23 results on '"Akihiro Wakisaka"'
Search Results
2. Azeotropy of alcohol–water mixtures from the viewpoint of cluster-level structures
- Author
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Mamoru Takahashi, Akihiro Wakisaka, Makoto Uranaga, Taisuke Sekimoto, and Kazuo Matsuura
- Subjects
Ethanol ,Chemistry ,Analytical chemistry ,Alcohol ,Condensed Matter Physics ,Mass spectrometry ,Mass spectrometric ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Fragmentation (mass spectrometry) ,Materials Chemistry ,Cluster (physics) ,Organic chemistry ,Molecule ,Physical and Theoretical Chemistry ,Spectroscopy - Abstract
We showed that there is a close relation between evaporation properties and cluster-level structures in alcohol–water binary mixtures, on the basis of the mass spectrometric analyses of clusters generated through fragmentation of liquid droplets. The azeotropy for alcohol (ethanol, 1-propanol or 1-butanol)–water mixtures is caused by the change of the evaporation properties attributed to the cluster-level structures in the mixtures. When the hydrogen-bonding network of water molecules is stable at the cluster level in the water-rich mixtures, the alcohol molecules included in the water-rich clusters are evaporated primarily. On the other hand, when the alcohol self-association clusters are formed with an increase of the alcohol concentration in the mixtures, evaporation of the water existing around the alcohol self-association clusters is increased.
- Published
- 2011
3. Hydrogen-bonding self-association of 1-pentanol controlled by the relativity of interaction energies
- Author
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Akihiro Wakisaka, Toru Iwakami, Takahiro Ohki, and Miki Nakagawa
- Subjects
Chemistry ,Hydrogen bond ,Interaction energy ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Theory of relativity ,Chemical physics ,Materials Chemistry ,Molecule ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Atomic physics ,Solvent effects ,Adiabatic process ,Cluster analysis ,Spectroscopy ,Mixing (physics) - Abstract
Molecular clustering in the liquid state is controlled by the relativity of interaction energies. This means that the clustering is strongly promoted by the coexistence of relatively weakly interacting molecules in the solution. This relativity-controlled clustering was observed for 1-pentanol clustering through the mass spectrometry for clusters isolated from liquid droplets via adiabatic expansion in a vacuum chamber. The 1-pentanol clustering through hydrogen-bonding interaction was significantly promoted by the mixing with water, methanol, acetonitrile or dichloromethane, but it was not promoted by the mixing with 1-propanol or 1, 2-dichloroethane. This solvent effect on the 1-pentanol clustering is explained by the relativity of the 1-pentanol–1-pentanol interaction energy to the 1-pentanol–solvent interaction energy. Thermodynamic analysis on this solvent-induced clustering also supports that the clustering controlled by the relativity of interaction energy is inherent in the liquid state.
- Published
- 2009
4. Cluster structures determined by ion–molecular interactions: preferential solvation and acid–base neutralization
- Author
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Akihiro Wakisaka
- Subjects
Molecular interactions ,Reaction mechanism ,Chemistry ,Inorganic chemistry ,Solvation ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Neutralization ,Electronic, Optical and Magnetic Materials ,Ion ,Crystallography ,Fragmentation (mass spectrometry) ,Materials Chemistry ,Cluster (physics) ,Molecule ,Physical and Theoretical Chemistry ,Spectroscopy - Abstract
The neutralization of CH 3 COOH by NaOH in water has been studied by the mass spectrometric analysis of clusters generated via fragmentation of liquid droplets. In water, CH 3 COOH molecules form self-association clusters at higher acid concentrations like the molar ratio of CH 3 COOH:H 2 O=1:10. At these concentrations, the neutralization takes place via interaction between the CH 3 COOH clusters and NaOH to afford Na + (CH 3 COOH) a (CH 3 COONa) b clusters. Furthermore, Na + is preferentially solvated by CH 3 COOH in water to form Na + (CH 3 COOH) α clusters. In consideration with these cluster structure, the reaction mechanism in solution can be realized more precisely.
