ChemInform Abstract: Infrared Spectra of H+(H2O)5—8 Clusters: Evidence for Symmetric Proton Hydration.

Jiang, Jyh-Chiang; Wang, Yisheng; Chang, Hai‐Chou; Lin, Sheng Hsien; Lee, Yuan T.; Niedner‐Schatteburg, Gereon; Chang, H.R.

doi:10.1002/chin.200017011

Cited by 31 publications

(90 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…11 It also confirms the prevalence of such structures at n = 10 in the cold cluster regime, independent of the way that the clusters are prepared, either by fast adiabatic cooling in a supersonic expansion described in ref 11 or by slow thermalization in a buffer-gas-filled ion trap described here. For bare protonated water clusters, 8−10 cage-like 3D structures are observed only at larger cluster sizes (n > 10), which has been 7 are also shown (f−i). The intensities of the free OH stretches have been scaled (×8) for better comparability.…”

mentioning

confidence: 60%

“…This band becomes the most intense feature in the free O−H stretching region for n = 10 and has been shown to be characteristic for ring formation. 7 The absence of dangling waters for n = 10 can only be rationalized by the presence of a cage-like 3D structure. 8,10,21,23 On the other hand, the presence of a dangling water at n = 9 does not exclude an assignment to a 3D structure, and indeed, such a cage-like structure is likely also for n = 9, as we will discuss in more detail later.…”

mentioning

confidence: 98%

“…The sharp features above 3615 cm −1 are assigned to fundamental transitions involving free OH stretching vibrations, while the bands at lower energies are attributed to modes associated with hydrogen-bonded O−H oscillators. 7 The bands are labeled according to their assignment to vibrational modes, either of the ionic core (H 5 Bands associated with A-H 2 O persist up to n = 9 and are not observed in the spectrum of n = 10. The less intense band at 3714 cm −1 in the n = 6 spectrum originates from a single acceptor−single donor (AD) H 2 O and is observed throughout the spectra up to n = 10.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Disentangling the Contribution of Multiple Isomers to the Infrared Spectrum of the Protonated Water Heptamer

Heine

Fagiani

Asmis

2015

J. Phys. Chem. Lett.

View full text Add to dashboard Cite

We use infrared/infrared double-resonance population labeling (IR(2)MS(2)) spectroscopy in the spectral region of the free and hydrogen-bonded OH stretching fundamentals (2880-3850 cm(-1)) to identify the number and to isolate the vibrational signatures of individual isomers contributing to the gas-phase IR spectra of the cryogenically cooled protonated water clusters H(+)(H2O)n·H2/D2 with n = 7-10. For n = 7, four isomers are identified and assigned. Surprisingly, the IR(2)MS(2) spectra of the protonated water octa-, nona-, and decamer show no evidence for multiple isomers. The present spectra support the prediction that the quasi-2D to 3D structural transition occurs in between n = 8 and 9 in the cold cluster regime. However, the same models have difficulty explaining the remarkable size dependence of the isomer population reported here.

show abstract

mentioning

confidence: 60%

mentioning

confidence: 98%

mentioning

confidence: 99%

See 1 more Smart Citation

Disentangling the Contribution of Multiple Isomers to the Infrared Spectrum of the Protonated Water Heptamer

Heine

Fagiani

Asmis

2015

J. Phys. Chem. Lett.

View full text Add to dashboard Cite

show abstract

“…Density functional theory (DFT) calculations for structural optimization and vibrational frequencies were also performed at the B3LYP/6-31+G(d) level, which has been proved to provide highly reliable estimations of structures and IR spectra of H-bonded systems. 57 All the calculations were performed by the Gaussian 09 program suite. 58 Figure 1 provides an overview of the potential energy curves and excitation schemes of 2 and they have established that the most stable structure of this cluster is cyclic in the electronic ground (S 0 ) state.…”

