217 results on '"Hiroatsu Matsuura"'
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2. Molecular Conformation and Melting Behavior of Alkyl/Oligo(oxyethylene)/Alkyl Triblock Position Isomers: Effect of the Position of an Oligo(oxyethylene) Block
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Koichi Fukuhara, Hiroatsu Matsuura, and Hirotaka Kumamoto
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chemistry.chemical_classification ,Infrared spectroscopy ,Crystal structure ,Block (periodic table) ,Surfaces, Coatings and Films ,Crystallography ,Differential scanning calorimetry ,chemistry ,Metastability ,Polymer chemistry ,Materials Chemistry ,Melting point ,Molecule ,Physical and Theoretical Chemistry ,Alkyl - Abstract
The molecular conformation and melting behavior of triblock position isomers H(CH(2))(k)(OCH(2)CH(2))(4)O(CH(2))(12)(-)(k)H (abbreviated as C(k)E(4)C(12)(-)(k)) with k = 6-11 have been studied by infrared spectroscopy and differential scanning calorimetry (DSC), with focus on the effect of the position of an oligo(oxyethylene) block in the molecule. The analysis of infrared spectra has revealed that the stable molecular form changes from a fully planar structure (gamma form) to a planar/helical/planar structure (beta form) with a change of the position of the tetrakis(oxyethylene) block from the center to the end of the molecule. The DSC measurements have shown that the melting points of the gamma-form solid decrease and the melting points of the beta-form solid increase with a shift of the tetrakis(oxyethylene) block toward the terminal of the molecule. The stabilities of the two molecular forms change over between k = 8 and 9. C(8)E(4)C(4) and C(9)E(4)C(3) exhibit contrasting conformational behavior with temperature; when the temperature is increased, the metastable beta form of C(8)E(4)C(4) transforms into the stable gamma form, while the metastable gamma form of C(9)E(4)C(3) transforms into the stable beta form. The metastable gamma form with a planar oligo(oxyethylene) block is a new finding in the present work. The experimental results of the stabilities of molecular forms are explained by the relative stabilities of partial crystal lattices formed by the alkyl and oligo(oxyethylene) blocks.
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- 2006
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3. Raman spectra and conformational analyses for a series of diethyl ether and its organosilicon derivatives, CH3MH2OM′H2CH3 (M, M′=C and Si), by density functional theory
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Keiichi Ohno, Hiroatsu Matsuura, Koichi Kawasaki, Keijiro Taga, Yasushi Yamamoto, and Tadayoshi Yoshida
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Organic Chemistry ,Ether ,Analytical Chemistry ,Inorganic Chemistry ,symbols.namesake ,chemistry.chemical_compound ,chemistry ,Computational chemistry ,Metastability ,symbols ,Molecule ,Physical chemistry ,Density functional theory ,Diethyl ether ,Raman spectroscopy ,Conformational isomerism ,Spectroscopy ,Organosilicon - Abstract
The molecular structures of a series of diethyl ether and its organosilicon derivatives of CH 3 MH 2 OM′H 2 CH 3 (M, M′=C and Si) have been studied by Raman spectroscopy and density functional theory (DFT) with the B3LYP/6-31G* and 6-311+G** methods. Raman spectra for these molecules were measured in the liquid and solid states. Normal vibrations and calculated Raman spectra were also obtained by using the Raman activities and the scaled wavenumbers from the B3LYP/6-311+G** method. For diethyl ether, CH 3 CH 2 OCH 2 CH 3 , the trans – trans ( TT ) and trans – gauche ( TG ) forms were the stable conformers in the liquid state, while only the TT form existed in the solid state. Additionally, two solid states were obtained and the conformer in both the stable and metastable solids was the TT . For bis(methylsilyl) ether, CH 3 SiH 2 OSiH 2 CH 3 , geometry optimization and the DFT calculation showed that only the TT and skew – skew ( SS ) forms existed in the liquid state and the SS form existed in the solid state. While, for ethyl methylsilyl ether, CH 3 CH 2 OSiH 2 CH 3 , the TT , TG and GT forms coexisted in the liquid state and only the TT form existed in the solid state.
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- 2006
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4. Chain-length-dependent conformational transformation and melting behaviour of alkyl/oligo(oxyethylene)/alkyl triblock compounds: α-octyl-ω-octyloxyoligo(oxyethylene)s
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Koichi Fukuhara, Takahiro Mizawa, Hiroatsu Matsuura, Kyriakos Viras, Hirotaka Kumamoto, Tomohiro Inoue, and Yoshihide Terai
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chemistry.chemical_classification ,Materials science ,Intermolecular force ,General Physics and Astronomy ,Infrared spectroscopy ,Crystallography ,Differential scanning calorimetry ,Planar ,chemistry ,Phase (matter) ,Intramolecular force ,Polymer chemistry ,Melting point ,Physical and Theoretical Chemistry ,Alkyl - Abstract
The chain-length-dependent conformational transformation and the melting behaviour of triblock compounds alpha-octyl-omega-octyloxyoligo(oxyethylene)s, H(CH2)8(OCH2CH2)mO(CH2)8H (abbreviated as C8EmC8) (m = 1-8), have been studied by infrared spectroscopy and differential scanning calorimetry. The compounds with m = 1-5 assume the all-trans planar form (gamma-form) in the solid state, while those with m = 7 and 8 assume the planar/ helical/planar form with conformational defects in the alkyl chain (beta'-form). Conformational polymorphism was observed for C8E6C8: the gamma-form for the annealed solid and the planar/helical/planar form without conformational defects (beta-form) for the unannealed solid. The conformational transformation from the planar form into the planar/helical/planar form takes place at a length of the oligo(oxyethylene) chain m = 6. This result for C8EmC8 and a similar conformational transformation for C6EmC6 at m = 5 (previous work) demonstrate that the conformation of the CnEmCn triblock compounds in the solid state is determined by intramolecular conformational restoring force in the central oligo(oxyethylene) block, intermolecular dipole-dipole interaction of the C-O bonds and intermolecular packing force in the end alkyl blocks. The melting points of the gamma-form solid of C8EmC8 are much lower than the melting points of n-alkanes with similar molecular masses. The observed thermodynamic quantities show that the planar structure of the oligo(oxyethylene) chain is stabilized by the force of the magnitude that maintains the rotator phase of n-alkanes. For the beta'-form solid of C8EmC8, the alkyl blocks, which are partially noncrystalline, and the oligo(oxyethylene) block melt together at the melting point, unlike the beta-form solid of C6EmC6, for which the melting of the alkyl blocks takes place before the melting of the oligo(oxyethylene) block. The beta-form solid of C8E6C8 (unannealed) melts via the gamma-form solid.
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- 2005
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5. Raman spectroscopic study of the hydration of short-chain poly(oxyethylene)s C 1EnC 1 (n=1−4)
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Georgi P. Georgiev, Nikolay Goutev, Mircho Georgiev, Tatiana Popova, Zhorro S. Nickolov, and Hiroatsu Matsuura
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Mole ratio ,Aqueous solution ,Ether oxygen ,Hydrogen bond ,Ether ,General Chemistry ,hydrogen bonding ,Chemistry ,chemistry.chemical_compound ,symbols.namesake ,raman spectroscopy ,chemistry ,hydrophobic hydration ,Raman band ,Polymer chemistry ,Materials Chemistry ,symbols ,short-chain poly(oxyethylene)s ,Molecule ,Physical chemistry ,Raman spectroscopy ,QD1-999 - Abstract
The hypothesis that the degree of hydration of poly(oxyethylene) (POE) in aqueous solution depends on the mole ratio of water molecules to ether oxygen atoms in the molecule has been verified by studying the isotropic Raman spectra in the O−H stretching region for four short-chain POEs (C 1E n C 1 withn=1−4). Excellent coincidence of the O−H stretching Raman band for all four POEs studied in the range of mole ratio H2O/O ether from 25 to 0.6 was observed, thus confirming the assumption stated above. A conclusion that all ether oxygen atoms in the POE molecule participate in hydrogen bonding with water molecules has been made.
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- 2004
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6. Relationship between force constants and bond lengths for CX (X = C, Si, Ge, N, P, As, O, S, Se, F, Cl and Br) single and multiple bonds: formulation of Badger’s rule for universal use
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Keiichi Ohno, Eiichi Kurita, and Hiroatsu Matsuura
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Force constant ,Series (mathematics) ,Period (periodic table) ,Stereochemistry ,Chemistry ,Elements ,Vibration ,Atomic and Molecular Physics, and Optics ,Analytical Chemistry ,Interpretation (model theory) ,Bond length ,Crystallography ,Models, Chemical ,Harmonic ,Wavenumber ,Density functional theory ,Instrumentation ,Spectroscopy - Abstract
Geometries and harmonic vibrational wave numbers were calculated on a series of simple compounds that contain the atoms of elements in the groups 14-17 by density functional theory at the B3LYP/6-311++G(3df,2pd) level. The calculated wave numbers agree well with the observed harmonic wave numbers with substantially the same accuracy for the compounds of the different groups. The stretching force constants of the CX (X = C, Si, Ge, N, P, As, O, S, Se, F, Cl and Br) single and multiple bonds were obtained. The CX stretching force constants increase with a decrease of the bond lengths as the element X in the same period goes from left to right in the periodic table. The individual intrinsic properties of the CX bonds are lost gradually with increasing the period of the element X. The unified interpretation of Badger's rule has enabled the formulation of a common equation for universal use f = 2.8 R(-3) to relate the force constants f (10(2) N m(-1)) and the reduced bond lengths R (10(-10) m).