- Published
- 2005
5. Phase separation of water–alcohol binary mixtures induced by the microheterogeneity
- Author
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Takahiro Ohki and Akihiro Wakisaka
- Subjects
chemistry.chemical_compound ,chemistry ,Fragmentation (mass spectrometry) ,Phase separation process ,Intermolecular force ,Mass spectrum ,Analytical chemistry ,Cluster (physics) ,Molecule ,Alcohol ,Physical and Theoretical Chemistry - Abstract
The relationship between liquid-liquid phase separation and microheterogeneity in water-primary alcohol mixtures was examined by analysing the mass spectra of clusters generated through the fragmentation of liquid droplets. By comparing the cluster structures of water-ethanol, -1-propanol, and -1-butanol binary mixtures at various alcohol concentrations, we discovered differences in the molecular clusters that control phase separation. We also studied the role of water in alcohol self-association. Alcohol self-association is promoted in the presence of a small amount of water (ca. 10 approximately 20 wt%), in which the water-water hydrogen-bonding network is weak and does not contribute to alcohol self-association. We have demonstrated that alcohol self-association is also promoted by non-ideal mixing with other alcohols. The self-association of alcohol molecules complements the loss of stabilization energy caused by the relatively weak coexisting interactions. This complementary relationship among intermolecular interactions is an inherent property of solutions, and plays a key role in the phase separation process.
- Published
- 2005
6. Preferential Solvation and Self-Association in Alcohol−Acetonitrile Mixtures Observed through Mass Spectrometric Analysis of Clusters: Influence of Alkyl Chain Length
- Author
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Akihiro Wakisaka, Giacomo Saielli, Alessandro Bagno, and Federico Rastrelli
- Subjects
preferential solvation ,mass spectrometry ,md simulations ,chemistry.chemical_classification ,Hydrogen bond ,Solvation ,Analytical chemistry ,Alcohol ,Surfaces, Coatings and Films ,Solvent ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Molecule ,lipids (amino acids, peptides, and proteins) ,Methanol ,Physical and Theoretical Chemistry ,Acetonitrile ,Alkyl - Abstract
Molecular clusters formed by fragmentation of liquid droplets of alcohol (methanol or n-butanol)-acetonitrile mixtures have been detected and analyzed by means of a specially designed mass spectrometer. In the methanol-acetonitrile mixture, methanol clusters retain a sizable magnitude through most of the composition range, whereas acetonitrile clusters decrease in intensity upon increasing the concentration of methanol. Hydrogen bonding among methanol molecules controls the clustering. On the other hand, in n-butanol-acetonitrile mixtures, self-association of n-butanol through hydrogen bonding is remarkably promoted by the mixing with acetonitrile. With decreasing the acetonitrile contents, however, n-butanol self-associated clusters disintegrate completely. The interaction among n-butanol molecules changes from hydrogen bonding to dispersive, depending on the mixing ratio. When phenol is added as a solute to these binary mixtures, the solvation of phenol is found to be controlled by the solvent molecular clustering.
- Published
- 2004
7. Molecular Association in Binary Mixtures of tert-Butyl Alcohol−Water and Tetrahydrofuran−Heavy Water Studied by Mass Spectrometry of Clusters from Liquid Droplets
- Author
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Toshiko Fukasawa, Akihiro Wakisaka, and Yasunori Tominaga
- Subjects
Heavy water ,chemistry.chemical_compound ,tert-Butyl alcohol ,chemistry ,Mixing ratio ,Analytical chemistry ,Molecule ,Alcohol ,Physical and Theoretical Chemistry ,Mass spectrometry ,Mole fraction ,Tetrahydrofuran - Abstract
The cluster structures observed by means of mass spectrometry for binary mixtures-tert-bulyl alcohol (TBA)-H 2 O and tetrahydrofuran (THF)-D 2 O-with varying mixing ratios exhibit striking contrast, even though both TBA andTHF are miscible with water at any mixing ratio. In the TBA-H 2 O mixtures at TBA mole fractions of (X T B A ) ≤ 0.01-0.025, some of the H 2 O molecules in the H 2 O clusters are replaced by TBA molecules. For 0.01-0.025 ≤ X T B A ≤ 0.2-0.3, the self-aggregation of TBA forms dominant cluster structures, and the hydrogen-bonded water clusters are disintegrated with increasing X T B A . This TBA self-aggregation is reduced with further increasing TBA at X T B A ≥ 0.3. However, in the THF-D 2 O mixtures, THF molecules have a weak additional interaction with D 2 O clusters, and the self-aggregation of THF is not promoted in the THF-D 2 O mixtures. The D 2 O clusters still exist, even at a THF mole fraction of X T H F = 0.3. On the basis of the observed cluster structure, the mechanism for the mixing between water and the organic solvent and the controlling factors in the self-aggregation are proposed.
