Steric Effects in Aluminum Compounds Containing Monoanionic Potentially Bidentate Ligands:  Toward a Quantitative Measure of Steric Bulk

1999 ◽  
Vol 18 (21) ◽  
pp. 4399-4416 ◽  
Author(s):  
Julie A. Francis ◽  
C. Niamh McMahon ◽  
Simon G. Bott ◽  
Andrew R. Barron
Keyword(s):  
Quantitative Measure ◽  
Steric Effects ◽  
Bidentate Ligands ◽  
Aluminum Compounds

Fluorinated alkoxides. Part XII. Studies on potentially tridentate fluorinated diols; zwitterionic and five-coordinate complexes of Ni2+ and Cu2+

1978 ◽  
Vol 56 (17) ◽  
pp. 2369-2373 ◽  
Author(s):  
Stephen J. Loeb ◽  
John W. L. Martin ◽  
Christopher J. Willis
Keyword(s):  
Steric Effects ◽  
Bidentate Ligands ◽  
Tridentate Ligands ◽  
The Third ◽  
Complexing Ability ◽  
Fluorinated Alcohol ◽  
Fluorinated Alkoxides

The complexing ability towards Ni2+ and Cu2+ of the potentially tridentate ligands HOC(CF3)2CH2C(O)CH2C(CF3)2OH, HOC(CF3)2CH2CH(OH)CH2C(CF3)2OH, and HOC(CF3)2CH2CH2N:C(CH3)CH2C(CF3)2OH has been studied. The first two act as bidentate ligands, uninegative or dinegative according to the extent of ionization of the fluorinated alcohol groups; when both were ionized, the complexes had a zwitterionic structure. The third ligand was exclusively tridentate in its complexes; this difference is ascribed to its greater flexibility. Both four- and five-coordinate complexes of nickel were observed, the latter being produced either by choice of co-ligands or by solvation, but no six-coordinate complex was formed in this series. Limitations on coordination for the metal are ascribed to steric effects.

Procedures for the Quantitative Determination of Autoprothrombin C

1962 ◽  
Vol 08 (03) ◽  
pp. 434-441 ◽  
Author(s):  
Edmond R Cole ◽  
Ewa Marciniak ◽  
Walter H Seegers
Keyword(s):  
Quantitative Determination ◽  
Plasma Sample ◽  
Quantitative Measure ◽  
The Other ◽  
Clotting Time ◽  
Bovine Plasma ◽  
Autoprothrombin C

SummaryTwo quantitative procedures for autoprothrombin C are described. In one of these purified prothrombin is used as a substrate, and the activity of autoprothrombin C can be measured even if thrombin is in the preparation. In this procedure a reaction mixture is used wherein the thrombin titer which develops in 20 minutes is proportional to the autoprothrombin C in the reaction mixture. A unit is defined as the amount which will generate 70 units of thrombin in the standardized reaction mixture. In the other method thrombin interferes with the result, because a standard bovine plasma sample is recalcified and the clotting time is noted. Autoprothrombin C shortens the clotting time, and the extent of this is a quantitative measure of autoprothrombin C activity.

Epigenetic Target Prediction with Accurate Machine Learning Models

2021 ◽  
Author(s):  
Norberto Sánchez-Cruz ◽  
Jose L. Medina-Franco
Keyword(s):  
Machine Learning ◽  
Small Molecules ◽  
Predictive Models ◽  
Large Scale ◽  
Target Prediction ◽  
Quantitative Measure ◽  
Learning Models ◽  
Discovery Research ◽  
Drug Discovery Research ◽  
Machine Learning Models

<p>Epigenetic targets are a significant focus for drug discovery research, as demonstrated by the eight approved epigenetic drugs for treatment of cancer and the increasing availability of chemogenomic data related to epigenetics. This data represents a large amount of structure-activity relationships that has not been exploited thus far for the development of predictive models to support medicinal chemistry efforts. Herein, we report the first large-scale study of 26318 compounds with a quantitative measure of biological activity for 55 protein targets with epigenetic activity. Through a systematic comparison of machine learning models trained on molecular fingerprints of different design, we built predictive models with high accuracy for the epigenetic target profiling of small molecules. The models were thoroughly validated showing mean precisions up to 0.952 for the epigenetic target prediction task. Our results indicate that the herein reported models have considerable potential to identify small molecules with epigenetic activity. Therefore, our results were implemented as freely accessible and easy-to-use web application.</p>

Electronic or steric effects: Detailed DFT investigations of titanium amino based Kaminsky type olefin catalysts

2018 ◽  
Author(s):  
Jörg Saßmannshausen
Keyword(s):  
Density Functional Theory ◽  
Strong Correlation ◽  
Density Functional ◽  
Steric Effects ◽  
Aryl Group ◽  
Functional Theory

We report detailed Density Functional Theory (DFT) investigations of a series of structurally similar titanium (IV) chelating σ-aryl catalysts. Particular attention was paid to the electronic charges of the Ti, C ipso of the substituted aryl group and the benzylic CH<sub>2</sub> and C<i><sub>ipso</sub></i> atoms. The Bader and NBO derived charges were compared with the recently reported polymerisation results by Chan. We found a strong correlation between the relative energies of one of the computed isomers and the activity of the catalyst. Neither NBO nor Bader charges could be convincingly correlated to the observed activity.

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