Cation interaction calix arenes

The corresponding dependence of cation complex stability on the anion differs profoundly from that of most other cation receptors such as cyclophanes or calix-arenes [16]. For these cation complex stability decreases on changing the anion from picrate through iodide to tosylate, a dependence that has been attributed to ion-pair aggregation in non-polar solvents. Because the interaction of quaternary ammonium ions with tosylate or iodide in chloroform is considerably stronger than with picrate, cation complexes in the presence of the latter anion are usually more stable. Only when iodide or tosylate cooperatively contributes to cation binding, as in 3 or in some recently described calixarene derivatives [17], is reversal of this order observed. 

Cation Interaction with Carbonyl Functionalized Calix[4]arenes... 

Cation Interaction with Calix[4]arene Crown Ethers... 

Cation Interaction with Sulfur Containing Calix[4]arene ... 

Abraham. W. Inclusion of organic cations by calix[n]ai enes. J. Inch Phenom. Macrocycl. Chem. 2002, 43, 159-174. Nachtigall, F.F. Lazzarotto. M. Noine, F. Interaction of Calix[4]arene and amines A combined NMR. spectromet-ric and conductimetric investigation. J. Braz. Chem. Soc. 2002, 13. 295-299. 

Ikeda, A., