Infrared photodissociation of aniline(H2O)n+ (n=7–12) clusters

Alauddin, M.; Song, Jae Kyu; Park, Seung Min

doi:10.1016/j.ijms.2012.02.004

Cited by 11 publications

(23 citation statements)

References 32 publications

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“…This view is consistent with the proton affinity of the t-C 6 H 5 −N−COH radical calculated as 929 kJ/mol being still higher than that of (H 2 O) 4 reported as 913 ± 12 kJ/mol. 87 In contrast to the OH groups in the isoelectronic phenol cations, 84,86 the NH groups in the aniline cation and its derivatives are much less acidic, 83,95 and proton transfer to the solvent requires a much higher degree of hydration.…”

Section: Further Discussionmentioning

confidence: 99%

Stepwise Microhydration of Aromatic Amide Cations: Formation of Water Solvation Network Revealed by Infrared Spectra of Formanilide⁺–(H₂O)_n Clusters (n ≤ 5)

et al. 2015

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Hydration of peptides and proteins has a strong impact on their structure and function. Infrared photodissociation spectra (IRPD) of size-selected clusters of the formanilide cation, FA(+)-(H2O)n (n = 1-5), are analyzed by density functional theory calculations at the ωB97X-D/aug-cc-pVTZ level to determine the sequential microhydration of this prototypical aromatic amide cation. IRPD spectra are recorded in the hydride stretch and fingerprint ranges to probe the preferred interaction motifs and the cluster growth. IRPD spectra of cold Ar-tagged clusters, FA(+)-(H2O)n-Ar, reveal the important effects of temperature and entropy on the observed hydration motifs. At low temperature, the energetically most stable isomers are prominent, while at higher temperature less stable but more flexible isomers become increasingly populated because of entropy. In the most stable structures, the H2O ligands form a hydrogen-bonded solvent network attached to the acidic NH proton of the amide, which is stabilized by large cooperative effects arising from the excess positive charge. In larger clusters, hydration bridges the gap between the NH and CO groups (n ≥ 4) solvating the amide group rather than the more positively charged phenyl ring. Comparison with neutral FA-(H2O)n clusters reveals the strong impact of ionization on the acidity of the NH proton, the strength and topology of the interaction potential, and the structure of the hydration shell.

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Section: Further Discussionmentioning

confidence: 99%

Stepwise Microhydration of Aromatic Amide Cations: Formation of Water Solvation Network Revealed by Infrared Spectra of Formanilide⁺–(H₂O)_n Clusters (n ≤ 5)

et al. 2015

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“…14 On the other hand, our calculations of the ABN + -H 2 O dimer potential and the various ABN + -(H 2 O) n isomers indicates that interior ion solvation may become competitive with the formation of a solvent network at cluster sizes n ≥ 5, a scenario which has been completely neglected in all previous spectroscopic and theoretical studies of ABN + -(H 2 O) n and AN + -(H 2 O) n . 11,12,14 …”

Section: Comparison To An + -(H 2 O) Nmentioning

confidence: 99%

“…[11][12][13][14] While IRPD spectra of [AN-(H 2 O) n ] + clusters generated by electron impact have been interpreted to have proton-transferred geometries for n ≥ n c = 6 (without theoretical support), 12 the corresponding spectra of [AN-(H 2 O) n ] + generated by photoionization of neutral clusters are assigned to non proton-transferred geometries up to n = 12 (with theoretical support of low level DFT calculations). 14 As the NH protons of the ABN + cation studied in the present work are slightly more acidic than in the AN + cation due to the electron-withdrawing effect of the additional cyano group, 15 n c of ABN + is expected to be smaller than n c of AN + . A further interesting aspect of microhydrated aromatic cations is the structure of their hydration shell.…”

Section: Introductionmentioning

confidence: 99%

“…2,5 For aromatic cations with acidic OH/NH x functional groups, such as phenol or aniline, their H-bond interaction with the H 2 O ligands is so strong that the formation of a solvent network is favored already for small n and interior ion solvation has not yet been observed. [9][10][11][12][13][14] The bifunctional ABN + cation offers several competing binding sites for H 2 O ligands, namely the NH, CH, CN, and aromatic π sites, and the IRPD spectra and calculations for ABN + -(H 2 O) n presented here address the issue of its preferred structure of the hydration shell.…”

Section: Introductionmentioning

confidence: 99%

“…25,26 Moreover, for n = 1 the tag can adopt different binding sites and the resulting different impact on the structural and spectral properties of the ABN + -(H 2 O) n chromophore provides further information on the interaction of ABN + with polar and nonpolar/quadrupolar ligands. (3) Finally, comparison between AN + -(H 2 O) n [11][12][13][14]27 and ABN + -(H 2 O) n reveals the subtle effects of H → CN substitution in para position on the acidity of the NH 2 group, the interaction potential, and the hydration structure.…”

Section: Introductionmentioning

confidence: 99%

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Microhydrated aromatic cluster cations: Binding motifs of 4-aminobenzonitrile-(H2O)n cluster cations with n ≤ 4

