Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 79 , Issue 11
Showing 1-21 articles out of 21 articles from the selected issue
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The Chemical Society of Japan Award for Creative Work for 2004
  • Hideki Tanaka, Kenichiro Koga
    2006 Volume 79 Issue 11 Pages 1621-1644
    Published: 2006
    Released: November 09, 2006
    JOURNALS FREE ACCESS
    We have investigated various anomalous properties of water such as the divergent character of the thermodynamic functions and liquid–liquid transition in supercooled water, the phase behaviors of water and new ices in nanoscale confinement, the thermodynamic stability of clathrate hydrates over a wide range of pressure, and anomalous thermodynamic and structural properties of ices. These are studied by some theoretical calculations and Monte Carlo/molecular dynamics computer simulations. It is demonstrated that the potential energy surface and the connectivity of supercooled water are keys to understand why liquid–liquid transition can take place in deeply supercooled water. A tetrahedral coordination of water is preserved even in extreme confinements, forming tubule ice and bilayer crystalline (or amorphous) ice, although the heavy stress makes the bond angles and lengths different from the ideal values. Thermodynamic stability of clathrate hydrates, including double occupancy, is more accurately predicted by considering the host–guest coupling and other factors. The negative thermal expansivity and the change in slope of the Debye–Waller factor of ice are explained with a simple model of water.
Accounts
  • Hiromu Sakurai, Akira Katoh, Yutaka Yoshikawa
    2006 Volume 79 Issue 11 Pages 1645-1664
    Published: 2006
    Released: November 09, 2006
    JOURNALS FREE ACCESS
    The number of patients suffering from diabetes mellitus (DM), which is a chronic metabolic disorder and mainly classified as either insulin-dependent type 1 or non-insulin-dependent type 2, is increasing throughout the world. The sequence of DM progression makes this disease a major health risk in regard to microvascular disease that leads to kidney failure, blindness, and nerve damage as well as macrovascular disease that leads to amputations, cardiovascular disease, and stroke. To treat DM, several types of insulin preparations and synthetic drugs for type 1 and type 2 DM, respectively, are in clinical use. However, there are several problems concerning the insulin preparations and synthetic drugs, such as physical and mental pain due to daily insulin injections and defects involving several side effects, respectively. Thus, the disease demands extraordinary effects to define pathobiochemical pathways and strategies for prevention and to find new therapeutic approaches. For this purpose, oxovanadium(IV) (vanadyl, VO2+) and zinc(II) containing complexes have been explored as treatments for both types of DM. This article reviews the current state of research on insulin-mimetic and antidiabetic metal complexes, with special focus on paramagnetic vanadyl and diamagnetic zinc(II) complexes with different coordination modes, together with possible reaction mechanisms. New drug delivery systems involving enteric-coated capsulation and a biopolymer are also reviewed.
  • Hiroyuki Ohno
    2006 Volume 79 Issue 11 Pages 1665-1680
    Published: 2006
    Released: November 09, 2006
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    Ionic liquids, molten salts at temperatures lower than 100 °C, preferably below room temperature, are unique liquids having very different characteristics from ordinary molecular liquids. Since these ionic liquids are prepared by coupling relatively large organic ions, there are many chances to create novel functionalities by changing structure of component ions. To develop such novel and functional ionic liquids, we first developed a facile preparation method, i.e., neutralization of tertiary amines with organic acids. By this convenient method, we prepared hundreds of salts having low melting points. We, then, tried to prepare ionic salts containing small ions such as lithium cation, proton, or chloride anion. Because small ions received stronger electrostatic force due to higher surface charge density, which results in the formation of salts with higher melting points, case must be taken. Ionic liquids containing halogen-free salts are another interesting subject to challenge from the viewpoint of environmentally friendly materials. Heteroaromatic rings such as azolates gave excellent ionic liquids having very low viscosity by coupling with suitable cations. Amino acids have also been used as anions to prepare salts with low melting points or amorphous glasses. They are helpful to analyze the relationship between ion structure and characteristics of the salts. Zwitterions, in which both cation and anion were tethered with a covalent bond, were prepared to function as ionic liquids. These ions should not migrate under a potential gradient and should be an excellent ion conductive matrix for added ions. Tethering of ions caused the Tm to be high, and the zwitterions with melting points around room temperature have not been synthesized yet. However, lots of solid zwitterions became liquids by adding suitable solid salts or acid such as lithium bis(trifluoromethanesulfonyl)imide. In this mixture, lithium cations had a transport number higher than 0.5, meaning that the lithium cations are the major mobile ions in the mixture. Some of the functionality is achieved by dimension control, such as polymerization of ions, and so on. Other functional modifications and design of ionic liquids are also mentioned.