- Published
- 2003
8. Complementary Relation between Ion−Counterion and Ion−Solvent Interaction in Lithium Halide−Methanol Solutions
- Author
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Tamás Radnai, Tünde Megyes, and Akihiro Wakisaka
- Subjects
chemistry.chemical_classification ,Inorganic chemistry ,Solvation ,Halide ,chemistry.chemical_element ,Ion ,Solvent ,chemistry ,Mass spectrum ,Molecule ,Physical chemistry ,Lithium ,Physical and Theoretical Chemistry ,Counterion - Abstract
Mass spectrometric study on the cluster structure of methanol solutions containing lithium halides (LiX = LiCl, LiBr, and LiI) is reported. Solvated ions: Li+(CH3OH)n and X-(CH3OH)k, and salt clusters: Li+(Li+X-)s(CH3OH)m and X-(Li+X-)p(CH3OH)r, were observed in the mass spectra. The number of methanol molecules around Li+, especially in Li+(Li+X-)s(CH3OH)m clusters, increased when changing the anions from Cl- to I-, which suggested that there was a complementary relation between a Li+−CH3OH interaction and a Li+−X- interaction. In the case of X- = I-, the Li+−CH3OH interaction was enhanced in comparing with the case of X- = Cl-, because a Li+−I- interaction is weaker than a Li+−Cl- interaction. This observed complementary relation is a kind of intrinsic property of a liquid phase. Furthermore, mass distribution of the solvated ions and the salt clusters had correlations with physicochemical properties such as solvation energies and molar conductivities.
- Published
- 2002
9. Cluster Structures in Aqueous HNO3 and H2SO4 Solutions: In Relation with Equivalent Conductivity
- Author
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Takashi Ibusuki, Akihiro Wakisaka, Hitomi Kobara, and Koji Takeuchi
- Subjects
Delocalized electron ,Aqueous solution ,Mass distribution ,Chemistry ,Cluster (physics) ,Analytical chemistry ,Molecule ,Protonation ,Physical and Theoretical Chemistry ,Conductivity ,Mass spectrometry - Abstract
A part of microscopic structure in aqueous HNO3, and H2SO4 solutions was directly observed as ionic clusters isolated from these aqueous solutions by means of a specially designed electrospray mass spectrometer. The difference in the hydration structure for these acids was partially visualized on the basis of the molecular composition in the observed ionic clusters. For aqueous HNO3 solutions, the protonated water clusters, H+(H2O)n: n = 1, 2, 3 ..., which have similar mass distribution to the inherent water clusters, were observed predominantly. This is in good agreement with microscopic picture that the protons released from HNO3 are hopping and delocalized among water clusters. Such a cluster structure was independent of the HNO3 concentrations of [HNO3] < 1 mol/dm3. On the other hand, for aqueous H2SO4 solution, cluster structure was drastically changed with varying H2SO4 concentration. For diluted H2SO4 solution, clusters that consisted of only water molecules were mainly observed. This means that t...
- Published
- 2002
10. Theoretical study on the structure and stability of the clusters of tropylium ion solvated by methanol molecules
- Author
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Akiya Suzuki, Kazunari Yoshizawa, Tomomi Kinoshita, Ken'ichi Takeuchi, and Akihiro Wakisaka
- Subjects
Range (particle radiation) ,Chemistry ,Hydrogen bond ,solvated cluster ,Condensed Matter Physics ,Chemical communication ,hydrogen bonding ,Biochemistry ,tropylium ion ,Ion ,chemistry.chemical_compound ,Crystallography ,magic-numbered species ,Computational chemistry ,Cluster (physics) ,Molecule ,Density functional theory ,Methanol ,Physical and Theoretical Chemistry ,density functional theory - Abstract
Density functional theory (DFT) B3LYP calculations characterize the structure and stability of the clusters of tropylium ion (Tr+) coordinated by methanol molecules Tr+(MeOH)n with n=1–7. Methanol molecules are bound together through strong O–H⋯O type hydrogen bonds, resulting in a cyclic structure when n≥3, and the methanol cluster thus formed coordinates to Tr+ through weak C–H⋯O type hydrogen bonds. Thus, the formation of the Tr+(MeOH)n clusters is mediated by two kinds of hydrogen bonds. Calculated distances of the O–H⋯O hydrogen bonds lie in the range 1.570–1.991 A (1.712 A in average) while those of the C–H⋯O hydrogen bonds lie in the range 2.083–2.319 A (2.160 A in average). Mass spectroscopic experiments demonstrated that Tr+(MeOH)4 is a dominant, magic-numbered species and that Tr+(MeOH)3 and Tr+(MeOH)5 are minor [Chemical Communication, (2001) in press]. The experimental result is analyzed from the viewpoint of energetics. The specific size effect on the stability of Tr+(MeOH)n is a direct consequence of the stability of the (MeOH)n fragment itself.
