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Colm Crean John F. Gallagher Albert C. Pratt 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(1):o36-o38
The title complex, C17H9N5·C6H4S4, contains π‐deficient bis(dinitrile) and TTF molecules stacked alternately in columns along the a‐axis direction; the interplanar angle between the TTF molecule and the isoindolinyl C4N[C(CN)2]2 moiety is 1.21 (4)°. The N‐allyl moiety in the TCPI molecule is oriented at an angle of 87.10 (10)° with respect to the five‐membered C4N ring, and the four C[triple‐bond]N bond lengths range from 1.134 (3) to 1.142 (3) Å, with C—C[triple‐bond]N angles in the range 174.3 (3)–176.9 (2)°. In the TTF system, the S—C bond lengths are 1.726 (3)–1.740 (3) and 1.751 (2)–1.763 (2) Å for the external S—C(H) and internal S—C(S) bonds, respectively. 相似文献
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PHOTOLYSIS OF PHOSPHODIESTER BONDS IN PLASMID DNA BY HIGH INTENSITY UV LASER IRRADIATION 总被引:1,自引:0,他引:1
David T. Choke Werner Blau Colm Ohuigin John M. Kelly David J. Mcconnell 《Photochemistry and photobiology》1988,47(4):527-536
Abstract— The cleavage of phosphodiester bonds in DNA exposed to high intensity UV laser pulses in aerated aqueous solution has been investigated using a krypton fluoride excimer laser (248 nm) and bacterial plasmid DNA. The dependence of strand breakage on fluence and intensity has been studied in detail and shows that the process is non-linear with respect to intensity. The relationship between the quantum yield for strand breakage and intensity shows that the strand breakage reaction involves two-photon excitation of DNA bases. The quantum yield rises with intensity from a lower value of 7 times 10-5 until a maximum value of 4.5 times 10-4 is attained at intensities of 1011 W m-2 and above. This value is approximately fifty-fold higher than the quantum yield for strand breakage induced by exposure to low density UV irradiation (254 nm, 12 W m-2 ). DNA sequencing experiments have shown that strand breakage occurs by the specific cleavage of the phosphodiester bond which lies immediately 3' to guanine residues in the DNA, leaving some alkali-labile remnant attached to the terminal phosphate. A mechanism for DNA strand breakage which involves the generation of guanine radical cations is proposed. 相似文献
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Gregory B. Kharas Sonia E. Chavez Harrison S. Browning Jennifer A. Sepe Mario E. Romanelli Melissa K. Susnis 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):751-755
Electrophilic trisubstituted ethylenes, ring-disubstituted methyl 2-cyano-3-phenyl-2-propenoates, RPhCH?C(CN)CO2CH3, where R is 2,5-dichloro, 3,5-dichloro, 2,3-difluoro, 3-chloro-2-fluoro, 3-chloro-4-fluoro, 4-chloro-3-fluoro, 2-chloro-5-nitro, and 2-chloro-6-nitro were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-disubstituted benzaldehydes and methyl cyanoacetate, and characterized by CHN analysis, IR, 1H and 13C-NMR. All the ethylenes were copolymerized with styrene (M1) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, 1H and 13C-NMR. The order of relative reactivity (1/r1) for the monomers is 4-Cl-3-F (4.87) > 2,3-F2 (4.49) > 3-Cl-4-F (3.50) > 3-Cl-2-F (2.96) > 2-Cl-5-NO2 (2.02) > 2,5-Cl2 (1.54) > 2-Cl-6-NO2 (1.00) > 3,5-Cl2 (0.41). Relatively high Tg of the copolymers in comparison with that of polystyrene indicates a decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500ºC range with residue (1.5–34.5% wt), which then decomposed in the 500-800ºC range. 相似文献
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Colm Browne Tanya K. Ronson Jonathan R. Nitschke 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(40):10877-10881
The reaction of 2,6‐diformylpyridine with diverse amines and PdII ions gave rise to a variety of metallosupramolecular species, in which the PdII ion is observed to template a tridentate bis(imino)pyridine ligand. These species included a mononuclear complex as well as [2+2] and [3+3] macrocycles. The addition of pyridine‐containing macrocyclic capping ligands allows for topological complexity to arise, thereby enabling the straightforward preparation of structures that include a [2]catenane, a [2]rotaxane, and a doubly threaded [3]rotaxane. 相似文献
8.
The Origin of Shape Sensitivity in Palladium‐Catalyzed Suzuki–Miyaura Cross Coupling Reactions
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Dr. Gillian Collins Michael Schmidt Dr. Colm O'Dwyer Prof. Justin D. Holmes Dr. Gerard P. McGlacken 《Angewandte Chemie (International ed. in English)》2014,53(16):4142-4145
The shape sensitivity of Pd catalysts in Suzuki–Miyaura coupling reactions is studied using nanocrystals enclosed by well‐defined surface facets. The catalytic performance of Pd nanocrystals with cubic, cuboctahedral and octahedral morphologies are compared. Superior catalytic reactivity is observed for Pd NCs with {100} surface facets compared to {111} facets. The origin of the enhanced reactivity associated with a cubic morphology is related to the leaching susceptibility of the nanocrystals. Molecular oxygen plays a key role in facilitating the leaching of Pd atoms from the surface of the nanocrystals. The interaction of O2 with Pd is itself facet‐dependent, which in turn gives rise to more efficient leaching from {100} facets, compared to {111} facets under the reaction conditions. 相似文献
9.
Additive manufacturing and 3D printing in particular have the potential to revolutionize existing fabrication processes, where objects with complex structures and shapes can be built with multifunctional material systems. For electrochemical energy storage devices such as batteries and supercapacitors, 3D printing methods allows alternative form factors to be conceived based on the end use application need in mind at the design stage. Additively manufactured energy storage devices require active materials and composites that are printable, and this is influenced by performance requirements and the basic electrochemistry. The interplay between electrochemical response, stability, material type, object complexity and end use application are key to realising 3D printing for electrochemical energy storage. Here, we summarise recent advances and highlight the important role of methods, designs and material selection for energy storage devices made by 3D printing, which is general to the majority of methods in use currently. 相似文献