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161.
Alain C. Tagne Kuate Swagat K. Mohapatra Constantin G. Daniliuc Peter G. Jones Matthias Tamm 《Journal of organometallic chemistry》2012,696(26):4281-4292
Cp-functionalized monotroticenes [(η7-C7H7)Ti(η5-C5H4E)] (2, E = Ph2SiCl; 3, E = tBu2SnCl; 12, E = I) and bitroticenes [(η7-C7H7)Ti(η5-C5H4)]2E′ (5, E′ = PPh; 6, E′ = BN(SiMe3)2; 7, E′ = Cp2Ti) were prepared by salt elimination metathesis between the monolithiated troticene [(η7-C7H7)Ti(η5-C5H4Li)]·pmdta (1b) (pmdta = N,N′,N′,N″,N″-pentamethyldiethylene-triamine) and the appropriate electrophile. The troticenyl-substituted zirconocene monochloride [(η7-C7H7)Ti(η5-C5H4ZrClCp*2)] (Cp* = η5-C5Me5) (8) and hafnocene ethoxide [(η7-C7H7)Ti{η5-C5H4Hf(OEt)Cp2}] (Cp = η5-C5H5) (11), and the heterobimetallic μ-oxo complexes [(η7-C7H7)Ti(η5-C5H4MCp2)]2O (9, M = Zr; 10, M = Hf) were obtained instead of the expected zircona- and hafna[1]troticenophanes by reaction of the dilithiated troticene [(η7-C7H6Li)Ti(η5-C5H4Li)]·pmdta (1a) with [Cp2MCl2] (M = Zr, Hf) or [Cp*2ZrCl2] in stoichiometric amounts. These compounds were characterized by single crystal X-ray diffraction analyses and, in the case of 2, 3, 5–7, 9, 10 and 12, also by elemental analyses and 1H, 13C and 119Sn NMR spectroscopy. Exposure of the troticenyl organotin chloride 3 to moisture resulted in its partial hydrolysis and formation of the organostannoxane-bridged bitroticene 4, while palladium-catalyzed Negishi C–C cross-coupling reaction between the troticenylzinc chloride [(η7-C7H7)Ti(η5-C5H4ZnCl)] (13) and the iodotroticene 12 or iodobenzene (PhI) led to the fulvalene complexes [(η7-C7H7)Ti(η5-C5H4)]2 (14) and [(η7-C7H7)Ti(η5-C5H4Ph)] (15). Compound 4 displays an unsymmetrical structure with the troticenyl fragments cis with respect to the Sn–O–Sn core, whereas compound 14 is centrosymmetrically trans oriented. 相似文献
162.
Mudassir Iqbal Prasanta K. Mohapatra Seraj A. Ansari Jurriaan Huskens Willem Verboom 《Tetrahedron》2012,68(38):7840-7847
Different diglycolamide (DGA)-substituted calix[4]arene-based extractants were synthesized and evaluated for the extraction of Am(III) and Eu(III), representative trivalent actinide and lanthanide ions, respectively. On the narrow rim of the calix[4]arene platform, the DGA moiety was either 1,3-di- or tetrasubstituted with a varying spacer length between the oxygen and amide nitrogen atom. In addition, DGA groups were appended both to the wide rim and to both rims of calix[4]arenes and their efficiencies were compared for Am(III) and Eu(III) extraction at three different feed acidities. The extraction and separation efficiencies strongly depended on the N-alkyl substituent as well as the spacer length. 1,3-Di-DGA-substituted calix[4]arenes are inferior extractants to the corresponding tetra-DGA-substituted ones. Narrow rim DGA-functionalized derivatives resulted in high extraction efficiencies, while the wide rim DGA-functionalized calix[4]arenes showed practically no extraction. 相似文献
163.
Two 3D porous terbium(III) mucicate frameworks, {[Tb(2)(Mu(2-))(3)(H(2)O)(2)]·4H(2)O}(n) (1) and {[Tb(Mu(2-))(Ox(2-))(0.5)(H(2)O)]·H(2)O}(n) (2), have been synthesized under hydrothermal conditions by changing the pH of the reaction medium. Isostructural europium(III) and seven mixed terbium(III)-europium(III) mucicates were synthesized by doping different percentages of Eu(III) under similar reaction conditions and unveiling different emission colors ranging from green to red under the same wavelength. Both dehydrated Tb(III) metal-organic frameworks exhibit selective H(2)O vapor sorption over other solvent molecules (MeOH, MeCN, and EtOH) of less polarity and bigger size and have been correlated to the highly hydrophilic pore surfaces decorated with -OH groups and O atoms from the carboxyl groups of mucicate. 相似文献
164.
A series of novel photocatalysts Zn/Cr LDH with different Zn/Cr molar ratios (2?:?1, 3?:?1, 4?:?1 and 2?:?1-CO(3)) were fabricated by a co-precipitation method and evaluated for photodecomposition of water using visible light irradiation. Various characterization methods were employed to investigate the structures, morphologies and photocatalytic properties. In comparison to Zn/Cr (2?:?1) LDH, Zn/Cr-CO(3) (2?:?1) LDH extends the absorption edges to the visible region and exhibits good photocatalytic activity, even without the assistance of co-catalysts. The visible light photocatalytic activity is ascribed to the charge transfer spectra of octahedral Cr ions in LDH. Zn/Cr-CO(3) LDH shows enhanced photocatalytic activities compared to Zn/Cr LDH as carbonate ions oxidise by holes to form carbonate radicals, inhibit the rapid recombination of e(-) and h(+) charge carriers and thereby suppress the backward reaction to some extent. This work provides a detailed understanding of the semiconductor properties of LDHs for photocatalytical hydrogen evolution. 相似文献
165.
