TY - JOUR
T1 - Infrared multiple photon dissociation action spectroscopy of sodium cationized halouracils
T2 - Effects of sodium cationization and halogenation on gas-phase conformation
AU - Kaczan, C. M.
AU - Rathur, A. I.
AU - Wu, R. R.
AU - Chen, Y.
AU - Austin, C. A.
AU - Berden, G.
AU - Oomens, J.
AU - Rodgers, M. T.
N1 - Funding Information:
Financial support for this work was provided by the National Science Foundation , Grants OISE-0730072 and CHE-1409420 . C.M.K. also thanks the Wayne State University Honors Program for partial financial support via her Undergraduate Research and Creative Projects Award. We would also like to thank WSU C&IT for computer time and support. This work is part of the research program of FOM, which is financially supported by the Nederlandse Organisatie voor Wetenschapplelijk Onderzoek (NOW). The skillful assistance of the FELIX staff is gratefully acknowledged.
Publisher Copyright:
© 2014 Elsevier B.V. All rights reserved.
PY - 2015/2/15
Y1 - 2015/2/15
N2 - Abstract The gas-phase structures of sodium cationized complexes of 5- and 6-halo-substituted uracils are examined via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical electronic structure calculations. The halouracils examined in this investigation include: 5-flourouracil, 5-chlorouracil, 5-bromouracil, 5-iodouracil, and 6-chlorouracil. Experimental IRMPD action spectra of the sodium cationized halouracil complexes are measured using a 4.7 T Fourier transform ion cyclotron resonance mass spectrometer coupled to the FELIX free electron laser (FEL). Irradiation of the mass selected sodium cationized halouracil complexes by the FEL was carried out over the range of frequencies extending from 950 to 1900 cm-1. Theoretical linear IR spectra predicted for the stable low-energy conformations of the sodium cationized halouracils, calculated at B3LYP/6-31G(d) level of theory, are compared with the measured IRMPD action spectra to identify the structures accessed in the experiments. Relative stabilities of the low-energy conformations are determined from single-point energy calculations performed at the B3LYP/6-311+G(2d,2p) level of theory. The evolution of IRMPD spectral features as a function of the size (F, Cl, Br, and I) and position (5 versus 6) of the halogen substituent are examined to elucidate the effects of the halogen substituent and noncovalent interactions with sodium cations on the structure of the nucleobase. Present results are compared with results from energy-resolved collision-induced dissociation and IRMPD action spectroscopy studies previously reported for the protonated and sodium cationized forms of uracil, and halo-, methyl-, and thioketo-substituted uracils. The present results suggest that only a single conformer is accessed for all of the 5-halouracil complexes, whereas multiple conformers are accessed for the Na+(6ClU) complex. In all cases, the experimental IRMPD action spectra confirm that the sodium cation binds to the O4 carbonyl oxygen atom of the canonical diketo tautomer in the ground-state conformers, and gains additional stabilization via chelation interactions with the halogen substituent in the complexes to the 5-halouracils as predicted by theory.
AB - Abstract The gas-phase structures of sodium cationized complexes of 5- and 6-halo-substituted uracils are examined via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical electronic structure calculations. The halouracils examined in this investigation include: 5-flourouracil, 5-chlorouracil, 5-bromouracil, 5-iodouracil, and 6-chlorouracil. Experimental IRMPD action spectra of the sodium cationized halouracil complexes are measured using a 4.7 T Fourier transform ion cyclotron resonance mass spectrometer coupled to the FELIX free electron laser (FEL). Irradiation of the mass selected sodium cationized halouracil complexes by the FEL was carried out over the range of frequencies extending from 950 to 1900 cm-1. Theoretical linear IR spectra predicted for the stable low-energy conformations of the sodium cationized halouracils, calculated at B3LYP/6-31G(d) level of theory, are compared with the measured IRMPD action spectra to identify the structures accessed in the experiments. Relative stabilities of the low-energy conformations are determined from single-point energy calculations performed at the B3LYP/6-311+G(2d,2p) level of theory. The evolution of IRMPD spectral features as a function of the size (F, Cl, Br, and I) and position (5 versus 6) of the halogen substituent are examined to elucidate the effects of the halogen substituent and noncovalent interactions with sodium cations on the structure of the nucleobase. Present results are compared with results from energy-resolved collision-induced dissociation and IRMPD action spectroscopy studies previously reported for the protonated and sodium cationized forms of uracil, and halo-, methyl-, and thioketo-substituted uracils. The present results suggest that only a single conformer is accessed for all of the 5-halouracil complexes, whereas multiple conformers are accessed for the Na+(6ClU) complex. In all cases, the experimental IRMPD action spectra confirm that the sodium cation binds to the O4 carbonyl oxygen atom of the canonical diketo tautomer in the ground-state conformers, and gains additional stabilization via chelation interactions with the halogen substituent in the complexes to the 5-halouracils as predicted by theory.
KW - Density function theory
KW - Fourier transform ion cyclotron resonance mass spectrometry
KW - Halouracils
KW - Infrared multiple photon dissociation
KW - Sodium cation
UR - http://www.scopus.com/inward/record.url?scp=84939887500&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84939887500&partnerID=8YFLogxK
U2 - 10.1016/j.ijms.2014.07.016
DO - 10.1016/j.ijms.2014.07.016
M3 - Article
AN - SCOPUS:84939887500
SN - 1387-3806
VL - 378
SP - 76
EP - 85
JO - International Journal of Mass Spectrometry
JF - International Journal of Mass Spectrometry
M1 - 15240
ER -