Size-dependent development of the hydrogen bond network structure in large sized clusters protonated water, H+(H2O)n (n = 4 to 27), was probed by infrared spectroscopy OH stretches. Spectral changes with cluster size demonstrate that chain structures at small sizes less, similar 10) develop into two-dimensional net (approximately 10 < n 21), and then nanometer-scaled cages >/= 21).

Recently reported high-level ab initio calculations and gas phase spectroscopic measurements show that the nature of CH/π interactions is considerably different from conventional hydrogen bonds, although were often regarded as weakest class bonds. The major source attraction in interaction dispersion electrostatic contribution small, while mainly responsible for "typical" similar to van der Waals interactions, if some exceptional "activated" highly acidic C–H bonds are excluded. Shifts...

Vibrational spectroscopies of small-sized hydrogen-bonded clusters organic acids and related molecules, as well their ions, are reviewed based on our recent results. OH stretching vibrations the jet-cooled generated by supersonic expansions observed various size-selected population-labelling spectroscopic methods; ionization detected infrared (IR) or stimulated Raman for neutral in electronical ground state (S ) fluorescence IR spectroscopy electronically excited ). The hydrogen-bond...

We report infrared spectra of hydrogen-bonded phenol−amine clusters, phenol−NH3, −N(CH3)3, −NH(C2H5)2, and −N(C2H5)3, prepared in jet expansions. The OH, NH, CH stretching fundamentals were studied. Infrared−ultraviolet double-resonance techniques utilized for vibrational spectroscopy size-selected clusters. OH stretch frequencies the phenol moieties showed extremely large red-shifts from that bare phenol, reflecting strong proton affinities amines. Moreover, non-proton-transferred...

The accurate CH/pi interaction energy of the benzene-methane model system was experimentally and theoretically determined. In experiment, mass analyzed threshold ionization spectroscopy applied to cluster in gas phase, prepared a supersonic molecular beam. binding neutral ground state cluster, which is regarded as for this system, evaluated from dissociation measurements cation. determined (D(0)) 1.03-1.13 kcal/mol. calculated by ab initio orbital methods. estimated CCSD(T) at basis set...

The CCSD(T) level interaction energies of CH/π complexes at the basis set limit were estimated. estimated benzene with CH4, CH3CH3, CH2CH2, CHCH, CH3NH2, CH3OH, CH3OCH3, CH3F, CH3Cl, CH3ClNH2, CH3ClOH, CH2Cl2, CH2FCl, CH2F2, CHCl3, and CH3F3 are −1.45, −1.82, −2.06, −2.83, −1.94, −1.98, −2.31, −2.99, −3.57, −3.71, −4.54, −3.88, −3.22, −5.64, −4.18 kcal/mol, respectively. Dispersion is major source attraction, even if substituents attached to carbon atom C−H bond. dispersion between chlorine...

Although messenger mediated spectroscopy is a widely-used technique to study gas phase ionic species, effects of messengers themselves are not necessarily clear. In this study, we report infrared photodissociation H+(H2O)6·Mm (M = Ne, Ar, Kr, Xe, H2, N2, and CH4) in the OH stretch region investigate messenger(M)-dependent cluster structures H+(H2O)6 moiety. The H+(H2O)6, protonated water hexamer, smallest system which both H3O+ (Eigen) H5O2+ (Zundel) hydrated proton motifs coexist. All...

The accurate interaction energies of the CH/π in benzene−X clusters (X = ethylene and acetylene) were experimentally theoretically determined. Two-color multiphoton ionization spectroscopy was applied, binding neutral ground state evaluated from dissociation threshold measurements cluster cations. experimental (D0) 1.4 ± 0.2 2.7 kcal/mol, respectively. Estimated CCSD(T) for at basis set limit (De) 2.2 2.8 Calculated D0 values (1.7 2.4 respectively) are close to values. Large electron...

Precisely size-selected protonated water clusters H+(H2O)n (n=20–200) were studied by IR spectroscopy to provide insights into the structures of large-scale H-bonded networks. The spectral features reveal that cluster gradually approach bulk-water network and involve a greater number four-coordinate molecules with increasing size (see picture). Detailed facts importance specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset....

Copolymers bearing DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and DBN (1,5-diazabicyclo[4.3.0]non-5-ene) moieties fixed carbon dioxide under atmospheric pressure. The copolymers faster than those owing to the lower steric hindrance around imine structure. These held trapped CO2 a N2 flow at 25 °C, whereas corresponding low-molecular weight amidines release same conditions. in was quantitatively released by 120 °C. trapping efficiency of copolymer is competitive with that an amidine-containing...

Size-selective infrared (IR) spectroscopy of gas phase water-containing clusters is performed to probe microscopic natures hydrogen-bonded water networks. observation extended the size range a few tens hundreds molecules bridge gap between simple but unique networks in small-sized and those bulk water. IR spectra two types large clusters, phenol-(H2O) n (n < ∼50) H+(H2O) ⩽ 221), are measured OH stretching vibrational region. Clear dependence observed interpreted terms coordination numbers...

Various vibrational spectroscopic techniques combined with vacuum-ultraviolet one-photon ionization mass spectrometry have recently been developed for jet-cooled molecules and clusters. These open general applications of size-selected infrared also Raman spectroscopies to neutral clusters by overcoming difficulties in the conventional methods Their principles demonstrated investigations simple protic without an ultraviolet chromophore, which is necessary gas phase based on fluorescence or...

