Theoretical studies on the electronic and geometric structures, the trend in DNA-binding affinities as well as the the structure-activity relationship （SAR） of a series of water-soluble Ru（II） methylimidazole comp...Theoretical studies on the electronic and geometric structures, the trend in DNA-binding affinities as well as the the structure-activity relationship （SAR） of a series of water-soluble Ru（II） methylimidazole complexes, i.e. [Ru（Mehn）4iip]^2＋ （1） （MeIm=l-methylimidazole, iip=2-（1H-imidazo-4-group）-lH-imidazo[n,5-f][1,10]phenanthroline）, [Ru（MeIm）4tip]^2＋ （2） （tip=2-（thiophene-2-group）-lH-imidazo[4,5-f] [i,10]phenanthroline）, and [Ru（Melm）42ntz]^2＋ （3） （2ntz=2-（2-nitro-l,3-thiazole-5-group）-lH-imidazo[4,5-f][1,10]phenanthroline）, were car- ried out using the density functional theory （DFT）. The electronic structures of these Ru（II） complexes were analyzed on the basis of their geometric structures optimized in aqueous solution, and the trend in the DNA-binding constants （Kb） was reasonably explained. The results show that the replacement of imidazole ligand by thiophene ligand can effectively improve the DNA-binding affinity of the complex. Meanwhile, it was found that introduc- ing the stronger electronegative N atom and NO2 group on terminal loop of intercalative ligand can obviously reduce the complex＇s LUMO and HOMO-LUMO gap energies. Based on these findings, the designed complex [Ru（MeIm）42ntz]^2＋ （3） can be expected to have the greatest Kb value in complexes 1-3. In addition, the structure-activity relationships and antitumor mechanism were also carefully discussed, and the antimetastatic activity of the designed complex 3 was predicted. Finally, the electronic absorption spectra of this series of complexes in aqueous solution were calculated, simulated and assigned using DFT/TDDFT methods as well as conductor-like polarizable continuum model （CPCM）, and were in good agreement with the experimental results.展开更多
This study investigates the projected changes in interannual variability of South Asian summer monsoon and changes of ENSO–monsoon relationships in the 21st century under the Intergovernmental Panel on Climate Change...This study investigates the projected changes in interannual variability of South Asian summer monsoon and changes of ENSO–monsoon relationships in the 21st century under the Intergovernmental Panel on Climate Change （IPCC） scenarios A1B and A2, respectively, by analyzing the simulated results of twelve Coupled Model Intercomparison Project Phase 3 （CMIP3） coupled models. The dynamical monsoon index （DMI） was adopted to describe the interannual variability of South Asian summer monsoon, and the standard deviation （SD） was used to illustrate the intensity of interannual variability. It was found that most models could project enhanced interannual variability of monsoon in the 21st century. The multi-model ensemble （MME） results showed increases in the interannual variability of DMI： 14.3% and 20.0% under scenarios A1B and A2, respectively. The MME result also showed increases in the rainfall variability are of about 10.2% and 22.0% under scenarios A1B and A2. The intensification of interannual variability tended to occur over the regions that have larger variability currently; that is, ＂the strong get stronger＂. Another finding was that ENSO–monsoon relationships are likely to be enhanced in the 21st century. The dynamical component of the monsoon will be more closely correlated to ENSO in the future under global warming, although the ENSO–summer rainfall relationship cannot be reasonably projected by current models. This suggests that the South Asian summer monsoon is more predictable in the future, at least dynamically.展开更多
A series of novel N-[（1-aryl-3-phenyl-pyrazol-4-yl）methylene]-2-（halo-o-hydroxyphenyl）hydrazide derivatives was synthesized and the antibacterial activity of each of them was evaluated. The supposed reaction mecha...A series of novel N-[（1-aryl-3-phenyl-pyrazol-4-yl）methylene]-2-（halo-o-hydroxyphenyl）hydrazide derivatives was synthesized and the antibacterial activity of each of them was evaluated. The supposed reaction mechanism of acquiring compounds 3a--3d is that catalytic activity is enhanced by the electron-donating groups of the first phenyl ring while decreased by electron-withdrawing groups of that ring. The result of preliminary bioassay shows that the lowest minimal inhibitory concentration（MIC） of the title compounds against Escherichia coli is 2 ℃g/mL. MIC values against Monilia albiean and Staphloeoeeus aureus are as low as 4 ~g/mL. They will be a series of potential antibacterial compounds against fungi and gram-negative bacteria.展开更多
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20903027）, the Natural Science Foundation of Guangdong Province of China （No.9452402301001941）, the Medical Scientific Research Foundation of Guangdong Province of China （No.B2013297）, and the University Student in Guangdong Province Innovation and Entrepreneurship Train ing Program （No.1057112019 and No.1057112013）.
