Cryogenic IR and UV spectroscopy of isomer-selected cytosine radical cation

Molina, Franco; Dezalay, Jordan; Soorkia, Satchin; Broquier, Michel; Hochlaf, M.; Pino, Gustavo A.; Grégoire, Gilles

doi:10.1039/d2cp03953b

Cited by 3 publications

(8 citation statements)

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“…This clearly indicates that excited state geometry optimization at the TD-DFT level is quite reliable even for such high transition energy (D 0 → D 4 ) as it was already reported for C(KK) +• . 25 However, the large error predicted for the first ππ* state (D 0 → D 2 ) in all species may be explained by the predicted low energy gap with the first or second dark nπ* electronic states that lie close in energy to the first ππ* state in each radical cation. A conical intersection (CI) of D 2 with D 0 and D 1 states of U(KK) +• and T(KK) +• , respectively, has been reported in a theoretical work performed at the XMS-CAPT2 level.…”

Section: Spectroscopy Of T +mentioning

confidence: 92%

“…The experimental setup in Orsay has already been described in detail. , It is based on an electrospray ion source, a cryogenic cooled 3D quadrupole ion trap (QIT, Jordan TOF, Inc.), and a homemade linear time-of-flight mass spectrometer. A water/methanol solution (1:1) of a nucleobase (NB) (200 μM) and AgNO 3 (100 μM) is electrosprayed in front of a heated capillary.…”

Section: Methodsmentioning

confidence: 99%

“…Overall, the excitation spectrum of T-Ag + shares many similarities with the ones recorded for U−Ag + and C−Ag + . 25 So, one might expect to observe only the KK isomers of the T−Ag + complex as for the two other pyrimidine nucleobases. However, as it will be discussed below, the KE tautomer also contributes to the experimental spectrum.…”

Section: The Journal Of Physical Chemistrymentioning

confidence: 99%

“…23,24 We have recently developed an original way to produce isomer-selected radical cations of cytosine (C •+ ) in a cold ion trap from the photodissociation of the cytosine−Ag + (C−Ag + ) complex that allowed recording high-resolution electronic and vibrational spectroscopy of two different tautomers of C •+ . 25 These results were compared with calculations performed at different levels of theory and benchmark experimental results to improve or develop new theoretical methods for studying the ground and excited states of open-shell species.…”

Section: ■ Introductionmentioning

confidence: 99%

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Selective Tautomer Production and Cryogenic Ion Spectroscopy of Radical Cations: The Uracil and Thymine Cases

Molina,

Broquier,

Soorkia

et al. 2024

J. Phys. Chem. A

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The vibrational and electronic spectroscopy of the radical cations of two nucleobases (NB) (uracil and thymine) was studied by cryogenic ion photodissociation spectroscopy. The radical cations have been generated from the photodissociation of NB−Ag + complexes. A charge transfer process from the NB to Ag + governs the deactivation mechanism, leading to the formation of the radical cation without further tautomerization. Single-and double-resonance spectroscopy allows for structural assignments of both the silver complexes and the radical cations by comparison with DFTbased calculations. Interestingly, a tautomer-dependent fragmentation is observed in the thymine enol form that involves the loss of NCO, a fragment which was never reported before for this NB. This selective photodissociation of silver complexes containing aromatic chromophore greatly expands the current technique to produce isomer-selected radical cations in the gas phase providing benchmark experimental data to assess calculations of open-shell species.

