Study of the effect of the ligand structure on the catalytic activity of Pd@ ligand decorated halloysite: Combination of experimental and computational studies

2019 ◽  
Vol 33 (5) ◽  
pp. e4891 ◽  
Author(s):  
Sevda Dehghani ◽  
Samahe Sadjadi ◽  
Naeimeh Bahri‐Laleh ◽  
Mehdi Nekoomanesh‐Haghighi ◽  
Albert Poater
Keyword(s):  
Catalytic Activity ◽  
Computational Studies ◽  
Ligand Structure

Lanthanide catalysts for the hetero Diels–Alder reaction: effect of ligand structure and acidity

1997 ◽  
Vol 75 (8) ◽  
pp. 1047-1054 ◽  
Author(s):  
Claude Spino ◽  
Laurel L. Clouston ◽  
David J. Berg
Keyword(s):  
Catalytic Activity ◽  
Vinyl Ether ◽  
Alder Reaction ◽  
Diels Alder ◽  
Ethyl Vinyl Ether ◽  
Ethyl Vinyl ◽  
Catalytic Activities ◽  
Ligand Structure ◽  
Bite Angle ◽  
Diels Alder Reaction

A series of yttrium, ytterbium, and lanthanum hexa-or heptacoordinate complexes were prepared and their catalytic activities tested in the hetero Diels–Alder reaction between crotonaldehyde and ethyl vinyl ether. It was found that a pKa below 7 of the ligand was necessary but not sufficient for catalytic activity. It was determined that the ligand should possess a perfluoromethyl-β-diketonate functionality. Other factors such as bite angle and hinging motion may also play a determining role. Keywords: lanthanide, catalyst, hetero Dielsis–Alder, yttrium, ytterbium, lanthanum.

scholarly journals Unexpected Catalytic Activity of the Regulatory Protein QacR

2020 ◽  
Author(s):  
Cora Gutiérrez de Souza ◽  
Lur Alonso-Cotchico ◽  
Manuela Bersellini ◽  
Gerard Roelfes
Keyword(s):  
Catalytic Activity ◽  
Multidrug Resistance ◽  
Regulatory Protein ◽  
Binding Pocket ◽  
Computational Studies ◽  
Protonation Reaction ◽  
Catalytic Reactivity

Natural proteins often present binding or functional promiscuity. In biocatalysis, this promiscuity has been exploited for accessing new-to-nature reactions. Here, we report an unexpected catalytic reactivity for the regulatory protein QacR from the TetR family of multidrug resistance regulators. QacR is able to catalyze the enatioselective tandem Friedel-Crafts / enantioselective protonation reaction of indoles with alpha substituted conjugated enones with up to 40% yield and 83% ee. Mutagenesis and computational studies support the hypothesis that an acidic residue in the binding pocket of the protein is responsible for protonating the enolate intermediate.

scholarly journals Electronic effects in mixed N-heterocyclic carbene/phosphite indenylidene ruthenium metathesis catalysts

2019 ◽  
Vol 48 (30) ◽  
pp. 11326-11337 ◽  
Author(s):  
Yannick D. Bidal ◽  
César A. Urbina-Blanco ◽  
Albert Poater ◽  
David B. Cordes ◽  
Alexandra M. Z. Slawin ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Electronic Properties ◽  
Computational Studies ◽  
Electronic Effects ◽  
Metathesis Catalysts ◽  
Shed Light

Experimental and computational studies shed light on the role played by sacrificial ligand electronic properties on catalytic activity.

Catalytic activity of systems based on titanium bis(phenoxy imine) complexes: Effect of the ligand structure

2007 ◽  
Vol 80 (9) ◽  
pp. 1515-1522 ◽  
Author(s):  
M. Yu. Malinskaya ◽  
N. I. Ivancheva ◽  
I. I. Oleinik ◽  
G. A. Tolstikov ◽  
S. S. Ivanchev
Keyword(s):  
Catalytic Activity ◽  
Ligand Structure

Alternating ring-opening copolymerization of phthalic anhydride with epoxides catalysed by salophen chromium(iii) complexes. An effect of substituents in salophen ligands

2018 ◽  
Vol 9 (16) ◽  
pp. 2147-2156 ◽  
Author(s):  
K. Bester ◽  
A. Bukowska ◽  
B. Myśliwiec ◽  
K. Hus ◽  
D. Tomczyk ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Phthalic Anhydride ◽  
Ring Opening ◽  
Effect Of Substituents ◽  
Ligand Structure

The effect of a ligand structure on the catalytic activity of salophen chromium(iii) complexes in the ring-opening copolymerization of phthalic anhydride with a series of epoxides was studied.

scholarly journals Novel Insights into the Thioesterolytic Activity of N-Substituted Pyridinium-4-oximes

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2385
Author(s):  
Blaženka Foretić ◽  
Vladimir Damjanović ◽  
Robert Vianello ◽  
Igor Picek
Keyword(s):  
Free Energy ◽  
Catalytic Activity ◽  
Computational Studies ◽  
Hydrolytic Cleavage ◽  
Competitive Reaction ◽  
Hydrolytic Reaction ◽  
Pyridinium Oximes ◽  
Enzyme Catalyst ◽  
Ph Range ◽  
Energy Reaction

The pyridinium oximes are known esterolytic agents, usually classified in the literature as catalysts, which mimic the catalytic mode of hydrolases. Herein, we combined kinetic and computational studies of the pyridinium-4-oxime-mediated acetylthiocholine (AcSCh+) hydrolysis to provide novel insights into their potential catalytic activity. The N-methyl- and N-benzylpyridinium-4-oximes have been tested as oximolytic agents toward the AcSCh+, while the newly synthesized O-acetyl-N-methylpyridinium-4-oxime iodide was employed for studying the consecutive hydrolytic reaction. The relevance of the AcSCh+ hydrolysis as a competitive reaction to AcSCh+ oximolysis was also investigated. The reactions were independently studied spectrophotometrically and rate constants, koxime, kw and kOH, were evaluated over a convenient pH-range at I = 0.1 M and 25 °C. The catalytic action of pyridinium-4-oximes comprises two successive stages, acetylation (oximolysis) and deacetylation stage (pyridinium-4-oxime-ester hydrolysis), the latter being crucial for understanding the whole catalytic cycle. The complete mechanism is presented by the free energy reaction profiles obtained with (CPCM)/M06–2X/6–311++G(2df,2pd)//(CPCM)/M06–2X/6–31+G(d) computational model. The comparison of the observed rates of AcSCh+ oximolytic cleavage and both competitive AcSCh+ and consecutive pyridinium-4-oxime-ester hydrolytic cleavage revealed that the pyridinium-4-oximes cannot be classified as non-enzyme catalyst of the AcSCh+ hydrolysis but as the very effective esterolytic agents.

scholarly journals Restoration of catalytic activity by the preservation of ligand structure: Cu-catalysed asymmetric conjugate addition with 1,1-diborylmethane

2021 ◽  
Author(s):  
Changhee Kim ◽  
Byeongdo Roh ◽  
Hong Geun Lee
Keyword(s):  
Catalytic Activity ◽  
Addition Reaction ◽  
Conjugate Addition ◽  
Ligand Structure

A novel Cu-catalysed asymmetric conjugate addition reaction with bis[(pinacolato)boryl]methane using α,β-unsaturated enones as substrates has been developed on the basis of strategic preservation of the supporting ligand.

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