- Published
- 2001
11. Molecular Self-Assembling of Butan-1-ol, Butan-2-ol, and 2-Methylpropan-2-ol in Carbon Tetrachloride Solutions as Observed by Near-Infrared Spectroscopic Measurements
- Author
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Yukihiro Ozaki, Hideyo Matsuzawa, Norihisa Katayama, Akihiro Wakisaka, Masayuki Suzuki, Makio Iwahashi, and Mirosław A. Czarnecki
- Subjects
chemistry.chemical_classification ,Hydrogen bond ,Overtone ,010401 analytical chemistry ,Near-infrared spectroscopy ,Inorganic chemistry ,Alcohol ,Polymer ,01 natural sciences ,0104 chemical sciences ,010309 optics ,chemistry.chemical_compound ,Monomer ,chemistry ,0103 physical sciences ,Carbon tetrachloride ,Molecule ,Physical chemistry ,Instrumentation ,Spectroscopy - Abstract
The self-associations of butan-1-ol, butan-2-ol, and 2-methylpropan-2-ol ( tert-butanol) in the pure liquid state and in carbon tetrachloride solutions have been studied mainly through near-infrared spectroscopic observation at various temperatures. A new analysis assuming a successive association process for the alcohol molecules was applied to the sharp band around 1410 nm (the first-overtone band of the OH stretching vibration mode attributed to free OH monomer and partly to OH polymer); it became clear that the mean association number for each alcohol increases with increasing concentration and decreases with increasing temperature. Comparisons of the association numbers at various constant temperatures for the three kinds of alcohols show that the association abilities are on the order butan-1-ol > butan-2-ol > 2-methylpropan-2-ol.
- Published
- 2000
12. Solvent effect on acid–base clustering between acetic acid and pyridine
- Author
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Yoshikatsu Akiyama, Kengo Sakaguchi, Fujio Mizukami, and Akihiro Wakisaka
- Subjects
chemistry.chemical_classification ,Solvent ,chemistry.chemical_compound ,Acetic acid ,Base (chemistry) ,chemistry ,Pyridine ,Polymer chemistry ,Inorganic chemistry ,Molecule ,Solvent effects ,Brønsted–Lowry acid–base theory ,Acetonitrile - Abstract
The solvent effect on the acid–base interaction between acetic acid and pyridine has been studied by the mass spectrometric analysis of clusters isolated from liquid droplets. The clusters resulting from the acetic acid–pyridine, acid–base, interaction in water are quite different from those in acetonitrile solvent. In water (acetic acid∶pyridine∶water = 1∶1∶10) the acid–base interaction occurs through the intercluster interaction between acetic acid and pyridine clusters. On the other hand, in acetonitrile (acetic acid∶pyridine∶acetonitrile = 1∶1∶10), the acid–base interaction proceeds through an intermonomer interaction between an acetic acid molecule and pyridine molecule, and the clusters are produced through the aggregation of a polar (acetic acid)δ–(pyridine)δ+ complex. This solvent effect is mainly attributed to the cluster structure of acetic acid and pyridine in water and acetonitrile solvent.
