Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 83 , Issue 5
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  • Takakazu Yamamoto
    2010 Volume 83 Issue 5 Pages 431-455
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    Organometallic polycondensations give various π-conjugated polymers. For example, nickel complex-promoted dehalogenative polycondensation of dihaloaromatic compounds and dihalogenataed heterocyles, X–Ar–X (Ar = aromatic unit or heterocyclic unit), affords poly(arylene)s and poly(heterocycles), (Ar)n, such as poly(p-phenylene), poly(thiophene-2,5-diyl), poly(3-alkylthiophene-2,5-diyl), and poly(pyridine-2,5-diyl). Pd-catalyzed polycondensation gives poly(aryleneethynylene) type polymers and alternating copolymers of Ar and Ar′. These polymers have well defined bonds between the monomeric units, and they are electrochemically active, electrically conductive, and light-emitting. Their well-characterized linear structure brings about unique packing of the polymer molecules in the solid and alignment of the polymer molecules on the surface of substrates. In this paper, we describe synthesis of π-conjugated polymers by organometallic polycondensations. Basic chemical and physical properties of the synthesized π-conjugated polymers, as well as ordered structures in the solid and applications for electronic and optical devices of the π-conjugated polymers, are also described.
    π-Conjugated polymers such as poly(p-phenylene), poly(thiophene-2,5-diyl), poly(3-alkylthiophene-2,5-diyl), and poly(aryleneethynylene)s are prepared by organometallic polycondensation. Basic organometallic chemistry related to the polycondensation and structure and functionalities of obtained π-conjugated polymers are also described. Fullsize Image
BCSJ Award Article
  • Akihiro Tsurusaki, Noriyoshi Nagahora, Takahiro Sasamori, Kazunari Mat ...
    2010 Volume 83 Issue 5 Pages 456-478
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    The first stable anthryldiphosphenes, 1 and 2, were synthesized by utilizing kinetic stabilization of 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt) and 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl (Bbt) groups, and were characterized by spectroscopic and X-ray crystallographic analyses. The UV–visible spectroscopic data suggested the electronic communication between the anthryl moiety and the P=P unit. It was found that TbtP=P(9-Anth) (1a: 9-Anth = 9-anthryl) showed weak fluorescence in hexane solution. Furthermore, the reactivities of anthryldiphosphene 1 with a chromium complex, chalcogenation reagents, a diene, and electron-deficient olefins have been revealed.
    The first stable 9-anthryldiphosphenes and 9,10-anthrylene-bridged bisphosphenes were synthesized and characterized by spectroscopic and X-ray crystallographic analyses. They should be novel π-conjugated systems between the anthryl and P=P moieties (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, Bbt = 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl). Fullsize Image
 
  • Hassan Talaat, El-Wallid S. Sedik, M. Tag El-Din Kamal
    2010 Volume 83 Issue 5 Pages 479-485
    Published: May 15, 2010
    Released: May 15, 2010
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    Laser atom/ion–molecule reaction interaction through dipole moments leads to potential energy surface crossings in ion molecule (Li+ + CH4) and barrier reshaping in atom–molecule reaction (Li + CH4). We will show here by using gauge representation (electric field gauge) that we can create laser-induced surface crossing in the region (4 au) where the dipole moment changes sign for the LiH + CH3+ Li+ + CH4 reaction and reshape the barrier height (increase/decrease the height) by changing the laser phase for Li + CH4 → LiH + CH3 where dipole moment changes sign in the transition state region.
  • Yoshiyuki Koyano, Norio Takenaka, Yukinori Nakagawa, Masataka Nagaoka
    2010 Volume 83 Issue 5 Pages 486-494
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    The free energy gradient (FEG) method combined with the QM/MM–MD calculation has realized full-atomic structural optimization of the solute NH3–H2O molecule pair in aqueous solution, exploring successful tracing of the reaction path on the free energy surface from the neutral state (H3N–H2O) to the ionized (H4+N–OH) through the transition state (H3N···H+···OH). To reproduce accurately the structural change of the hydrated molecule pair, the LJ parameter calibration in the QM/MM nonelectrostatic interaction was essential for four kinds of QM solute species, i.e., OH, H2O, NH3, and NH4+, treated in the NDDO-SSRP framework with the ab initio quality. Two linear interpolations of these calibrated LJ parameters optimized at the NSS and ISS were utilized in the path-dependent FEG calculation, as is common in the free energy perturbation treatment. After including the effects of the intramolecular entropic contribution and quantum tunneling, the free energies of activation and reaction were satisfactorily estimated to be 13.8 and 9.8 kcal mol−1 (1 kcal = 4.184 kJ), respectively. It is expected that far more agreement with the experimental values should be reasonably attained if the QM region were extended to three surrounding water molecules to take in the electron delocalization effect adequately.