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- 2004
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7. Density functional study of n-propyltrichlorogermane and n-propyltrichlorostannane
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Shigetaka Hamada, Keiichi Ohno, Yasushi Yamamoto, Hiroatsu Matsuura, Norihiro Shida, Hiroshi Yoshida, Keijiro Taga, Tadayoshi Yoshida, and Yasuomi Jibu
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Chemistry ,Organic Chemistry ,Enthalpy ,Solid-state ,Analytical Chemistry ,Inorganic Chemistry ,symbols.namesake ,Crystallography ,Liquid state ,Computational chemistry ,Atom ,symbols ,Molecule ,Density functional theory ,Raman spectroscopy ,Spectroscopy - Abstract
The IR and Raman spectra of n -propyltrichlorogermane (PTCG), CH 3 CH 2 CH 2 GeCl 3 , and n -propyltrichlorostannane (PTCS), CH 3 CH 2 CH 2 SnCl 3 , were measured in the liquid and solid states. The fundamental vibrations were assigned with the aid of a density functional theory (DFT) method using gaussian 98. For the calculation of the DFT method, the B3LYP/6-31G* and the 6-311+G** levels were used for C, H, Cl and Ge atoms and the B3LYP/CEP-31G level for Sn atom. The trans ( T ) and gauche ( G ) forms around the central C–C bond coexisted in the liquid state for both the molecules. While, the T form existed in the solid state for PTCG and the G form existed for PTCS. From the temperature dependent measurements of the Raman spectra in the liquid state, the enthalpy differences were found to be Δ H ( G − T )=0.26±0.03 kcal mol −1 with the T form being more stable for PTCG and to be Δ H ( G − T )=−0.03±0.01 kcal mol −1 with the G form being slightly stable for PTCS, respectively. However, the energy differences between the forms calculated by the DFT method showed that the T form was more stable than the G form for both the molecules.
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- 2004
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8. Chain-Length-Dependent Conformational Transformation and Melting Behavior of Alkyl/Oligo(oxyethylene)/Alkyl Triblock Compounds: α-Hexyl-ω-hexyloxyoligo(oxyethylene)s
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Hirotaka Kumamoto, Tomohiro Inoue, Hiroatsu Matsuura, Koichi Fukuhara, and Takahiro Mizawa
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chemistry.chemical_classification ,Intermolecular force ,Infrared spectroscopy ,Surfaces, Coatings and Films ,Gibbs free energy ,symbols.namesake ,Differential scanning calorimetry ,chemistry ,Intramolecular force ,Polymer chemistry ,Materials Chemistry ,Melting point ,symbols ,Molecule ,Physical and Theoretical Chemistry ,Alkyl - Abstract
The chain-length-dependent conformational transformation and melting behavior of triblock compounds α-hexyl-ω-hexyloxyoligo(oxyethylene)s, H(CH 2 ) 6 (OCH 2 CH 2 ) m O(CH 2 ) 6 H (abbreviated as C 6 E m C 6 s) (m = 1-7), have been studied by differential scanning calorimetry and infrared spectroscopy. With an increase in the number of oxyethylene units (m), the molecular form of the triblock compounds in the solid state changes from an all-trans planar form (y form) to a planar/helical/planar triblock form (β form) at m = 5. The melting points of the y form C 6 E m C 6 s are much lower than the melting points of n-alkanes with similar molecular masses. This result is interpreted as due to the higher Gibbs energy of crystal for C 6 E m C 6 s. The observed thermodynamic quantities indicate that the planar structure of the oligo(oxyethylene) chain is stabilized by the force of the magnitude that maintains the rotator phase of n-alkanes. The /3-form C 6 E m C 6 s melt stepwise through a solid-solid transition, at which the melting of only the alkyl blocks of the molecule occurs. The alkyl chains in the β-form C 6 E m C 6 s are loosely packed in the crystal even below the solid-solid transition temperature, while the crystallinity of the oligo(oxyethylene) block is significantly high. The molecular form of the alkyl/oligo(oxyethylene)/alkyl triblock compounds in the solid state is determined by the balance of the intramolecular conformational restoring force in the central oligo(oxyethylene) block and the intermolecular packing force in the end alkyl blocks. The conformational restoring force results from a tendency of the oligo(oxyethylene) chain to resume its intrinsic helical structure.
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- 2003
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9. Quantum chemical calculations and vibrational analysis of compounds containing carbon–phosphorus multiple and single bonds
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Shingo Matsumoto, Yuichiro Tomonaga, Keiichi Ohno, Hiroatsu Matsuura, and Eiichi Kurita
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Quantum chemical ,Infrared ,Chemistry ,Phosphorus ,chemistry.chemical_element ,Condensed Matter Physics ,Biochemistry ,Bond length ,Crystallography ,Deuterium ,Computational chemistry ,Single bond ,Wavenumber ,Physical and Theoretical Chemistry ,Carbon - Abstract
Quantum chemical calculations (MP2 and B3LYP methods) and vibrational analysis were performed on the compounds that contain carbon–phosphorus multiple and single bonds: HCP, FCP, ClCP, CH3CP, (CH3)3CCP, CH2PCl, CF2PH, CF2PCF3, CH3PCl2, CF3PH2 and their deuterated species. The calculations gave vibrational wavenumbers in good agreement with the observed wavenumbers. The stretching modes of the carbon–phosphorus bonds are apt to couple with other modes, giving relevant infrared and Raman bands in extensive wavenumber ranges. The intrinsic CP, CP and C–P stretching wavenumbers are estimated to be around 1250, 980 and 700 cm−1, respectively. The calculated values (B3LYP method) of the stretching force constants for the CP and CP bonds, 915–987 and 512–598 N m−1, are roughly three and two times, respectively, the values for the single bond, 266–284 N m−1. The relationship between the stretching force constants f (N m−1) and the bond lengths r (10−10 m) for the carbon–phosphorus multiple and single bonds is represented by f=2.9×102/(r−0.87)3.
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- 2003
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10. Infrared spectroscopic study of conformational properties of a short-chain poly(oxyethylene) (C1E3C1) complexed with lithium halides in water
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Shaheda A. Wahab, Hiroatsu Matsuura, and Md. Ruhul Matin
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Stereochemistry ,Chemistry ,Infrared ,Organic Chemistry ,Halide ,chemistry.chemical_element ,Infrared spectroscopy ,Ether ,Analytical Chemistry ,Ion ,Inorganic Chemistry ,Molecular dynamics ,Crystallography ,chemistry.chemical_compound ,Molecule ,Lithium ,Spectroscopy - Abstract
The conformation of a short-chain poly(oxyethylene), CH 3 (OCH 2 CH 2 ) 3 OCH 3 (C 1 E 3 C 1 ), complexed with LiX (X Cl or Br) in water was studied by infrared spectroscopy. The effects of the cation and the anion on the conformation were examined on the basis of the observed spectra, in conjunction with reported molecular dynamics simulations and a proposed hydration structure model for ions. The cation Li + is coordinated to ether oxygens, resulting in disruption of the hydration structure favorable for C 1 E 3 C 1 molecules to be incorporated, and the anions Cl − and Br − break water structure, resulting in unfavorable hydration of C 1 E 3 C 1 with water. The anion Cl − alters the conformation of C 1 E 3 C 1 to a greater degree than Br − . The cation and the anion likewise distort the favorable conformation ( gauche for the C–C bond and trans for the C–O bond) of POE in water.
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- 2003
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11. A Combined Raman and Deuterium NMR Spectroscopic Study on the Molecular and Phase Structure of a Nonionic Surfactant C12E5−Water System
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Akimitsu Tonegawa, Tsutomu Okuda, Hiroatsu Matsuura, Keiichi Ohno, and and Koji Yamada
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Deuterium NMR ,symbols.namesake ,Materials science ,Phase (matter) ,Materials Chemistry ,symbols ,Organic chemistry ,Physical chemistry ,Nonionic surfactant ,Physics::Atomic Physics ,Physical and Theoretical Chemistry ,Raman spectroscopy ,Surfaces, Coatings and Films - Abstract
A combined C−D stretching Raman and deuterium NMR spectroscopic method was applied to a study of the molecular and phase structure of the C12E5−water system, where C12E5 denotes a nonionic surfacta...
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- 2002
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12. Conformational stabilities of 1-methoxy-2-(methylthio)ethane and relevant intramolecular CH⋯O interaction studied by matrix-isolation infrared spectroscopy and density functional calculations
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Keiichi Ohno, Hiroatsu Matsuura, Hiroshi Yoshida, and Takanori Harada
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Chemistry ,Matrix isolation ,General Physics and Astronomy ,Infrared spectroscopy ,Bond length ,Crystallography ,symbols.namesake ,Computational chemistry ,Molecular vibration ,Intramolecular force ,symbols ,Molecule ,Physical and Theoretical Chemistry ,van der Waals force ,Conformational isomerism - Abstract
Conformational stabilities of 1-methoxy-2-(methylthio)ethane were studied by matrix-isolation infrared spectroscopy, and the relevant intramolecular 1,5-CH⋯O interaction was examined by density functional calculations. The conformer with trans–trans–gauche± around the CH3O–CH2–CH2–SCH3 bonds is the most stable in an argon matrix and the conformer with trans–gauche±–gauche∓ is the second most stable. The energy difference between the two conformers was determined to be 0.7±0.4 kJ mol −1 using thermal effusive sources. The 1,5-CH⋯O interaction is responsible for the high stability of the trans–gauche±–gauche∓ conformer, since the nonbonded (C)H⋯O distance associated with this interaction is shorter than the corresponding van der Waals separation by 0.15 A. The energy of the 1,5-CH⋯O interaction was evaluated to be 4.0 kJ mol −1 .
