排序方式: 共有18条查询结果,搜索用时 15 毫秒
1.
2.
3.
Gagik G. Melikyan Boghos Mikailian Ruth Sepanian Pogban Toure 《Journal of organometallic chemistry》2009,694(5):785-3562
The novel high-temperature reaction of Co2(CO)6-complexed propargyl cations, occurring in the spontaneous and stereoselective (90-97% d,l-) manner and yielding the radical dimers, d,l-3,4-diaryl-1,5-hexadiynes (2, 11, 14), is described. Despite the alleged thermal lability and delicate nature of the requisite Co2(CO)6-complexed propargyl cations, the reaction temperature can be elevated from 20 °C to 147 °C, shortening the reaction time from 660 min to less than 1 min. Isotopic enrichment experiments detected (MS TOF/ESI/APCI) an incorporation of upto, eight 13CO ligands into the metal core, suggesting a single electron, cluster-to-cluster reduction along the reaction coordinate. The reaction kinetics is found to be sensitive toward the electronic nature of the substituents (H, OMe) and to the substitution pattern (0-, 4-, 3,4,5-) on the periphery of the aromatic ring. Calculation data suggest that the spontaneous transfer of a single electron from the metal cluster, onto a π-bonded propargyl moiety, is dependent upon the negative charge on aromatic C1′ carbon atom, located alpha to the cationic center. The spontaneous conversion of diamagnetic species (propargyl cation) to paramagnetic counterparts (propargyl radical) indicates that the π-bonded organometallic cations can act as the prototypes for transition metal-based thermal sensors. Their application in photochemical research, electronic devices, molecular electronics, and biomedical fields can also be envisioned. 相似文献
4.
In this work, we study the existence and regularity of solutions for some partial functional integrodifferential equations in Banach spaces. We suppose that the undelayed part admits a resolvent operator in the sense given by Grimmer in [R. Grimmer, Resolvent operators for integral equations in a Banach space, Transaction of American Mathematical Society 273 (1982) 333–349]. The delayed part is assumed to be locally Lipschitz. Firstly, we show the existence of the mild solutions. Secondly, we give sufficient conditions ensuring the existence of the strict solutions. 相似文献
5.
Aiquan Jiao Na Yang Jinpeng Wang Alhassane Toure Xueming Xu Zhengyu Jin 《Journal of inclusion phenomena and macrocyclic chemistry》2012,74(1-4):335-341
To elucidate the importance of the goodness of fit in complexes between substrates and glutathione peroxidise (GPX) mimics, we examined the decomposition of a variety of structurally distinct hydroperoxides at the expense of glutathione (GSH) catalyzed by 2,2′-ditellurobis(2-deoxy-γ-cyclodextrin) (2-Te-γ-CD), and by the corresponding derivatives of β-cyclodextrin (β-CD) and α-cyclodextrin. The good fit of the cumene group into the γ-CD binding cavity reflected the result of well-defined reaction geometry, leading to the most excellent peroxidase activity with high substrate specificity. Furthermore, the catalytic constant and the combination with the best binding also exhibited the highest regioselectivity in the substrate decomposition. Saturation kinetics were observed and the catalytic reaction agreed with a ping-pong mechanism, in analogy with natural GPX, and might exert its thiol peroxidase activity via tellurol, tellurenic acid, and tellurosulfide. The stoichiometry of the inclusion complex was determined to be of 2:1 host-to-guest. The value of stability constant K c for (2-Te-γ-CD)2/GSH at room temperature was calculated to be 3.815?×?104?M?2, which suggested that 2-Te-γ-CD had a moderate ability to bind GSH. Importantly, the proposed mode of the (2-TeCD)2/GSH complex was the possible important noncovalent interactions between enzymes and substrates in influencing catalysis and binding. 相似文献
6.
In this work, we study the existence and regularity of solutions for some partial functional integrodifferential equations with infinite delay in Banach spaces. We suppose that the undelayed part admits a resolvent operator in the sense of Grimmer [R. Grimmer, Resolvent operators for integral equations in a Banach space, Transactions of the American Mathematical Society 273 (1982) 333–349]. The delayed part is assumed to be locally Lipschitz. Firstly, we show the existence of the mild solutions. Secondly, we give sufficient conditions ensuring the existence of strict solutions. 相似文献
7.
8.
We analyze in detail projective modules over two-dimensional noncommutative tori and complex structures on these modules. We concentrate our attention on properties of holomorphic vectors in these modules; the theory of these vectors generalizes the theory of theta-functions. The paper is self-contained; it can be used also as an introduction to the theory of noncommutative spaces with simplest space of this kind thoroughly analyzed as a basic example. 相似文献
9.
Harald O. Jeschke Momar S. Diakhate Martin E. Garcia 《Applied Physics A: Materials Science & Processing》2009,96(1):33-42
A theoretical approach to treat laser induced femtosecond structural changes in covalently bonded nanostructures and solids
is described. Our approach consists in molecular dynamic simulations performed on the basis of time-dependent, many-body potential
energy surfaces derived from tight-binding Hamiltonians. The shape and spectral composition of the laser pulse is explicitly
taking into account in a non-perturbative way. We show a few examples of the application of this approach to describe the
laser damage and healing of defects in carbon nanotubes with different chiralities and the ultrafast nonequilibrium melting
of bulk germanium, initiated by the laser-induced softening and destabilization of transversal acoustic phonon modes. 相似文献
10.
Momar S. Diakhate Eeuwe S. Zijlstra Martin E. Garcia 《Applied Physics A: Materials Science & Processing》2009,96(1):5-10
We parameterize the potential energy surface of bismuth after intense laser excitation using accurate full-potential linearized
augmented plane wave calculations. Anharmonic contributions up to the fifth power in the A
1g phonon coordinate are given as a function of the absorbed laser energy. Using a previously described model including effects
of electron–phonon coupling and carrier diffusion due to Johnson et al., we obtain the time-dependent potential energy surface
for any given laser pulse shape and duration. On the basis of this parameterization we perform quantum dynamical simulations
to study the experimentally observed amplitude collapse and revival of coherent A
1g phonons in bismuth considering work of Misochko et al. Our results strongly indicate that the observed beatings are not related
to quantum effects and are most probably of classical origin. 相似文献