Stable isomeric structures of the pyridine cation (C5H5N•+) and protonated pyridine (C5H5NH+) elucidated by cold ion infrared spectroscopy

Rap, Daniël B.; Marimuthu, Aravindh N.; Redlich, Britta; Brünken, Sandra

doi:10.1016/j.jms.2020.111357

Cited by 17 publications

(9 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These ions are the σ-type distonic radical cations targeted in this study and are herein referred to as 2Pyr (2-dehydropyridinium, m / z 79), 3Pyr (3-dehydropyridinium, m / z 79), 4Pyr (4-dehydropyridinium, m / z 79), 2Anl (2-dehydroanilinium, m / z 93), 3Anl (3-dehydroanilinium, m / z 93), 4Anl (4-dehydroanilinium, m / z 93), 2Bzn (2-dehydrobenzonitrilium, m / z 103), 3Bzn (3-dehydrobenzonitrilium, m / z 103), and 4Bzn (4-dehydrobenzonitrilium, m / z 103) radical cations. As previously reported, isomerization between these nine radical cations is negligible under the experimental conditions due to large potential energy barriers for hydrogen atom migration. − For the Anl radicals, however, an appreciable population of unreactive ions at m / z 93 are also detected, especially in the 2Anl case. This unreactive ion population is attributed to formation of the conventional radical cation along with the target distonic radical ions (as noted in ref ), and its origins will be discussed in further detail below.…”

Section: Resultssupporting

confidence: 60%

Reactivity Trends in the Gas-Phase Addition of Acetylene to the N-Protonated Aryl Radical Cations of Pyridine, Aniline, and Benzonitrile

Shiels

Kelly

Bright

et al. 2021

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N-containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. This paper investigates the gas-phase ion−molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl), and benzonitrilium (Bzn) ions. Three isomers are studied in each case (radical sites at the ortho, meta, and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios, and reaction efficiencies are measured. The rate coefficients increase from para to ortho positions. The second-order rate coefficients can be sorted into three groups: low, between 1 and 3 × 10 −12 cm 3 molecule −1 s −1 (3Anl and 4Anl); intermediate, between 5 and 15 × 10 −12 cm 3 molecule −1 s −1 (2Bzn, 3Bzn, and 4Bzn); and high, between 8 and 31 × 10 −11 cm 3 molecule −1 s −1 (2Anl, 2Pyr, 3Pyr, and 4Pyr); and 2Anl is the only radical cation with a rate coefficient distinctly different from its isomers. Quantum chemical calculations, using M06-2X-D3(0)/6-31++G(2df,p) geometries and DSD-PBEP86-NL/aug-cc-pVQZ energies, are deployed to rationalize reactivity trends based on the stability of prereactive complexes. The G3X-K method guides the assignment of product ions following adduct formation. The rate coefficient trend can be rationalized by a simple model based on the prereactive complex forward barrier height.

show abstract

Section: Resultssupporting

confidence: 60%

Reactivity Trends in the Gas-Phase Addition of Acetylene to the N-Protonated Aryl Radical Cations of Pyridine, Aniline, and Benzonitrile

Shiels

Kelly

Bright

et al. 2021

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

show abstract

“…In addition, the structure of H + (Pyd) was investigated by low-temperature Fourier transform infrared (FTIR) spectroscopy . A characteristic feature of Pyd + is its isomerization to a distonic cation, in which the H atom moves from the carbon to the neighboring nitrogen. ,,, Several mass spectrometric studies suggested − that a covalent bond is formed between Pyd + and aromatic molecules via reactions involving the distonic pyridine cation. However, so far there has been no direct spectroscopic evidence confirming such a covalently bound structure.…”

mentioning

confidence: 99%

Vacuum Ultraviolet Photoionization Induced Proton Migration and Formation of a New C–N Bond in Pyridine Clusters Revealed by Infrared Spectroscopy and Mass Spectrometry