- Published
- 1998
13. Rigid or floppy water-containing dipole-bound dimer anions
- Author
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Jean-Pierre Schermann, Yves Bouteiller, Akihiro Wakisaka, Charles Desfrançois, and H. Abdoul-Carime
- Subjects
Bond dipole moment ,Proton ,Hydrogen bond ,Dimer ,Chemical polarity ,Atomic and Molecular Physics, and Optics ,Ion ,Dipole ,chemistry.chemical_compound ,Crystallography ,chemistry ,Molecule ,Physics::Atomic Physics ,Physics::Chemical Physics ,Atomic physics ,Physics::Atmospheric and Oceanic Physics - Abstract
We here report a comparative experimental and theoretical study of dipole-bound electron attachment on four polar hydrogen-bonded dimers containing one water molecule (water-water, ammonia-water, phenol-water and pyridine-water). When the water molecule is the proton acceptor in the neutral complex, with a trans-linear hydrogen bond (water-water and phenol-water), it is shown that the equilibrium geometry of the dipole-bound anion tends to a cis-linear hydrogen bond for which the total dipole moment is larger. On the contrary, when the water molecule is the proton donor to a nitrogen atom (ammonia-water and pyridine-water), dipole-bound electron attachment does not lead to subsequent modifications of the complex geometry.
- Published
- 1997
14. Non-covalent binary interactions between some organic acids and bases
- Author
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C. Desfrancois, Akihiro Wakisaka, J. P. Schermann, H. Takeo, V. Periquet, J. Flugge, and H. Abdoul-Carime
- Subjects
Valence (chemistry) ,Chemistry ,Dimer ,Intermolecular force ,Binding energy ,Cyclohexanol ,Photochemistry ,Crystallography ,chemistry.chemical_compound ,Rydberg atom ,Pyridine ,Physics::Atomic and Molecular Clusters ,Molecule ,Physics::Chemical Physics ,Physical and Theoretical Chemistry - Abstract
Very-low-energy electron attachment to homogeneous and mixed pyridine, phenol and cyclohexanol dimers is studied by means of collisions with laser-excited Rydberg atoms and several new dipole-bound anions are observed. The corresponding structures and binding energies of their neutral parents are determined by model calculations of the intermolecular interactions between these polar closed-shell molecules. In the case of the phenol–pyridine dimer, a valence negative ion is observed. The geometry of its neutral parent is obtained from both abinitio and model calculations.
- Published
- 1997
15. Molecular self-assembly composed of aromatic hydrogen-bond donor[ndash ]acceptor complexes
- Author
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Tetsuo Koyama and Akihiro Wakisaka
- Subjects
Crystallography ,chemistry.chemical_compound ,Chemistry ,Stereochemistry ,Hydrogen bond ,Dimer ,Monolayer ,Cluster (physics) ,Molecule ,Molecular self-assembly ,Acid–base reaction ,Physical and Theoretical Chemistry ,Acceptor - Abstract
Molecular self-assembling systems derived from the clustering of acid and base molecules have been investigated by mass spectrometric analysis of clusters isolated from liquid droplets. N–H···N and O–H···N hydrogen-bonded acid–base systems were compared. When heteroaromatic N–H···N hydrogen-bonding acid–base systems, such as 7-azaindole dimer, the indole–quinoline pair, etc. were used as acid–base pairs, the clusters composed of equimolar acid and base molecules were generated. This means that the hydrogen-bonding acid–base complex, N–H···N, behaves like a single molecule in cluster formation. On the other hand, clustering of the aromatic O–H···N hydrogen-bonding systems, such as phenol–pyridine, phenol–pyrazine, etc., was controlled by the acid–base interaction determined by the pKa values, giving a multilayer structure for a relatively strong acid–base pair and a monolayer structure for a relatively weak acid–base pair. Molecular self-assembling systems containing hydrogen-bond donor and acceptor molecules have been systematically described here.
- Published
- 1997
16. Clusters in the Liquid and on the Surface
- Author
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Kenji Koga, Akihiro Wakisaka, and Harutoshi Takeo
- Subjects
Surface (mathematics) ,Field (physics) ,law ,Chemical physics ,Chemistry ,Molecule ,Crystallization ,Atomic physics ,Chemical reaction ,law.invention - Abstract
Clusters, ensemble of atoms and/or molecules with less number enough to form stable bulk, are thought to play important roles in various phenomena such as, crystallization, phase separation, chemical reactions, etc. Several techniques to produce clusters have been developed and studies in this field are becoming active. Two new methods to produce clusters and the investigations on their characteristics are described in this paper. One is the characteristics of clusters formed from liquid (solution), and the other is the formation and the stabilization of clusters on the surface and their structural investigation.
