Faculty Profiles - Ryo Kanzaki

Papers - Ryo Kanzaki

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Tetsuya Sukizaki, Shuhei Fukuda, Taishi Yamaguchi, Kenta Fujii, Ryo Kanzaki, Kazumi Chiba, Hideo Yamamoto, Yasuhiro Umebayashi, Shin-ichi Ishiguro . Raman spectroscopic study and DFT calculations on the conformation of 5-azonia-spiro[4.4]nonane cation in crystal and dimethyl carbonate solution . ELECTROCHEMISTRY75 ( 8 ) 628 - 634 2007.8Reviewed

Language：English Publishing type：Research paper (scientific journal) Publisher：ELECTROCHEMICAL SOC JAPAN

5-Azonia-spiro[4.4]nonane tetrafluoroborate [(CH2)(4)N(CH2)(4)](+) BF4- is dissolved in dimethyl carbonate (DMC) to yield two liquid phases, DMC and salt-rich DMC solutions. The molecular structure of the [(CH2)(4)N(CH2)(4)](+) ion in the crystalline state and in the salt-rich DMC solution was studied by means of Raman spectroscopy at 298 K and theoretical DFT calculations. The [(CH2)(4)N(CH2)(4)](+) ion involves two pyrrolidinium (CH2)(4)N rings bridged through the N atom, and each pyrrolidinium ring involves various types of conformation. Theoretical DFT calculations for the [(CH2)(4)N(CH2)(4)](+) ion show that the distorted envelope-envelope conformers of the type E1-E1 and E1-E3 give relatively small energies. Observed Raman spectra of [(CH2)(4)N(CH2)(4)](+) BF4- crystals and the salt-rich DMC solution were satisfactorily explained in terms of the favorable presence of the sole envelope-envelope conformer of the type E1-E1.

DOI： 10.5796/electrochemistry.75.628

Ryo Kanzaki, Kumaki Uchida, Shota Hara, Yasuhiro Umebayashi, Shin-ichi Ishiguro, Satoshi Nomura . Acid-base property of ethylammonium nitrate ionic liquid directly obtained using ion-selective field effect transistor electrode . CHEMISTRY LETTERS36 ( 5 ) 684 - 685 2007.5Reviewed

Language：English Publishing type：Research paper (scientific journal) Publisher：CHEMICAL SOC JAPAN

Ethylammonium nitrate (EAN) is a protic room-temperature ionic liquid and classified into an amphoteric solvent. The equilibrium constant K-S = [EtNH2][HNO3] has directly been obtained for the first time by using an ion-selective field effect transistor (ISFET) electrode. The obtained K-S value is of 10(-10.0) mol(2) dm(-6), indicating that the neutral EAN involves HNO3 and EtNH2 molecules as much as 1.0 x 10(-5) mol dm(-3), or the pH (= - log[HNO3]) is 5 at 298 K.

DOI： 10.1246/cl.2007.684

Mitsunori Asada, Takao Fujimori, Kenta Fujii, Ryo Kanzaki, Yasuhiro Umebayashi, Shin-ichi Ishiguro . Solvation structure of magnesium, zinc, and alkaline earth metal ions in N,N-dimethylformamide, N,N-dimethylacetamide, and their mixtures studied by means of Raman spectroscopy and DFT calculations - Ionic size and electronic effects on steric congestion . JOURNAL OF RAMAN SPECTROSCOPY38 ( 4 ) 417 - 426 2007.4Reviewed

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY

The solvation structure of magnesium, zinc(II), and alkaline earth metal ions in N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA), and their mixtures has been studied by means of Raman spectroscopy and DFT calculations. The solvation number is revealed to be 6, 7, 8, and 8 for Mg2+, Ca2+, Sr2+, and Ba2+, respectively, in both DMF and DMA. The delta (O-C-N) vibration of DMF shifts to a higher wavenumber upon binding to the metal ions and the shift Delta nu (= nu(bound) - nu(free)) becomes larger, when the ionic radius of the metal ion becomes smaller. The nu (N-CH3) vibration of DMA also shifts to a higher wavenumber upon binding to the metal ions. However, the shift Delta nu saturates for small ions, as well as the transition-metal (II) ions, implying that steric congestion among solvent molecules takes place in the coordination sphere. It is also indicated that, despite the magnesium ion having practically the same ionic radius as the zinc(II) ion of six-coordination, their solvation numbers in DMA are significantly different. DFT calculations for these metalsolvate clusters of varying solvation numbers revealed that not only solvent-solvent interaction through space but also the bonding nature of the metal ion plays an essential role in the steric congestion. The individual solvation number and the Raman shift Delta nu in DMF-DMA mixtures indicate that steric congestion is significant for the magnesium ion, but not appreciable for calcium, strontium, and barium ions, despite the solvation number of these metal ions being large. Copyright (c) 2006 John Wiley & Sons, Ltd.

DOI： 10.1002/jrs.1662

神崎亮, 梅林泰宏, 竹内宗孝, 藤井健太 . 分子シミュレーションおよびX線回折法によるイオン液体の構造とダイナミクス . アンサンブル9 ( 3 ) 18 - 21 2007.4分子シミュレーションおよびX線回折法によるイオン液体の構造とダイナミクス

梅林泰宏, 福田周平, 竹内宗孝, 神崎亮, 石黒慎一, 藤井健太, 高椋利幸 . 広角X線散乱実験および分子動力学計算によるイオン液体の液体構造 . 溶融塩および高温化学50 ( 3 ) 117 - 125 2007.4広角X線散乱実験および分子動力学計算によるイオン液体の液体構造Invited Reviewed

Takao Fujimori, Kenta Fujii, Ryo Kanzaki, Kazumi Chiba, Hideo Yamamoto, Yasuhiro Umebayashi, Shin-ichi Ishiguro . Conformational structure of room temperature ionic liquid N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl) imide - Raman spectroscopic study and DFT calculations . JOURNAL OF MOLECULAR LIQUIDS131 ( SPEC. ISS. ) 216 - 224 2007.3Reviewed

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Conformational structure of the N-butyl-N-methyl-pyrrolidinium (P-14(+)) ion within its bis(trifluoromethanesulfonyl) imide (TFSI-) and bromide salts has been studied by means of DFT calculations and Raman spectroscopy. The P-14(+) ion gives various types of conformations with respect to the pyrrolidinium ring and N-butyl group. DFT calculations indicate that, among others, the eq- and ax-envelope conformers with the N-butyl group at equatorial and axial positions, respectively, against planar C-4 atoms of the envelope pyrrolidinium ring (-NCH2CH2CH2CH2-) are relatively stable, and the former gives the global minimum. It revealed by comparing observed and calculated Raman spectra that the P-14(+) ion is present mainly as the ax-envelope conformer in the P14+Br- crystal, whilst the eq- and ax-envelope conformers are present in equilibrium in the P14+TFSI- ionic liquid. The presence of conformational equilibrium is further supported by Raman spectra measured by varying temperature. It is also established that conformation of the N-butyl group is restricted to the trans-TT, in which the butyl group locates trans against its nearest carbon atom in the pyrrolidinium ring, and all carbon atoms in the butyl chain are located trans each other. (C) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molliq.2006.08.054

Ryo Kanzaki, Yasuhiro Umebayashi, Mitsunori Asada, Shin-ichi Ishiguro, Taisuke Matsumoto, Akihiro Wakisaka . Binuclear mu-perchlorato complexes of alkaline earth metal ions studied by electrospray ionization mass spectrometry and DFT calculations . CHEMISTRY LETTERS35 ( 10 ) 1118 - 1119 2006.10Reviewed

Language：English Publishing type：Research paper (scientific journal) Publisher：CHEMICAL SOC JAPAN

Metal-ion clusters involving alkaline earth metal and perchlorate ions, and N,N-dimethylformamide (DMF) have been studied by electrospray ionization mass spectrometry (ESI-MS). Three types of metal-ion clusters, [M(DMF)(n)](2+), [M(ClO4)-(DMF)(n)](+), and [M-2(CIO4)(3)(DMF)(n)](+) (M = Mg, Ca, and Sr) are found. It is proposed on the basis of DFT calculations that the metal ion in the [M-2(CIO4)(3)(DMF)(6)](+) clusters is six-coordinated with three mu-CIO4- ions and three DMF molecules.

DOI： 10.1246/cl.2006.1118

Shin-ichi Ishiguro, Yasuhiro Umebayashi, Kenta Fujii, Ryo Kanzaki . Solvent conformation and ion solvation: From molecular to ionic liquids . PURE AND APPLIED CHEMISTRY78 ( 8 ) 1595 - 1609 2006.8Reviewed

Language：English Publishing type：Research paper (scientific journal) Publisher：INT UNION PURE APPLIED CHEMISTRY

Metal ions are solvated in solution, and, in a sterically congested organic solvent, those solvent molecules that are simultaneously bound to the metal ion will be subject to consequential steric interactions through space. The molecular structure of a solvent, particularly that of any functional groups in the vicinity of the coordinating atom to the metal ion, plays a key role in the solvation steric effect. Weak solvation steric effects lead to a distorted octahedral structure for six-coordinate transition-metal(II) ions, whereas strong steric effects lead to a decreased solvation number. In particular cases, the conformation of a solvent may undergo a change in response to coordination to the metal ion. Solvation steric effects play a decisive role in reaction thermodynamics and kinetics of the metal ion. Here, we show our recent results on solvation steric effects in terms of structure and thermodynamics, particularly, the conformational change of solvent and its effect on the metal-ion complexation.

DOI： 10.1351/pac200678081595

Kenta Fujii, Takao Fujimori, Toshiyuki Takamuku, Ryo Kanzaki, Yasuhiro Umebayashi, Shin-Ichi Ishiguro . Conformational equilibrium of bis(trifluoromethanesulfonyl) imide anion of a room-temperature ionic liquid: Raman spectroscopic study and DFT calculations . Journal of Physical Chemistry B110 ( 16 ) 8179 - 8183 2006.4Reviewed

Language：Japanese

The structure of bis(trifluoromethanesulfonyl) imide (TFSI) in the liquid state has been studied by means of Raman spectroscopy and DFT calculations. Raman spectra of 1-ethyl-3-methylimidazolium (EMI + ) TFSI - show relatively strong bands arising from TFSI - at about 398 and 407 cm - . Interestingly, the 407 cm -1 band, relative to the 398 cm -1 one, is appreciably intensified with raising temperature, suggesting that an equilibrium is established between TFSI - conformers in the liquid state. According to DFT calculations followed by normal frequency analyses, two conformers of C 2 and C 1 symmetry, respectively, constitute global and local minima, with an energy difference 2.2-3.3 kJ mol -1 . The wagging ω-SO 2 vibration appears at 396 and 430 cm -1 for the C 1 conformer and at 387 and 402 cm -1 for the C 2 one. Observed Raman spectra over the range 380-440 cm -1 were deconvoluted to extract intrinsic bands of TFSI - conformers, and the enthalpy of conformational change from C 2 to C 1 was evaluated. The enthalpy value is in good agreement with that obtained by theoretical calculations. We thus conclude that a conformational equilibrium is established between the C 1 and C 2 conformers of TFSI - in the liquid EMI + TFSI - , and the C 2 conformer is more favorable than the C 1 one. © 2006 American Chemical Society.

DOI： 10.1021/jp0612477

梅林泰宏, 藤森崇夫, 藤井健太, 神崎亮, 石黒慎一 . DFT計算およびMDシミュレーションによるイオン液体中の金属イオン溶媒和 . 九州大学情報基盤センター広報 2006.4DFT計算およびMDシミュレーションによるイオン液体中の金属イオン溶媒和

Yasuhiro Umebayashi, Takao Fujimori, Tetsuya Sukizaki, Mitsunori Asada, Kenta Fujii, Ryo Kanzaki, Shin-Ichi Ishiguro . Evidence of conformational equilibrium of 1-ethyl-3-methylimidazolium in its ionic liquid salts: Raman spectroscopic study and quantum chemical calculations . Journal of Physical Chemistry A109 ( 40 ) 8976 - 8982 2005.10Reviewed