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- 2002
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13. Deuterium NMR and Raman Spectroscopic Studies on Conformational Behavior of Lipophilic Chains in the C12E3 / Decane / Water System
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Tsutomu Okuda, Koji Yamada, Akimitsu Tonegawa, Takashi Masuda, Keiichi Ohno, Hiroatsu Matsuura, and Ayako Michiue
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chemistry.chemical_classification ,Deuterium NMR ,Phase transition ,Ternary numeral system ,General Physics and Astronomy ,Decane ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,Pulmonary surfactant ,symbols ,Organic chemistry ,Molecule ,Physical chemistry ,Physical and Theoretical Chemistry ,Raman spectroscopy ,Mathematical Physics ,Alkyl - Abstract
The order parameter and the conformations of the lipophilic chains in the C12E3 / decane / water ternary system have been studied by deuterium NMR and C-D stretching Raman spectroscopy. The order parameter and the trans fraction of the C-C bond of decane molecules decrease steadily or remain nearly constant with increasing decane concentration without noticeable changes at the phase transitions. On addition of decanemolecules to the C12E3 /water system, the effective volume of the lipophilic part of a single surfactant molecule increases as a result of the penetration of the added decane molecules into the lipophilic layer, leading to a high mobility of the alkyl chain. To minimize the resulting increase in the effective cross-sectional area of a surfactant molecule, the molecular chains of the surfactant reorient remarkably in the concentration region near the phase transitions, and the shape of the self-organizing structure changes to the one with a larger packing parameter.
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- 2002
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14. Vibrational spectra and density functional study of propylgermane
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Keijiro Taga, Hiroshi Yoshida, Keiichi Ohno, Hideto Fukui, Hiroatsu Matsuura, and Shigetaka Hamada
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Chemistry ,Organic Chemistry ,Enthalpy ,Solid-state ,Analytical chemistry ,Infrared spectroscopy ,Analytical Chemistry ,Inorganic Chemistry ,symbols.namesake ,Liquid state ,symbols ,Density functional theory ,Raman spectroscopy ,Spectroscopy ,Basis set ,Vibrational spectra - Abstract
Raman and infrared spectra of propylgermane, CH3CH2CH2GeH3, and its Ge-deuterated analog, CH3CH2CH2GeD3, were investigated in their gaseous, liquid and solid states. The normal coordinate treatment was carried out by density functional theory (DFT) calculation, using B3LYP/6-31G∗ and 6-311++G∗∗ basis sets, and the corresponding fundamental vibrations were assigned. The trans (T) and gauche (G) forms around the central C–C bond coexisted in the gaseous and liquid states and only the T form existed in the solid state. From the temperature dependent measurements of the Raman spectra in the liquid state, the enthalpy difference was found to be Δ H(T−G)=−0.36±0.02 kcal mol −1 with the T form being more stable. The energy differences between the isomers obtained by DFT calculations were Δ E(T−G)=−0.46 kcal mol −1 and Δ E(T−G)=−0.87 kcal mol −1 by the 6-31G∗ basis set and 6-311++G∗∗ basis set, respectively.
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- 2002
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15. Raman spectroscopic study of temperature dependence of water structure in aqueous solutions of a poly(oxyethylene) surfactant
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Hiroatsu Matsuura and Vladimir S. Marinov
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Aqueous solution ,Component (thermodynamics) ,Liquid crystalline ,Chemistry ,Organic Chemistry ,Inorganic chemistry ,Atmospheric temperature range ,Analytical Chemistry ,Inorganic Chemistry ,symbols.namesake ,Pulmonary surfactant ,Phase (matter) ,Thermal ,symbols ,Physical chemistry ,Raman spectroscopy ,Spectroscopy - Abstract
The temperature dependence of the water structure in aqueous solutions of a poly(oxyethylene) surfactant C 12 E 5 was examined at concentrations 0, 20, 30, 45, 70 and 90 wt% by Raman spectroscopy of the O–H stretching band. The ratio of the intensities of the component around 3200 cm −1 (the collective in-phase O–H stretching vibrations of bonded aggregates) to the component around 3400 cm −1 (the O–H stretches in which the phase relations are lost) was monitored in the temperature range from 0 to 39 °C. The results show that the speed of the thermal destruction of the H-bond network increases as the concentration increases from 0 to 45 wt%. This change is attributed to the existence of a substantial amount of water in the system that takes part in the hydrophobic hydration of the poly(oxyethylene) headgroups, despite their predominantly hydrophilic character. The conclusion that this kind of water, which is known to have restricted mobility, plays an important role in the surfactant–water systems is consistent with the high viscosity of the liquid crystalline phases.
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- 2002
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16. A New Approach to Vibrational Analysis of Large Molecules by Density Functional Theory: Wavenumber-Linear Scaling Method
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Kumi Takeda, Hiroshi Yoshida, and Akito Ehara, Hiroatsu Matsuura, and Junko Okamura
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Chemistry ,Anharmonicity ,Diatomic molecule ,Molecular physics ,Ion ,Physics::Fluid Dynamics ,Computational chemistry ,Normal mode ,Linear scale ,Wavenumber ,Density functional theory ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Nonlinear Sciences::Pattern Formation and Solitons ,Scaling - Abstract
Normal vibration calculations were performed on 164 basic organic and inorganic compounds by the density functional method of B3LYP/6-311+G** using the wavenumber-linear scaling (WLS) method, in which essentially only one parameter is involved for the whole wavenumber region. The average deviation of the WLS-scaled calculated wavenumbers from the observed wavenumbers for a total of 1223 normal modes was 3.4%. The present results and the previous results on 205 compounds have shown the high performance of the WLS method in vibrational analysis of a variety of compounds. The effect of anharmonicity on the observed wavenumbers was examined on the basis of the calculated wavenumbers for 224 diatomic molecules and ions in comparison with their experimental harmonic wavenumbers. The results indicate that the larger positive deviations of the unscaled calculated wavenumbers from the observed values at higher wavenumbers are attributed almost exclusively to the neglect of anharmonicity in the calculated wavenumbe...
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- 2002
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17. Hydrogen Bonding in Concentrated Aqueous Solutions of 1,2-Dimethoxyethane: Formation of Water Clusters
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Nikolay Goutev, Zhorro S. Nickolov, and Hiroatsu Matsuura
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Aqueous solution ,Hydrogen bond ,Photochemistry ,Decomposition ,Spectral line ,Dimethoxyethane ,chemistry.chemical_compound ,symbols.namesake ,Monomer ,chemistry ,symbols ,Physical chemistry ,Molecule ,Physical and Theoretical Chemistry ,Raman spectroscopy - Abstract
The hydrogen bonding in concentrated aqueous solutions of 1,2-dimethoxyethane was studied by Raman spectroscopy of the O−H stretching band of water at various concentrations in the temperature range 218−315 K. The isotropic Raman spectra were analyzed by band decomposition, and two major components were identified in the spectra. They were assigned to the O−H stretching vibrations of water monomers and water molecules participating in clusters, respectively. The following picture of the hydration structure in the solutions emerged. Water molecules in concentrated aqueous solutions of 1,2-dimethoxyethane can exist in two stable configurationseither participating in water clusters enclosed in cavities of 1,2-dimethoxyethane molecules, or as monomers bridging ether oxygen atoms. The clustering of water is driven by the cooperative strengthening of the hydrogen bonds in the clusters. The clusters and the cavities are mutually stabilized by the extensive hydrogen bonding, and the size of the clusters is almost...
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- 2001
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18. IR spectroscopic study of conformational properties of a short-chain poly(oxyethylene) (C1E3C1) in binary mixtures with liquids of different hydrogen-bonding abilities
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Shaheda A. Wahab and Hiroatsu Matsuura
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chemistry.chemical_classification ,Chloroform ,Hydrogen bond ,Stereochemistry ,General Physics and Astronomy ,Infrared spectroscopy ,Ether ,Polymer ,Bond order ,chemistry.chemical_compound ,Crystallography ,chemistry ,Molecule ,Methanol ,Physical and Theoretical Chemistry - Abstract
The conformational properties of a short-chain poly(oxyethylene), CH3(OCH2CH2)3OCH3 (C1E3C1), in binary mixtures with water, methanol, chloroform, N,N-dimethylformamide and carbon tetrachloride have been studied by IR spectroscopy. The changes in the conformation populations of the C–C and C–O bonds of C1E3C1 with varying composition were examined by observing relative intensities of the conformation key bands. The results of the spectral analysis show that the conformational changes around the C–C bond depending on the properties of the added liquid are much larger than those around the C–O bond. Hydrogen bonding between the ether oxygens of the POE chain and the second component liquid dominates over electrostatic interactions in stabilizing the gauche conformation around the C–C bond. The magnitudes of the gauche preference of the C–C bond in the hydrogen-bonding liquids are well correlated with their hydrogen bond acidities. It is suggested that the stability of the gauche conformation around the major C–C bond in hydrogen-bonding liquids is reinforced by the trans conformation around the minor C–O bond. Most of the unusual properties of POE are closely related to the conformational flexibility of the polymer chain, or more specifically the conformational flexibility of the C–C bond.
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- 2001
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19. Raman Spectroscopic Study of Water Structure in Aqueous Nonionic Surfactant Solutions
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Vladimir S. Marinov, Hiroatsu Matsuura, and and Zhorro S. Nickolov
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Aqueous solution ,Chemistry ,Isotropy ,Analytical chemistry ,Polarization (waves) ,Isothermal process ,Surfaces, Coatings and Films ,Condensed Matter::Soft Condensed Matter ,symbols.namesake ,Pulmonary surfactant ,Lamellar phase ,Materials Chemistry ,symbols ,Physical and Theoretical Chemistry ,Anisotropy ,Raman spectroscopy - Abstract
Water structure in aqueous solutions of two poly(oxyethylene) surfactants, C12E5 and C12E6, were studied by Raman spectroscopy in the whole range of concentrations. A method based on recording Raman spectra with polarization rotated to 60° with respect to the excitation light was used, allowing one to follow isothermal paths that intersect phases with different polarization properties, viz., the micellar solution phase (isotropic), lamellar phase (anisotropic), and reverse micellar solution phase (isotropic). Besides the O−H stretching band, the conformational bands of the oxyethylene groups were measured to evaluate the dehydration process of the hydrophilic headgroups of the surfactant. The results showed that the behavior of the water structure outlines three main concentration regions, which closely coincide with the three phases intersected by the experimental isotherms. In the micellar solution phase, no significant changes of the water structure are indicated, while, in the lamellar phase, rapid de...