Feng

Lee

Witek

et al. 2021

J. Phys. Chem. Lett.

View full text Add to dashboard Cite

The structures and reactions of pyridine (Pyd) cluster cations in a supersonic molecular beam generated upon photoionization at 9.2–9.4 eV were investigated by infrared (IR) action spectroscopy. The mass spectrum showed prominent peaks of (Pyd) m + and H+(Pyd) m , m = 1–5. In the pyridine/pyridine-d 5 mixture, the mass pattern indicated that H+ and D+ migrated during the formation and dissociation of the cluster cations. The IR photodissociation spectra of both (Pyd)2 + and H+(Pyd)2 revealed a N–H stretching band near 3400 cm–1, indicating that their structures are 1-(2-pyridyl)pyridin-1-ium and pyridinium–pyridine, respectively. Observation of the former product implies that the reaction proceeds via an α-distonic cation intermediate, while the latter product is formed via proton migration. The IR spectra of (Pyd) m + and H+(Pyd) m , m ≥ 3, suggested that these clusters consist of a covalently bound (Pyd)2 + or H+(Pyd)2 core, respectively, with additional pyridines attached to them via hydrogen bonds and/or weak dispersive interactions.

show abstract

“…For all benzene derivatives containing CF 3 groups, an asymmetric C-F stretching vibration at 1330 cm -1 appears with very strong intensity (Yadav and Singh 1985). A band at 1553 cm -1 (C=N) and bands at 1611 and 1666 cm -1 (C=C) can be assigned to stretching vibrations in the aromatic rings of the carbon (N) skeleton (Rap et al 2020). According to Singh and Yadav (2001), three mid-intensity bands peaked at 697 cm -1 , 797 cm -1 , and 890 cm -1 are due to the C-C-C inplane bending mode, the symmetric C-F stretching vibration in the CF 3 group that mixed with the ring-breathing mode vibrations, and the out-of-plane C-H bending vibrations, correspondingly.…”

Section: Resultsmentioning

confidence: 99%

Preparation and characterization of F-, O-, and N-containing carbon nanoparticles for pH sensing

et al. 2021

View full text Add to dashboard Cite

A novel sensing system was designed for pH measurements based on the enhanced and quenched photoluminescence (PL) and UV-Vis absorption of the diluted water solutions of F-, O-, and N-containing carbon nanoparticles (FON-CNPs). These FON-CNPs were solvothermally synthesized, dissolved, ultra-iltrated, and separated by thin-layer chromatography. The total luorine content in them was found to be 1.2-1.5 mmol per gram. Their TGA showed a total weight loss of 52.7% because of the thermal decomposition and detachment of the surface groups and the partial burning of the functionalized shell on the carbon core at temperatures below 1200 °C. TEM and Raman data conirmed the presence of graphitic structures in the carbon core. From the results of ATR FTIR and UV-Vis spectroscopies, we showed that a carbon shell incorporates diferent functional groups covering the carbon core. The surface groups of the carbon shell include carboxyl, phenolic, and carbonyl groups. Heterocyclic N-containing and amino groups and triluoromethyl groups supporting the hydrophobicity were also found. We suggested the possible reasons for the pH responses obtained with the sensing system considering them dependent on the de-protonation of functional groups with pH change.

show abstract

Stable isomeric structures of the pyridine cation (C5H5N•+) and protonated pyridine (C5H5NH+) elucidated by cold ion infrared spectroscopy

Cited by 17 publications

References 67 publications

Reactivity Trends in the Gas-Phase Addition of Acetylene to the N-Protonated Aryl Radical Cations of Pyridine, Aniline, and Benzonitrile

Reactivity Trends in the Gas-Phase Addition of Acetylene to the N-Protonated Aryl Radical Cations of Pyridine, Aniline, and Benzonitrile

Vacuum Ultraviolet Photoionization Induced Proton Migration and Formation of a New C–N Bond in Pyridine Clusters Revealed by Infrared Spectroscopy and Mass Spectrometry

Preparation and characterization of F-, O-, and N-containing carbon nanoparticles for pH sensing

Contact Info

Product

Resources

About