The nature of water networks exposed to ionizing radiation is important in various radiation-related chemistry and biology. To understand structural evolution ionized at the molecular level, we report here infrared spectra watercluster radical cations (H2O)n+ (n = 3 − 11) gas phase. Spectral features free OH stretch modes are quite similar those protonated waterclustersH+(H2O)n, which hydrogen-bond network structures have been revealed. In addition, observed an extra band attributed (H2O)n+....

Infrared spectroscopy of gas-phase hydrated clusters provides us much information on structures and dynamics water networks. However, interpretation spectra is often difficult because high internal energy (vibrational temperature) coexistence many isomers. Here we report an approach to vary these factors by using the inert gas (so-called “messenger”)-mediated cooling technique. Protonated with a messenger (M), H+(H2O)4–8·M (M = Ne, Ar, (H2)2), are formed in molecular beam probed infrared...

An attractive intermolecular interaction between an aliphatic C−H bond and a π-electron system (C−H/π interaction) was characterized on the basis of infrared spectroscopy high level ab initio calculations. Infrared applied to several isolated methane clusters with benzene, toluene, p-xylene, mesitylene, naphthalene in gas phase, spectral changes stretch bands moiety upon cluster formation were observed. In theoretical approach, energies evaluated by high-level The forbidden symmetric...

The CH/pi interaction energies between benzene and halomethanes (CH(2)Cl(2) CHCl(3)) were accurately determined. Two-color ionization spectroscopy was applied to the benzene-CH(2)Cl(2) -CHCl(3) clusters, binding in neutral ground state, i.e. these model cluster systems, precisely evaluated on basis of dissociation threshold measurements clusters cationic state potential value bare molecule. experimentally determined 3.8 +/- 0.2 5.2 kcal mol(-1) for respectively, remarkable enhancement energy...

The nature of the S−H⋅⋅⋅S hydrogen-bonding interaction in H2 S dimer and its structure has been focus several theoretical studies. This is partly due to structural similarity close relationship with well-studied water because it represents simplest prototypical example hydrogen bonding involving a sulfur atom. Although there some IR data on higher homomers from cold matrix experiments, are no spectroscopic reports gas phase to-date. We present experimental evidence using VUV...

OH stretching vibrations of hydrogen-bonded cluster ions phenol (PhOH), [PhOH−(H2O)n]+ (n = 1−4), (PhOH)2+, and (PhOH−methanol)+ have been observed with infrared photodissociation spectroscopy in combination an ion-trapping technique. Cluster were efficiently generated by ionization followed a jet expansion mass-selectively stored the radio frequency ion trap method, which allows us to observe multiphoton dissociation yield spectra size-selected ions. For [PhOH−(H2O)n]+, water moieties...

The CH/π interaction energies in benzene-alkane model clusters were precisely determined by laser spectroscopy and theoretical calculations. Two-color resonant two-photon ionization was employed to experimentally determine the with isomer selectivity. High precision ab initio calculations also performed evaluate CCSD(T) level of various isomers at basis set limit. Binary benzene ethane, propane, n-butane, iso-butane, cyclohexane studied. experimental well reproduced evaluations. magnitude...

To investigate hydrogen bond network structures of tens water molecules, we report infrared spectra moderately size (n)-selected phenol−(H2O)n (∼10 ≤ n ∼50), which have essentially the same as (H2O)n+1. The phenyl group in allows us to apply photoionization-based selection and infrared-ultraviolet double resonance spectroscopy. show a clear low-frequency shift free OH stretching band with increasing n. Detailed analyses density functional theory calculations indicate that this is accounted...

We present infrared spectra of nominal water cluster radical cations (H(2)O)(n)(+) (n = 3-8), or to be precise, ion-radical complexes H(+)(H(2)O)(n-1)(OH), with and without an Ar tag. These clusters are closely related the ionizing radiation-induced processes in a good model characterize solvation structures pair. The Ar-tagged species show narrower bandwidths relative those bare due reduced internal energy via Ar-attachment. observed analyzed by comparing similar system, H(+)(H(2)O)(n),...

The ionization of protic molecules such as H2O and NH3 in the condensed phase initiates ion–molecule reactions, which remain poorly understood. Studies structure reactivity small ionic clusters molecular beams have yielded a wealth information on protonated clusters. However, unprotonated radical cation low concentration typical experiment thus challenging. Here we report infrared spectra (NH3)2+ (NH3)3+ cations solvated helium nanodroplets. Radical often several isomers with different...

The hemibond, a nonclassical covalent bond involving three electrons shared between two centers, has attracted considerable attention due to its significance in radiation chemistry. Water radical cation clusters, [H2O–X]+, exhibit primary bonding motifs: the hemibond and hydrogen bond. Although formation typically dominates, recent studies have identified instances of some systems water molecules. This study focuses on [H2O–N2O]+ cluster, rare system exhibiting formation. We investigate...

The hemibond is a non-classical covalent bond formed by the overlap of non-bonding orbitals radical (cation) and closed-shell molecule. For (H2O-Arn)+ cation clusters, competition between hemibonded type hydrogen-bonded (H-bonded) isomers has been discussed on basis infrared spectroscopy theoretical computations. It commonly recognized that H-bonded predominant, while coexistence remains topic debate. Hemibonded species are known to exhibit very strong electronic transitions in ultraviolet...