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- 2001
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20. Hydrogen Bonding in Chloroform Solutions of Ethylenedioxy Ethers. Spectroscopic Evidence of Bifurcated Hydrogen Bonds
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Hiroatsu Matsuura and Nikolay Goutev
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Chloroform ,Hydrogen ,Hydrogen bond ,chemistry.chemical_element ,Ether ,Deuterated chloroform ,Photochemistry ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,Molecule ,Physical and Theoretical Chemistry ,Equilibrium constant ,Ethylenedioxy - Abstract
Chloroform solutions of 1,4-dioxane, 1,2-dimethoxyethane, and diethylene glycol dimethyl ether were studied by means of IR absorption spectroscopy. The intensity of the C−D stretching band of a small amount of deuterated chloroform added to the solutions was used as a probe of the strength of hydrogen bonding between the ethers and chloroform. A two-component model, which assumes that the chloroform molecules can be classified as hydrogen bonded and non-hydrogen bonded, was used to interpret the variations of the intensity of the C−D stretching band on changing the concentration of chloroform. In the frame of this model, the hydrogen bonding was considered as a chemical reaction between the lone electron pairs of the ether oxygens and the chloroform molecules. As a result, the equilibrium constant of hydrogen bonding was estimated and the stoichiometry of the hydrogen bonded complexes of ethers and chloroform was revealed. It was found that the lone electron pairs of the ether oxygens do not participate e...
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- 2001
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21. Implications of Intramolecular OH···Se Hydrogen Bonding and CH···O Interaction in the Conformational Stabilization of 2-(Methylseleno)ethanol Studied by Vibrational Spectroscopy and Density Functional Theory
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and Keiichi Ohno, Takanori Harada, Hiroatsu Matsuura, Jian Zhang, and Michio Iwaoka, Hiroshi Yoshida, and Shuji Tomoda
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Ethanol ,Argon ,Chemistry ,Hydrogen bond ,Infrared spectroscopy ,chemistry.chemical_element ,Photochemistry ,chemistry.chemical_compound ,Crystallography ,Intramolecular force ,Molecule ,Density functional theory ,Physical and Theoretical Chemistry ,Conformational isomerism - Abstract
The conformational stability of 2-(methylseleno)ethanol has been studied by vibrational spectroscopy and density functional theory. In an argon matrix, the molecules assume primarily the gauche±−gauche±−gauche∓ (GGg‘) and gauche∓−gauche±−gauche∓ (G‘Gg‘) conformations around the CH3Se−CH2−CH2−OH bonds, being consistent with the theoretical energies of the conformers. The GGg‘ and G‘Gg‘ conformers are stabilized by intramolecular OH···Se hydrogen bonding. The conformational stabilization energy by this hydrogen bonding was estimated by density functional calculations as 14.5 kJ mol-1, which is substantially the same as the corresponding energies for OH···O and OH···S hydrogen bonding. These experimental and theoretical results show that intramolecular OH···Se hydrogen bonding is as strong as OH···O and OH···S hydrogen bonding. An additional intramolecular CH···O interaction with its stabilization energy 5.6 kJ mol-1 stabilizes the G‘G conformation around the CH3Se−CH2−CH2OH bonds. The spectral observation t...
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- 2001
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22. Vibrational spectroscopic and theoretical calculation studies on conformational behavior of simple sodium 1-alkanesulfonates
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Keiichi Ohno, H Tamaoki, Hiroatsu Matsuura, Hiroshi Yoshida, and M Fukuda
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Aqueous solution ,Chemistry ,Sodium ,Organic Chemistry ,Enthalpy ,chemistry.chemical_element ,Analytical Chemistry ,Ion ,Inorganic Chemistry ,symbols.namesake ,Crystallography ,Computational chemistry ,symbols ,Molecule ,Hydrate ,Raman spectroscopy ,Conformational isomerism ,Spectroscopy - Abstract
The conformational behavior of sodium 1-propanesulfonate and sodium 1-butanesulfonate has been studied in the solid state and in aqueous solution by Raman spectroscopy and theoretical calculations. For sodium 1-butanesulfonate, the molecules of the anhydride and the hydrate crystallize in two different conformations. The characteristic C–S stretching bands were observed at 790–805 cm −1 for the trans (T) conformation around the CC–CS bond and at 728–766 cm −1 for the gauche ± (G ± ) conformation. The enthalpy difference between the G ± and T conformers of 1-propanesulfonate ion, H G ± − H T , was obtained as 4.3±0.4 kJ mol −1 in aqueous solution, while the energy difference between these conformations was calculated as 3.07, −0.41 and 0.02 kJ mol −1 by the HF, MP2 and B3LYP methods, respectively, using the 6-31G ∗∗ basis set. The inconsistency of the conformational stability between the experimental and theoretical results was discussed. The relationship between the isolated C–D stretching wavenumbers and the conformations around the CC–C(D)–CSO 3 − bonds is used to determine the local conformation.
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- 2000
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23. Raman Spectroscopic Study on the Conformation of 1,2-Dimethoxyethane in the Liquid Phase and in Aqueous Solutions
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Nikolay Goutev, Hiroatsu Matsuura, and and Keiichi Ohno
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Aqueous solution ,Chemistry ,Analytical chemistry ,Liquid phase ,Decomposition ,Dimethoxyethane ,chemistry.chemical_compound ,symbols.namesake ,Phase (matter) ,symbols ,Wavenumber ,Physical and Theoretical Chemistry ,Raman spectroscopy ,Conformational isomerism - Abstract
The conformation of 1,2-dimethoxyethane in the liquid phase and in aqueous solutions was studied by Raman spectroscopy. The conformation-sensitive Raman bands of 1,2-dimethoxyethane, located in the wavenumber region 300−600 cm-1, were analyzed by means of the band decomposition based on normal coordinate analysis. The populations of the conformers of 1,2-dimethoxyethane, their relative energies, and their relative entropies in the liquid phase were estimated and compared with the relevant data for the gas phase of 1,2-dimethoxyethane. The condensed phase effects on the conformation of 1,2-dimethoxyethane were discussed on the basis of the experimental data. The populations of the conformers at 318 K in aqueous solutions with different concentrations were estimated. It was revealed that the populations of the TTT and TGG‘ conformers of 1,2-dimethoxyethane decrease on increasing concentration of water, while the populations of the TGT and TGG conformers increase. The entropies of the less hydrophilic TTT an...
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- 2000
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24. Density functional vibrational analysis using wavenumber-linear scale factors
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Hiroatsu Matsuura, Akito Ehara, and Hiroshi Yoshida
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Computational chemistry ,Chemistry ,Vibrational partition function ,Molecular vibration ,Linear scale ,General Physics and Astronomy ,Wavenumber ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,London dispersion force ,Molecular physics ,Scaling - Abstract
Normal coordinate calculations were performed by the density functional method of B3LYP/6-311+G ∗∗ on 205 basic organic and inorganic compounds taken from the `Tables of Molecular Vibrational Frequencies' (T. Shimanouchi, 1972). The calculated wavenumbers, νcalc, of 1729 vibrational modes were correlated with the observed wavenumbers, νobs, by a single least-squares fitting. The relationship obtained, after omitting the vibrational modes that give deviations of more than 10%, is νobs/νcalc=1.0087−0.0000163 (νcalc/cm−1). The wavenumber-linear scaling method with this relationship predicts vibrational wavenumbers with high accuracy and is applicable to any compounds, except for the compounds for which the effect of dispersion forces is significant.
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- 2000
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25. Block crystallization effect on the conformation of triblock oligomers α-n-alkyl-ω-n-alkoxyoligo(oxyethylene)s in the solid state
- Author
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Koichi Fukuhara, K Takayama, K Hashiwata, and Hiroatsu Matsuura
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chemistry.chemical_classification ,Chemistry ,Organic Chemistry ,Solid-state ,Infrared spectroscopy ,Liquid nitrogen ,Block (periodic table) ,Analytical Chemistry ,law.invention ,Inorganic Chemistry ,Crystallinity ,Chain (algebraic topology) ,law ,Polymer chemistry ,Crystallization ,Spectroscopy ,Alkyl - Abstract
The IR spectra of triblock oligomers α- n -alkyl-ω- n -alkoxyoligo(oxyethylene)s, C 6 E m C 6 ( m =6–8), C 8 E m C 8 ( m =6–8) and C 10 E m C 10 ( m =1–8), were measured in the solid state at liquid nitrogen temperature, and the crystallinity and conformational behavior with changing block chain length was studied. The results of the spectral analysis showed that the solid of the C n E m C n compounds with n ≳ m is crystalline and the molecular form is definitive, while the alkyl block in the compounds with n ≲ m is partially crystalline or noncrystalline and contains conformational defects such as end- gauche and kink. The crystallinity and conformational properties of the C n E m C n compounds are elucidated in terms of rate of crystallization of the constituent blocks. If the oxyethylene block crystallizes faster than the alkyl block, the alkyl chain deforms with formation of conformational defects to fit in the void formed by the helical oxyethylene chain. If the crystallization of the alkyl block takes place faster, on the other hand, the oxyethylene chain assumes an all- trans planar conformation with a cross-sectional area similar to that for the alkyl chain.