Language：Japanese

Raman spectra of liquid 1-ethyl-3-methylimidazolium (EMI + ) salts, EMI + BF 4 - , EMI + PF 6 , EMI + CF 3 SO 3 - , and EMI + N(CF 3 SO 2 ) 2 - , were measured over the frequency range 200-1600 cm -1 . In the range 200-500 cm -1 , we found five bands originating from the EMI + ion at 241, 297, 387, 430, and 448 cm -1 . However, the 448 cm -1 band could hardly be reproduced by theoretical calculations in terms of a given EMI + conformer, implying that the band originates from another conformer. This is expected because the EMI + involves an ethyl group bound to the N atom of the imidazolium ring, and the ethyl group can rotate along the C-N bond to yield conformers. The torsion energy for the rotation was then theoretically calculated. Two local minima with an energy difference of ca. 2 kJ mol -1 were found, suggesting that two conformers are present in equilibrium. Full geometry optimizations followed by normal frequency analyses indicate that the two conformers are those with planar and nonplanar ethyl groups against the imidazolium ring plane, and the nonplanar conformer is favorable. It elucidates that bands at 241, 297, 387, and 430 cm-1 mainly originate from the nonplanar conformer, whereas the 448 cm-1 band does originate from the planar conformer. Indeed, the enthalpy for conformational change from nonplanar to planar EMI + experimentally obtained by analyzing band intensities of the conformers at varying temperatures is practically the same as that evaluated by theoretical calculations. We thus conclude that the EMI + ion exists as either a nonplanar or planar conformer in equilibrium in its liquid salts. © 2005 American Chemical Society.

DOI： 10.1021/jp053476j

Kenta Fujii, Yasuhiro Umebayashi, Ryo Kanzaki, Daisuke Kobayashi, Ryoko Matsuura, Shin-Ichi Ishiguro . Thermodynamic aspects of metal-ion complexation in the structured solvent, N-methylformamide . Journal of Solution Chemistry34 ( 7 ) 739 - 753 2005.7Reviewed

Language：Japanese

Chloride complexation of cobalt(II), nickel(II) and zinc(II) ions has been studied by calorimetry and spectrophotometry in N-methylformamide (NMF) containing 1.0 mol-dm -3 (n-C 4 H 9 ) 4 NClO 4 as an ionic medium at 298 K. A series of mononuclear complexes, MCl n (2 -n)+ (M=Co, Ni and Zn) with n = 1, 3 and 4 for cobalt(II), n = 1 for nickel(II), and n = 1-4 for zinc(II), are formed and their formation constants, enthalpies and entropies were obtained. It revealed that complexation is suppressed significantly in NMF relative to that in N,N-dimethylformamide (DMF) in all metal systems examined. The suppressed complexation in NMF is mainly ascribed to the smaller formation entropies in NMF reflecting that the solvent-solvent interaction or solvent structure in the bulk NMF is much stronger than that in the bulk DMF. Formation entropies, ΔS 1 o , of the monochloro complex in DMF, dimethyl sulfoxide and NMF are well correlated with the Marcus' solvent parameter, ΔΔ v S o /R, according to ΔS 1 o /R = aΔΔ v S o /R+b. The a value is negative and similar in all metal systems examined, whereas the b value depends on the metal system. When a gaseous ion is introduced into a solvent, the ionic process of solvation is divided into two stages: the ion destroys the bulk solvent structure to isolate solvent molecules at the first stage and the ion then coordinates a part of isolated solvent molecules around it at the second stage. We propose that the a and b values may reflect the changes in the freedom of motion of solvent molecules at the first and second stages, respectively, of the ionic process of solvation. © 2005 Springer Science+Business Media, Inc.

DOI： 10.1007/s10953-005-5114-9

Kanzaki R., Umebayashi Y., Maki T., Ishiguro S.I. . Thermodynamics and fluorescence spectra of 1,10-phenanthroline in micelles of poly (ethylene oxide)-type nonionic surfactant . Journal of Solution Chemistry33 ( 6-7 ) 699 - 709 2004.6

