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91.
Jean-Pierre Dutasta Brigitte Bibal Jean-Paul Declercq Beatrice Dubessy Jean-Christophe Mulatier Bernard Tinant 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1485-1488
The recent results in the chemistry of cavitands have proved that they are very efficient molecular receptors and potential precursors of molecular devices. In this context, we have investigated the synthesis and binding properties of phosphorylated cavitands. The stereoselective synthesis and the structural studies of the new compounds showed that these bowl-shaped molecules possess a well defined aromatic cavity surrounded by four phosphoryl groups (P=O or P=S). They are very efficient ligands for metal and organic cations. They are able to encapsulate cationic species by cooperative effect of the preorganized aromatic cavity and the four phosphorylated groups. Moreover, the upper and lower rim functionalitics can lead to the formation of molecular capsules and supramolecular assemblies whose properties and structures have been investigated by X-ray diffraction and NMR studies in solution. 相似文献
92.
Antonio Garrido Montalban Antonio J. HerreraJes Johannsen Andrew J.P. WhiteDavid J. Williams 《Tetrahedron》2014
Mono- and tri-topic ligands, based on dipyrromethenes and the 1,10-phenanthroline nucleus, as well as BF2 complexes derived thereof are described. While BODIPY 12 has been X-ray crystallographically characterized, the structural features of the free ligands 9 and 10 may render them useful as precursors for the elaboration of novel supramolecular architectures. 相似文献
93.
《Journal of Saudi Chemical Society》2020,24(12):1051-1059
Four novel heterocyclic1,3,4-oxadiazole, 1,2,4-triazole derivatives, namely: 5-[1-amino-3-(methylsulfanyl)propyl]-1,3,4-oxadiazole-2(3H)-thione (4), 4-amino-5-[1-amino-3-(methylsulfanyl)propyl]-4H-1,2,4-triazole-3-thiol (5), 1-amino-3-[1-amino-3-(methylsulfanyl)propyl]-1H-1,2,4-triazole-5-thiol (7), and 5-[1-amino-3-(methylsulfanyl)propyl]-1H-1,2,4-triazole-3-thiol (9) have been synthesized from l-methionine and characterized by different spectroscopic techniques (FT-IR, UV–Vis, 1H NMR, 13C NMR and MS). Complex formation with Hg++ and Fe+++ ions were formed from the four heterocyclic 4, 5, 7 and 9. The antimicrobial activities for synthetic intermediates and final four products were assisted using paper disk diffusion method against Gram-negative bacteria: Escherichia coli, Pseudomonas aeroginosae and Gram-positive bacteria: Staphylococus aureus 25923, Staphylococus aureus 43300 and showed variant activity against some of the microorganisms tested. 相似文献
94.
The sorption of inorganic lead(II) on two cationic resins containing different complexing groups, the iminodiacetic Chelex
100 and the carboxylic Amberlite CG-50, was investigated. The Gibbs-Donnan model was used to describe and predict the sorption
through the determination of the intrinsic complexation constants. These quantities, even though non-thermodynamic, characterize
the sorption as being independent of experimental conditions. The sorption mechanism for metals on complexing resins was also
studied by adding a competitive soluble ligand that shifts the sorption curves to higher pH. The ligand competes with the
resin for complexation with the metal ion. Lead(II) is strongly sorbed on Chelex 100 through the formation of two complexes
in the resin phase: MHL with log 10
β
111i
=−0.3 and ML with log 10
β
111i
=−3.7. The presence of the competitive ligand in solution allows for the determination of a third complex. Furthermore, on
Amberlite CG-50 the sorption is rather strong and involves the formation of the complex ML, in more acidic solution, with
log 10
β
110i
=−2.0. In the presence of the ligand PyDA, the ML(OH) complex was characterized by log 10
β
11−1i
=−5.6. In all the experiments the hydrolysis reactions in the aqueous phase are considered quantitatively. 相似文献
95.
Edward E. Foos Mark E. Twigg Arthur W. Snow Mario G. Ancona 《Journal of Cluster Science》2008,19(4):573-589
Reduction of a mixture of Ph3PAuCl and CH3(CH2)5SH with NaBH4 yields predominately phosphine encapsulated nanoclusters with Au cores <1 nm, similar to the product isolated when the alkane
thiol is not present in the reaction. When Et3N is added to a solution of Ph3PAuCl and CH3(CH2)5SH, a Au–S bond is formed, and the subsequent reduction of this thiolate results in the formation of >2 nm core thiol encapsulated
Au nanoclusters as the majority product. This latter reduction has been examined in more detail through in situ 31P NMR experiments, and a solution exchange reaction is observed wherein the PPh3 generated by the reduction displaces thiol from the surface of the nanocluster product. This thiol displacement occurs with
loss of a Au atom from the nanocluster core, as observed by NMR.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Edward E. FoosEmail: |
96.