- Published
- 1997
17. Molecular self-assembly controlled by acid–base non-covalent interactions: a mass spectrometric study of some organic acids and bases
- Author
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Kengo Sakaguchi, Yoshitaka Yamamoto, Yoshikatsu Akiyama, Harutoshi Takeo, Theo Engst, Akihiro Wakisaka, Fujio Mizukami, and Harold Jones
- Subjects
chemistry.chemical_classification ,Base (chemistry) ,chemistry ,Computational chemistry ,Monolayer ,Stacking ,Analytical chemistry ,Non-covalent interactions ,Molecular self-assembly ,Molecule ,Acid–base reaction ,Physical and Theoretical Chemistry ,Mass spectrometry - Abstract
Molecular clusters generated from vacuum adiabatic expansion of liquid droplets including acid and base molecules provide an insight into molecular self-assembly through non-covalent interactions. The mass spectrometric analysis for the resulting clusters indicates a systematic structure change which is dependent on the acid–base interaction: a multilayer stacking structure for relatively strong acid–base pairs (phenol–pyridine, phenol–N,N-dimethylaniline, etc.), and a monolayer structure for relatively weak acid–base pairs (phenol–pyrazine, cyclohexanol–pyridine, etc.). As another viewpoint, mass spectrometry of the molecular clusters composed of acid and base molecules can be presented as a new method to characterise the acid–base interaction.
- Published
- 1996
18. Preferential solvation controlled by clustering conditions of acetonitrile–water mixtures
- Author
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Nobuyuki Nishi, Satoru Takahashi, and Akihiro Wakisaka
- Subjects
Solvent ,chemistry.chemical_compound ,chemistry ,Clathrate hydrate ,Analytical chemistry ,Solvation ,Phenol ,Molecule ,Organic chemistry ,Emission spectrum ,Physical and Theoretical Chemistry ,Mole fraction ,Acetonitrile - Abstract
Experimental evidence for the preferential solvation of phenol in a mixed solvent of acetonitrile and water has been obtained by mass spectrometric analysis of the clusters isolated from liquid droplets by the adiabatic expansion. The effect of temperature on the formation of phenol–hydrate clusters, (C6H5OH)(H2O)n : n= 1,2,3, …, showed that phenol molecules are solbated preferentially by acetonitrile molecules at xw(water mole fraction) < 0.85, the phenol–hydrate clusters were hardly observed at temperatures lower than 50 °C but appeared at higher temperatures. On the contrary, at xw 0.85, hydrate formation became preferable at lower temperatures. The observed temperature effect confirmed microscopically inhomogeneous clustering of the solvent and solute molecules in the mixtures. A. similar temperature effect was also observed in the emission spectra of 2-naphthol in the same mixtures.
- Published
- 1995
19. Preferential Solvation of Na+ in N,N-Dimethylformamide−Water Binary Mixture
- Author
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Hitomi Kobara, Takashi Ibusuki, Koji Takeuchi, and Akihiro Wakisaka
- Subjects
Hydrogen bond ,Chemistry ,Inorganic chemistry ,Solvation ,Binary number ,Electron ,Mass spectrometry ,Surfaces, Coatings and Films ,Crystallography ,Materials Chemistry ,Cluster (physics) ,N dimethylformamide ,Molecule ,Physical and Theoretical Chemistry - Abstract
Preferential solvation of Na+ by N,N-dimethylformamide (DMF) in a DMF−water binary mixture is observed at the cluster level through mass spectrometry. Since DMF is highly electron donating, the Na+−DMF interaction is more favorable than the DMF−H2O interaction. The observed clusters in a DMF−water mixture with and without NaCl, show that once a DMF molecule interacts with Na+, the DMF molecule hardly forms a hydrogen bond with a water molecule or cluster.
- Published
- 2003
20. Solvent Effects and Molecular Clusters: Especially in Aqueous Organic Solvents
- Author
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Akihiro Wakisaka
- Subjects
Solvent ,Hydrophobic effect ,chemistry.chemical_compound ,Aqueous solution ,Chemistry ,Organic Chemistry ,Inorganic chemistry ,Solvation ,Molecule ,Solvent effects ,Photochemistry ,Acetonitrile ,Chemical reaction - Abstract
Ethanol, acetonitrile, acetone etc. are miscible with water at any mixing ratio; however, the mixtures are not homogeneous in view of the molecular level owing to the hydrogen-bonding interaction between water molecules and the hydrophobic interaction between water and organic solvent molecules. Through these interactions, molecular clusters are easy to be formed in the aqueous organic solvents. The clustering structure of the aqueous organic solvents influences the microscopic environment of substrates in these solvents and controls various chemical reactions such as the hydrolysis of tert-butyl chloride (SN1 reaction).This review will focus on the solvent effects studied in terms of the molecular clusters which reflect the microscopic environment around the substrates. Furthermore, it will be described that the fluctuation of solvent molecules in the solvation cluster is another important factor to trigger a chemical reaction.