  • Hirotsugu Hiramatsu, Ming Lu, Yuji Goto, Teizo Kitagawa
    2010 Volume 83 Issue 5 Pages 495-504
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    Amyloid fibril structures of peptides having the sequence of the #20–41 region of β2-microglobulin (β2m20–41 and β2m21–29) were investigated with FTIR microscope spectroscopy. pH dependence of the amide I band of the IR absorption spectra was analyzed. For β2m20–41, the β-sheet content at pH 6.0 was 55% (12.1 residues) and the β-sheet was located in the N21–G29 and I35–V37 regions, but at pH 2.5 it was 60% (13.1 residues) and located in the F22–V27 and P32–V37 regions. The two structures with different amounts of β-sheet were switched at pH 4.5, which was close to the pI of this sequence (ca. 4.3) rather than the pKa of the carboxyl groups (5.8 ± 0.3 and 3.3 ± 0.4), suggesting the importance of the total number of charges rather than protonation of specific residue(s). The spectral characteristics of the IR linear dichroism and 13C isotope labeling indicated the formation of parallel β-sheet structure in both regions, and the stacking direction was unaltered by pH change. Unexpectedly however, the IR spectra of the β2m21–29 fibril demonstrated the simultaneous presence of parallel/anti-parallel β-sheets. The relevance of the pH dependence of the β2m20–41 fibril structure to that of β2m fibrils is discussed.
  • Hiromi Minemawari, Toshio Naito, Tamotsu Inabe
    2010 Volume 83 Issue 5 Pages 505-513
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    Mellitate is a unique anion that can form hydrogen-bonding anionic networks. In this study, crystal structures of the salts with quaternary ammonium and phosphonium cations that bear no hydrogen-bonding functional groups are investigated. When the number of deprotonation (n) from the parent mellitic acid is one, two kinds of networks, a two-dimensional sheet and a three-dimensional network containing helical chains, have been obtained. Both networks involve a common network motif, and this variation arises from the difference in the connection sequence of the motif. When n = 2, a rhombic motif that frequently occurs in the salts with proton-donating cations is also found to form. However, the vacant proton accepting sites of the anions are occupied by water molecules, and a sheet-like network with corner-sharing connection of the rhombic motifs occurs. For the salt of n = 3, a triangular motif that has commonly been found in the other mellitate salts of n = 3 with proton-donating cations is also involved in the network. Because the charge density in the simple two-dimensional sheet composed solely of the triangular motif is rather high, the network is divided into one-dimensional belts.
  • Hirotaka Tanimura, Ayumi Kitahori, Chie Kuzuoka, Yasushi Honda, Masahi ...
    2010 Volume 83 Issue 5 Pages 514-519
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    We calculated 55Mn and 13C magnetic shielding constants for Mn(CO)5X (X = H, F, Cl, Br, I, and CH3) and M(CO)(NH3)3 (M = Cr2+, Fe2+, Cu+, and Zn2+), respectively. For the first molecular group, we compared the calculated 55Mn chemical shifts with the experimental values, and clarified effects of the basis sets. The calculated magnetic shielding constants using the second-order Douglas–Kroll–Hess (DKH2) method showed good agreement with the experimental results. According to the atomic orbital (AO) contribution analysis, the origin of the chemical shifts was attributed to the d–d transitions of Mn. In particular, the 3dπ orbital mainly contributed to the paramagnetic term of the Mn chemical shift. For the second molecular group, the 13C chemical shifts were dependent on the metal atoms. When the metal centers were Cr2+ or Fe2+, lower field shifts were seen. When the metal centers were Cu+ or Zn2+, upper field shifts were observed. These results were in good agreement with the experimental trends. The change of the paramagnetic term mainly depended on the d orbital configurations of the metal of centers, and the donation from the metal d orbital to the CO anti-bonding π* orbitals is expected to affect the chemical shift.
