Language：English   Publishing type：Rapid communication, short report, research note, etc. (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The 500 MHz(1)H NMR NOESY spectra of membrane-promoted multi-point hydrophobic interactions between peptide catalysts and enantiomeric amino acid esters were detected for clarifying the role of muti-point interactions between the reactants in the highly stereoselective hydrolysis reactions in a vesicular membrane.

DOI： 10.1016/1381-1169(96)00157-4

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Language：English   Publisher：ELSEVIER SCIENCE SA LAUSANNE  

The photocatalytic asymmetrical synthesis of Delta (or Lambda)-[Co(acac)(3)] (acac, pentane-2,4-dione) from [Co(acac)(2)(H2O)(2)] and Hacac was successfully performed with novel helical ruthenium(II) complexes of Delta-[Ru(Menbpy)(3)](2+) (1; Menbpy, 4,4'-bis{(1R,2S,5R)-(-)-menthoxycarbonyl}-2,2'-bipyridine), Delta-[Ru(R-PhEtbpy)(3)](2+) (2a), Lambda-[Ru(S-PhEtbpy)(3)](2+) (2b) (R- or S-PhEtbpy, 4,4'-bis[(R)-(+)- or (S)-(-)-1-phenylethylaminocarbonyl]-2,2'-bipyridine) and Delta-[Ru(bpy)(3)](2+) (3; bpy, 2,2'-bipyridine); photocatalyst 1 possesses the most efficient extent of minus (counterclockwise) M(C-3) helicity along the C-3 symmetry axis, resulting in a maximum enantiomeric excess (37% e.e.) of Lambda-[Co(acac)(3)] in 50% v/v EtOH-H2O at 298 K.

DOI： 10.1016/1010-6030(95)04263-6

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Language：English   Publisher：HUTHIG & WEPF VERLAG  

The peptide catalyst having the amino acid sequence (Z-L-Leu (or Phe)-L-His) was found to be the most stereoselective among the L-histidyl group-containing di-, tri-, or tetrapeptide catalysts in the hydrolysis of enantiomeric amino acid substrates in vesicular membranes. The role of the membrane-assisted hydrophobic interaction between the peptide catalyst and enantiomeric substrates for the improvement of the hydrolysis stereoselectivity was demonstrated by means of direct measurements of nuclear Overhauser effect spectroscopy (NOESY) spectra of the interaction system and by the extremely high stereoselectivity itself obtained by intensifying the membrane-promoted hydrophobic interaction between the catalyst and the substrates.

DOI： 10.1002/marc.1996.030170206

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

In the vesicular membrane systems comprising N,N-didodecyl-N,N-dimethylammonium bromide and tri- or tetra-peptide catalysts (pH 7.68; ionic strength mu = 0.15; 298 K), Z-L-Leu-L-His-L-Leu (or Z-L-Leu-L-His-L-Leu-L-Leu), having a hydrophobic terminal L-leucine (or L-leucyl-L-leucine) unit, contributed to the stereoselective binding of long-chain p-nitrophenyl N-hexadecanoyl-L (and D)-phenyalanates with the remarkably high binding ratio K-b(L/D) = 11 (or 7.3) and overall stereoselectivity [k(cat)(L/D) = 35 (or 8.1)].

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Language：English   Publisher：ROYAL SOC CHEMISTRY  

The H-1 NMR NOESY spectra of the multi-point interaction between N-(N-benzyloxycarbonyl-L-leucyl)-L-histidine-[(Z)-L-Leu-L-His] and methyl N-hexanoyl-L-phenylalanate in a N,N-bisdodecyl-N,N-dimethylammonium bromide membrane confirms that the membrane-assisted, hydrophobic interaction between the peptide catalyst and enantiomeric substrates enhances the stereoselective hydrolysis of p-nitrophenyl N-acetyl (or decanoyl)-L (or D)-phenylalanate with (Z)-L-Leu-L-His (most effective in di-, tri- or tetra-peptide catalysts with an introduced L-histidyl group).