BCSJ Award Article
  • Yusuke Mori, Yoshiyuki Sugahara
    2006 Volume 79 Issue 11 Pages 1681-1687
    Published: 2006
    Released: November 09, 2006
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    Soluble precursors possessing both Al–N and B–N backbones have been prepared from LiAlH4, LiBH4, and RNH2·HCl (R = Me and Et) in one pot. The infrared (IR) and nuclear magnetic resonance (NMR) spectra of the precursors indicate that the precursors possess Al–H and B–H groups as well as Al–N, B–N, Al–(μ-H)2–Al, and Al–(μ-H)2–B bonds. TG analysis reveals that the ceramic yield of the precursor [AB11_Me (LiAlH4/LiBH4/MeNH2·HCl = 1/1/2)] up to 1000 °C under an argon atmosphere is 74.4 mass %. The transmission electron microscopic (TEM) images and the X-ray diffraction (XRD) pattern of AB11_Me that was pyrolyzed at 1600 °C indicate that the average size of crystalline aluminum nitride (AlN) is about 14 nm and that crystalline AlN particles are distributed homogeneously in an amorphous matrix.
Articles
  • Anil Kumar Nain
    2006 Volume 79 Issue 11 Pages 1688-1695
    Published: 2006
    Released: November 09, 2006
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    Ultrasonic speeds (u) and viscosities (η) of binary mixtures of acetonitrile (ACN) with formamide (FA), N,N-dimethylformamide (DMF), N-methylacetamide (NMA), and N,N-dimethylacetamide (DMA), including those of pure liquids, over the entire composition range expressed by mole fraction x1 of ACN (0 ≤ x1 ≤ 1) were measured at 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15 K. From the experimental data, the deviations in isentropic compressibility (Δks), in ultrasonic speed (Δu), and in viscosity (Δη), and partial molar compressibilities, ( and ) for ACN in amide and amide in ACN at infinite dilution, respectively, were calculated. The variation of these parameters with composition and temperature of the mixtures are discussed in terms of the molecular interactions in these mixtures. It was observed that the ACN–amide interaction in these mixtures follows the order: FA > NMA > DMA > DMF. The effect of the number and position of the methyl group on the amide on the molecular interactions in these mixtures is also discussed. Finally, the free energy (ΔG*), enthalpies (ΔH*), and entropies (ΔS*) of activation of viscous flow have also been obtained by using Eyring’s viscosity equation, and the dependence of ΔG*, ΔH*, and ΔS* on composition of the mixtures is also discussed.
  • Akihisa Shioi, Kanako Yamada, Runa Shiota, Fumie Hase, Takahiko Ban
    2006 Volume 79 Issue 11 Pages 1696-1703
    Published: 2006
    Released: November 09, 2006
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    Fluctuation in the interfacial tension in an oil/water interface composed of di(2-ethylhexyl)phosphoric acid (DEHPA) and divalent cations (Mg2+, Ca2+, Sr2+, and Ba2+) were investigated. Only a combination of Ca2+ and DEHPA caused noticeable tension fluctuation and spontaneous interfacial flow. Light-scattering experiments and the extraction of cations with DEHPA indicated that both a high reactivity between cation and DEHPA, of which only Ca2+ had a high reactivity, and strong attractive interactions between M(DEHP)2 molecules were required for fluctuation. These may induce a collective desorption of Ca(DEHP)2. This was supported by the observation of alternating pH-change with m-Cresol Purple. An N-shape dependency of interfacial pressure on the DEHPA concentration was observed only for Ca-containing interface. Due to this dependency, there was a DEHPA concentration range in the interfacial pressure vs the concentration curve, which satisfies two different conditions. First, the dependency of the interfacial pressure on the concentration is negative, and second, there are other two concentrations with the same interfacial pressure value. The DEHPA concentration range involving tension fluctuation almost agreed with the concentration range, which is discussed. The interface may be a chemical generator predicted by Vedove and Sanfeld.