  • Teruo Atsumi, Tomohiro Abe, Kin-ya Akiba, Hiromi Nakai
    2010 Volume 83 Issue 5 Pages 520-529
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    Theoretical study of the mechanism of bond-switching of 5-(1-aminoethylimino)-3-methyl-1,2,4-thiadiazole and 5-(2-aminovinyl)isothiazole was carried out by using simplified models of 1,6-dihydro-6a-thia-1,6-diazapentalene (10-S-3) systems and corresponding oxygen analogs. Geometries and energetics were examined along unimolecular and bimolecular reaction paths by hybrid density functional theory (DFT) calculations with triple-zeta class basis sets by taking into account solvent effects which is estimated by the polarizable continuum model. It was clarified that the unimolecular reactions cannot proceed due to the high energy barriers around 70 kcal mol−1. On the other hand, the bimolecular processes in neutral and acidic conditions can be accomplished for the sulfur compounds, not for the oxygen ones. The differences of the reactivities between the sulfur and oxygen compounds were found to be due to the difference of the stability of the symmetric intermediates with the hypervalent three-center four-electron bonds.
  • Tetsuro Tano, Yoshitaka Doi, Masayuki Inosako, Atsushi Kunishita, Mino ...
    2010 Volume 83 Issue 5 Pages 530-538
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    Nickel(II) complexes supported by a series of tpa {tris[(pyridin-2-yl)methyl]amine} ligand derivatives containing different numbers of phenyl substituent on the 6-position of pyridine donor group (Phntpa, n = 0–3) have been prepared and structurally characterized. Ligand tpa and its derivatives with one or two 6-Ph substituent(s) (Ph0tpa, Ph1tpa, and Ph2tpa) afforded nickel(II) complexes 1[0], 1[1], and 1[2] with a distorted octahedral geometry, whereas the ligand having three 6-Ph groups (Ph3tpa) gave nickel(II) complex 1[3] with a five-coordinate trigonal bipyramidal structure. All the complexes exhibited a high spin ground state (S = 1). Reactivity of the nickel(II) complexes 1[0] and 1[1] toward H2O2 was very poor, whereas 1[2] and 1[3] readily gave bis(μ-oxo)dinickel(III) complexes 2[2] and 2[3], respectively, in the reaction with H2O2 at a low temperature. The bis(μ-oxo)dinickel(III) complexes 2[2] and 2[3] gradually decomposed to cause an aromatic hydroxylation reaction of one of the 6-Ph groups of the supporting ligands. The ligand substituent effects on the formation and decomposition processes of the bis(μ-oxo)dinickel(III) complexes are discussed based on the structures and the redox potentials of the starting nickel(II) complexes.
  • Ping-Jyun Sung, Bo-Yuan Chen, Michael Y. Chiang, Chi-Hung Hou, Yin-Di ...
    2010 Volume 83 Issue 5 Pages 539-545
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    Chemical investigations on the cultured octocoral Briareum excavatum have led to the isolation of five new 8,17-epoxybriarane diterpenoids, excavatoids G–K (15). The structures of briaranes 15 were determined on the basis of spectroscopic methods and the structure of 1 was further confirmed by a single-crystal X-ray diffraction analysis. Cytotoxicity of these metabolites toward various tumor cell lines is described. Excavatoid I (3) was found to show mild inhibitory effects on elastase release and superoxide anion generation by human neutrophils.
  • Masanori Miura, Norihito Muranaka, Ryoji Abe, Takahiro Hohsaka
    2010 Volume 83 Issue 5 Pages 546-553
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    Incorporation of non-natural amino acid derivatives containing fluorescent groups into proteins is a useful method for protein analyses. Here, we investigated the incorporation of fluorescent-labeled non-α-amino carboxylic acids into the N-terminus of proteins in response to the UAG initiation codon. A series of TAMRA-labeled amino carboxylic acids were synthesized and attached to an amber suppressor initiator tRNA derived from Escherichia coli initiator tRNA. Fluorescent-labeled amino carboxylic acids were successfully incorporated into the N-terminus of streptavidin by adding TAMRA-acylated initiator tRNAs to an E. coli cell-free translation system, although the incorporation efficiency differed depending on the amino carboxylic acid chain length. Based on this observation, 3-aminopropionic acid derivatives labeled with BODIPY, rhodamine, and cyanine fluorophores were designed and synthesized. The fluorescent-labeled 3-aminopropionic acid derivatives developed using BODIPY and rhodamine dyes could be incorporated with good efficiency. On the other hand, 6-aminohexanoic acid was effectively incorporated when labeled with cyanine dyes. The present study demonstrates that translation initiation can accept a wide variety of non-natural substrates and provides a useful method for N-terminal-specific labeling of proteins with various fluorophores.
  • Jinshui Chen, Masaaki Tanaka, Akhila K. Sahoo, Masahide Takeda, Akira ...