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- 2000
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26. Density functional vibrational analysis of N-methylthiourea and three deuterated analogues
- Author
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Hiroshi Yoshida, K. Nabesaka, Hiroatsu Matsuura, Y. Mido, and A. Miwa
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N-methylthiourea ,Deuterium ,Electronic correlation ,Chemistry ,Computational chemistry ,Intermolecular force ,Ab initio ,Molecular orbital theory ,Density functional theory ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Biochemistry ,Scaling - Abstract
The vibrational analysis using various methods of density functional theory (DFT) as well as molecular orbital theory has been performed on undeuterated and three deuterated analogues of N -methylthiourea (CH 3 NHCSNH 2 , CH 3 NDCSND 2 , CD 3 NHCSNH 2 and CD 3 NDCSND 2 ). The ab initio methods including electron correlation excellently reproduced without any empirical scaling the observed wavenumbers in the region where intermolecular interactions are not important. The observed wavenumber shifts due to the deuteration effect were well explained by the calculations. Among the methods of calculations used in this work, density functional theory with Becke's three-parameter exchange functional using large basis sets gave the best results of vibrational wavenumbers for the four isotopic species of N -methylthiourea.
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- 2000
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27. Vibrational spectra and normal coordinate analysis of N-methylthiourea and three deuterated analogues
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Masao Hashimoto, Yoshiyuki Mido, Hiroatsu Matsuura, and Isao Kitagawa
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Chemistry ,Analytical chemistry ,Infrared spectroscopy ,Atomic and Molecular Physics, and Optics ,Spectral line ,Analytical Chemistry ,symbols.namesake ,Crystallography ,N-methylthiourea ,Deuterium ,Scissoring ,symbols ,Molecule ,Raman spectroscopy ,Instrumentation ,Spectroscopy ,Vibrational spectra - Abstract
IR and Raman spectra of N-methylthiourea and three deuterated analogues, CH3NHCSNH2, CH3NDCSND2, CD3NHCSNH2 and CD3NDCSND2, have been studied in the solid state. A complete interpretation of the spectra has been made for the cis conformation on the basis of the N- and C-deuteration effects and of a normal coordinate analysis using the Urey–Bradley force field. The temperature dependence of the IR spectra has been studied in the 300–100 K range. At low temperatures, the NH2 scissoring vibration gives a well-defined doublet band due to the presence of two asymmetric molecules in the unit cell. Some of the overlapped bands are well separated at low temperatures.
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- 1999
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28. Conformational analysis of alkylamino chains using isolated C–D stretching vibrations
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Shin-ichiro Nomura, Hiroatsu Matsuura, Keiichi Ohno, and Hiroshi Yoshida
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Bond length ,Biological substances ,Chemistry ,Computational chemistry ,Ab initio ,Infrared spectroscopy ,Molecular orbital ,Instrumentation ,Spectroscopy ,Atomic and Molecular Physics, and Optics ,Analytical Chemistry - Abstract
The conformation of alkylamino chains has been analyzed by using isolated C–D stretching vibrations. The compounds studied are N-methylpiperidine-2,6-d2, N-ethylpiperidine-1′-d1, N-propylpiperidine-1′-d1, N-butylpiperidine-1′-d1, N,N-dimethylpentylamine-1-d1, N,N′,5,5-tetramethylhexahydropyrimidine-2-d1, N,N-dimethylbutylamine-2-d1, N,N-dimethylpentylamine-2-d1 and N,N-dimethylhexylamine-2-d1. The observed C–D stretching wavenumbers for different conformations at different positions of the alkylamino chain have been correlated linearly to the C–D bond lengths calculated by ab initio molecular orbital methods. The C–D stretching wavenumbers depend significantly on the conformation in the close vicinity of the C–D bond. Isolated C–D stretching vibrational spectroscopy has great potential for being used in conformational analysis of alkylamino chains in functional and biological substances.
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- 1999
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29. FTIR-ATR Studies of the Hydration of 15-Crown-5 and 18-Crown-6 in Aqueous Solutions
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Keiichi Ohno, Zhorro S. Nickolov, and Hiroatsu Matsuura
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chemistry.chemical_compound ,Solvation shell ,Aqueous solution ,chemistry ,15-Crown-5 ,Inorganic chemistry ,18-Crown-6 ,Molecule ,Physical chemistry ,Physical and Theoretical Chemistry ,Spectroscopy ,Decomposition ,Spectral line - Abstract
The hydration of 15-crown-5 (15C5) and 18-crown-6 (18C6) in aqueous solutions has been studied by FTIR-ATR spectroscopy. A model of decomposition of the O−H stretching band of water into four components, accounting for bound and bulk water in the solutions, has been employed in the analysis of the spectra. The dependencies of the relative areas and peak wavenumbers of the resolved components on concentration reveal similarities and differences in the hydration of the two crown ethers. The number of water molecules influenced by the hydration is ca. 18−20 for 18C6 solutions and ca. 12−15 for 15C5 solutions at sufficiently high dilutions. The immediate hydration shell for both crown ethers consists of 4−5 water molecules directly H-bonded to the crown ring. The most probable hydration structure around 18C6 is composed of two bridging water molecules and two other water molecules singly bound to the ring, while, due to differences in its conformational structure, 15C5 is hydrated mostly by singly H-bonded wa...
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- 1999
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30. Reaction of Aqueous 2-(N-Methylamino)ethanol Solutions with Carbon Dioxide. Chemical Species and Their Conformations Studied by Vibrational Spectroscopy and ab Initio Theories
- Author
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Yutaka Inoue, Hiroatsu Matsuura, Hiroshi Yoshida, and Keiichi Ohno
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Reaction mechanism ,Crystallography ,Tertiary amine ,Chemistry ,Hydrogen bond ,Intramolecular force ,Inorganic chemistry ,Ab initio ,Infrared spectroscopy ,Protonation ,Physical and Theoretical Chemistry ,Chemical reaction - Abstract
The recovery and removal of carbon dioxide from flue gases by using CO{sub 2}-amine-H{sub 2}O systems have been of fundamental interest and industrial importance in the problem of preventing global warming. The reaction systems of aqueous 2-(N-methylamino)ethanol (MAE) solutions with dissolved CO{sub 2} (CO{sub 2}-MAE-H{sub 2}O system) and of liquid MAE with dissolved CO{sub 2} (CO{sub 2}-MAE system) have been studied by vibrational spectroscopy and ab initio theories. The chemical species, molecular conformations, and intramolecular and intermolecular hydrogen bonding in these systems have been elucidated. The species produced in the CO{sub 2}-MAE-H{sub 2}O system are the carbamate anion (MAECO{sub 2}{sup {minus}}), the protonated cation (MAEH{sup +}), hydrogencarbonate ion (HCO{sub 3}{sup {minus}}), and carbonate ion (CO{sub 3}{sup 2{minus}}) while the species produced in the CO{sub 2}-MAE system are MAECO{sub 2}{sup {minus}} and MAEH{sup +}. In the CO{sub 2}-MAE-H{sub 2}O system, MAE (secondary amine) reacts with CO{sub 2} to form MAECO{sub 2}{sup {minus}} and MAEH{sup +}, and MAECO{sub 2}{sup {minus}} subsequently reacts with H{sub 2}O and CO{sub 2} to form MAEH{sup +} and HCO{sub 3}{sup {minus}}. This reaction mechanism is contrasted with the mechanism for 2-(N,N-dimethylamino)ethanol (DMAE, tertiary amine), which reacts with CO{sub 2} and H{sub 2}O to form directly DMAEH{sup +}more » and HCO{sub 3}{sup {minus}}.« less
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- 1999
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31. Vibrational Spectroscopic and ab Initio Studies on Conformations of the Chemical Species in a Reaction of Aqueous 2-(N,N-Dimethylamino)ethanol Solutions with Carbon Dioxide. Importance of Strong NH+···O Hydrogen Bonding
- Author
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Keiichi Ohno, Hiroshi Yoshida, Taiichiro Suda, Hisashi Matsumoto, Toru Iwaki, and Hiroatsu Matsuura
- Subjects
Crystallography ,Aqueous solution ,Computational chemistry ,Hydrogen bond ,Chemistry ,Intramolecular force ,Ab initio ,Molecule ,Protonation ,Molecular orbital ,Physical and Theoretical Chemistry ,Lone pair - Abstract
The process of a reaction of aqueous 2-(N,N-dimethylamino)ethanol (DMAE) solutions with carbon dioxide and the conformations of the chemical species present in the reaction system have been studied by infrared and Raman spectroscopy and ab initio molecular orbital and density functional theories. The products of the reaction are protonated ion of DMAE (DMAEH+), hydrogencarbonate ion, and carbonate ion. The DMAEH+ species in the aqueous solution assumes predominantly the G∓G±t conformation around the HN+−C−C−OH bonds. DMAEH+ in solid DMAEH+Cl- and in acidic aqueous solution also assumes the same conformation. This conformational property of DMAEH+ is contrasted with the results for the DMAE molecules in the liquid state and in aqueous solution that they assume the G∓Tx (x = t, g∓, or g±) and G∓G±g∓ conformations around the LN−C−C−OH bonds (L, lone pair). The G∓G±t conformation of DMAEH+ is stabilized by strong intramolecular 1,4-NH+···O hydrogen bonding, while the G∓Tx and G∓G±g∓ conformations of DMAE are ...
- Published
- 1998
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32. Conformational behaviour of cyclic and open-chain poly(oxyethylene) compounds in water studied by infrared spectroscopy
- Author
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Roksana Begum, Takeshi Yonemitsu, and Hiroatsu Matsuura
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Chemical substance ,Chemistry ,Hydrogen bond ,Organic Chemistry ,Infrared spectroscopy ,Ether ,Ring (chemistry) ,Photochemistry ,Analytical Chemistry ,Inorganic Chemistry ,Crystallography ,chemistry.chemical_compound ,Chain (algebraic topology) ,Molecule ,Ring geometry ,Spectroscopy - Abstract
The conformational behaviour of cyclic and open-chain poly(oxyethylene) compounds in water was studied by infrared spectroscopy. The compounds studied are 15-crown-5 [cyclo-(OCH2CH2)5], 18-crown-6 [cyclo-(OCH2CH2)6] and CH3(OCH2CH2)mOCH3 with m = 5 and 6. The conformational changes of the CC and CO bonds with varying concentration were analysed by examining the intensity ratio of the relevant conformational key bands. The analysis has shown that the gauche conformation around the CC bond for the cyclic compounds is much more stabilized in water than that for the corresponding open-chain compounds, although the conformational behaviour of the CO bond is similar for these compounds. The stronger gauche preference of the CC bond in the cyclic compounds is associated with their ring structure. The ring geometry constrains the ether oxygens in the molecule to be located in a certain spatial region, where the water molecules can favourably form concerted hydrogen bonds with these oxygens. The hydration structure is suggested to be similar to that in the crystalline hydrates of 18-crown-6.
