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101.
A new helically chiral pentacyclic system containing one pyrrole ring was prepared in a good yield and purity via a three-step sequence involving Heck coupling and classical oxidative photocyclization. X-ray crystal structure analysis indicated that the conformation resembled that of unsubstituted pentahelicene, the idealized symmetry of which is C2. The optical properties of the pentacyclic helicene were investigated and show interesting behaviour.  相似文献   
102.
Co/SSZ-13 zeolites were prepared by heating the finely dispersed mixture of NH4-SSZ-13 and different cobalt salts up to 550 °C. Investigations by thermogravimetry – differential scanning calorimetry – mass spectrometry provided new insight into details of the solid-state reaction. Formation of Co carrying hydrate melt or volatile species was shown to proceed from chloride, nitrate, or acetylacetonate Co precursor salts upon thermal treatment. This phase change allows the transport of the Co species into the zeolite pores. The reaction of the NH4+ or H+ zeolite cations and the mobile Co precursors generates vapor or gas products, readily leaving the zeolite pores, and cobalt ions in lattice positions suggesting that solid-state ion-exchange is the prevailing process. The obtained catalysts are of good activity and N2 selectivity in the CH4/NO-SCR reaction. The thermal treatment of acetate or formate salts give solid intermediates that are unable to get in contact and react with the cations in the zeolite micropores. These catalysts contain mainly Co-oxide clusters located on the outer surface of the zeolite crystallites and have poor catalytic performance.  相似文献   
103.
A clean and partially green route to monoalkyled thiacalix[4]arenes has been demonstrated. We have discovered that tetraalkylammonium halide can cleave selectively one of the two aryl alkyl ethers of dialkylated para-tert-butylthiacalix[4]arenes. Thus, p-tert-butyl thiacalix[4]arenes differently monoalkyled at the lower rim with acetyl, propyl, and benzyl group were synthesized in good yield.  相似文献   
104.
In the title compound, disodium cobalt tetrakis­(dihydrogen­phosphate) tetrahydrate, the CoII ion lies on an inversion centre and is octahedrally surrounded by two water molecules and four H2PO4 groups to give a cobalt complex anion of the form [Co(H2PO4)4(OH2)]2?. The three‐dimensional framework results from hydrogen bonding between the anions. The relationship with the structures of Co(H2PO4)2·2H2O and K2CoP4O12·5H2O is discussed.  相似文献   
105.
106.
High yield of cationic palladium β-diimine complexes [(CH2(MeCNAr)2)Pd(η3-C4H7)][Y] (Ar = C6H5, Y = PF6 (8); 2-Me-C6H4, Y = PF6 (9); 2,6-Me2-C6H3, Y = PF6 (10); 2,6-iPr2-C6H3, Y = PF6 (11), Y = B(3,5-(CF3)2-C6H3)4 (12)) have been obtained by an oxidative addition of the methallyloxyphosphonium salts (5, 6) to a preformed complex Pd(dba)2 (7) in the presence of the β-iminoamine ligands (1-4).These complexes are thermally stable and have been characterized by 1H and 13C{1H} NMR as well as IR spectroscopy. The structure of the cationic allyl palladium complex (12) has been solved by X-ray crystallography.  相似文献   
107.
The crown ethers dibenzo-16-crown-4 and dibenzo-18-crown-5 and a diaryl polyether were complexed by the chromium tricarbonyl group for the purpose of selective functionalization. This complexation did indeed permit exclusive functionalization of the complexed ring. CHO and CH2OH functionalities were introduced ortho to the ether group. It was noted that the nature of the two ether chains had a strong influence on the regioselectivity of the functionalization, which occurred preferentially on the side with the polyether chain. Photochemical decomplexation produced functionalized organic crown ethers.  相似文献   
108.
A new non‐centrosymmetrical form of lithium molybdyl arsenate has been synthesized and grown as a single crystal. The structure of β‐LiMoO2(AsO4) is built up of corner‐sharing AsO4 tetrahedra and MoO6 octahedra which form a three‐dimensional framework containing tunnels running along the a axis, wherein the Li+ cations are located. This novel structure is compared with the compound LiMoO2(AsO4) of the same formula, and with those of AMO2(XO4) (A is Na, K, Rb or Pb, M is Mo or V, and X is P or As) and B(MoO2)2(XO4)2 (B is Ba, Pb or Sr).  相似文献   
109.
In0.21Ga0.79As multiple quantum wells MQW, with different well thickness L, are grown on [001] and [113] A GaAs growth directions by molecular beam epitaxy MBE. An asymmetric photoluminescence PL line shape denoted LEA and LEB in the lower energies side has been observed in both structures. These emissions of deep localized states can be related to the energy potential modulation associated to Indium cluster formation. Temperature dependence of photoluminescence properties has been reported. Localized state ensemble LSE model has investigated atypical behaviors of PL peak energies and the full width at half maximum FWHM of both emissions. These abnormal behaviors are explained by carriers captured by localized recombination centers. Competition processes between localized and delocalized excitons have been occurred to interpret the PL properties. The degree of localization induced by quantum-dot-like states and critical temperatures between different temperatures regions increase as far as away [001] growth direction.  相似文献   
110.
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