    2010 Volume 83 Issue 5 Pages 554-569
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    Through intramolecular activation, highly stable aryl[2-(hydroxymethyl)phenyl]dimethylsilanes can selectively transfer their aryl groups to effect a cross-coupling reaction with various aryl bromides and chlorides in the presence of a weak non-fluoride base and a palladium/copper catalyst. This reaction tolerates a wide range of functional groups, producing the corresponding functionalized biaryls in high yields with excellent chemoselectivity. Newly disclosed reaction conditions allow the recovery of a cyclic silyl ether in modest-to-good yields and reuse for the synthesis of the arylsilanes. The introduction of two isopropyl groups on the silicon center instead of methyl groups improves the stability and allows quantitative recovery of the silicon residue. Finally, aryl halides having an O-protected [2-(hydroxymethyl)phenyl]dimethylsilyl group cross-couple with the arylsilane reagents to give silyl-functionalized biaryls. Upon deprotection, the biaryls further react with the silylated electrophiles. The iterative cross-coupling–deprotection sequences allow rapid assembly of silylated oligoarenes. Syntheses of di- and trisilyloligoarenes are also achieved by use of orthogonal O-protecting groups.
  • Toru Kawakami, Sakiko Shimizu, Saburo Aimoto
    2010 Volume 83 Issue 5 Pages 570-574
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    In protein synthesis, peptide thioesters are frequently used as key building blocks for the ligation strategy. We report herein on the synthesis of a peptide thioester using an N to S acyl shift reaction. A peptide containing a Cys–Pro–Cys (CPC) sequence was transformed into a peptide diketopiperazine (DKP) thioester under acidic conditions. In this reaction, the CPC moiety undergoes a tandem N to S acyl shift, followed by DKP formation to give the desired thioester. Since proteins containing a CPC sequence can be prepared by recombinant DNA techniques, the CPC peptide represents a new method for preparing peptide thioesters as recombinant proteins for protein synthesis.
  • Keiko Omata, Masashi Mamada, Jun-ichi Nishida, Shizuo Tokito, Yoshiro ...
    2010 Volume 83 Issue 5 Pages 575-581
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    Dibenzotetrathiafulvalene (DBTTF) analogs containing fused thiophene spacers were synthesized and characterized by cyclic voltammetry, UV–vis absorption spectroscopy, quantum chemical calculations, single-crystal X-ray analysis, overlap integral calculations, field-effect transistor (FET) characteristics, X-ray diffraction, and atomic force microscopy (AFM). The single-crystal X-ray analysis revealed that the DBTTF with a thieno[3,2-b]thiophene spacer has a molecular geometry with short intramolecular S···S contacts and a herringbone packing structure with short intermolecular S···S contacts leading to large two-dimensional overlap integrals. The molecule afforded a crystalline thin film with well-ordered molecular orientation corresponding to the single-crystal structure. The FET device based on this molecule exhibited good mobility of 0.29 cm2 V−1 s−1 and low threshold voltage of −0.3 V. The effects of the thiophene spacer on the properties, structure, and FET performances were investigated here.
  • Masaharu Tsuji, Takashi Kawahara, Naohiro Kamo, Masato Miyano
    2010 Volume 83 Issue 5 Pages 582-591
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    The photochemical removal of benzene was investigated in N2/O2 mixtures (0–20% O2) using a 172 nm Xe2 excimer lamp at atmospheric pressure. After 20 min photoirradiation, about 97% of C6H6 (1000 ppm) in N2/O2 mixtures (10–20% O2) was converted to HCOOH, CO, and CO2. In the 172 nm photolysis of C6H6, not only direct photolysis by VUV photons but also reactions of O(3P,1D) and O3 can take part in the decomposition of C6H6. To examine effects of direct photolysis, C6H6 was decomposed in N2, whereas the contribution of O3 was studied by observing the O3 + C6H6 reaction. The contribution of O(1D) was examined by reducing the total pressure to suppress the collisional quenching of O(1D) by N2/O2 mixtures. It was found that the O(3P) + C6H6 reaction plays a significant role in the initial stage of the removal reaction of C6H6.
  • Joji Sonoda, Takashi Kamegawa, Yasutaka Kuwahara, Kohsuke Mori, Hiromi ...
    2010 Volume 83 Issue 5 Pages 592-594
    Published: May 15, 2010
    Released: May 15, 2010
    [Advance publication] Released: April 29, 2010
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    Hydrophobic modification of Ti-containing zeolite (TS-1) was performed by using triethoxyfluorosilane (TEFS). TS-1 after modification with TEFS (w = 1%) showed higher catalytic activity for the ammoximation of cyclohexanone than those on unmodified and modified TS-1 with TEFS (w = 5%) due to effective modification without covering the underlying catalytically active Ti-oxide species.
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