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- 1998
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33. Hydration structure of 1,2-dimethoxyethane (C1E1C1): OH Raman band studies
- Author
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Nicolai Goutev, Zhorro S. Nickolov, and Hiroatsu Matsuura
- Subjects
Range (particle radiation) ,Hydrogen bond ,Inorganic chemistry ,Ether ,Condensed Matter Physics ,Mole fraction ,Atomic and Molecular Physics, and Optics ,Dimethoxyethane ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Crystallography ,chemistry ,Raman band ,Materials Chemistry ,Molecule ,Physical and Theoretical Chemistry ,Methylene ,Spectroscopy - Abstract
We present a study of the hydration of the short chain poly(oxyethylene) CH3OCH2CH2OCH3 (C1E1C1) in the range of concentrations up to 0.25 mole fraction (m.f.) by analyzing the parameters of the main components of the water OH stretching band at about 3200 and 3400 cm−1. Two regions of enhancement of the hydrogen bond network in the solution were detected and were attributed to different hydration structures. Around 0.04 m.f. the coordination of the water network around the C1E1C1 molecules has a local maximum due to hydrogen bonding at the sites of the ether oxygens from one side, and the hydrophobic hydration around the methylene groups and the methyl end groups, from the other. The increased local order in this hydration structure is most probably a consequence of the favourable incorporation of the oxyethylene groups of C1E1C1 molecules with gauche conformation in the water network because of their similar OO distances. The second type of hydration structure around 0.10 m.f. is attributed to the build-up of a most compact homogeneous hydrogen bond network in which C1E1C1 molecules are interconnected with direct hydrogen bonds with most water molecules. Above 0.10 m.f. the hydrogen bond network in the system is gradually destroyed. The influence of temperature on the second type of hydration structure is stronger than in the case of the first type and is expressed in a greater rate of disruption of the H-bond network
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- 1998
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34. Density Functional Study of the Conformations and Vibrations of 1,2-Dimethoxyethane
- Author
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Hiroatsu Matsuura and Hiroshi Yoshida
- Subjects
Chemistry ,Analytical chemistry ,Infrared spectroscopy ,Dimethoxyethane ,chemistry.chemical_compound ,symbols.namesake ,Physics::Atomic and Molecular Clusters ,symbols ,Physical chemistry ,Density functional theory ,Molecular orbital ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Raman spectroscopy ,Scaling ,Conformational isomerism ,Basis set - Abstract
The conformations and vibrations of 1,2-dimethoxyethane (DME) have been studied by density functional theory (DFT) in comparison with the molecular orbital (MO) methods. The calculations using the 6-31G* basis set were performed by five DFT methods (BVWN, BP86, BLYP, B3PW91, and B3LYP) and two MO methods (HF and MP2). The energies of conformers were better predicted by the DFT methods using the B3 exchange functional than other methods. The vibrational wavenumbers calculated by the DFT and MO methods explained, after correcting with uniform scaling, the observed Raman and infrared spectra of the normal and perdeuterated species of DME. It was confirmed that the conformer of DME present in the solid state is TGT, and the conformers in the liquid state are TGT, TTT, TGG‘, and TTG. The present calculations further indicated that the TGG and GGG conformers are also present in the liquid state. The distributions of the ratio of the unscaled calculated wavenumber to the experimental wavenumber are narrower with...
- Published
- 1998
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35. Chain-length dependent conformational behaviour of triblock oligomers α-octyl-ω-n-alkoxytetrakis(oxyethylene)s in the solid state studied by Raman spectroscopy
- Author
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Takeshi Yonemitsu, Sei Masatoki, Hiroatsu Matsuura, and Koichi Fukuhara
- Subjects
chemistry.chemical_classification ,Chemistry ,Organic Chemistry ,Solid-state ,Block (periodic table) ,Molecular conformation ,Analytical Chemistry ,Inorganic Chemistry ,symbols.namesake ,Crystallography ,Chain length ,Chain (algebraic topology) ,Polymer chemistry ,symbols ,lipids (amino acids, peptides, and proteins) ,Spectral analysis ,Raman spectroscopy ,Spectroscopy ,Alkyl - Abstract
The Raman spectra of triblock oligomers α-octyl-ω-n-alkoxytetrakis(oxyethylene)s, H(CH2)8(OCH2CH2)4O(CH2)nH with n = 2–7, were measured in the solid state, and the conformational behaviour with changing alkyl chain length was examined. The molecular conformations of these compounds were determined by spectral analysis based on normal coordinate calculations. The conformation changes from the extended/helical/extended form to the fully extended form with increasing alkyl chain length (n). The extended structure of the oxyethylene chain is stabilised at n ≥ 3. This experimental finding suggests that the extended structure of the oxyethylene block in the triblock compounds is stabilised by the end alkyl blocks with the length comparable to or longer than that of the oxyethylene block. The results of this study, together with those of previous studies, demonstrate that the conformation of the oxyethylene chain is affected strongly by adjoining alkyl chains.
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- 1998
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36. Infrared spectroscopic study of conformational properties of short chain poly(oxyethylene)s in methanol and carbon tetrachloride
- Author
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Tatsuya Sagawa, Hiroatsu Matsuura, Roksana Begum, and Sei Masatoki
- Subjects
Aqueous solution ,Infrared ,Hydrogen bond ,Organic Chemistry ,Infrared spectroscopy ,Dielectric ,Photochemistry ,Analytical Chemistry ,Inorganic Chemistry ,Solvent ,Crystallography ,chemistry.chemical_compound ,chemistry ,Carbon tetrachloride ,Methanol ,Spectroscopy - Abstract
Conformational properties of short chain poly(oxyethylene)s (POEs), CH 3 (OCH 2 CH 2 ) m OCH 3 with m = 1–4, in methanol and carbon tetrachloride were studied by infrared spectroscopy. The conformational changes of the CC and CO bonds of the POE chain with varying concentration were analysed by examining the intensity ratio of the relevant conformational key bands. With increasing solvent fraction, the gauche preference of the CC bond and the trans preference of the CO bond increase in methanol, while the conformational preference of these bonds in carbon tetrachloride is opposite to that in methanol. The observed conformational behaviour with varying concentration is consistent with the effects of dielectric properties of the medium, hydrogen bonding between the POE chain and the solvent, and structure of the solvent. The results for the methanol solutions are similar to those for the aqueous solutions, except for anomalous conformational preference of the CC bond in water in low-concentration regions. This peculiar phenomenon in water may be explained by specific hydration structure around the POE chain.
- Published
- 1998
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37. Spectroscopic evidence for an intramolecular C–H⋯N hydrogen bond: infrared and Raman spectroscopy and ab initio molecular orbital calculations of N,N-dimethylpropylamine and propyltrimethylammonium bromide
- Author
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Hiroatsu Matsuura, Keiichi Ohno, Akimitsu Tonegawa, and Hiroshi Yoshida
- Subjects
Steric effects ,Quantitative Biology::Biomolecules ,Chemistry ,Hydrogen bond ,Organic Chemistry ,Ab initio ,Hydrogen atom ,Photochemistry ,Analytical Chemistry ,Condensed Matter::Soft Condensed Matter ,Inorganic Chemistry ,Crystallography ,Ab initio quantum chemistry methods ,Intramolecular force ,Molecular orbital ,Physics::Chemical Physics ,Conformational isomerism ,Spectroscopy - Abstract
The infrared and Raman spectra were measured for N , N -dimethylpropylamine (DPA) in an argon matrix, the liquid and glassy states and aqueous solution, and for propyltrimethylammonium bromide (PTAB) in the solid state and aqueous solution. The ab initio molecular orbital calculations were performed on possible conformers of DPA and propyltrimethylammonium ion. In an argon matrix, the conformational stability of DPA is in the order G′G>GT>TT, which agrees with the prediction by ab initio calculations. The experimentally confirmed high stability of the G′G conformer indicates that an appreciably strong attractive interaction occurs between the methyl hydrogen atom and the nitrogen atom. This interaction may be called the intramolecular 1,4-C–H⋯N hydrogen bonding. In the liquid and glassy states, the GT conformer is the most stable. In aqueous solution of DPA, the GT and TT conformers are more stabilized than in the neat liquid, possibly because of the formation of more significant intermolecular hydrogen bonds between the nitrogen atom of DPA and water molecules. For PTAB, only the T conformer exists in the solid state, and this conformer is more stable than the G conformer in aqueous solution. The GG and TG conformers of DPA and the G conformer of PTAB are significantly less stabilized by steric repulsions between the CH 3 (N) and (C)CH 3 groups.
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- 1997
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38. The cis form of N-methylthiourea in the solid state: Raman spectroscopy, X-ray diffraction and ab initio molecular orbital calculations
- Author
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N. Fujita, I. Kitagawa, Hiroshi Yoshida, Masao Hashimoto, Yoshiyuki Mido, Hiroatsu Matsuura, H. Okada, and T. Kitahata
- Subjects
Aqueous solution ,Chemistry ,Organic Chemistry ,Solid-state ,Ab initio ,Analytical Chemistry ,Inorganic Chemistry ,symbols.namesake ,Crystallography ,X-ray crystallography ,symbols ,Proton NMR ,Molecular orbital ,Raman spectroscopy ,Conformational isomerism ,Spectroscopy - Abstract
The Raman spectra of N-methylthiourea have been studied and the conformation in solutions and in the solid state has been investigated. Prominent Raman bands are observed at about 700 and 775 cm−1 in the aqueous solution but only the latter band persists in the solid state. The normal coordinate analysis based on ab initio molecular orbital calculations has shown that the 700 cm−1 band is due to the CS stretching mode of the trans form and the 775 cm−1 band is due to the same mode of the cis form. This spectral interpretation leads to a conformational form of N-methylthiourea in the solid state to be the cis form but not the trans form as has been thought for a long time. This result was confirmed by the present X-ray structure analysis. From the temperature dependence of the relative intensities of the two CS stretching bands, in combination with the previous results of methyl proton nuclear magnetic resonance data, the cis form has been found to be more stable in solution, in agreement with the results of ab initio molecular orbital calculations.