DOI： 10.1039/c39950002301

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Language：English   Publishing type：Book review, literature introduction, etc.   Publisher：VSP BV  

Radical pairs were generated in reversed micelles by laser excitation of zinc tetraphenylporphyrin-viologen linked compounds (ZPnV) with a polymethylene spacer (-(CH2)(n)-; n = 4, 6 and 8). The optical transient-absorption and chemically induced dynamic electron polarization (CIDEP) spectra indicated that paramagnetic lanthanide ions invariably accelerated the decay process of the radical pairs at 0.3 T. The typical E/A/E/A spectra for the ZP6V and ZP8V systems were explained as due to S-T-0 mixing and electron-spin relaxation between Zeeman-splitted triplet sublevels. In the case of ZP4V, the paramagnetic Gd3+ ion accelerated the radical decay process even at zero-magnetic field, and strong emissive CIDEP spectra evolved with the elapsed time after laser excitation. Appreciable contribution of S-T level crossing in the radical decay process was suggested to account for the novel features of the ZP4V system.

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Language：English  

The molecular composition and reaction circumstances of supramolecules which include a simple peptide and a double-chain surfactant vesicle were determined for the highly efficient catalytic and stereoselective esterolysis of enantiomeric amino acid esters through the effective multi-hydrophobic substrate-peptide interaction. In the simple peptides (1, 2a~g, and 3a~c) including L-histidine residue and cationic double-chain surfactants (4a, b), a supramolecule composed of 2c and 4b incorporated short-chain substrates (5a) into its vesicular membrane efficiently. It hydrolyzed 5a stereoselectively with an enantiomer rate ratio of L/D=167 though a suitable multi-point interaction between 2c and 5a in the esterolyses of the substrates (5a~f) in 3 vol% MeCN/Tris-KCl buffer (pH 7.68, μ= 0.01) at 298 K. © 1995, The Society of Polymer Science, Japan. All rights reserved.

DOI： 10.1295/koron.52.650

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Molecular design of polymer catalysts for the esterolysis of a marked amino acid ester substrate Z-L-Leu-PNP (PNP=p-nitrophenol) was performed. Either a transition-state analogue of Z-Leu-PP (phenyl l-benzyloxycarbonly-3-methylpentylphosphonate) or a ground-state analogue of Z-L-Leu-AA (ethyl N-benzyloxycarbonyl-L-leucine- anthranilate) was used as a template molecule. In the esterolyses of amino acid esters in 10 vol% dimethyl sulfoxide (DMSO)-Tris buffer (pH 7.15) at 293~308 K, several water-soluble or insoluble polymer catalysts containing a L-histidine catalytic site, which were synthesized by the radical polymerization with acrylamide derivatives, incorporated the marked substrate into their reaction cavities effectively. An ammonium-chain containing water-soluble polymer catalyst exhibited a remarkable acceleration of the present reaction. The free energy of activation (23.9 kcal/mol at 303 K) of the uncatalyzed reaction decreased 7.0 kcal/mol. © 1995, The Society of Polymer Science, Japan. All rights reserved.

DOI： 10.1295/koron.52.644

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Language：Japanese   Publisher：SOC POLYMER SCIENCE JAPAN  

The molecular composition and reaction circumstances of supramolecules which include a simple peptide and a double-chain surfactant vesicle were determined for the highly efficient catalytic and stereoselective esterolysis of enantiomeric amino acid esters through the effective multi-hydrophobic substrate-peptide interaction. In the simple peptides (1, 2a similar to g and 3a similar to c) including L-histidine residue and cationic double-chain surfactants (4a, b), a supramolecule composed of 2c and 4b incorporated short-chain substrates (5a) into its vesicular membrane efficiently. It hydrolyzed 5a stereoselectively with an enantiomer-rate ratio of L/D=167 though a suitable multi-point interaction between 2c and 5a in the esterolyses of the substrates (5a similar to f) in 3 vol% MeCN/Tris-KCl buffer (pH 7.68, mu=0.01) at 298 K.