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Section: Spectroscopy Of T +mentioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: The Journal Of Physical Chemistrymentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Selective Tautomer Production and Cryogenic Ion Spectroscopy of Radical Cations: The Uracil and Thymine Cases

Molina,

Broquier,

Soorkia

et al. 2024

J. Phys. Chem. A

Self Cite

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“…The yield of rare tautomers depends on the local environment of a cell. In particular, the presence of alkali metal cations (M + , M = Li, Na, K, Rb, and Cs) increases the yields of rare tautomers. − Nucleobase complexes containing alkali metal cations have been extensively studied as a model system to elucidate the roles of alkali metal cations in the formation of rare tautomers at a molecular level. − Recently, cryogenic ion spectroscopy has become a powerful tool to investigate the structures and excited-state properties of metal ion complexes in the gas phase, which are produced by electrospray ionization (ESI) and stored in a cryogenic ion trap. − UV photofragmentation spectra of cold cytosine–Na + (CytNa + ), CytK + , and CytAg + complexes were obtained and analyzed through comparison with theoretical calculations of the ground and excited states . UV photodissociation (UVPD) spectra of adenine complexes with alkali metal cations (M + A) were also investigated using cryogenic ion spectroscopy .…”

Section: Introductionmentioning

confidence: 99%

Cryogenic Ion Spectroscopy of Protonated and Sodiated Methyladenine Derivatives

et al. 2023

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Ultraviolet photodissociation (UVPD) spectra of protonated 9-methyladenine (H + 9MA), protonated 7-methyl adenine (H + 7MA), protonated 3-methyladenine (H + 3MA), and sodiated 7methyladenine (Na + 7MA) near the origin bands of the S 0 −S 1 transition were obtained using cryogenic ion spectroscopy. The UV− UV hole burning, infrared (IR) ion-dip, and IR-UV double resonance spectra showed that all the ions were present as single isomers in a cryogenic ion trap. The UVPD spectrum of H + 9MA exhibited only a broad absorption band, whereas the spectra of H + 7MA, H + 3MA, and Na + 7MA displayed moderately or well-resolved vibronic bands. Potential energy profiles were computed to understand the reason for the different bandwidths of the vibronic bands in the spectra. The broadening of the bands was correlated with the slopes between the Franck−Condon point and the conical intersection between the S 1 and S 0 states in the potential energy profiles, thus reflecting the deactivation rates in the S 1 state.

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On Prototropy and Bond Length Alternation in Neutral and Ionized Pyrimidine Bases and Their Model Azines in Vacuo

Raczyńska

2023

Molecules

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In this review, the complete tautomeric equilibria are derived for disubstituted pyrimidine nucleic acid bases starting from phenol, aniline, and their model compounds—monosubstituted aromatic azines. The differences in tautomeric preferences for isolated (gaseous) neutral pyrimidine bases and their model compounds are discussed in light of different functional groups, their positions within the six-membered ring, electronic effects, and intramolecular interactions. For the discussion of tautomeric preferences and for the analysis of internal effects, recent quantum-chemical results are taken into account and compared to some experimental ones. For each possible tautomer-rotamer of the title compounds, the bond length alternation, measured by means of the harmonic oscillator model of electron delocalization (HOMED) index, is examined. Significant HOMED similarities exist for mono- and disubstituted derivatives. The lack of parallelism between the geometric (HOMED) and energetic (ΔG) parameters for all possible isomers clearly shows that aromaticity is not the main factor that dictates tautomeric preferences for pyrimidine bases, particularly for uracil and thymine. The effects of one-electron loss (positive ionization) and one-electron gain (negative ionization) on prototropy and bond length alternation are also reviewed for pyrimidine bases and their models.

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Cryogenic IR and UV spectroscopy of isomer-selected cytosine radical cation

Abstract: Oxidation of the nucleobases is of great concern for the stability of DNA strands and is considered as a source of mutagenesis and cancer. However, precise spectroscopy data, in particular...

Cited by 3 publications

References 51 publications

Selective Tautomer Production and Cryogenic Ion Spectroscopy of Radical Cations: The Uracil and Thymine Cases

Selective Tautomer Production and Cryogenic Ion Spectroscopy of Radical Cations: The Uracil and Thymine Cases

Cryogenic Ion Spectroscopy of Protonated and Sodiated Methyladenine Derivatives

On Prototropy and Bond Length Alternation in Neutral and Ionized Pyrimidine Bases and Their Model Azines in Vacuo

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