- Published
- 1997
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39. Conformational and vibrational analyses of 2-methoxyethanol and 2-(methylthio)ethanol by density functional theory
- Author
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Takanori Harada, Hiroatsu Matsuura, and Hiroshi Yoshida
- Subjects
Hydrogen ,Hydrogen bond ,Organic Chemistry ,Ab initio ,chemistry.chemical_element ,Analytical Chemistry ,Inorganic Chemistry ,Molecular geometry ,chemistry ,Computational chemistry ,Intramolecular force ,Physical chemistry ,Density functional theory ,Conformational isomerism ,Spectroscopy ,Basis set - Abstract
Conformational and vibrational analyses were performed on 2-methoxyethanol (ME) and 2-(methylthio)ethanol (MTE) by density functional theory (DFT). The energies, molecular geometries and vibrational wavenumbers were calculated for the TGg′, GGg′, TTt and TGt conformers of ME and the GGg′, G′Gg′, TGg′ and GGt conformers of MTE (T or t: trans; G or g: gauche) by the BLYP, B3LYP and B3PW91 methods using the 6-31G∗ basis set. The calculations by the HF and MP2 methods were also carried out on the same conformers. The calculated energies are consistent with the experimental findings that the TGg′ conformer of ME and the GGg′ and G′Gg′ conformers of MTE are present in low-temperature matrix. The DFT calculations give the stabilization energy by the OH⋯S hydrogen bonding substantially the same as the energy by the OH⋯O hydrogen bonding. The vibrational wavenumbers for the TGg′ conformer of ME and the GGg′ conformer of MTE are successfully predicted by the MP2, B3LYP and B3PW91 methods using the uniform scale factors for the respective methods. The experimental large wavenumber difference between ME and MTE of the intramolecular hydrogen bonded O-H stretching vibrations is reproduced much better with the DFT calculations than with the ab initio MO calculations. The present study has shown that Becke's three-parameter exchange functional methods overall give the most accurate results.
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- 1997
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40. Raman spectroscopic study of conformational variety of triblock homologous oligomers α-n-alkyl-ω-n-alkoxyoligo(oxyethylene)s in the solid state
- Author
-
Koichi Fukuhara, Hiroatsu Matsuura, and Fumiyasu Sakogawa
- Subjects
chemistry.chemical_classification ,Chemistry ,Stereochemistry ,Organic Chemistry ,Solid-state ,Molecular conformation ,Spectral line ,Analytical Chemistry ,law.invention ,Inorganic Chemistry ,symbols.namesake ,law ,symbols ,Spectral analysis ,Crystallization ,Raman spectroscopy ,Spectroscopy ,Alkyl - Abstract
The Raman spectra of triblock homologous oligomers α- n -alkyl-ω- n -alkoxyoligo(oxyethylene)s, H(CH 2 ) n (OCH 2 CH 2 ) m O(CH 2 ) n H, with n = 3–7 and m = 1–5, were measured in the solid state, and the molecular conformations of these compounds were determined by spectral analysis based on normal coordinate calculations. The spectral features vary with changing lengths of the oxyethylene and alkyl chains. Some of the compounds exhibit two different spectra depending on the solidification conditions. The conformations of the homologous oligomers are classified roughly into two types; one is a highly extended form and the other is an extended/helical/extended triblock form. The former is relevant to the homologues with longer alkyl chains and a shorter oxyethylene chain. The conformational variety of the triblock oligomers in the solid state is explained by the conformational competition between the alkyl and oxyethylene chains, which implies competition in the local crystallization between the two different chains.
- Published
- 1997
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41. Conformational Stabilization by Intramolecular OH···S and CH···O Interactions in 2-(Methylthio)ethanol. Matrix-Isolation Infrared Spectroscopy and ab Initio MO Calculations
- Author
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Tomoko Murase, Keiichi Ohno, Takanori Harada, Hiroshi Yoshida, and Hiroatsu Matsuura
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Crystallography ,Computational chemistry ,Chemistry ,Hydrogen bond ,Intramolecular force ,Matrix isolation ,Ab initio ,chemistry.chemical_element ,Infrared spectroscopy ,Hydrogen atom ,Physical and Theoretical Chemistry ,Conformational isomerism ,Sulfur - Abstract
The conformational stability of 2-(methylthio)ethanol has been studied by matrix-isolation infrared spectroscopy and ab initio MO calculations. In an argon matrix, the conformer with gauche−gauche−gauche‘ (GGg‘) around the CS−C−C−OH bonds is the most stable and the G‘Gg‘ conformer is the second most stable. These and the TGg‘ conformers are stabilized by intramolecular hydrogen bonding between the hydroxyl hydrogen atom and the sulfur atom. The relative strength of the hydrogen bonding in these conformers is in the order GGg‘ > TGg‘ > G‘Gg‘, as estimated from the nonbonded OH···S distance. In the G‘Gg‘ conformer, an additional intramolecular interaction between the methyl hydrogen atom and the hydroxyl oxygen atom is involved. The relative strength of this 1,5-CH···O interaction in the G‘Gg‘ conformer is the least among the three relevant conformers with G‘G around the CS−C−COH bonds. The calculated results indicate that the geometry of this conformational form is considerably distorted so that it is simu...
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- 1997
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42. CyberMol-A Molecular Graphics Program System on the World Wide Web Using the Common Gateway Interface
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Hiroshi Yoshida and Hiroatsu Matsuura
- Subjects
World Wide Web ,Search engine ,symbols.namesake ,Computer science ,Computer graphics (images) ,Gaussian ,VRML ,symbols ,Common Gateway Interface ,computer.file_format ,computer ,Molecular graphics ,ComputingMethodologies_COMPUTERGRAPHICS - Abstract
CyberMol, an interactive molecular graphics program system on the World Wide Web (WWW) using the Common Gateway Interface (CGI) is presented. The molecular coordinates which are inputted from the WWW browser can be transferred to the Virtual Reality Modeling Language (VRML) format file and viewed as a molecular model by using a VRML viewer on the WWW. The vibrational modes calculated by the ab initio molecular orbital program GAUSSIAN 94 can be visualized. The organic molecular structure database and the search engine for displaying molecular models by using the VRML viewer are also provided.
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- 1997
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43. MOLDA for Windows-A Molecular Modeling and Molecular Graphics Program Using a VRML Viewer on Personal Computers
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Hiroatsu Matsuura and Hiroshi Yoshida
- Subjects
symbols.namesake ,Molecular model ,Computer science ,Interface (Java) ,VRML ,Computer graphics (images) ,Gaussian ,symbols ,computer.file_format ,computer ,Molecular graphics - Abstract
MOLDA for Windows, an interactive personal-computer molecular modeling and molecular graphics program, which can be used as an interface to the ab initio molecular orbital program GAUSSIAN 94, the molecular dynamics simulation program AMBER 4.0 and the molecular mechanics program MM2, is described. The molecular model constructed by using MOLDA can be transferred to the Virtual Reality Modeling Language (VRML) format file and viewed by using a VRML viewer on the World Wide Web (WWW).
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- 1997
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44. Hydration of a short chain poly(oxyethylene) (C1E2C1) studied by analysis of the O—H Raman band
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Nicolai Goutev, Georgi P. Georgiev, Zhorro S. Nickolov, and Hiroatsu Matsuura
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chemistry.chemical_compound ,Crystallography ,chemistry ,Chain (algebraic topology) ,Homogeneous ,Hydrogen bond ,Stereochemistry ,Raman band ,Molecule ,Ether ,Physical and Theoretical Chemistry ,Methylene ,Mole fraction - Abstract
The hydration of the short chain poly(oxyethylene) CH 3 (OCH 2 CH 2 ) 2 O CH 3 (C 1 E 2 C 1 ) has been studied in the range of concentrations up to 0.3 mole fraction (m.f.) by analysing the parameters of the main components of the water O–H stretching band at ca. 3200 and 3400 cm -1 . Two interesting regions of enhancement of the hydrogen bond network in the solution characterize different hydration structures. In the first at ca. 0.03 m.f., the coordination of the water network around the C 1 E 2 C 1 molecules has a local maximum owing to hydrogen bonding at the sites of the ether oxygens from one side, and the hydrophobic hydration around the methylene groups and the CH 3 end groups, from the other. The increased local order in the hydration structure is a consequence of the favourable incorporation of the oxyethylene groups of C 1 E 2 C 1 molecules with gauche conformation in the water network because of their similar O···O distances. In contrast, the second type of hydration structure at ca. 0.11 m.f. can be explained by the build up of the most compact homogeneous hydrogen bond network in which C 1 E 2 C 1 molecules are interconnected with direct hydrogen bonds to the most water molecules possible and the effect of hydrophobic hydration is diminished. Above 0.11 m.f. the hydrogen bond network in the system is gradually destroyed.