Language：Japanese Publisher：Journal of Solution Chemistry

The distribution of 1,10-phenanthroline (phen) in micellar solutions of the nonionic surfactants Triton X and C 12E n with varying poly (ethylene oxide) chain lengths has been studied by potentiometry, calorimetry, and fluorometry at 298 K. Micelles accommodate 1,10-phenanthroline according to the reaction, phen + Y m = Y m(phen), where Y m denotes a surfactant molecule aggregated in micelles. The constant K m for the reaction of Triton X increases as a linear function of n*, the number of ethylene oxide (EO) groups, as K m = K EOn* + K c. Nonzero K EO and K c values suggest a heterogeneous inner structure of the micelle, i.e., the hydrophobic core surrounded by a hydrophilic poly (ethylene oxide) (PEO) shell. On the basis of molar volumes, the intrinsic thermodynamic parameters of transfer of 1,10-phenantholine were extracted. The enthalpy and entropy of transfer of 1,10-phenanthroline from the PEO shell to the core are found to be small and negative. By using K EO and K c values for C 12E n obtained by fluorometry, individual fluorescence spectra of 1,10-phenanthroline in the PEO shell and core were extracted. The fluorescence intensity of 1,10-phenathroline accommodated in the core, like in organic solvents, is significantly reduced relative to that in water. These facts indicate that the aromatic rings of 1,10-phenanthroline penetrate into the hydrophobic core, while its hydrophilic N site is still hydrated in the PEO shell.

DOI： 10.1023/B:JOSL.0000043634.09653.cb

R Kanzaki, Y Umebayashi, T Maki, S Ishiguro . Thermodynamics and fluorescence spectra of 1,10-phenanthroline in micelles of poly (ethylene oxide)-type nonionic surfactant . JOURNAL OF SOLUTION CHEMISTRY33 ( 6-7 ) 699 - 709 2004.6Thermodynamics and fluorescence spectra of 1,10-phenanthroline in micelles of poly (ethylene oxide)-type nonionic surfactantReviewed

Language：English Publishing type：Research paper (scientific journal) Publisher：KLUWER ACADEMIC/PLENUM PUBL

The distribution of 1,10-phenanthroline (phen) in micellar solutions of the nonionic surfactants Triton X and C12En with varying poly (ethylene oxide) chain lengths has been studied by potentiometry, calorimetry, and fluorometry at 298 K. Micelles accommodate 1,10-phenanthroline according to the reaction, phen + Y-m = Y-m(phen), where Ym denotes a surfactant molecule aggregated in micelles. The constant Km for the reaction of Triton X increases as a linear function of n*, the number of ethylene oxide (EO) groups, as K-m = K(EO)n* + K-c. Nonzero K-EO and K-c values suggest a heterogeneous inner structure of the micelle, i.e., the hydrophobic core surrounded by a hydrophilic poly (ethylene oxide) (PEO) shell. On the basis of molar volumes, the intrinsic thermodynamic parameters of transfer of 1,10-phenantholine were extracted. The enthalpy and entropy of transfer of 1,10-phenanthroline from the PEO shell to the core are found to be small and negative. By using KEO and Kc values for C12En obtained by fluorometry, individual fluorescence spectra of 1,10-phenanthroline in the PEO shell and core were extracted. The fluorescence intensity of 1,10-phenathroline accommodated in the core, like in organic solvents, is significantly reduced relative to that in water. These facts indicate that the aromatic rings of 1,10-phenanthroline penetrate into the hydrophobic core, while its hydrophilic N site is still hydrated in the PEO shell.

Ishiguro S.I., Umebayashi Y., Kanzaki R. . Characterization of Metal Ions in Coordinating Solvent Mixtures by Means of Raman Spectroscopy . Analytical Sciences20 ( 3 ) 415 - 421 2004.3

Language：Japanese Publisher：Analytical Sciences

Titration Raman spectroscopy has been developed for studying the solvation structure of metal ions in solution. The method affords us the solvation number, and the value thus obtained in neat solvents is in good agreement with that determined by EXAFS. The method is then applied to solvent mixtures, and the individual solvation number for each solvent is extracted. In a solvent mixture of N,N-dimethylformamide (DMF) and N,N,N′,N′-tetramethylurea (TMU), the metal ion prefers DMF to TMU, which is ascribed to the solvation steric effect. The same applies also for the solvent mixture of N,N-dimethylpropionamide (DMPA) and DMF. However, unlike TMU, DMPA changes its conformation from the planar cis to non-planar staggered upon solvation to the metal ion. The enthalpy for the conformational change of DMPA is positive in the bulk, while it is significantly negative in the coordination sphere of the manganese(II) ion. Here, we briefly describe the procedure of measurements and analyses for the titration Raman spectroscopy, and review the solvation structure of the alkaline earth, first transition metal(II) and lanthanide(III) ions in some solvent mixtures in view of solvation steric effect.

