-oscillator depurturbation model to determine the energies and couplings of the zeroth-order azido-stretching state and the perturbing dark state that couples to it. Based on these results, we conclude that the azido-stretching vibration is, in fact, sensitive to the protonation state of the pyridine shifting up in frequency by 8 cm{sup -1} in the complex with trifluoroacetic acid relative to the formic acid complex. These results suggest that, although 3-azidopyridine is not suitable as a spectroscopic probe, the approach of employing an organic azide as a remote probe of protonation state holds significant promise.

• OSTI ID: 21559924
• Journal Information: Journal of Chemical Physics, Vol. 133, Issue 13; Other Information: DOI: 10.1063/1.3483688; (c) 2010 American Institute of Physics; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
74 ATOMIC AND MOLECULAR PHYSICS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
AZIDES
COMPLEXES
EIGENSTATES
FERMI RESONANCE
FORMIC ACID
INFRARED SPECTRA
INTERACTIONS
KINETICS
OSCILLATORS
POTENTIALS
PROBES
PYRIDINE
TWO-DIMENSIONAL CALCULATIONS
AZINES
CARBOXYLIC ACIDS
ELECTRONIC EQUIPMENT
EQUIPMENT
HETEROCYCLIC COMPOUNDS
MONOCARBOXYLIC ACIDS
NITROGEN COMPOUNDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIDINES
RESONANCE
SPECTRA