Bulletin of the Chemical Society of Japan

Murakami, Masahiro; Makino, Masaomi; Ashida, Shinji; Matsuda, Takanori

doi: 10.1246/bcsj.79.1315pmid: N/A

New catalytic reactions in which transition-metal cyclobutanolates undergo β-carbon elimination have been developed in our laboratory. Rhodium(I) cyclobutanolate generated by the addition of an arylrhodium(I) species to a cyclobutanone undergoes β-carbon elimination to cause ring opening of the four-membered carbocyclic framework. The synthetic potential of the ring-opening process through β-carbon elimination has been demonstrated by its application to a ring-expansion reaction forming a seven-membered ring. Furthermore, a formal alkyne insertion into the cyclobutanone framework is achieved by combining oxidative cyclization of a cyclobutanone and an alkyne on nickel(0) and β-carbon elimination from the resulting nickel(II) cyclobutanolate.

Kyotani, Takashi

doi: 10.1246/bcsj.79.1322pmid: N/A

Using uniform nanochannels of an aluminum anodic oxide film as a template, uniform and unique multiwalled carbon nanotubes can be synthesized with a selectivity of 100%. This technique allows one to precisely control the diameters and the length of nanotubes. Moreover, it is possible to chemically modify only the inner surface of carbon nanotubes and to prepare carbon nanotubes with a double coaxial structure of heteroatom-doped multiwalls. The test tube like carbon prepared by this technique was found to be dispersible in water without any post treatment. In addition to this one-dimensional approach, unique microporous carbon can be prepared by the template technique using zeolite Y. The resulting microporous carbons are characterized by their regular ordering, originating from the regularity of the parent zeolite. When the synthesis conditions were optimized, the specific surface area and the micropore volume of the zeolite-templated carbon reach more than 4000 m2 g−1 and 1.8 cm3 g−1, respectively. This review introduces such a template-mediated approach and highlights how useful and versatile the template technique is for the production of nano carbons.

Tsuji, Hayato; Sasaki, Mikio; Shibano, Yuki; Toganoh, Motoki; Kataoka, Takeshi; Araki, Yasuyuki; Tamao, Kohei; Ito, Osamu

doi: 10.1246/bcsj.79.1338pmid: N/A

A zinc porphyrin–fullerene dyad with a disilane as a σ-conjugated linker has been newly synthesized to evaluate the electron transfer ability of the oligosilane chain. Its photoinduced processes have been studied using the time-resolved fluorescence and absorption measurements. Photoexcitation of the dyad causes the energy and/or electron transfer from the excited singlet state of the ZnP to C60 moiety in polar solvents. The charge separation takes place as a final step in the excited-state process to yield the radical-ion pair with a radical cation on the zinc porphyrin and a radical anion on the fullerene, similar to other porphyrin–fullerene dyads. Its lifetime has been estimated to be 0.43–0.52 μs on the basis of the decay rate of the fullerene radical anion in polar solvents.

Koga, Yoshikata; Katayanagi, Hideki; Davies, James V; Kato, Hitoshi; Nishikawa, Keiko; Westh, Peter

doi: 10.1246/bcsj.79.1347pmid: N/A

We use the thermodynamic behaviour of 1-propanol (1P) as a probe in ternary 1P–salt–H2O systems to elucidate the effect of a salt on the molecular organization of H2O. For salts, we have chosen CaCl2, NH4Cl, and (CH3)4NCl (TMAC). Having fixed the counter anion at Cl−, we compare here mainly the effects of chosen cations on H2O. Together with an earlier study on NaCl, we found that Ca2+, Na+, and NH4+ are hydrated by a number of H2O molecules and leave the bulk H2O away from the hydration shell unperturbed. The hydration numbers were found to be 6.4 ± 1.6, and 1.2 ± 0.4, for Ca2+ and NH4+, respectively with the hydration number 5.2 for Na+, the result of a simulation study, chosen as a reference. Thus, a salting out (also referred to as structure making, stabilizing, or kosmotropic) tendency would decrease in the order; Ca2+ > Na+ > NH4+. TMA+, on the other hand, showed a more hydrophilic characteristics than the probing 1P. Thus, TMA+ is rather chaotropic (salting in, structure breaking or destabilizing) within this methodology.