DOI： 10.2116/analsci.20.415

Tei Maki, Ryo Kanzaki, Yasuhiro Umebayashi, Shin-Ichi Ishiguro . Hysteretic behavior on the heat of protonation of diethylenetriamine in aqueous solution . Chemistry Letters33 ( 2 ) 186 - 187 2004.2Reviewed

Language：Japanese Publishing type：Research paper (scientific journal)

Hysteretic behavior was found on the heat of protonation of diethylenetriamine (dien) in aqueous solution at 298 K. We propose the presence of two conformers for Hdien+, which have significantly different proton affinities. Mutual transformation between the conformers may be practically forbidden, but is strongly accelerated upon their protonation to form H2dien2+.

DOI： 10.1246/cl.2004.186

Yasuhiro Umebayashi, Mari Shin, Ryo Kanzaki, Shin-Ichi Ishiguro . Thermodynamics of [Co(NCS)4]2- at poly(ethylene oxide) and octylphenyl moieties in micelles of nonionic surfactants . Journal of Colloid and Interface Science237 ( 2 ) 167 - 173 2001.5Reviewed

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Academic Press Inc.

Formation of cobalt(II)-thiocyanato complexes in nonionic surfactant solutions of poly(ethylene oxide) type with varying poly(ethylene oxide) chain lengths of 7.5 (Triton X-114), 30 (Triton X-305), and 40 (Triton X-405) has been studied by titration spectrophotometry and calorimetry at 298 K. Data were analyzed by assuming formation of a series of ternary complexes Co(NCS)nYm (2-n)+ (Y = surfactant) with an overall formation constant βnm. In all the surfactant systems examined, data obtained can be explained well in terms of formation of Co(NCS)+ and Co(NCS)2 in an aqueous phase (aq), and Co(NCS)4Y2- in micelles, and their formation constants, enthalpies, and entropies have been determined. The β41/β20 ratio increases and the corresponding enthalpy becomes significantly less negative with an increasing number of ethylene oxide groups. This suggests that micelles of these nonionic surfactants have a heterogeneous inner structure consisting of ethylene oxide and octylphenyl moieties. Indeed, on the basis of molar volumes of ethylene oxide and octylphenyl groups, intrinsic thermodynamic parameters have been extracted for the reaction Co(NCS)2(aq) + 2NCS-(aq) = Co(NCS)4Y2- (ΔrG°, ΔrH°, and ΔrS°) at each moiety. The ΔrG°, ΔrH°, and ΔrS° values are -16 kJ mol-1, -15 kJ mol-1, and 3 J K-1 mol-1, respectively, for the ethylene oxide moiety, and -15 kJ mol-1, -70 kJ mol-1, and -183 J K-1 mol-1 for octylphenyl. Significantly less negative ΔrH° and ΔrS° values for ethylene oxide imply that the hydrogen-bonded network structure of water is extensively formed at the ethylene oxide moiety, and the structure is thus broken around the Co(NCS)4 2- complex with weak hydrogen-bonding ability. © 2001 Academic Press.

DOI： 10.1006/jcis.2001.7457

Kanzaki R., Umebayashi Y., Uemura K., Ishiguro S.I. . Distribution thermodynamics of 1,10-phenanthroline in non-ionic surfactant triton X-100 micelles . Physical Chemistry Chemical Physics3 ( 5 ) 824 - 828 2001.3

Language：Japanese Publisher：Physical Chemistry Chemical Physics

The distribution thermodynamics of 1,10-phenanthroline (phen) and 2,9-dimethyl-1,10-phenanthroline (dmphen) in micelles of the non-ionic surfactant Triton X-100 were studied by potentiometry and titration calorimetry at 298 K. Both of these ligands form HL+ and HL2+ (L = phen and dmphen) in acidic solution. Their formation constants were determined in aqueous solutions containing various concentrations of Triton X-100, and were found to decrease with increasing concentration of the surfactant. The decrease is explained in terms of accommodation of neutral phenanthrolines in micelles by taking into account the surfactant solution as a heterogeneous solvent mixture. The case in which the surfactant is treated as the third reactant was also examined, and thermodynamic parameters for the interaction between the surfactant and phenanthrolines, i.e. the Gibb's energies, enthalpies and entropies of transfer of phenanthrolines from aqueous solution to a micellar pseudo-phase, were obtained. The Gibb's energies of transfer of the neutral ligand L are -8.2 and -11.7 kJ mol-1 for L = phen and dmphen, respectively. The corresponding enthalpies of transfer are both small and negative, implying that these neutral 1,10-phenanthrolines are still strongly hydrated in micelles, as well as in water, through the hydrophilic nitrogen sites.