Section: Methodsmentioning

confidence: 99%

Infrared Spectroscopy of Warm and Neutral Phenol–Water Clusters

Shimamori

Fujii

2015

J. Phys. Chem. A

View full text Add to dashboard Cite

Although many studies have been reported on structures of neutral water clusters, most of experimental information has been restricted to their most stable structures. With elevation of temperature, however, transient structures as well as higher energy stable structures can be formed, as recently demonstrated in small-sized neat water clusters (Zischang, J.; Suhm, M. A. J. Chem. Phys. 2014, 140, 064312). In the present study, we performed infrared spectroscopy of warm phenol-(H2O)2, which is an analogue of (H2O)3 concerning the hydrogen-bond structure, in order to overcome the size uncertainty in the neat water cluster study. The strict size selection was achieved by infrared-ultraviolet double-resonance spectroscopy combined with mass spectrometry. The temperature control of the cluster was accomplished by the reduction of the stagnation pressure of the jet expansion and the internal energy selective detection of the cluster. A remarkable shift to higher frequency of the phenolic OH stretch band was observed with elevation of temperature, suggesting deformation of the cluster from the most stable cyclic structure to the transient chain-type structure.

show abstract

“…Although far less work has been done, recent studies show that HO − cannot exist as such in water either [30–32]. Recent very high-quality IR measurements on acid solutions [33,34] show that the only structure that has any kind of real existence in them is the proposed H 13 O 6 + [35], shown in Scheme II [34], but even this has a very short lifetime; the authors state [36]: “The lifetime of the five central protons is close to the time of their vibrational transitions. In ~70% of these cations it is shorter than the time of normal vibrations and the IR spectrum degenerates to a continuum absorption”.…”

Section: Introductionmentioning

confidence: 99%

A Greatly Under-Appreciated Fundamental Principle of Physical Organic Chemistry

Cox

2011

IJMS

View full text Add to dashboard Cite

If a species does not have a finite lifetime in the reaction medium, it cannot be a mechanistic intermediate. This principle was first enunciated by Jencks, as the concept of an enforced mechanism. For instance, neither primary nor secondary carbocations have long enough lifetimes to exist in an aqueous medium, so SN1 reactions involving these substrates are not possible, and an SN2 mechanism is enforced. Only tertiary carbocations and those stabilized by resonance (benzyl cations, acylium ions) are stable enough to be reaction intermediates. More importantly, it is now known that neither H3O+ nor HO− exist as such in dilute aqueous solution. Several recent high-level calculations on large proton clusters are unable to localize the positive charge; it is found to be simply “on the cluster” as a whole. The lifetime of any ionized water species is exceedingly short, a few molecular vibrations at most; the best experimental study, using modern IR instrumentation, has the most probable hydrated proton structure as H13O6+, but only an estimated quarter of the protons are present even in this form at any given instant. Thanks to the Grotthuss mechanism of chain transfer along hydrogen bonds, in reality a proton or a hydroxide ion is simply instantly available anywhere it is needed for reaction. Important mechanistic consequences result. Any charged oxygen species (e.g., a tetrahedral intermediate) is also not going to exist long enough to be a reaction intermediate, unless the charge is stabilized in some way, usually by resonance. General acid catalysis is the rule in reactions in concentrated aqueous acids. The Grotthuss mechanism also means that reactions involving neutral water are favored; the solvent is already highly structured, so the entropy involved in bringing several solvent molecules to the reaction center is unimportant. Examples are given.

show abstract

ChemInform Abstract: Infrared Spectra of H⁺(H₂O)_5—8 Clusters: Evidence for Symmetric Proton Hydration.

Cited by 31 publications

References 1 publication

Disentangling the Contribution of Multiple Isomers to the Infrared Spectrum of the Protonated Water Heptamer

Disentangling the Contribution of Multiple Isomers to the Infrared Spectrum of the Protonated Water Heptamer

Infrared Spectroscopy of Warm and Neutral Phenol–Water Clusters

A Greatly Under-Appreciated Fundamental Principle of Physical Organic Chemistry

Contact Info

Product

Resources

About