Gharibi, Hussein; Behjatmanesh-Ardakani, Reza; Hashemianzadeh, Seyed Majid; Sohrabi, Beheshteh; Javadian, Soheila

doi: 10.1246/bcsj.79.1355pmid: N/A

We use a modified version of Larson’s model to investigate the behaviors of amphiphile molecules in different states of interaction parameters. The regular excluded volume and periodic boundary conditions are used to mimic a box of simulation as a bulk of solution. Several thermodynamic parameters are studied by lattice Monte Carlo simulation, including polydispersity, premicellar phenomena, critical micelle concentration, aggregation number, and cluster shape. For higher interaction parameters aggregation starts at lower concentration, i.e. critical micelle concentration is reduced. Behaviors are linear. With linearizing matrix of gyration, it is shown that at higher interactions micelles tends to reduce their contacts with water, so they take the shape of a sphere. In all of the cases, cluster size distribution has only one peak. Polydispersity behavior indicates that it is possible to determine critical micelle concentration from the polydispersity curve. Configurational bias and reptation moves are used with equal probability to relax the amphiphilic systems. To investigate meta-stability in the thermodynamic parameters two different initial conditions are used.

Hoshino, Manabu; Uekusa, Hidehiro; Ohashi, Yuji

doi: 10.1246/bcsj.79.1362pmid: N/A

When a chloroform solvate crystal of the three-coordinated Au(I) complex [AuCl(PPh3)2]·CHCl3 was irradiated with a mercury lamp at low temperatures, the crystal showed bright green emission from the excited molecules. From X-ray analysis, the unit-cell volume significantly decreased under photoirradiation. The three-dimensional intensity data were collected in the dark (light-off) and under photoirradiation (light-on) at 175, 156, 136, and 84 K. As the temperature decreased, the difference in unit-cell volume between the light-off and -on experiments increased. The molecular structures in the light-off and -on experiments revealed that the Au–P and Au–Cl bonds are significantly contracted by photoirradiation at every temperature. The changes in the other bond lengths were within the experimental errors. The shortening becomes greater as the temperature is lowered. The bond shortening, which causes the decrease in unit-cell volume, is in good agreement with the theoretical assumption that excitation from an anti-bonding orbital to a bonding orbital occurs in the Au(I) complex by photoirradiation.

Kameda, Yasuo; Sasaki, Motoya; Hino, Shuji; Amo, Yuko; Usuki, Takeshi

doi: 10.1246/bcsj.79.1367pmid: N/A

Neutron diffraction measurements were carried out at 25 °C on aqueous 15 mol % urea heavy water solutions, [(ND2)2*C=O]0.15(D2O)0.85, in which the 12C/13C isotopic composition of the carbonyl-carbon atom was changed. The hydration structure around the carbonyl-carbon atom was derived from the least-squares fitting analysis of the observed first-order difference function, ΔC(Q). From the analysis, 4.3(3) water molecules are hydrogen-bonded to the carbonyl-oxygen atom with the intermolecular C···DW1 (DW1: water deuterium atom) distance of 2.46(3) Å. The average angle, ∠C···DW1–OW (OW: water oxygen atom), was determined to be 124(5)°.