Substrate binding to cytochromes P450 总被引:1,自引:0,他引:1
P450s have attracted tremendous attention owing to not only their involvement in the metabolism of drug molecules and endogenous
substrates but also the unusual nature of the reaction they catalyze, namely, the oxidation of unactivated C–H bonds. The
binding of substrates to P450s, which is usually viewed as the first step in the catalytic cycle, has been studied extensively
via a variety of biochemical and biophysical approaches. These studies were directed towards answering different questions
related to P450s, including mechanism of oxidation, substrate properties, unusual substrate oxidation kinetics, function,
and active-site features. Some of the substrate binding studies extending over a period of more than 40 years of dedicated
work have been summarized in this review and categorized by the techniques employed in the binding studies.
相似文献
Emre M. IsinEmail: |
97.
Niklas F. Both Dr. Anke Spannenberg Prof. Dr. Haijun Jiao Dr. Kathrin Junge Prof. Dr. Matthias Beller 《Angewandte Chemie (International ed. in English)》2023,62(35):e202307987
The use of bis(NHC) manganese(I) complexes 3 as catalysts for the hydrogenation of esters was investigated. For that purpose, a series of complexes has been synthesized via an improved two step procedure utilizing bis(NHC)-BEt3 adducts. By applying complexes 3 with KHBEt3 as additive, various aromatic and aliphatic esters were hydrogenated successfully at mild temperatures and low catalyst loadings, highlighting the efficiency of the novel catalytic system. The versatility of the developed catalytic system was further demonstrated by the hydrogenation of other substrate classes like ketones, nitriles, N-heteroarenes and alkenes. Mechanistic experiments and DFT calculations indicate an inner sphere mechanism with the loss of one CO ligand and reveal the role of BEt3 as cocatalyst. 相似文献
98.
Sebastián Martínez-Vivas Prof. Dmitry G. Gusev Dr. Macarena Poyatos Prof. Eduardo Peris 《Angewandte Chemie (International ed. in English)》2023,62(48):e202313899
We report the rhodium(I) complex [Rh(CNC−NDI)(CO)]+, in which CNC−NDI refers to a pincer-CNC ligand decorated with a naphthalenediimide moiety. Due to the presence of the planar CNC ligand and the naphthalenediimide moiety, the electronic nature of the complex can be modulated by means of supramolecular and redox stimuli, respectively. The metal complex shows a strong π–π-stacking interaction with coronene. This interaction has an impact on the electron-richness of the metal, as demonstrated by the shifting of the ν(CO) stretching band to a lower frequency. The addition of tetrabutylammonium fluoride facilitates the sequential one- and two-electron reduction of the NDI moiety of the ligand, thus resulting in a situation in which the ligand can increase its electron-donor strength in two levels. The nature of the interaction with the fluoride anion was studied computationally. The catalytic activity of the [Rh(CNC−NDI)(CO)]+ complex was tested in the cycloisomerization of alkynoic acids, where it is observed that the activity of the catalyst can be modulated between four levels of activity, which correspond to i) the use of the unmodified catalyst, ii) catalyst+coronene, iii) catalyst+2 equivalents of fluoride, and iv) catalyst+5 equivalents of fluoride. 相似文献
99.
Jian Shen Bo Cui Junwei Huang Prof. Dr. Shenghui Lin Prof. Dr. Xiuling Cui 《European journal of organic chemistry》2023,26(13):e202300064
A highly efficient strategy to construct benzo[d][1,3]diazepines via selective C−H bond activation of N-aryl amidines and coupling with alkynyl cyclobutyl acetates was achieved successfully by RuII-catalyzed [5+2] cyclization. This protocol features excellent regioselectivity, wide substrate tolerance, mild reaction conditions, which might be potentially applied in the discovery of lead compounds for the developing new drugs. 相似文献
100.
Dr. Ilia Kochetygov Jocelyn Roth Dr. Jordi Espín Sophia Pache Dr. Anita Justin Till Schertenleib Dr. Nazanin Taheri Dr. Dmitry Chernyshov Prof. Wendy L. Queen 《Angewandte Chemie (International ed. in English)》2023,62(16):e202215595
The design of metal–organic frameworks (MOFs) having large pore sizes and volumes often requires the use of complex organic ligands, currently synthesized using costly and time-consuming palladium-catalyzed coupling chemistry. Thus, in the present work, a new strategy for ligand design is reported, where piperazine and dihydrophenazine units are used as substitutes for benzene rings, which are the basic building block of most MOF ligands. This chemistry, which is based on simple, nucleophilic aromatic substitution (SNAr) reactions, is used for the transition metal catalyst-free construction of 21 new, carboxylate-based ligands with varying sizes, shapes, and denticity and 15 linear di- and tetra-nitriles. Moreover, to demonstrate the utility of the ligands as building blocks, 16 new structurally diverse MOFs having surface areas up to 3100 m2 g−1 were also synthesized. 相似文献