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61.
Adachi K Sugiyama Y Yoneda K Yamada K Nozaki K Fuyuhiro A Kawata S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(22):6616-6628
Novel triply hydrogen bonded suprastructures based on [M(tdpd)2(L)2]2- (H2tdpd=1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarbonitrile, L=solvent) and melamine-analogous cations have been synthesized and characterized. The use of anions containing two AAA sets from [M(tdpd)2(L)2]2- together with cations containing one DDD set (A=hydrogen-bond acceptor, D=hydrogen-bond donor) leads to the formation of complementary triply hydrogen bonded modules in the solid state. In all cases, the building module is further extended via additional hydrogen-bonding interactions to produce a tape, and tapes are assembled into sheets. These results show that a hydrogen-bonded module consisting of different kinds of building blocks, one of which is a metal complex that includes hydrogen-bond acceptor sites and the other is a hydrogen-bond donor molecule, will be attractive for constructing metal-containing supramolecular systems by the self-assembly technique. 相似文献
62.
Mitsuru Ueda Yoshikatu Seino Yuko Haneda Masanobu Yoneda Jun-Ichi Sugiyama 《Journal of polymer science. Part A, Polymer chemistry》1994,32(4):675-681
tert-Butyl substituted poly (aryl ether ketone)s with relatively high molecular weights were prepared by the Ni-catalyzed polymerization of tert-butyl substituted aromatic dichlorides containing ether ketone unit. These polymers were amorphous and soluble in common organic solvents, such as THF, dichloromethane, and chloroform. De-tert-butylation of the polymer by the treatment of trifluoromethanesulfonic acid in the presence of toluene proceeded smoothly and produced crystalline poly (aryl ether ketone). © 1994 John Wiley & Sons, Inc. 相似文献
63.
Sugiyama T Schweinberger E Kazimierczuk Z Ramzaeva N Rosemeyer H Seela F 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(2):369-378
2-Aza-2'-deoxyadenosine (2, z2Ad) is synthesized via its 1,N6-etheno derivative 7 and enzymatically deaminated to 2-aza-2'-deoxyinosine (3). Compound 2 is converted into the phosphoramidite building block 10b. This is employed in solid-phase oligonucleotide synthesis. The 2-azapurine base forms a strong base pair with guanine, but a much weaker one with adenine, thymine, and cytosine. Oligonucleotide duplexes with dangling nucleotide residues, such as 2-aza-2'-deoxyadenosine and 7-deaza-2'-deoxyadenosine (4, c7Ad), either on one or both termini, are synthesized, and the thermal stability of the duplexes is correlated with the hydrophobic properties of the dangling nucleotide residues. 相似文献
64.
An effective method was developed to use an enzyme in ionic liquids; the asymmetric reduction of ketones by Geotrichum candidum in ionic liquids proceeded smoothly with excellent enantioselectivity when the cell was immobilized on water-absorbing polymer containing water, while the reaction without the polymer did not proceed. 相似文献
65.
Tatsuhiko Kashimura Tomoya Ikezaki Yusuke Ohta Satoshi Yabushita 《Journal of computational chemistry》2019,40(2):482-499
One of the most spectacular yet unsolved problems for the ICN -band photodissociation is the non-statistical spin-rotation F1 = N + 1/2 and F2 = N − 1/2 populations for each rotation level N of the CN fragment. The F1/F2 population difference function f(N) exhibits strong N and λ dependences with an oscillatory behavior. Such details were found to critically depend on the number of open-channel product states, namely, whether both I (2P3/2) and I (2P1/2) are energetically available or not as the dissociation partner. First, in the asymptotic region, the exchange and dipole-quadrupole inter-fragment interactions were studied in detail. Then, as the diabatic basis, we took the appropriate symmetry adapted products of the electronic and rotational wavefunctions for the F1 and F2 levels at the dissociation limits. We found that the adiabatic Hamiltonian exhibits Rosen–Zener–Demkov type nonadiabatic transitions reflecting the switch between the exchange interaction and the small but finite spin-rotation interaction within CN at the asymptotic region. This non-crossing type nonadiabatic transition occurs with the probability 1/2, that is, at the diabatic limit through a sudden switch of the quantization axis for CN spin S from the dissociation axis to the CN rotation axis N . We have derived semiclassical formulae for f(N) and the orientation parameters with a two-state model including the 3A′ and 4A′ electronic states, and with a four-state model including the 3A′ through 6A′ electronic states. These two kinds of interfering models explain general features of the F1 and F2 level populations observed by Zare's group and Hall's group, respectively. © 2018 Wiley Periodicals, Inc. 相似文献
66.
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68.
Koichiro Koyama Yusuke Hirasawa Tomohiro Hoshino Norimichi Nakahata 《Tetrahedron》2005,61(15):3681-3690
Seven new Lycopodium alkaloids, lannotinidines A-G (1-7), have been isolated from the club moss Lycopodium annotinum and L. annotinum var. acrifolium. Stereochemistry of 1-7 was elucidated by combination of NOESY correlations and chemical transformation. Lannotinidines B-E (2-5) elevated NGF mRNA expression. 相似文献
69.
Ohno H Ando K Hamaguchi H Takeoka Y Tanaka T 《Journal of the American Chemical Society》2002,124(51):15255-15266
The base-mediated intramolecular amination of bromoallenes having an axial chirality is described. The treatment of (4S,aR)-4-alkyl-4-[N-(arylsulfonyl)amino]-1-bromobuta-1,2-dienes with NaH in DMF affords 2,3-cis-2-ethynylaziridines in good to excellent selectivity (2,3-cis:trans = 92:8-99:1). The reaction of (4S,aS)-bromoallenes with NaH/DMF also gives 2,3-cis-2-ethynylaziridines selectively (79:21-91:9). These experimental results have been rationalized by B3LYP density functional calculations together with the 6-31+G(d) basis set and the Onsager solvation model. The transition structures for cis-aziridine formation of both (4S,aR)- and (4S,aS)-bromoallenes in DMF are favored over the corresponding trans transition structures by 4.35 and 1.41 kcal/mol, respectively. Furthermore, the calculations predicted that a less polar solvent gives higher cis selectivity for (4S,aS)-bromoallenes. In fact, improvement of the cis selectivity to 99:1 has been realized by using a less polar solvent such as THF. The cyclization of bromoallenes bearing a beta- or gamma-amino group also affords four- and five-membered azacycles in a highly cis-selective manner. 相似文献
70.
An air-segmented continuous-flow method has been developed for the determination of molybdenum at ultra trace levels using
the catalytic effect of molybdate during the oxidation of L-ascorbic acid by hydrogen peroxide. Incorporation of an on-line
ion exchange column improved the tolerance limit for various ions. The detection limits with and without the column were 64 pmol L−1 and 17 pmol L−1, and the reproducibilities at 10 nmol L−1 were 2.1% and 0.2%, respectively. The proposed method was applied to the determination of molybdenum in seawater and lake
water as well as in rock and sediment samples. This method has the highest sensitivity among the available literature to our
knowledge, and is also convenient for routine analysis of molybdenum in various natural samples.
Author for correspondence. E-mail: masahito.sugiyama@ sojin0206.mbox.media.kyoto-u.ac.jp
Received October 23, 2002; accepted January 28, 2003
Published online May 19, 2003 相似文献