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Language：Japanese   Publisher：SOC POLYMER SCIENCE JAPAN  

Molecular design of polymer catalysts for the esterolysis of a marked amino acid ester substrate Z-L-Leu-PNP (PNP=p-nitrophenol) was performed. Either a transition-state analogue of Z-Leu-PP (phenyl 1-benzyloxycarbonly-3-methylpentylphosphonate) or a ground-state analogue of Z-L-Leu-AA (ethyl N-benzyloxycarbonyl-L-leucine-anthranilate) was used as a template molecule. In the esterolyses of amino acid esters in 10 vol% dimethyl sulfoxide (DMSO)-Tris buffer (pH 7.15) at 293 similar to 308 K, several water-soluble or insoluble polymer catalysts containing a L-histidine catalytic site, which were synthesized by the radical polymerization with acrylamide derivatives, incorporated the marked substrate into their reaction cavities effectively. An ammonium-chain containing water-soluble polymer catalyst exhibited a remarkable acceleration of the present reaction. The free energy of activation (23.9 kcal/mol at 303 K) of the uncatalyzed reaction decreased 7.0 kcal/mol.

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Language：English   Publishing type：Rapid communication, short report, research note, etc. (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

1,1'-Bi-2-naphthol was oxidized catalytically and enantioselectively (less-than or-equal-to 15.2% e.e.), by using the chiral ruthenium complex, DELTA-[Ru(menbpy)3]2+ (menbpy = 4,4'-dimenthoxycarbonyl-2,2'-bipyridine) as a photocatalyst and [Co(acac)3] (Hacac = pentane-2,4-dione) as an oxidant under photoirradiation.

DOI： 10.1016/0304-5102(93)E0271-H

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Language：English   Publisher：CHEMICAL SOC JAPAN  

Laser photolysis of two-electron-reduced 1,1'-bis(3-sulfonatepropyl)-4,4'-bipyridinium (pVS2-) produced by the reduction of PVS0 with Na2S2O4 in the cationic micelles of hexadecyltrimethylammonium chloride induced the photoionization of PVS2- to generate comparable amounts of PVS-. and hydrated electrons. Pyrene with a considerably negative reduction potential of -2.09 vs. SCE was observed to be reduced in the system.

DOI： 10.1246/cl.1993.2089

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Language：English   Publisher：ROYAL SOC CHEMISTRY  

The asymmetric synthesis of (R)-(+)-1,1'-bi-2-naphthol [or (R)-(+)-1,1'-bi-3-methoxy-2-naphthol] from 2-naphthol (or 3-methoxy-2-naphthol) is performed photocatalytically by using the chiral ruthenium complex, M(C3)-DELTA-[Ru(menbpy)3]2+ [M(C3) = counterclockwise molecular helicity along the C3 axis, menbpy = 4,4'-di(1R,2S,5R)-(-)-menthoxycarbonyl-2,2'-bipyridine] as a photosensitizer and [Co(acac)3] (acac- = acetylacetonato) as an oxidant.

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Language：English   Publishing type：Rapid communication, short report, research note, etc. (scientific journal)   Publisher：AMER CHEMICAL SOC  

Photoinduced electron transfer from the zinc tetraphenylporphyrin moiety to the viologen unit in linked compounds in reversed micelles generated radical pairs, which afforded chemically induced dynamic electron polarization (CIDEP) spectra at room temperature. The CIDEP spectra varied with the number of methylene groups (n) in the alkyl spacer of the linked compounds. In the case of longer spacers (n = 6 and 8), common E/A/E/A patterns were observed throughout the measurement (0.7-5 mus). The signal pattern could be simulated by a formula for the well-known spin-correlated radical pair mechanism, and the corresponding exchange coupling (J) was evaluated (-0.4mT). In the case of ZP4V, the CIDEP signals rapidly changed with elapsed time (O.5-3 mus) from the absorptive to emissive mode. The observation was explained on the basis of a strong contribution of the triplet mechanism in the photogeneration of the radical pair in the early period of measurement.

DOI： 10.1021/j100105a002

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Language：English   Publisher：CHEMICAL SOC JAPAN  

Two strands of an amphiphilic alpha-helical 22-peptide were anchored on ruthenium trisbipyridine complex. The hybrid was equipped with the triad of the ruthenium complex, anthraquinone, and viologen as photo-induced electron transfer system embedded in bilayer membrane.

