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991.
992.
Petr Zuman 《Journal of Solid State Electrochemistry》2006,10(10):841-851
Examples of recent applications—applied, analytical, and fundamental are given. For these types of applications, an understanding of at least the number of electrons and protons transferred and the sequences of electron transfers and chemical reactions is essential. Polarography can be used for the determination of the active component in tablets and injection solutions, where it offers speed and sensitivity of the analytical method. Electroactive species can also be determined in heterogeneous systems without pre-separation. This has been taken advantage of in the investigation of reactions of bile salts with heavy metal ions or of binding of pesticides and other toxins on lignin. Polarography can also be used in the investigation of alkaline cleavage of lignin under mild conditions. Kinetics of this cleavage was used as a tool in proving that humic acids are not natural products. Among fundamental applications belong proofs of limited delocalization in groupings >C=N–N=C<, of diprotonation of hydrazones and oximes at the electrode surface, as well as of formation of imines as intermediates in reductions of hydrazones and oximes. Simultaneous determination of benzaldehyde and its hydrazone enabled providing experimental evidence for formation of carbinolamines as reaction intermediates and interpretation of the pH dependence of the equilibrium constant of this reaction. Differences in hydration of three isomeric phthalaldehydes are discussed as well as the covalent hydration of 1,2,4- and 1,3,5-triazines and pyrimidines. The ω,ω,ω-trifluoroacetophenone oxime the C=N bond is covalently hydrated.Dedicated to Professor Dr. Alan Bond on the occasion of his 60th birthday. 相似文献
993.
5-Substituted-4-amino-3-thiol-1, 2, 4-triazoles (1a- b) react with orthonitrochloro- benzene or para-nitrochlorobenzene to give N-N bond cleavage products 2a-d, one structure of which (2b) has been unambiguously confirmed by an X-ray structural analysis. 相似文献
994.
《应用有机金属化学》2017,31(10)
A novel tetradentate dianionic Schiff base ligand, N ,N ′‐bis(2‐carboxyphenylimine)‐2,5‐thiophenedicarboxaldhyde (H2L) and some first row d‐transition metal chelates (Co(II), Cu(II), Ni(II) and Zn(II)) were synthesized and characterized using various physicochemical and spectroscopic methods. The spectroscopic data suggested that the parent Schiff base ligand coordinates through both deprotonated carboxylic oxygen and imine nitrogen atoms. The free Schiff base and its metal chelates were screened for their antimicrobial activities for various pathogenic bacteria and fungi using the agar well diffusion method. The antibacterial and antifungal activities of all the newly synthesized compounds are significant compared to the standard drugs ciprofloxacin and nystatin. The antioxidant activities of the compounds were determined by reduction of 1,1‐diphenyl‐2‐picrylhydrazyl and compared with that of vitamin C as a standard. DNA binding ability of the novel Schiff base and its complexes was investigated using absorption spectroscopy, fluorescence spectroscopy, viscosity measurements and thermal denaturation. The obtained results clearly demonstrate that the binding affinity with calf thymus DNA follows the order: Cu(II) complex > Ni(II) complex > Zn(II) complex > Co(II) complex >H2L. Furthermore, the DNA cleavage activity of the newly synthesized ligand and its metal complexes was investigated using supercoiled plasmid DNA (pUC18) gel electrophoresis. 相似文献
995.
《合成通讯》2013,43(9):1537-1544
Abstract A methodology for the synthesis of compounds containing the cis-anti-cis fused triquinane system has been developed starting from tricyclo[5.2.1.02,6]deca-4,8-dien-3-(exo)ol 6 involving Ireland ester Claisen rearrangement and intramolecular diazo ketone cyclopropanation reactions as key steps. 相似文献
996.
