Cations effect

Zeohte type Designation Cation Effective pore diameter, E Unit cell parameter, E... 

If the cation has been unchanged, its ability to act as a hydrogen-bond donor has been unchanged, so why is an effect seen at all I propose that there is competition between the anion and the Reichardt s dye solute for the proton. Thus, the values of the ionic liquids are controlled by the ability of the liquid to act as a hydrogen bond donor (cation effect) moderated by its hydrogen bond acceptor ability (anion effect). This may be described in terms of two competing equilibria. The cation can hydrogen bond to the anion [Equation (3.5-2)] ... 

Theoretical and Experimental Studies of the Benzene Radical Cation Effects of Selective... 

Licht S, Tenne R, Flaisher H, Manassen J (1984) A pronounced cation effect on performance and stability of Cd- chalcogenide/polysulfide photoelectrochemical cells. J Electrochem Soc 131 950-951... 

Essentially identical results were obtained by a second group with fcj = 1.4+0.3 l.mole . sec at 25 °C (/i = 0.02 M). Specific cation effects were also found with rate sequences K > Na" N(C2H40H)4. > Li" " and positive deviations of the reaction orders above unity were also noted. 

PE permeability was enhanced by CaCl2 at lower concentrations than effective for NaCl. Pi8o in O.IM CaCL was approximately 0.33, and similar to the permeability in 0.4M NaCl at pH 3.8. There seems to be a unique cation effect rather than ionic strength effect. At equivalent ionic strength (0.3M NaCl and O.IM CaCl2, pH 3.8), Pjso of PE with CaCl2, was approximately four fold higher. 

R.M.McCready et al.[l] demonstrate that the adding of O.IM NaCl to 0.33 M ammonia hydroxide enhances the deesterification more than twice. The adding of other chlorides, such as KCl, MgCb and CaCb also enhances the reaction. The effectiveness of the ions in relation to the deesterification and rate constant is arranged in the following order Ca>Mg>Na, K. The equal values of pH and ion strength prove that only the specific cation effect is responsible for the enhanced velocity. 

For example, how does the presence of the cations effect the hydrogen consumption A question that needs also to be considered in the context of the observations of White (18). ... 

As the divalent cation effect on CYP3A4 activity appears to be substrate dependent, the benefit of including MgCl2 (1-30 mM) in the oxidative incubation should be examined for each substrate. 

Adsorption enthalpies and vibrational frequencies of small molecules adsorbed on cation sites in zeolites are often related to acidity (either Bronsted or Lewis acidity of H+ and alkali metal cations, respectively) of particular sites. It is now well accepted that the local environment of the cation (the way it is coordinated with the framework oxygen atoms) affects both, vibrational dynamics and adsorption enthalpies of adsorbed molecules. Only recently it has been demonstrated that in addition to the interaction of one end of the molecule with the cation (effect from the bottom) also the interaction of the other end of the molecule with a second cation or with the zeolite framework (effect from the top) has a substantial effect on vibrational frequencies of the adsorbed molecule [1,2]. The effect from bottom mainly reflects the coordination of the metal cation with the framework - the tighter is the cation-framework coordination the lower is the ability of that cation to bind molecules and the smaller is the effect on the vibrational frequencies of adsorbed molecules. This effect is most prominent for Li+ cations [3-6], In this contribution we focus on the discussion of the effect from top. The interaction of acetonitrile (AN) and carbon monoxide with sodium exchanged zeolites Na-A (Si/AM) andNa-FER (Si/Al= 8.5 and 27) is investigated. 

Fig. 20 Cation effect on an intrazeolite singlet oxygen ene reaction in Y-zeolite.

As expected, the cation 15+ exhibited high stability. In fact, its exact pAR+ value could not be determined by the earlier method due to its high stability. The p/fR+ value for 15+PF6was well beyond 14.0. Consequently, the combination of 1-azulenyl groups with methoxy substituents stabilized the methyl cation effectively. 

Campion, R. J. Deck, C. F. King, P., Jr. Wahl, A. C. Inorg. Chem. 1967, 6, 672]. The cation effect was tremendous—spanning two or three orders of magnitude—and occurred at low concentration levels. 

Salt effects (chlorides and bromides of alkali metal, alkaline earth, and ammonium cations) on rate constants for aquation of [Fe(bipy3] " " and [Fe(phen)3] " " in aqueous solution have been interpreted in terms of added cation effects on the activity of the water. 

Paramasivan S, Rujan I, Bolton PH (2007) Circular dichroism of quadruplex DNAs Applications to structure, catione effects and ligand binding. Methods 43 324-331... 

Shankar K, Mor GK, Fitzgerald A, Grimes CA (2007) Cation effect on the electrochemical formation of very high aspect ratio Ti02 nanotube arrays in formamide-water mixtures. J Phys Chem C 111 21-26... 

In this study, Xe NMR was employed to study the cation effects in Na-Y,... 

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