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Language：English   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The substituent effect on the solvolysis of 2,2-dimethylindan-1-yl chlorides was analyzed in terms of the LArSR Eq., to give rho = -5.81 and r = 1.14. The coplanarity of alpha-t-butylbenzyl cation system was discussed.

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Language：English   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/j100362a012

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Language：Japanese   Publisher：CHEMICAL SOC JAPAN  

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Language：Japanese   Publisher：CHEMICAL SOC JAPAN  

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The gas-phase basicities (GB) of 2-(m, p-substituted phenyl)propenes were determined based on proton-transfer equilibrium method using a pulsed ion cyclotron resonance (TCR) mass spectrometer. The substituent effect on the GB was correlated linearly by σ∗ to give a ρ of, -13.0. The correlation which, Covered a wide range of 35 kcal.mol-1 from p-NMe2 to 3,5-(CF3)2 group revealed that σ∗ values determined in solution for most of substituents were applicable to the gas-phase substituent effects without modification accounting for solvation of substituents. This result suggested that the resonance demand (r) of LArSR Eq. (1) for the gas-phase stability of α-cumyl (1-methyl-1-Phenylethyl) cation was identical with an r of 1.00 for the solvolysis of a-cumyl chlorides. The identity of the r value between in the gas phase and in solution was also observed for basicities of a series of benzoyl compounds. The charge derealization in the aryl ring within a cation will remain essentially the same in the gas phase as in solution. The solvation of cation reduces the central charge to lower the response to substituent perturbation, essentially without change in intramolecular charge derealization. The present result leads us to the conclusion that the charge derealization in the SN 1 transition state in the solvolysis should be quite close to that of the carbocation intermediate. The same conclusion was given by the results for a series of relevant benzylic systems. On the basis of the substituent effect on the gas-phase stability of α-cumyl cation, the substituent effects of gas-phase basicities of benzaldehydes and chloride ion affinities of benzyl cations were analyzed to give r values of 1.00 and 1.29, respectively. The exalted r value of 1.29 for benzyl cation might be attributed to the lower stability than α-cumyl cation. The variation of the r value with the system is in complete agreement with the basic concept of varying resonance demand, supporting the validity of the LArSR Eq. © 1989, The Chemical Society of Japan. All rights reserved.

DOI： 10.1246/nikkashi.1989.1262

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DOI： 10.1246/nikkashi.1989.1477

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The gas-phase basicities (GS) were determined for a series of styrenes based on proton-transfer equilibrium method using a pulsed ion cyclotron resonance (ICR) mass spectrometer. The LArSR analysis of the substituent effect on the GB gave an r of 1.14 and a ρ of-13.6. The r value higher than unityt indicated clearly a greater resonance demand for 1-phenylethyl cation than that for α-cumyl cation while the ρ value was comparable to that of the latter. The exalted resonance demand might be attributed to the lower stability of 1-phenylethyl cation than α-cumyl cation. This trend in the r value is consistent with the observations for the relevant benzylic carbocations. Most importantly, the r value for gas-phase stability of the 1-phenylethyl cation has been found to be identical in magnitude with the r value for the solvdlysis of the corresponding substrates (r=1.15). The same is generally true for a series of benzylic carbocations. The identity of the r value between the SN 1 solvolysis and gas-phase carbocation stability suggests that the intramolecular charge derealization in the, transition state should be quite close to that of the carbocation intermediate. It is concluded that the r value of 1.15 for the 1-phenylethyl solvolysis must be intrinsic resonance demand characteristic of the parent 1-phenylethyl cation itself. The LArSR correlation with r=l.15 fpr the solvolysis in aq. ethanol and aq. acetone suggests a mechanistic involvement of solvent nucleophilic assistance for substrates less reactive than m-cyano derivative. © 1989, The Chemical Society of Japan. All rights reserved.

DOI： 10.1246/nikkashi.1989.1269

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Language：English   Publisher：CHEMICAL SOC JAPAN  

DOI： 10.1246/cl.1987.1779

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Language：English   Publisher：CHEMICAL SOC JAPAN  

DOI： 10.1246/cl.1987.1047

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