Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 90 , Issue 12
Showing 1-15 articles out of 15 articles from the selected issue
BCSJ Award Article
  • Koichi Kajihara, Naoto Tezuka, Mao Shoji, Jungo Wakasugi, Hirokazu Mun ...
    2017 Volume 90 Issue 12 Pages 1279-1286
    Published: December 15, 2017
    Released: December 15, 2017
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    A cubic boracite with substituted boron sites, Li4B4M3O12Cl (M = Al, Ga), derived by fully replacing the tetrahedral BO4 units in the parent lithium chloroboracite, Li4B7O12Cl, with AlO4 or GaO4 units, has been discovered. These substituted compounds have the largest unit cell dimensions of known boracites and are formed as the stable primary phase in highly crystalline glass-ceramics derived from the Li2O–B2O3M2O3–LiCl quarternary system. The conductivity of Li4B4M3O12Cl glass-ceramics at room temperature was ∼10−5 S cm−1, an order of magnitude larger than the highest conductivity recorded for Li4B7O12Cl glass-ceramics. The Li4B4Al3O12Cl glass-ceramic is stable in contact with Li metal and exhibits a wide electrochemical window between 0 and 6 V vs. Li/Li+ and a Li+ ion transport number of ∼1.

    A cubic boracite with substituted boron sites, Li4B4M3O12Cl (M = Al, Ga), derived by fully replacing the tetrahedral BO4 units in the parent compound, Li4B7O12Cl, with MO4 units, has been discovered. The Li4B4Al3O12Cl glass-ceramic is stable in contact with Li metal and exhibits a wide electrochemical window between 0 and 6 V vs. Li/Li+ and a Li+ ion conductivity of ∼10−5 S cm−1 at room temperature. Fullsize Image
     
 
  • Toru Koizuka, Masanori Yamamoto, Yuichi Kitagawa, Takayuki Nakanishi, ...
    2017 Volume 90 Issue 12 Pages 1287-1292
    Published: December 15, 2017
    Released: December 15, 2017
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    Thermostable mononuclear Eu(III) complexes with a π-expanded system, [Eu(btfa)3(DPEPO)] and [Eu(ntfa)3(DPEPO)] (DPEPO: bis[2-(diphenylphosphino)phenyl] ether oxide, btfa: benzoyltrifluoroacetonate, ntfa: 3-(2-naphthoyl)-1,1,1-trifluoroacetonate), are reported. Decomposition temperature (dp) of [Eu(btfa)3(DPEPO)] and that of [Eu(ntfa)3(DPEPO)] are estimated to be 320 °C and 318 °C, respectively. These values are higher than that of the previous [Eu(hfa)3(DPEPO)] (hfa: hexafluoroacetylacetonate, dp = 228 °C). The photosensitized emission quantum yield Φπ–π* and photosensitized energy transfer efficiency ηsens of [Eu(ntfa)3(DPEPO)] (Φπ–π* = 45%, ηsens = 77%) are larger than those of [Eu(btfa)3(DPEPO)] (Φπ–π* = 38%, ηsens = 55%). The thermostable Eu(III) complex with a π-expanded system is expected to be useful for fabrication of LED devices.

  • Kazuma Matsui, Yuko Nishihara, Tomoko Yamaguchi, Yasuhiro Sakurai, Yus ...
    2017 Volume 90 Issue 12 Pages 1293-1308
    Published: December 15, 2017
    Released: December 15, 2017
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    Based on the results of rapid-flow electron spin resonance (RF-ESR) and spin-trapping (ST-ESR) measurements, carbonyl-conjugated radicals derived from the vicinal diol moiety (2, i.e., the head-to-head structure) of poly(vinyl alcohol) (PVA) have been proposed to be the most probable intermediate species involved in the initial stages of the graft reaction of PVA with methyl methacrylate (MMA). A modified poly(vinyl alcohol) (PPVA) bearing a 1,2-propanediol pendant moiety (3) with a molar ratio of 8% (based on the monomer unit) was prepared to clarify the role of the carbonyl-conjugated radicals of PPVA in the graft reaction with MMA. The RF-ESR spectra observed for the mixtures composed of PPVA, hydrogen peroxide (HPO) or ammonium persulfate (APS), and Ti2(SO4)3 (pH ca. 2) revealed the formation of four radical species (A, B1, B2, and C) derived from PPVA. By comparison of the RF-ESR spectra observed for PPVA and PVA, species A (g = 2.0041) was confirmed to be the pendant derived radical of PPVA, and species B1 and B2 (g = 2.0023) and C (g = 2.0032) were assigned to be the PVA main-chain derived radicals. Species B1 and B2 were deduced to be a pair of carbonyl-conjugated radicals (4, 5, R1–CH2–CO–CH–CH2–R2) derived from the vicinal diol (2), and species C was assigned to be the secondary alcohol (1) derived radicals (6, R1–CH2COH–CH2–R2). In terms of g value and proton hyperfine coupling constants (hfcc), the molecular structure of species A was ascribed to be the carbonyl-conjugated radical of the pendant moiety (7, CH2–CO–CHR1R2). The results of ST-ESR measurements using the sodium salt of 3,5-dibromo-4-nitroso-benzene-sulfonate (DBNBS) show that a pair of pendant radicals (7) and (8, O=CH–CH–CHR1R2) was formed in the graft polymerization reaction solutions containing APS or HPO as an oxidant (80 °C, pH ca. 2). The grafted copolymers of PPVA and PVA (PPVA-g-MMA and PVA-g-MMA) were separated from similar graft reaction solutions composed of APS and MMA after heating at 70 °C for 1 h (pH ca. 2), and the grafting efficiencies of PPVA (PPVAge%) and PVA (PVAge%) were, respectively, estimated to be 4% and 2%. The molecular and electronic structure of the carbonyl-conjugated radicals derived from the main-chain (4, 5) and from the pendant moiety (7, 8) of PPVA will be discussed in relation to the reaction mechanisms of the initial reaction stage of the graft copolymerization with MMA.

Award Account
The Chemical Society of Japan Award for Creative Work for 2016
  • Takashi Morii
    2017 Volume 90 Issue 12 Pages 1309-1317
    Published: December 15, 2017
    Released: December 15, 2017
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    A combination of synthetic, organic, and biochemical approaches has been developed to study how protein and nucleic acid assemblies modulate the affinity, specificity and cooperativity of protein–nucleic acid interactions. These strategies have enabled formation of noncovalent peptide dimers on specific DNA sequences. A new framework from RNA and peptide into a stable complex of ribonucleopeptide was also developed to construct receptors and fluorescent sensors for small molecules. Attempts to design novel DNA-binding peptides, receptors and sensors will provide an ultimate test for our understanding of the principle of molecular recognition associated with protein–nucleic acid interactions.

    A combination of synthetic, organic, and biochemical approaches has been developed to study the specific and cooperative formation of assemblies by proteins and nucleic acids. These strategies enabled recognition of specific DNA sequences by peptide dimers and construction of receptors and the fluorescent sensors by a stable complex of ribonucleopeptide. Fullsize Image
     
 
Award Account
The Chemical Society of Japan Award for Creative Work for 2012
  • Yasuhisa Mizutani
    2017 Volume 90 Issue 12 Pages 1344-1371
    Published: December 15, 2017
    Released: December 15, 2017
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    Protein dynamics play a fundamental role in allosteric regulation, which is vital to the function of many proteins. In many proteins, rather than a direct interaction, mutual modulation of properties such as ligand affinity at spatially separated sites is achieved through a conformational change. Conformational changes of proteins are thermally activated processes that involve intramolecular and intermolecular energy exchanges. In this account, I review the work of my team on the development and applications of ultrafast time-resolved resonance Raman spectroscopy to observe functionally important protein dynamics. We gained insights into conformational dynamics upon external stimulus and energy flow with a spatial resolution of a single amino acid residue using time-resolved visible and ultraviolet resonance Raman spectroscopy. The results have contributed to a deeper understanding of the structural nature of protein motion and the relationship of dynamics to function. I discuss the protein dynamics and allosteric mechanism in terms of the nature of the high packing density of protein structures. In addition, I present a view of the future of molecular science on proteins.

