scholarly journals Dimerization of terminal alkynes promoted by a heterobimetallic Zr/Co complex

2020 ◽  
Vol 49 (8) ◽  
pp. 2407-2411 ◽  
Author(s):  
Jeffrey W. Beattie ◽  
Canning Wang ◽  
Hongtu Zhang ◽  
Jeremy P. Krogman ◽  
Bruce M. Foxman ◽  
...  
Keyword(s):  
Activation Process ◽  
Terminal Alkynes ◽  
Heterobimetallic Complex

A reduced ZrIV/Co−I heterobimetallic complex facilitates the formation of 1,3-enynes from terminal alkynes through a cooperative bimetallic C–H activation process.

SEM and Auger microanalysis studies of Cu-Be dynode surfaces at each activation condition

1978 ◽  
Vol 36 (1) ◽  
pp. 524-525
Author(s):  
T. Koshikawa ◽  
Y. Fujii ◽  
E. Sugata ◽  
F. Kanematsu
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Life Time ◽  
Activation Process ◽  
Beam Diameter ◽  
Activation Temperature ◽  
Electron Multiplier ◽  
Activation Condition ◽  
Activation Conditions

The Cu-Be alloys are widely used as the electron multiplier dynodes after the adequate activation process. But the structures and compositions of the elements on the activated surfaces were not studied clearly. The Cu-Be alloys are heated in the oxygen atmosphere in the usual activation techniques. The activation conditions, e.g. temperature and O2 pressure, affect strongly the secondary electron yield and life time of dynodes.In the present paper, the activated Cu-Be dynode surfaces at each condition are investigated with Scanning Auger Microanalyzer (SAM) (primary beam diameter: 3μmϕ) and SEM. The commercial Cu-Be(2%) alloys were polished with Cr2O3 powder, rinsed in the distilled water and set in the vacuum furnance.Two typical activation condition, i.e. activation temperature 730°C and 810°C in 5x10-3 Torr O2 pressure were chosen since the formation mechanism of the BeO film on the Cu-Be alloys was guessed to be very different at each temperature from the results of the secondary electron emission measurements.

The Binding of Calcium Ions to Bovine Factor X by Rate Dialysis

1978 ◽  
Vol 40 (02) ◽  
pp. 350-357
Author(s):  
Robert H Yue ◽  
Menard M Gertler
Keyword(s):  
Molecular Weight ◽  
Dissociation Constant ◽  
Calcium Ions ◽  
Activation Process ◽  
Factor X ◽  
The Real ◽  
High Affinity ◽  
Binding Data ◽  
Sequential Mechanism ◽  
Bovine Factor

SummaryThe binding of Ca+2 to bovine factor X (molecular weight of 74,000) (Yue und Gertler 1977) was studied by the technique of rate dialysis and with the use of 45Ca+2. The binding data are consistent with a model of sequential mechanism. One mole of Ca+2 binds to the glycoprotein with a dissociation constant of 5.2 × 10-5 M and an additional 39 ± 4 moles of Ca+2 bind to this zymogen with a dissociation constant of 3.7 × 10-3M. The binding of the high affinity Ca+2 causes a functionally significant change in the zymogen, and (calcium) (factor X) complex is the real substrate in the activation process by the protease in Russell’s viper venom.

Synthesis of Novel 1,2,3-Triazole Derivatives of Isocoumarins and 3,4-Dihydroisocoumarin with Potential Antiplasmodial Activity In Vitro

2020 ◽  
Vol 16 ◽  
Author(s):  
Lucas da Silva Santos ◽  
Matheus Fillipe Langanke de Carvalho ◽  
Ana Claudia de Souza Pinto ◽  
Amanda Luisa da Fonseca ◽  
Julio César Dias Lopes ◽  
...  
Keyword(s):  
Triazole Ring ◽  
Antiplasmodial Activity ◽  
World Health ◽  
Dipolar Cycloaddition ◽  
Terminal Alkynes ◽  
The World ◽  
Ic50 Values ◽  
Derivatives Of ◽  
Active Substances

Background: Malaria greatly affects the world health, having caused more than 228 million cases only in 2018. The emergence of drug resistance is one of the main problems in its treatment, demonstrating the urge for the development of new antimalarial drugs. Objective: Synthesis and in vitro antiplasmodial evaluation of triazole compounds derived from isocoumarins and a 3,4- dihydroisocoumarin. Method: The compounds were synthesized in 4 to 6-step reactions with the formation of the triazole ring via the Copper(I)-catalyzed 1,3-dipolar cycloaddition between isocoumarin or 3,4-dihydroisocoumarin azides and terminal alkynes. This key reaction provided compounds with an unprecedented connection of isocoumarin or 3,4-dihydroisocoumarin and the 1,2,3-triazole ring. The products were tested for their antiplasmodial activity against a Plasmodium falciparum chloroquine resistant and sensitive strains (W2 and 3D7, respectively). Results: Thirty-one substances were efficiently obtained by the proposed routes with an overall yield of 25-53%. The active substances in the antiplasmodial test displayed IC50 values ranging from 0.68-2.89 μM and 0.85-2.07 μM against W2 and 3D7 strains, respectively.

On-Surface Synthesis of Carbon-Based Scaffolds and Nanomaterials Using Terminal Alkynes

2015 ◽  
Vol 48 (7) ◽  
pp. 2140-2150 ◽  
Author(s):  
Florian Klappenberger ◽  
Yi-Qi Zhang ◽  
Jonas Björk ◽  
Svetlana Klyatskaya ◽  
Mario Ruben ◽  
...  
Keyword(s):  
Terminal Alkynes ◽  
Carbon Based

Importance of bases on the copper-catalyzed oxidative homocoupling of terminal alkynes to 1,4-disubstituted 1,3-diynes

2012 ◽  
Vol 53 (41) ◽  
pp. 5559-5561 ◽  
Author(s):  
Xinjiang Niu ◽  
Chunju Li ◽  
Jian Li ◽  
Xueshun Jia
Keyword(s):  
Terminal Alkynes ◽  
Oxidative Homocoupling

Dimethylzinc-mediated enantioselective addition of terminal alkynes to 1,2-diketones using perhydro-1,3-benzoxazines as ligands

2021 ◽  
Author(s):  
Elena Prieto ◽  
Rebeca Infante ◽  
Javier Nieto ◽  
Celia Andres
Keyword(s):  
Chiral Ligand ◽  
Terminal Alkynes ◽  
Conformationally Restricted ◽  
Enantioselective Addition

A conformationally restricted perhydro-1,3-benzoxazine derived from (-)-8-aminomenthol behaves as a good chiral ligand in the dimethylzinc-mediated enantioselective monoaddition of aromatic and aliphatic terminal alkynes to 1,2-diketones. The corresponding α-hydroxyketones were...

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