We have carried out a theoretical study of a series of para-substituted phenoxy radicals in an effort to understand the factors influencing spin and charge density distribution in open-shell systems. The calculations reveal that the distribution of spin and charge are not correlated: cases were found for which spin and charge move together, whereas for other substituents the two quantities exhi...

Diphenylamines, Inhibitors, Photosynthetic Electron Transport A number of 16 substituted diphenylamines have been tested for their inhibitory activity on photosynthetic NADP reduction and photophosphorylation. The most active compounds exhibited p l50 values of 6.0 in photosynthetic electron transport and 6.8 in cyclic photophosphorylation, respectively. The inhibition site in electron flow of ...

In this report, 1-butyl-3-methylimidazolium chloride ([C4C1im]Cl) is demonstrated to enhance the kinetics of acid-catalysed hydrolysis of 1,4-β-glucans in binary solvent mixtures. [C4C1im]Cl plays other roles in the reaction beyond acting as a solvent for cellulose, as currently accepted. In fact, the presence of the IL increases the Hammett acidity of the catalyst dissolved in the reaction med...

A computational docking approach, in combination with the Hammett relationship, has been employed to evaluate the electronic influence of substituents on ligand binding and the active site-directed inhibitory potency on acetylcholinesterase using nine N-aryl-substituted succinimides. Our results indicate that electronwithdrawing groups attached to benzene moiety of the compounds favor the inhib...

[reaction: see text] A new method for the synthesis of 5-arylethynyl-8-hydroxyquinoline ligands using Sonogashira-Hagihara coupling was developed. The electronic nature of arylethynyl substituents affects the emission color and quantum yield of the resulting Al(III) complex. Photophysical properties of the metallocomplexes correspond to the electron-withdrawing/-donating character of the arylet...

A series of C4 substituted alpha-ketooxazoles were examined as inhibitors of the serine hydrolase fatty acid amide hydrolase in efforts that further define and generalize a fundamental substituent effect on enzyme inhibitory potency. Thus, a plot of the Hammett sigma(m) versus -logK(i) provided a linear correlation (R(2)=0.90) with a slope of 3.37 (rho=3.37), that is of a magnitude that indicat...

Measurements are reported on the kinetics of the lysozyme-catalysed hydrolysis of several beta-aryl di-N-acetylchitobiosides, some of which have been synthesized for the first time. The catalytic rate constants (k(cat.)) at 45 degrees yield a curved Hammett plot (concave up) and the plot of DeltaH(double dagger) versus DeltaS(double dagger) has a sharp break. Substrates with electron-withdrawin...

We have developed an efficient protocol for copper-catalyzed olefin aziridination using 5-methyl-2-pyridinesulfonamide or 2-pyridinesulfonyl azide as the nitrenoid source. The presence of a 2-pyridyl group significantly facilitates aziridination, suggesting that the reaction is driven by the favorable formation of a pyridyl-coordinated nitrenoid intermediate. Using this chelation-assisted strat...

Heterogeneous catalysts, especially those produced with functionalized clays, can be used for methyl transesterification at moderate temperatures. The use of bentonite clay by potassium compounds (KF, KOH, K2CO3, KCl and K2SO4) in the cottonseed oil is object present study. catalysts were contacting aqueous solutions subsequent drying. characterized Hammett indicators to determine alkalinity. r...