  • Hitoshi Matsuki, Michio Yamanaka, Yuji Yamashita, Shoji Kaneshina
    2006 Volume 79 Issue 11 Pages 1704-1710
    Published: 2006
    Released: November 09, 2006
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    The surface tension of aqueous solutions of cationic, nonionic, and anionic surfactants was measured as a function of the size of drop formed under the tip of a glass capillary and the time for which the drop is allowed to stand by a previously developed apparatus based on the drop volume method. The surface tension of cationic and nonionic surfactant solutions was slightly dependent on the drop size and the adsorption time at low concentrations, and we could easily obtain the adsorption-equilibrium surface tension values by use of an intact capillary. However, the surface tension of anionic surfactant solutions showed a strong dependence on these factors, and the equilibrium surface tension values could not be obtained by use of the intact capillary at all. This situation was drastically improved by use of the water-repellent capillary coated with a silane-coupling reagent. We proposed that the equilibrium surface tension value of surfactant solutions can be determined by adopting the adsorption time at which the surface tension value becomes constant on the surface tension vs the drop size curves. Further, the conditions under which the equilibrium surface tension value of surfactant solutions could be acquired by means of the drop volume method were quite different than those of the Wilhelmy plate method.
  • Mahmoud M. Saleh, Maher H. El-Ankily, Mohamed S. El-Deab, B. E. El-Ana ...
    2006 Volume 79 Issue 11 Pages 1711-1718
    Published: 2006
    Released: November 09, 2006
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    Reticulated vitreous carbon (RVC) electrodes have been used as possible porous cathodes, operating in flow-through mode for the purpose of the electrolytic generation of hydrogen gas from flowing alkaline solutions. The electrocatalytic performance of the RVC cathode was tested under different operating conditions, such as electrolyte flow regimes and temperature. Also, the effect of electroplating the RVC with copper metal or Watts nickel in flowing electrolytes has been assessed. Potentiodynamic and galvanostatic techniques along with SEM images were used to investigate the performance of the different cathodes: bare (uncoated) RVC, copper-coated RVC (RVC/Cu), and Ni-coated RVC (RVC/Ni). The hydrogen evolution reaction (HER) was found to be enhanced by coating RVC either with Cu or Ni. Polarization behavior had higher rates for HER using RVC/Ni than using RVC/Cu or bare RVC. This trend was confirmed by using a planar glassy carbon electrode (GC) coated with Cu and Ni under the same conditions. The activation energies for HER using RVC and RVC/Ni were estimated to be 32 and 14 kJ mol−1, respectively. Current transient and SEM micrographs showed good electrocatalytic and mechanical stability of the metal loadings. There was no indication of loss of the catalytic properties after operation for 30 h. Model calculations helped to extract kinetic parameters for the HER using different electrodes.
  • Shigehiro Kagaya, Yuka Serikawa, Ryosuke Yashima, Toshiyuki Tanaka, Ki ...
    2006 Volume 79 Issue 11 Pages 1719-1724
    Published: 2006
    Released: November 09, 2006
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    A preconcentration-storing technique that does not require any special or expensive apparatus and reagents was developed to monitor mercury in rainwater and snow at many points as simultaneously as possible. A commercially available sodium hypochlorite solution was added to the sample solution to prevent a decrease in mercury concentration after sampling. Mercury(II) ion (0.5–50 ng) in 500 mL of the sample solution was concentrated by adding zinc(II) ion and a small amount of sulfide ion and then coagulating/coprecipitating with Zn(OH)2 or ZnS after reduction of residual hypochlorite by addition of hydroxylammonium chloride. The supernatant solution was discarded by decantation, and the solution including the precipitates could be stored for at least 20 days without any loss of mercury. The recoveries of mercury(II) ion from the 500 mL of the sample solutions spiked with mercury(II) ions were 99–109%, with standard deviation ranges of 3–8%, although the recovery of methylmercury(II) ion was 68 ± 5%. Using this technique, the determination of mercury in rainwater and snow was demonstrated at Toyama Prefecture, Japan, from April 2004 to February 2005; mercury levels ranging from 2.7 to 33.7 ng L−1 were found.
  • Katsuya Teshima, Kunio Yubuta, Shiori Sugiura, Takaomi Suzuki, Toetsu ...