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- 1997
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45. Conformational properties of short poly(oxyethylene) chains in water studied by IR spectroscopy
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Roksana Begum and Hiroatsu Matsuura
- Subjects
chemistry.chemical_classification ,Conformational change ,education.field_of_study ,Stereochemistry ,Gauche effect ,Hydrogen bond ,Population ,Infrared spectroscopy ,Crystallography ,chemistry ,PEG ratio ,Molecule ,Physical and Theoretical Chemistry ,education ,Alkyl - Abstract
Conformational properties of short-chain poly(oxyethylene) (POE) compounds in water have been studied by IR spectroscopy. The compounds examined are CH3(OCH2CH2)mOCH3 (m = 1–4), CH3CH2(OCH2CH2)2OCH2CH3, CH3(OCH2CH2)mOH (m = 2–4), CH3CH2(OCH2CH2)mOH (m = 2 and 3), CH3(CH2)3(OCH2CH2)mOH (m = 2 and 3), H(OCH2CH2)mOH (m = 1–4 and 6), PEG 600 and PEG 2000. The relative intensities of the gauche and trans conformational key bands of the C–C and C–O bonds have been measured with varying solution concentration, and the effects of the chain length and the terminal group on the conformation around the respective bonds have been studied. The relative population of the gauche conformation around the C–C bond increases significantly with increasing water fraction. The rate of increase in the gauche population does not depend practically on the length of the POE chain and the length of the terminal alkyl group as long as it is a butyl or shorter group. The terminal hydroxy group greatly restrains the preference of the gauche conformation around the C–C bond in water. The conformational change of the C–O bond with varying solution concentration is much smaller than that of the C–C bond. The population of the trans conformation around the C–O bond increases only slightly with increasing water fraction for the compounds with alkyl terminals, but no substantial conformational changes are observed for the compounds with hydroxy terminal(s). The conformational behaviour of the C–C bond suggests the presence of several types of hydrogen bonds between the POE chain and water. One is a hydrogen-bonded bridge by a water molecule between the adjacent ether oxygen atoms, and the others are bridges by one or more water molecules between the ether oxygen atoms separated by two oxyethylene units. The restrained gauche preference of the terminal O–CH2–CH2–OH segment may be accounted for by the destabilised hydration structure around the terminal part of the chain. The present results have shown the importance of both the hydrogen bonding and the structural matching between the POE chain and the water in the conformational stabilisation of the POE chain in water.
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- 1997
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46. Conformational behaviour of short poly(oxyethylene) compounds in formamide: a Raman spectroscopic study
- Author
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Roksana Begum, Sei Masatoki, and Hiroatsu Matsuura
- Subjects
Formamide ,education.field_of_study ,Aqueous solution ,Chemistry ,Stereochemistry ,Organic Chemistry ,Population ,Mole fraction ,Analytical Chemistry ,Inorganic Chemistry ,Solvent ,symbols.namesake ,Crystallography ,chemistry.chemical_compound ,symbols ,Raman spectroscopy ,education ,Spectroscopy ,Volume concentration - Abstract
Conformational behaviour of short poly(oxyethylene) compounds, CH 3 (OCH 2 CH 2 ) m OCH 3 with m = 1–4, has been studied in formamide by Raman spectroscopy. The spectral observations on the solutions with solute mole fractions 0.5-0.01 have shown that the population of the gauche conformation for the OCH 2 -CH 2 O segment increases progressively with increasing solvent fraction. This conformational behaviour differs from that for the aqueous solutions of the same compounds with m ≥ 2 studied previously, which showed the maximum of the gauche population at low concentration. The comparative discussions of the conformational behaviour of the short poly(oxyethylene) chain in formamide and water, which are analogous with respect to the polarity and hydrogen-bonding characters, suggest that the origin of the peculiar conformational properties in water may be attributed to specific interactions and/or structures relevant to the poly(oxyethylene)-water system.
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- 1996
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47. Conformational dependence of the isolated C-D stretching and CHD rocking vibrations of selectively monodeuterated alkyl chains as proved by conformational polymorphism of 1-bromopentane
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Hiroshi Yoshida, Keiichi Ohno, and Hiroatsu Matsuura
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chemistry.chemical_classification ,Quantitative Biology::Biomolecules ,Chemistry ,Infrared spectroscopy ,Atomic and Molecular Physics, and Optics ,1-bromopentane ,Analytical Chemistry ,Bond length ,Vibration ,Crystallography ,symbols.namesake ,Deuterium ,symbols ,Conformational polymorphism ,Raman spectroscopy ,Instrumentation ,Spectroscopy ,Alkyl - Abstract
The Raman and infrared spectra of three selectively monodeuterated species of 1-bromopentane (1-bromopentane-1-d 1 , -2-d 1 and -3-d 1 ) have been studied to examine the correlation between the isolated CD stretching and CHD rocking vibrations and the associated local conformation of the alkyl chain. The conformational polymorphism exhibited by this compound in the crystalline solid state makes unambiguous conformational assignments of the observed bands possible. The observed C-D stretching wavenumbers have been correlated with the C-D bond lengths calculated by the ab-initio MO method, and a linear relationship has been obtained between them. The present results on monodeuterated 1-bromopentanes show that the isolated CD stretching vibrations give different wavenumbers in the 2130–2230 cm −1 region, depending on the position of the deuterium substitution and the local conformation in the vicinity of the C-D bond. The isolated C-D stretching vibrations have great potential to be used as a probe for studying the conformational state of alkyl chains. The CHD rocking vibrations also provide useful key bands to study the chain conformation.
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- 1996
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48. Extended oxyethylene chain in triblock compounds α-octyl-ω-octyloxyoligo(oxyethylene)s studied by Raman spectroscopy
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Tatsuya Sagawa, Hiroatsu Matsuura, Koichi Fukuhara, and Seiji Kihara
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chemistry.chemical_classification ,Organic Chemistry ,Block (periodic table) ,Molecular conformation ,Analytical Chemistry ,Inorganic Chemistry ,chemistry.chemical_compound ,Crystallography ,symbols.namesake ,Monomer ,chemistry ,Chain (algebraic topology) ,Polymer chemistry ,symbols ,Raman spectroscopy ,Spectroscopy ,Alpha helix ,Alkyl - Abstract
The Raman spectra of α-octyl-ω-octyloxyoligo(oxyethylene)s CH3(CH2)7(OCH2CH2)mO(CH2)7CH3 with m = 1–5 were measured in the crystalline solid state at liquid-nitrogen temperature. The molecular conformation of these triblock compounds was determined by utilizing the conformational key bands previously established and by performing normal coordinate calculations. It is shown that the oxyethylene chain in the central block has an extended structure for the compounds with m = 1 to at least 5, although the intrinsically stable structure of this chain is a helix. A stable extended structure of the oxyethylene chain composed of up to five monomeric units is observed for the first time. The structural characteristics of the triblock compounds show that the conformation of the central oxyethylene chain depends significantly on the length of the adjoining alkyl blocks. The conformational behaviour of the oxyethylene chain is elucidated by the doubled effect of the extended structure of the two long alkyl chains bonded to the oxyethylene chain at the ends.
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- 1996
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49. Conformation-Sensitive Isolated C−D Stretching Vibrations in Alkoxyl Chains
- Author
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Sei Masatoki, Keiichi Ohno, and Hiroshi Yoshida, Hiroatsu Matsuura, and Hidetaka Abe
- Subjects
Cyclohexane ,Stereochemistry ,General Engineering ,Ab initio ,Infrared spectroscopy ,Ether ,Tetrahydropyran ,Bond length ,chemistry.chemical_compound ,Crystallography ,chemistry ,Alkoxy group ,Physical and Theoretical Chemistry ,Basis set - Abstract
The isolated C−D stretching vibrations have been studied for a number of selectively monodeuterated species of tetrahydropyran, methyl ethyl ether, methyl propyl ether, methyl butyl ether, methyl hexyl ether, and cyclohexane, and the dependence of the C−D stretching wavenumbers on the conformation of the CO−C(D)−CC, OC−C(D)−CC, and CC−C(D)−CC structures of the alkoxyl chain has been examined. The infrared spectra of three monodeuterated species of tetrahydropyran with a chair form gave definitive evidence for the conformational dependence of the C−D stretching wavenumbers. The observed wavenumbers of the C−D stretching vibrations for the monodeuterated compounds studied are correlated linearly to the C−D bond lengths calculated by the ab initio MO method using the basis set with polarization functions. The dependence of the C−D stretching wavenumbers on the conformational disposition of the C−D bond in the CO−C(D)−CC structure is more significant than that of the C−D bond in the OC−C(D)−CC or CC−C(D)−CC s...
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- 1996
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50. Conformational Analysis of Nonionic Surfactants in Water by a Selective Monodeuteration Method. C−D Stretching Infrared Spectroscopy of α-Monodeuterododecyl-ω-hydroxytris(oxyethylene)s
- Author
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Keiichi Ohno, Hiroshi Yoshida, Hiroatsu Matsuura, and Sei Masatoki
- Subjects
chemistry.chemical_classification ,Crystallography ,Conformational change ,Deuterium ,Chemistry ,Phase (matter) ,General Engineering ,Infrared spectroscopy ,Trans conformation ,Lamellar structure ,Physical and Theoretical Chemistry ,Photochemistry ,Alkyl - Abstract
The conformation of the alkyl chain in α-dodecyl-ω-hydroxytris(oxyethylene) (C12E3) in water has been studied by C−D stretching infrared spectroscopy. This conformational analysis is based on the fact that the wavenumbers of the isolated C−D stretching vibrations are sensitive to the conformation in the vicinity of the C−D bond. Infrared spectra were measured for five selectively monodeuterated species of C12E3, namely CH3(CH2)11-kCHD(CH2)k-1(OCH2CH2)3OH, where k = 1, 2, 4, 6, and 8, in the lamellar (Lα) and isotropic solution (L2) phases. The C−D stretching bands for each of the monodeuterated species were assigned to particular conformations of the specifically deuterated part of the chain. From the observed intensities of the C−D stretching bands, the fractions of the trans conformation around the dodecyl C−C bonds and the oxyethylene-adjoining O−C bond and the fractions of the consecutive trans conformations around the two adjoining bonds were evaluated. The conformational change at the phase transiti...
- Published
- 1996
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