Kanegawa, Shinji; Karasawa, Satoru; Nakano, Motohiro; Koga, Noboru

doi: 10.1246/bcsj.79.1372pmid: N/A

Three cobalt(II) complexes, [Co(X)2(4NOpy)4] (X = NCO−, NCS−, and Br−; 4NOpy = 4-(N-tert-butylaminoxyl)pyridine) were prepared, and their molecular structures were characterized by X-ray structure analysis. The molecular geometry of [Co(X)2(4NOpy)4] (X = NCO− and NCS−) is a compressed octahedron, in which the counter ions occupy the apical positions with short bond distances of 2.064–2.098 Å. In the crystalline state, from plots of χmol vs T and χ′mol vs T, [Co(NCO)2(4NOpy)4] and [Co(NCS)2(4NOpy)4] are antiferromagnets with TN = 4.5 and 15 K, respectively. In frozen solution, on the other hand, both complexes and [Co(Br)2(4NOpy)4] functioned as single-molecule magnets. The χ″mol vs T plot for [Co(Br)2(4NOpy)4] gave a effective activation barrier (Ueff) of 20 K for the reorientation of the spin. From the field dependence of magnetization at various temperatures below 5 K for [Co(X)2(4NOpy)4] (X = NCO−, NCS−, and Br−) the values of the zero-field splitting parameters, D/kB, were estimated to be −14, −9.7, and −4.5 K with S = 5/2, respectively. Theoretical studies based on the ligand-field theory model for [Co(NCO)2(4NOpy)4] gave an exchange coupling parameter, J/kB, of 29 K and a thermodynamic activation barrier, U, of 60 K.

Soneta, Yuji; Miyamura, Kazuo

doi: 10.1246/bcsj.79.1383pmid: N/A

Slow inter-diffusion of (NBu4)[Ni(dmit)2] (dmit = 2-thioxo-1,3-dithiole-4,5-dithiolato) and a metal complexes ligated with alkyl-substituted cyclam, [Ni(NMe2-dcyclam)](ClO4)2 (I), [Ni(NMe2-ax-dcyclam)](ClO4)2 (II), and [Ni(NMe4-dcyclam)]Cl2 (III), (NMe2-dcyclam = (1RS,4RS,5RS,8SR,11SR,12SR)-1,5,8,12-tetramethyl-1,4,8,11-tetraazacyclotetradecane, NMe2-ax-dcyclam = (1RS,4RS,5SR,8SR,11SR,12RS)-1,5,8,12–tetramethyl-1,4,8,11-tetraazacyclotetradecane, NMe4-dcyclam = (1RS,4RS,5RS,8SR,11SR,12SR)-1,4,5,8,11,12-hexamethyl-1,4,8,11-tetraazacyclotetradecane), yielded black crystals of [Ni(NMe2-dcyclam)(CH3CN)2][Ni(dmit)2]2 (1), [Ni(NMe2-ax-dcyclam)][Ni(dmit)2]2 (2), and [Ni(NMe4-dcyclam)][Ni(dmit)2]2 (3), respectively. In these complex salts, the cationic complex I adopted an octahedral six-coordination geometry with two molecules of acetonitrile occupying the trans coordination sites (structure A), while those of complexes II and III adopted a square-planar four-coordination geometry (structure B). The Ni–Ni distances between cation and anion in structure B were shorter than those of structure A. In the IR spectra, ν(C=S) of structure B was observed 10 cm−1 higher than that of structure A, and only in compound 2, ν(C=C) was split at 1346 and 1323 cm−1. Electric conductivities of compounds 1–3 were about 10−6 S cm−1 at room temperature behaving as semiconductors.

Ding, Xingcheng; Suzuki, Tatsuya; Nomura, Masao; Sugiyama, Yuichi; Kaneshiki, Toshitaka; Fujii, Yasuhiko

doi: 10.1246/bcsj.79.1389pmid: N/A

Zinc isotope fractionation has been studied in different cavities of crown ether resins that were synthesized in porous silica beads. Displacement chromatography was performed, as a breakthrough manner, in glass columns by feeding in a zinc chloride solution. From the mass analysis of effluents, the heavier isotopes of zinc were enriched at the beginning of the zinc adsorption band. The front maximum enrichment (1.0168), separation coefficient (8.1 × 10−4), and smaller HETP (0.205 cm) for the isotopic pair 68Zn/64Zn were obtained with the use of the benzo-15-crown-5 resin. Zinc isotope fractionation was obviously affected by the cavity size of the crown ethers.