文摘Theoretical studies on the electronic and geometric structures, the trend in DNA-binding affinities as well as the the structure-activity relationship （SAR） of a series of water-soluble Ru（II） methylimidazole complexes, i.e. [Ru（Mehn）4iip]^2＋ （1） （MeIm=l-methylimidazole, iip=2-（1H-imidazo-4-group）-lH-imidazo[n,5-f][1,10]phenanthroline）, [Ru（MeIm）4tip]^2＋ （2） （tip=2-（thiophene-2-group）-lH-imidazo[4,5-f] [i,10]phenanthroline）, and [Ru（Melm）42ntz]^2＋ （3） （2ntz=2-（2-nitro-l,3-thiazole-5-group）-lH-imidazo[4,5-f][1,10]phenanthroline）, were car- ried out using the density functional theory （DFT）. The electronic structures of these Ru（II） complexes were analyzed on the basis of their geometric structures optimized in aqueous solution, and the trend in the DNA-binding constants （Kb） was reasonably explained. The results show that the replacement of imidazole ligand by thiophene ligand can effectively improve the DNA-binding affinity of the complex. Meanwhile, it was found that introduc- ing the stronger electronegative N atom and NO2 group on terminal loop of intercalative ligand can obviously reduce the complex＇s LUMO and HOMO-LUMO gap energies. Based on these findings, the designed complex [Ru（MeIm）42ntz]^2＋ （3） can be expected to have the greatest Kb value in complexes 1-3. In addition, the structure-activity relationships and antitumor mechanism were also carefully discussed, and the antimetastatic activity of the designed complex 3 was predicted. Finally, the electronic absorption spectra of this series of complexes in aqueous solution were calculated, simulated and assigned using DFT/TDDFT methods as well as conductor-like polarizable continuum model （CPCM）, and were in good agreement with the experimental results.
基金supported bythe National Natural Science Foundation of China (Grant No. 40725016) the National Basic Research Pro-gram of China (Grant No. 2009CB421405)
文摘This study investigates the projected changes in interannual variability of South Asian summer monsoon and changes of ENSO–monsoon relationships in the 21st century under the Intergovernmental Panel on Climate Change （IPCC） scenarios A1B and A2, respectively, by analyzing the simulated results of twelve Coupled Model Intercomparison Project Phase 3 （CMIP3） coupled models. The dynamical monsoon index （DMI） was adopted to describe the interannual variability of South Asian summer monsoon, and the standard deviation （SD） was used to illustrate the intensity of interannual variability. It was found that most models could project enhanced interannual variability of monsoon in the 21st century. The multi-model ensemble （MME） results showed increases in the interannual variability of DMI： 14.3% and 20.0% under scenarios A1B and A2, respectively. The MME result also showed increases in the rainfall variability are of about 10.2% and 22.0% under scenarios A1B and A2. The intensification of interannual variability tended to occur over the regions that have larger variability currently; that is, ＂the strong get stronger＂. Another finding was that ENSO–monsoon relationships are likely to be enhanced in the 21st century. The dynamical component of the monsoon will be more closely correlated to ENSO in the future under global warming, although the ENSO–summer rainfall relationship cannot be reasonably projected by current models. This suggests that the South Asian summer monsoon is more predictable in the future, at least dynamically.
基金Supported by the National Natural Science Foundation of China（Nos.20976135, 21176194）.
文摘A series of novel N-[（1-aryl-3-phenyl-pyrazol-4-yl）methylene]-2-（halo-o-hydroxyphenyl）hydrazide derivatives was synthesized and the antibacterial activity of each of them was evaluated. The supposed reaction mechanism of acquiring compounds 3a--3d is that catalytic activity is enhanced by the electron-donating groups of the first phenyl ring while decreased by electron-withdrawing groups of that ring. The result of preliminary bioassay shows that the lowest minimal inhibitory concentration（MIC） of the title compounds against Escherichia coli is 2 ℃g/mL. MIC values against Monilia albiean and Staphloeoeeus aureus are as low as 4 ~g/mL. They will be a series of potential antibacterial compounds against fungi and gram-negative bacteria.