C. Garrett Campbell Robson F. Storey 《Journal of polymer science. Part A, Polymer chemistry》2017,55(12):1991-1997
Lewis‐acid catalyzed degradation of poly(isobutylene‐co‐isoprene) (butyl rubber) in the presence of an alkoxybenzene compound was studied as a new route toward low molecular weight multifunctional polyisobutylenes. Simultaneous cleavage and functionalization of butyl rubber was conducted at ?70 °C and ?40 °C under TiCl4 or AlCl3 catalysis in 60/40 hexane/methylene chloride cosolvents in the presence of (3‐bromopropoxy)benzene (BPB) for various times up to 24 h. The butyl rubber (EXXON? Butyl 365) possessed M n = 1.91 × 105 g/mol, PDI = 1.66 (GPC/MALLS), and 2.30 mol % isoprene units (nearly exclusively trans ?1,4). At ?70 °C with TiCl4, molecular weight was reduced to various values within the range 7 to 11 × 103 g/mol depending on conditions; lower BPB concentration produced lower molecular weight. However, the ratio of isobutylene repeat units to BPB units (IB/Q ) remained constant at about 43:1, which is approximately the same as the ratio of isobutylene to isoprene repeat units (IB/IP) in the starting butyl rubber (42.5:1). At ?40 °C with TiCl4, molecular weight was reduced to about 5 × 103 g/mol, and IB/Q was reduced below IB/IP, indicating nearly a difunctional telechelic structure. AlCl3 was a more active catalyst and produced results similar to TiCl4 at ?40 °C, even when used at seven times lower concentration. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1991–1997 相似文献
997.
Oxidation of an Oligonucleotide‐Bound CeIII/Multiphosphonate Complex for Site‐Selective DNA Scission
Yoshitaka Miyajima Dr. Jun Sumaoka Dr. Makoto Komiyama Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(3):855-859
Oligodeoxyribonucleotide conjugates of ethylenediamine‐N,N,N′,N′‐tetrakis(methylenephosphonic acid) (EDTP) have been used to place a CeIII/EDTP complex in close proximity to predetermined phosphodiester linkages of a complementary target oligonucleotide. In the presence of atmospheric oxygen, the CeIII is oxidized into CeIV which, in turn, efficiently cleaves the target phosphodiester linkage. No cleavage occurs at the other single‐stranded regions, which suggests that the catalytic Ce species is strictly localized next to the target phosphodiester linkage. No decrease in the reaction rate is observed upon introduction of scavengers for hydroxyl radicals (such as DMSO or MeOH) or singlet oxygen (such as NaN3) to the system; this indicates that the reaction proceeds via a hydrolytic pathway. Any significant contribution by an oxidative pathway is further ruled out by the observation that nucleosides remain intact after incubation with CeIV/EDTP complex for extended periods. 相似文献
998.
Guangjun Xu Wen Gu Xiaofang Ma Li Feng Shiping Yan Daizheng Liao Peng Cheng 《Frontiers of Chemistry in China》2008,3(2):138-142
The interaction between CT-DNA and a ternary copper (II) complex, [Cu(phendio)(L-Phe)(H2O)](ClO4)·H2O (CuPP, phendio = 1,10-phenanthroline-5,6-dione, L-Phe = L-phenylalanine), has been conducted by electronic spectra, fluorescence
spectroscopy and cyclic voltammetry. It has been found that the max. absorption peak from the electronic spectra is red shifted
and the intensity is weakened and that the values of peak current from cyclic voltammetry are decreased significantly in the
presence of DNA compared with that in the absence of DNA. At the same time, the complex can quench the emission intensity
of EB-DNA system. The existence of the intercalation mode between the complex and DNA was proven. By submarine gel electrophoresis,
we found that the copper(II) complex can cleave circular plasmid pBR322 DNA into nicked and linear forms in the presence of
ascorbic acid and H2O2.
__________
Translated from Acta Scientiarum Naturalium Universitatis Nankaiensis, 2007, 40(1): 32–36 [译自: 南开大学学报(自然科学版)] 相似文献
999.
《Analytical letters》2012,45(13-14):2771-2782
Abstract Electrophoresis followed by electroblotting is a fast method for isolation of purified peptides, which can be directly applied for sequence analysis with a pulsed liquid sequencer after amidoblack detection. 相似文献
1000.