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911.
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The exclusive self-sorting observed in the self-assembly process between tetraurea benzyl calix[4]pyrroles and tetraurea tolyl calix[4]arene to afford unprecedented hybrid dimeric capsules with polar interiors is described. The coencapsulation of a solvent molecule with an organic guest yields four particle aggregates in which the guests are confined and restricted into single hemispheres due to the polar requirements of the internal cavity. 相似文献
915.
Dr. Marcos Hernández‐Rodríguez Dr. Jian Xie Dr. Yazmin M. Osornio Prof. Dr. Ramanarayanan Krishnamurthy 《化学:亚洲杂志》2011,6(5):1252-1262
The (3′→2′)‐phosphodiester glyceric acid backbone containing an acyclic oligomer tagged with 2,4‐disubstituted pyrimidines as alternative recognition elements have been synthesized. Strong cross‐pairing of a 2,4‐dioxo‐5‐aminopyrimidine hexamer, rivaling locked nucleic acid (LNA) and peptide nucleic acid (PNA), with complementary adenine‐containing DNA and RNA sequences was observed. The corresponding 2,4‐diamino‐ and 2‐amino‐4‐oxo‐5‐aminopyrimidine‐tagged oligomers were synthesized, but difficulties in deprotection, purification, and isolation thwarted further investigations. The acyclic phosphate backbone structure of the protected oligomer seems to be prone to an eliminative degradation owing to the acidic hydrogen at the 2′‐position—an arrangement that renders the oligomer vulnerable to the conditions used for the removal of the protecting groups on the heterocyclic recognition element. However, the free oligomers seem to be stable under the conditions investigated. 相似文献
916.
Conway and Sloane constructed a 4-parameter family of pairs of isospectral lattices of rank four. They conjectured that all pairs in their family are non-isometric, whenever the parameters are pairwise different, and verified this for classical integral lattices of determinant up to 104. In this paper, we use our theory of lattice invariants to prove this conjecture. 相似文献
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919.
Long lasting phosphorescence in barium aluminates can be achieved by doping with rare earth ions in divalent charge states. The rare earth ions are initially in a trivalent charge state, but are reduced to a divalent charge state before being doped into the material. In this paper, the reduction of trivalent rare earth ions in the BaAl2O4 lattice is studied by computer simulation, with the energetics of the whole reduction and doping process being modelled by two methods, one based on single ion doping and one which allows dopant concentrations to be taken into account. A range of different reduction schemes are considered and the most energetically favourable schemes identified. 相似文献
920.
Oliveira FF dos Santos MR Lalli PM Schmidt EM Bakuzis P Lapis AA Monteiro AL Eberlin MN Neto BA 《The Journal of organic chemistry》2011,76(24):10140-10147
An acetate anion bearing an imidazolium cation as its charge tag was reacted with M(OAc)(2) complexes (where M = Ni, Cu, and Pd; in situ reaction) to form members of a new class of charge-tagged metal complexes. The formation of these unprecedented precatalysts with potential for cross-coupling reactions was confirmed by electrospray ionization (and tandem) mass spectrometry. The catalytic performance of the palladium complex was tested in Heck and Suzuki cross-coupling reactions, often with superior activity and yields as compared with Pd(OAc)(2). 相似文献