Let P(z) be a polynomial of degree at most n. We consider an operator D ?? which maps a polynomial P(z) into D ?? P(z) :=?nP(z)?+?(?? ? z)P??(z) and prove results concerning the estimates of |D ?? P(z)| on the disk |z|?=?R??? 1, and thereby obtain extensions and generalizations of a number of well-known polynomial inequalities. 相似文献
166.
Mithlesh Kumar T.K. Seshagiri M. Mohapatra V. Natarajan S.V. Godbole 《Journal of luminescence》2012,132(10):2810-2816
Eu3+-doped ZnAl2O4 phosphors were successfully synthesized in air atmosphere at 900 °C. The phosphors were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermally stimulated luminescence (TSL) and photoluminescence (PL) techniques. The average particle size of the system as determined from SEM was found to be 100–150 nm (for samples annealed at 900 °C). PL spectra of the doped phosphors showed emission peaks corresponding to Eu3+ ions. Lifetime studies revealed Eu3+ ions to be in two different sites. The asymmetric ratio (I616/I592) was observed to be about 3.75. This suggested that Eu3+ ion entered the host mainly substituting Al3+ site distorting the local environment and is partly located on surface of the phosphors. A prominent glow peak at 430 K was observed in the TSL of γ-irradiated Eu3+-doped ZnAl2O4 phosphors. Trap parameters for this peak have been determined and the probable mechanism for the glow peak is proposed. CIE chromaticity coordinates for the system were evaluated. It was observed that, the system could be employed as a potential red emitting phosphor. Commercial utility of the phosphor was investigated by comparing it with commercial red phosphor. The PL intensity of the as prepared phosphors was 63% of that of the commercial phosphor. Apart from this, various radiative properties such as the Judd–Ofelt intensity parameters, spontaneous emission probabilities, luminescence branching ratios, radiative lifetimes and quantum efficiency were evaluated for the system. 相似文献
167.
A number of single parameter variational approximations for single-mode graded-index fibers have been reported in the literature. One of these approximations was also proposed by us some time ago which describes the propagation characteristics of such fibers having power-law profile with a high degree of accuracy. Using these approximations we have computed the propagation constant and the normalized dispersion for single-mode fibers with smoothed-out and composite refractive index profiles which are of great current interest. We have shown that the single parameter approximation proposed by us earlier computes these propagation characteristics with a better degree of accuracy than all other single parameter approximations even for these special types of profiles. 相似文献
168.
Extending the minimal supersymmetric standard model to explain small neutrino masses via the inverse seesaw mechanism can lead to a new light supersymmetric scalar partner which can play the role of inelastic dark matter (IDM). It is a linear combination of the superpartners of the neutral fermions in the theory (the light left-handed neutrino and two heavy standard model singlet neutrinos) which can be very light with mass in ~5-20 GeV range, as suggested by some current direct detection experiments. The IDM in this class of models has keV-scale mass splitting, which is intimately connected to the small Majorana masses of neutrinos. We predict the differential scattering rate and annual modulation of the IDM signal which can be testable at future germanium- and xenon-based detectors. 相似文献
169.
A. Sargsyan M. G. Bason D. Sarkisyan A. K. Mohapatra C. S. Adams 《Optics and Spectroscopy》2010,109(4):529-537
Experimental results of the study of processes of electromagnetically induced transparency (EIT) and two-photon absorption
(TPA) are presented for the ladder Ξ-system obtained using the 5S-5P-nD, mS system of levels of the 85Rb and 87Rb atoms with n = 5, 26, and 27 and m = 39 and 48. To perform these studies, a high-temperature optical cell was designed with several regions with the following
thicknesses L: 2 mm, 0.7 mm, and the region of 2–6 μm. The advantages of using thin cells over ordinary cells several centimeters thick
are demonstrated. It is shown that the EIT resonance parameters for n = 5, 26, and 27 deteriorate insignificantly for thickness down to 700 μm. The TPA is recorded with the cell thickness decreasing
down to L = 6 μm. It is shown that using the EIT and TPA processes makes it possible to measure the hyperfine and fine structures of
highlying atomic levels. The influence of the cell walls is appreciable in recording the EIT resonances in the system 5S-5P-39S with L = 0.7 mm and in the system 5S-5P-48S with L = 2 mm. Possible applications of the processes studied are indicated. 相似文献
170.
Mohapatra D Nakao M Nishida S Abe K Abe K Adachi I Aihara H Anipko D Arinstein K Asano Y Aulchenko V Aushev T Bahinipati S Bakich AM Balagura V Barbero M Bedny I Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Browder TE Chao Y Chen A Chen KF Chen WT Cheon BG Chistov R Choi Y Chuvikov A Cole S Dalseno J Danilov M Dash M Dragic J Drutskoy A Eidelman S Epifanov D Fratina S Gabyshev N Gershon T Gokhroo G Golob B Gorisek A Ha HC Haba J Hara T Hastings NC Hayasaka K Hayashii H Hazumi M Hinz L 《Physical review letters》2006,96(22):221601
We report the observation of the flavor-changing neutral current process b-->dgamma using a sample of 386 x 106 B meson pairs accumulated by the Belle detector at the KEKB e+e- collider. We measure branching fractions for the exclusive modes B--->rho-gamma, B0rho0gamma, and B0omegagamma. Assuming that these three modes are related by isospin, we find B(B-->(rho,gamma)gamma)=[Formula: See Text] with a significance of 5.1sigma. This result is used to determine the ratio of Cabibbo-Kobayashi-Maskawa matrix elements /Vtd/Vts/ to be [Formula: See Text]. 相似文献