- Published
- 1994
21. ChemInform Abstract: Solvent Effects and Molecular Clusters: Especially in Aqueous Organic Solvents
- Author
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Akihiro Wakisaka
- Subjects
Solvent ,Hydrophobic effect ,chemistry.chemical_compound ,Aqueous solution ,Chemistry ,Solvation ,Molecule ,General Medicine ,Solvent effects ,Photochemistry ,Acetonitrile ,Chemical reaction - Abstract
Ethanol, acetonitrile, acetone etc. are miscible with water at any mixing ratio; however, the mixtures are not homogeneous in view of the molecular level owing to the hydrogen-bonding interaction between water molecules and the hydrophobic interaction between water and organic solvent molecules. Through these interactions, molecular clusters are easy to be formed in the aqueous organic solvents. The clustering structure of the aqueous organic solvents influences the microscopic environment of substrates in these solvents and controls various chemical reactions such as the hydrolysis of tert-butyl chloride (SN1 reaction).This review will focus on the solvent effects studied in terms of the molecular clusters which reflect the microscopic environment around the substrates. Furthermore, it will be described that the fluctuation of solvent molecules in the solvation cluster is another important factor to trigger a chemical reaction.
- Published
- 2010
22. Diluted effects on n-propanol
- Author
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Seiji Kojima, Kenji Koga, Miwako Takahashi, and Akihiro Wakisaka
- Subjects
Materials science ,integumentary system ,Hydrogen ,Relaxation (NMR) ,Analytical chemistry ,chemistry.chemical_element ,Condensed Matter Physics ,Mole fraction ,Electronic, Optical and Magnetic Materials ,symbols.namesake ,Nuclear magnetic resonance ,chemistry ,symbols ,Mass spectrum ,Molecule ,Coherent anti-Stokes Raman spectroscopy ,Electrical and Electronic Engineering ,Raman spectroscopy ,Raman scattering - Abstract
Raman scattering and mass spectra of n-propanol and p-dioxane mixtures have been measured in order to study diluted effects on n-propanol. The results of both high frequency Raman spectra and mass spectra show the rapid decrease of clusters of hydrogen bonded molecules with decreasing n-propanol mole fractions ( x np ). In the low frequency Raman spectra, line shapes were analyzed using the mode coupling theory. It is found that the minimum frequency of the imaginary part of dynamic susceptibility, ω min , becomes lower with decreasing x np . These concentration dependencies suggest a strong relation between the slow structural relaxation and the network structure of molecules in n-propanol.
- Published
- 1996
23. Continuous dispersion and size control of gas-phase fullerene C60 particles using a simple method
- Author
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M. Tamiya, Fumiyuki Ito, T. Iwakami, Akihiro Wakisaka, and Hitomi Kobara
- Subjects
Fullerene ,Chemistry ,Heat balance ,Biomedical Engineering ,Analytical chemistry ,Chemical modification ,Bioengineering ,Condensed Matter Physics ,Cavity ring-down spectroscopy ,Scanning mobility particle sizer ,Molecule ,General Materials Science ,Sublimation (phase transition) ,Spectroscopy - Abstract
C 60 aggregates generated by sublimation were characterised using scanning mobility particle sizer (SMPS) and cavity ring-down (CRD) spectroscopy. Sublimation under dried nitrogen atmosphere resulted in aggregates with a mode diameter ranging from 30 to 60 nm. The authors found the size reduction of the aggregates upon humidification of the carrier gas. CRD spectroscopy enabled on-line monitoring of C 60 structure that composed particles and showed no chemical modification of the sublimation product in the presence of water molecules. The authors concluded that the heat balance was modified in the presence of water, thereby the size of the aggregates was reduced.
- Published
- 2010
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