    Time-resolved visible and ultraviolet resonance Raman spectroscopy were used to determine conformational dynamics upon an external stimulus and energy flow with a spatial resolution of a single amino acid residue in proteins. This account summarizes the accomplishments that promoted an understanding of how proteins change structure to realize their functions and how energy dissipation is coupled to protein structure and dynamics. Fullsize Image
     
 
Vol. 90 Commemorative Account: Self-Organization
  • Yang Wang, Tsuyoshi Michinobu
    2017 Volume 90 Issue 12 Pages 1388-1400
    Published: December 15, 2017
    Released: December 15, 2017
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    Polymers are a good platform for the production of various functional materials, since functional moieties can be introduced into both the main chain backbone and side chain pendants by elegant molecular design and utilizing efficient synthetic protocols. Highly colored and fluorescent π-systems have often been employed as ion sensing units especially when heteroaromatic rings are included. The heteroaromatic rings can form supramolecular complexes with metal ions or anions, resulting in the visual color changes of absorption and fluorescence. Conjugated polymers have been traditionally employed to this end, because they are highly emissive and very sensitive to various ions. However, most of such conjugated polymers are synthesized by costly cross-coupling polycondensations, which do not meet the green chemistry concepts of this century. Click chemistry is a new concept representing an efficient and atom-economic synthesis, and one of the most common reactions is the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) yielding 1,2,3-triazole rings. The 1,2,3-triazole derivatives are electronically almost inert, but they possess fluorescent chemosensor properties. Recent examples of polymeric chemosensors based on the 1,2,3-triazole derivatives are introduced. Furthermore, an emerging click chemistry reaction, i.e., the alkyne-acceptor click chemistry, is also introduced. This reaction produces highly colored donor-acceptor (D-A) chromophores on a polymer platform, enabling visual detection of the ion sensing behavior. The polymeric chemosensors with the D-A chromophores show a specific discrimination between hard and soft metal ions by different color changes. These polymers are also useful for anion sensing.

    Synthesis of new polymeric chemosensors by click chemistry reactions is described, and the difference and progress from the old conjugated polymer sensors are discussed. In particular, donor-acceptor chromophores, prepared by the new alkyne-acceptor click chemistry reactions, are useful for the visual detection and discrimination of specific metal ions. Fullsize Image
     
Vol. 90 Commemorative Account: Fascinating Molecules and Reactions
Award Account
The Chemical Society of Japan Award for Creative Work for 2013
  • Sensuke Ogoshi
    2017 Volume 90 Issue 12 Pages 1401-1406
    Published: December 15, 2017
    Released: December 15, 2017
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    Nickel is one of the most popular first row transition metals for coupling reactions. For the past two decades, catalytic multi-component coupling reactions via nickelacycles have been developed. Although the formation of nickelacycles has been believed an important key step in the catalytic reactions, the generation of nickelacycles by oxidative cyclization has been less studied. Thus, we have been focusing on the formation of nickelacycles from nickel(0) species and development of catalytic reactions without using coupling reagents to construct highly atom economical nickel-catalyzed multi-component connecting reactions.

    Catalytic reactions via nickelacycles generated by oxidative cyclization of unsaturated compounds with nickel(0) are discussed in this review. The correlation between the reactivity and molecular structure of nickelacycle intermediates is also a focus for deeper insight into the reaction mechanism. In addition, the revealing key reaction intermediates allow us to develop new reactions. Fullsize Image
     
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