Schmies

Miyazaki

Fujii

et al. 2014

The Journal of Chemical Physics

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Infrared photodissociation (IRPD) spectra of mass-selected 4-aminobenzonitrile-(water)n cluster cations, ABN(+)-(H2O)n with n ≤ 4, recorded in the N-H and O-H stretch ranges are analyzed by quantum chemical calculations at the M06-2X/aug-cc-pVTZ level to determine the evolution of the initial microhydration process of this bifunctional aromatic cation in its ground electronic state. IRPD spectra of cold clusters tagged with Ar and N2 display higher resolution and allow for a clear-cut structural assignment. The clusters are generated in an electron impact source, which generates predominantly the most stable isomers. The IRPD spectra are assigned to single isomers for n = 1-3. The preferred cluster growth begins with sequential hydration of the two acidic NH protons of the amino group (n = 1-2), which is followed by attachment of secondary H2O ligands hydrogen-bonded to the first-shell ligands (n = 3-4). These symmetric and branched structures are more stable than those with a cyclic H-bonded solvent network. Moreover, in the size range n ≤ 4 the formation of a solvent network stabilized by strong cooperative effects is favored over interior ion hydration which is destabilized by noncooperative effects. The potential of the ABN(+)-H2O dimer is characterized in detail and supports the cluster growth derived from the IRPD spectra. Although the N-H bonds are destabilized by stepwise microhydration, which is accompanied by increasing charge transfer from ABN(+) to the solvent cluster, no proton transfer to the solvent is observed for n ≤ 4.

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Rearrangement of aniline(H₂O)_n (n = 0–12) clusters upon photoionization and their excited state properties: Density functional theory and time‐dependent density functional theory study

Alauddin

Roy

Song

et al. 2022

Bulletin Korean Chem Soc

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We have studied H‐bonded structural rearrangement in the S0, S1, and D0 states of neutral and cationic aniline+(H2O)n (n = 0–12) clusters by adopting density functional (DFT) and time‐dependent DFT (TD‐DFT) theory. DFT‐calculated structural rearrangement energies (SRE) increased sharply for n = 1, 2, remained nearly the same until n = 9, and increased again from n = 10 to larger clusters. This indicates that the intramolecular vibrational modes play a central role in the rearrangement energy. On the other hand, DFT‐calculated thermochemical data confirmed that there is no significant change in enthalpy (H), Gibb's free energy (G), and entropy (S) for neutral and ionized clusters. The maximum UV absorption wavelength, λmax red‐shifted gradually with the increase of cluster size with respect to aniline as the hydration reduces the excitation energies. On the other hand, there was no significant change in the highest occupied molecular orbital (HOMO)‐lowest unoccupied molecular orbital (LUMO) energy gap.

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Infrared photodissociation of aniline(H2O)n+ (n=7–12) clusters

Cited by 11 publications

References 32 publications

Stepwise Microhydration of Aromatic Amide Cations: Formation of Water Solvation Network Revealed by Infrared Spectra of Formanilide⁺–(H₂O)_n Clusters (n ≤ 5)

Stepwise Microhydration of Aromatic Amide Cations: Formation of Water Solvation Network Revealed by Infrared Spectra of Formanilide⁺–(H₂O)_n Clusters (n ≤ 5)

Microhydrated aromatic cluster cations: Binding motifs of 4-aminobenzonitrile-(H2O)n cluster cations with n ≤ 4

Rearrangement of aniline(H₂O)_n (n = 0–12) clusters upon photoionization and their excited state properties: Density functional theory and time‐dependent density functional theory study

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Infrared photodissociation of aniline(H2O)n+ (n=7–12) clusters

Cited by 11 publications

References 32 publications

Stepwise Microhydration of Aromatic Amide Cations: Formation of Water Solvation Network Revealed by Infrared Spectra of Formanilide+–(H2O)n Clusters (n ≤ 5)

Stepwise Microhydration of Aromatic Amide Cations: Formation of Water Solvation Network Revealed by Infrared Spectra of Formanilide+–(H2O)n Clusters (n ≤ 5)

Microhydrated aromatic cluster cations: Binding motifs of 4-aminobenzonitrile-(H2O)n cluster cations with n ≤ 4

Rearrangement of aniline(H2O)n (n = 0–12) clusters upon photoionization and their excited state properties: Density functional theory and time‐dependent density functional theory study

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Stepwise Microhydration of Aromatic Amide Cations: Formation of Water Solvation Network Revealed by Infrared Spectra of Formanilide⁺–(H₂O)_n Clusters (n ≤ 5)

Stepwise Microhydration of Aromatic Amide Cations: Formation of Water Solvation Network Revealed by Infrared Spectra of Formanilide⁺–(H₂O)_n Clusters (n ≤ 5)

Rearrangement of aniline(H₂O)_n (n = 0–12) clusters upon photoionization and their excited state properties: Density functional theory and time‐dependent density functional theory study