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961.
Fen Tan Cong Xiao Hong‐Gang Cheng Wei Wu Ke‐Rong Ding Prof. Dr. Wen‐Jing Xiao 《化学:亚洲杂志》2012,7(3):493-497
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Two new complexes, (CoIII)2(H3L?)2(0.5H2O)2(ClO4)4 (I) and (MnIII)2(H3L?)2(0.5H2O)2 (ClO4)4 (II), were synthesized and crystallographically characterized [H4L = 1,4,7,10‐tetra‐(2‐hydroxypropyl)‐l,4,7,10‐tetraazacyclododecane] using electrospray ionization mass spectrometry and X‐ray photoelectron spectrometery. The characterizations confirmed that the valences of the metal ions increased from divalent to trivalent due to deprotonation of one OH group (H4L was in the form of H3L?). Owing to the instability of Co(III) and Mn(III) in both air and in solution, they preferred to exist in divalent form. The two heptadentate complexes are extraordinary in that the chiral pendants of the complexes are different in configuration. Spectroscopic studies, viscosity measurements, thermal denaturation experiments and circular dichroism spectra demonstrated that the complexes were prone to interact with DNA by groove binding. At micromolar concentrations and under physiological conditions, the two complexes were able to oxidatively cleave the supercoiled pUC19 plasmid DNA into its nicked and linear forms. Mechanistic studies using various additives suggest the complexes had structures different from those of other inorganic complexes. These are the first reported inorganic complexes not containing planar aromatic ligands and yet binding at the major groove. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
968.
Xiao‐Ya Yuan 《合成通讯》2013,43(8):1057-1062
A new enantiopure 6‐monobromo‐substituted BINAP has been prepared via a one‐step nickel‐catalyzed coupling reaction in moderate yield. It is an important intermediate for asymmetric 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl (BINAP) derivatives. Its structure was elucidated by NMR spectral and elemental analysis. 相似文献
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Nikolaus M. Loening Barth‐Jan van Rossum Hartmut Oschkinat 《Magnetic resonance in chemistry : MRC》2012,50(4):284-288
In nuclear magnetic resonance spectroscopy, experimental limits due to the radiofrequency transmitter and/or coil means that conventional radiofrequency pulses (“hard pulses”) are sometimes not sufficiently powerful to excite magnetization uniformly over a desired range of frequencies. Effects due to nonuniform excitation are most frequently encountered at high magnetic fields for nuclei with a large range of chemical shifts. Using optimal control theory, we have designed broadband excitation pulses that are suitable for solid‐state samples under magic‐angle‐spinning conditions. These pulses are easy to implement, robust to spinning frequency variations, and radiofrequency inhomogeneities, and only four times as long as a corresponding hard pulse. The utility of these pulses for uniformly exciting 13C nuclei is demonstrated on a 900 MHz (21.1 T) spectrometer. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献