    2006 Volume 79 Issue 11 Pages 1725-1728
    Published: 2006
    Released: November 09, 2006
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    High quality, hexagonal prismatic Na2Ti6O13 whiskers were easily grown by the slow-cooling of a NaCl flux. Whisker growth was conducted by heating a mixture of solute (Na2CO3 + TiO2) and flux (NaCl) at 1100 °C and held at this temperature for 10 h, and then the mixture was cooled at a rate of 5 °C h−1 to 500 °C. The Na2Ti6O13 whiskers had average lengths of up to 100 μm and widths of up to 2.0 μm and were transparent and colorless. The whiskers were hexagonal prisms bounded by well-developed {010}, {100}, {001}, and {} faces. The whiskers exhibited good photocatalytic activity under UV light irradiation. Sodium chloride was found to be a very suitable flux for environmental friendly growth of photocatalytic whiskers.
  • Atsushi Kunishita, Takao Osako, Yoshimitsu Tachi, Junji Teraoka, Shino ...
    2006 Volume 79 Issue 11 Pages 1729-1741
    Published: 2006
    Released: November 09, 2006
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    The structure and O2-reactivity of the copper(I) complexes supported by bis[(6-phenyl-2-pyridyl)methyl]amine tridentate ligands (L5R) and bis(2-quinolylmethyl)amine tridentate ligands (L6R) have been investigated in detail in order to get insights into the steric effects of the tridentate ligands on copper(I)/O2 chemistry. In the cases of benzyl amine and phenethyl amine derivatives [R = –CH2Ph (Bz) and –CH2CH2Ph (Phe)], the reaction between the ligands and [CuI(CH3CN)4]+ gave the corresponding copper(I)–acetonitrile complexes having a distorted tetrahedral geometry. On the other hand, the 2,2-diphenylethyl amine derivative L6R [R = –CH2CHPh2 (PhePh)] afforded a copper(I) complex without an ancillary ligand (CH3CN) and having intramolecular d–π interaction between the copper(I) ion and the phenyl group of the alkyl substituent PhePh. The acetonitrile complexes were then converted to the corresponding CO-complexes by reacting with CO gas. The X-ray structures of all CO-complexes have been determined, and the complexes have a similar distorted tetrahedral geometry. In addition, the 6-phenyl group of L5R imparts a large steric effect on the metal-binding. The CO-complexes were converted to the copper(I) complexes without having any ancillary ligands in order to examine their O2-reactivity. Significantly large differences in O2-reactivity were found among the copper(I) complexes. On the basis of O2-reactivity together with the X-ray structures and the oxidation potentials of the copper(I) complexes, the steric effects of the hetero-aromatic donor groups (6-substituted pyridine and quinoline) as well as the alkyl substituents (R) are discussed in detail.
  • Masaaki Tabata, Ying Guang Wu, Thiraporn Charoenraks, Sethsiri Sunil S ...
    2006 Volume 79 Issue 11 Pages 1742-1744
    Published: 2006
    Released: November 09, 2006
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    This paper describes a new type of open tubular capillary liquid chromatography (OTCLC) which utilizes the microheterogenities and preferential solvation phenomena in organic-water mixed solvents. Several model compounds have been separated by the proposed OTCLC system, and it has been confirmed the separation occurs due to the micro-phase separation of the mobile phase enhanced by salts. The well-known Golay equations were applied to characterize and optimize the OTCLC system.
  • Takashi Yoshimura, Atsushi Shinohara, Masakazu Hirotsu, Keiji Ueno, Ta ...
    2006 Volume 79 Issue 11 Pages 1745-1747
    Published: 2006
    Released: November 09, 2006
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    The 1:1 reaction of [Ru(bpy)2(solvent)2]2+ (bpy = 2,2′-bipyridine) with [Ni(aet)2] (aet = 2-aminoethanethiolate) gave a S-bridged RuII2NiII2 tetranuclear complex with an eight-membered Ru2Ni2S4 metallacycle, [{Ru(bpy)2}2{Ni(aet)2}2]4+, while a S-bridged RuIINiII dinuclear complex with a four-membered RuNiS2 metallacycle, [Ru(bpy)2{Ni(aet)2}]2+, was obtained by the corresponding 1:2 reaction between [Ru(bpy)2(solvent)2]2+ and [Ni(aet)2].
  • Seema Kanwar, S. D. Sharma
    2006 Volume 79 Issue 11 Pages 1748-1752
    Published: 2006
    Released: November 09, 2006
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    The disulfide reagents 2,2′-dithiobisbenzothiazole (MBTS) and 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide (Lawesson’s Reagent, LR) mediate the cyclization of β-amino acids with remarkable product yields. Compared to other cyclodehydrating agents, these have been found to be superior in terms of their cost, making them industrially viable. The advantageous properties of MBTS and LR make them useful and unique additions to the arsenal of cyclodehydrating agents.
  • Naoko Senda, Atsuya Momotake, Yoshinobu Nishimura, Tatsuo Arai
    2006 Volume 79 Issue 11 Pages 1753-1757
    Published: 2006
    Released: November 09, 2006
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    The absorption spectra and fluorescence spectra of a coumarin derivative (1), designed to be a water-soluble photolabile protecting group for caged compounds, were successfully observed in aqueous buffer solutions at pH 2.0–12.5 for the first time. Coumarin 1 is highly soluble (>5 mM) in aqueous buffer at pH 7.2 and is stable in the dark at room temperature for up to a week. The pKa value for the protonation of anilino nitrogen in coumarin 1 was determined to be 4.5. Coumarin 1 has a fluorescence lifetime of 2.0 ns and undergoes intersystem crossing to the triplet state. Therefore, compound 1 can be used for the light absorbing part of the new water-soluble caged compounds, such as caged amino acids or caged nucleotides, which can release free amino acids or nucleotides, respectively, by excitation in the visible region.
  • Masahiro Minabe, Ayumi Yamazaki, Toshinobu Imai, Takumi Takanezawa, Mi ...
    2006 Volume 79 Issue 11 Pages 1758-1765
    Published: 2006
    Released: November 09, 2006
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    We studied the formation of 2,2′-diacyl-9,9′-bifluorenylidene from 2-acyl-9-bromofluorene. The E-isomer was obtained mainly when the acyl group was a short alkyl chain, such as an acetyl group, and Z-isomer was isolated predominantly when a long acyl chain such as stearoyl group was attached. 9,9′-Bifluorenylidene was formed via anti elimination of hydrogen bromide from the intermediate 9-bromo-9,9′-bifluorenyl. This indicated that the stereochemistry of 2,2′-diacyl-9,9′-bifluorenylidene was determined by the configuration of 9-bromo-9,9′-bifluorenyl isomers, giving Z- and E-isomers in a ratio of 1:1. Facile base-catalyzed Z/E isomerization of 9,9′-bifluorenylidenes followed the formation of the alkenes, which showed different stereoselectivity depending upon the length of the acyl side-chain. On the other hand, thermal treatment of 2,2′-diacyl-9,9′-bifluorenylidene afforded a ca. 1:1 mixture of Z- and E-isomers, suggesting that thermal isomerization took place through a different pathway than base-catalyzed isomerization.
  • Subramanian Manimekalai Malathy Sony, Mondikalipudur Nanjappa Ponnuswa ...
    2006 Volume 79 Issue 11 Pages 1766-1772
    Published: 2006
    Released: November 09, 2006
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    Non-covalent interactions involving halogen atoms play a major role in supramolecular chemistry, biochemistry, coordination and organometallic chemistry and also act as conformation-determining factors. Therefore, the hydrogen-bonding nature of the halogen acceptors in solid state are analyzed statistically, and the geometrical characteristics of weak hydrogen-bonded interactions are studied for the oxygen, nitrogen, and carbon atom donors. The hybridization states of the donor atoms and the different coordination environment of the halogen acceptors were also considered. The distance and the directionality characteristics that dictate the hydrogen bonds are given importance. Oxygen and nitrogen donors both showed the ability to form a strong hydrogen bond whereas carbon donors formed weak hydrogen bonds. The hydrogen-bonding nature of the carbon donor with a halogen acceptor was proven with this analysis; however, it had a hydrogen···acceptor distance cutoff of 2.7 Å for chlorine. Different hybridization states of the donor atoms did not significantly change the nature of the interaction; however, various coordination environments had some effect.
  • Ken’ichiroh Nakamura, Megumi Sumida, Toru Kawakami, Thomas Vorhe ...
    2006 Volume 79 Issue 11 Pages 1773-1780
    Published: 2006
    Released: November 09, 2006
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    An NS acyl shift reaction of thiol-containing peptides in a trifluoroacetic acid (TFA) solution was confirmed by a combination of 13C NMR spectroscopy, reversed-phase (RP) HPLC, and MS analyses. A model peptide containing a cysteine residue was transformed into an S-peptide in a TFA solution. The S-peptide was quickly transformed to the original peptide during RP-HPLC analysis even when an eluent that contained 0.1% TFA was used. A peptide that had an N-2-mercapto-4,5-dimethoxybenzyl (Dmmb) group was also transformed into an S-peptide, forming a thioester bond with the thiol of the Dmmb group by TFA treatment. The generated S-peptide was isolated by directly injecting the reaction mixture into a RP-HPLC and was readily converted to the corresponding 2-sulfoethyl thioester via an intermolecular thiol exchange reaction with sodium 2-mercaptoethanesulfonate. The 2-sulfoethyl peptide thioester is widely used as a building block in polypeptide synthesis. The NS acyl shift reaction observed in peptides with or without an auxiliary group provides a new route for the preparation of peptide thioesters.
  • Kenji Hara, Yoshikazu Kanamori, Masaya Sawamura
    2006 Volume 79 Issue 11 Pages 1781-1786
    Published: 2006
    Released: November 09, 2006
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    Palladium complexes with an imidazol-2-ylidene ligand functionalized with ester groups at its 4,5-positions were synthesized from a readily available imidazole derivative. σ-Donation from the carbene ligand to the palladium atom is considerably weakened by functionalization with the two ester moieties.
  • Akira Watanabe, Tomoko Watanabe, Yue Jin Shan, Keitaro Tezuka, Hideo I ...
    2006 Volume 79 Issue 11 Pages 1787-1792
    Published: 2006
    Released: November 09, 2006
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    Reversible photochromic reaction of hexacarbonyltungsten(0) caused by the photodissociation of a carbonyl ligand was studied in cross-linked transparent polymers: polymer of bis(hydroxymethyl)tricyclo[5,2,1,02,6]decane dimethacrylate (A) and polymer of tetrakis(hydroxymethyl)methane tetrakis(acrylate) (B). Rate constants of the photodissociation and recombination reactions were determined from the observed spectral changes. Because the dimensions of the cavities in these polymers, determined by the positron annihilation experiments, were similar to those of the complex [W(CO)6], the photoactivated complexes could contribute to the coloring of the polymer only when the dissociated CO molecule moved to the neighboring space. In polymer B, with a higher density of cross-links between polymer chains, the complex had a higher dissociation rate constant but a lower saturation concentration. These results indicated that the kinetics of the dissociation are controlled by thermal motion of the polymer chains around the gate to the neighboring space. The decay of the complex after recycling of the dissociation–recombination process was much smaller in polymers, especially in polymer B, than in DMF solution.
  • Makoto Kimura, Seiichi Kuwano, Kou Shimada, Ryouko Kamata, Shuji Yasud ...
    2006 Volume 79 Issue 11 Pages 1793-1797
    Published: 2006
    Released: November 09, 2006
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    In order to develop the thermally stable hole-transport materials (HTMs) in organic light-emitting diodes (OLEDs), hexabenzo-annulated [4.4.4]propellane that has three-biphenyl substructures around the C–C hub has been exploited as the core substance. Introduction of bis-, tetrakis-, or hexakis(diphenylamino) substituents at the 4 and 4′-positions of each biphenyl moiety leads to monomeric, dimeric, and trimeric derivatives of N,N,N′,N′-tetraphenylbenzidine; N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD) has excellent electroluminescent (EL) characteristics but low thermal stability. The key step in the preparation of these derivatives (2S-, 4S-, and 6S-P) was the coupling of appropriate fluorenes with requisite ortho-bromo biphenyl compounds. All of these had not only excellent EL characteristics, but also glass transition temperatures (Tg) of over 120 °C which was higher than that of TPD (62 °C) representative of the HTM. This result is consistent with that the parent hydrocarbon is unusually stable even at 300 °C. Structural effects of the present monomeric to trimeric TPD analogues on the thermal stability and EL characteristics are discussed.
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