DOI： 10.1039/b009132o

R Kanzaki, Y Umebayashi, K Uemura, S Ishiguro . Distribution thermodynamics of 1,10-phenanthroline in non-ionic surfactant Triton X-100 micelles . PHYSICAL CHEMISTRY CHEMICAL PHYSICS3 ( 5 ) 824 - 828 2001Distribution thermodynamics of 1,10-phenanthroline in non-ionic surfactant Triton X-100 micellesReviewed

Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

The distribution thermodynamics of 1,10-phenanthroline (phen) and 2,9-dimethyl-1,10-phenanthroline (dmphen) in micelles of the non-ionic surfactant Triton X-100 were studied by potentiometry and titration calorimetry at 298 K. Both of these ligands form HL+ and HL2+ (L = phen and dmphen) in acidic solution. Their formation constants were determined in aqueous solutions containing various concentrations of Triton X-100, and were found to decrease with increasing concentration of the surfactant. The decrease is explained in terms of accommodation of neutral phenanthrolines in micelles by taking into account the surfactant solution as a heterogeneous solvent mixture. The case in which the surfactant is treated as the third reactant was also examined, and thermodynamic parameters for the interaction between the surfactant and phenanthrolines, i.e. the Gibb's energies, enthalpies and entropies of transfer of phenanthrolines from aqueous solution to a micellar pseudo-phase, were obtained. The Gibb's energies of transfer of the neutral ligand L are -8.2 and -11.7 kJ mol(-1) for L = phen and dmphen, respectively. The corresponding enthalpies of transfer are both small and negative, implying that these neutral 1,10-phenanthrolines are still strongly hydrated in micelles, as well as in water, through the hydrophilic nitrogen sites.

R Kanzaki, T Egashira, T Nakazato, Y Umebayashi, S Ishiguro . Influence of charge on adduct formation of [M(phen)(3)](z+) (M = Ru2+, Co3+, Si4+) with 1,10-phenanthroline in aqueous solution . PHYSICAL CHEMISTRY CHEMICAL PHYSICS2 ( 17 ) 3825 - 3830 2000.9Reviewed

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

Adduct formation of the inert complexes Ru(phen)(3)(2+), Co(phen)(3)(3+) and Si(phen)(3)(4+) with 1,10-phenanthroline (phen) has been studied by potentiometry and calorimetry in aqueous solution containing 0.1 mol dm(-3) NaCl as an ionic medium at 298 K. Formation of a 1:1 adduct, in which planar 1,10-phenanthroline molecules are stacked, has been found for all the inert complexes and their formation constants, enthalpies and entropies were obtained. Adduct formation constants are hardly influenced by the ionic charges of the metal center. The enthalpy values are all negative, indicating that a specific pi-pi interaction operates between stacked 1,10-phenanthroline molecules. The corresponding entropy values are positive for Ru(phen)(3)(2+) and Co(phen)(3)(3+), while it is negative for Si(phen)(3)(4+). The positive entropies indicate that reduction of hydrophobic hydration upon stacking also plays a key role in the adduct formation. Both enthalpy and entropy values significantly decrease with increasing charge, and they strongly compensate to give similar formation constants. This implies that hydrophobic hydration around aromatic rings within the inert complexes is reduced to a greater extent with increasing charge, Ru(phen)(3)(2+)<Co(phen)(3)(3+)<Si(phen)(3)(4+). 1,10-Phenanthroline forms protonated H(phen)(+) and H(phen)(2)(+) species in an acidic solution, and 1,10-phenanthroline molecules are stacked in the latter. The enthalpy and entropy of formation of H(phen)(2)(+) are significantly negative, also indicating that pi-pi interaction play an essential role in the formation of H(phen)(2)(+). On the other hand, both the enthalpy and entropy of solution of 1,10-phenanthroline remain unchanged in solution containing NaCl over the range 0.05-1 mol dm(-3), suggesting that hydrophobic hydration shells are restricted at the vicinity of 1,10-phenanthroline.

DOI： 10.1039/b003854g

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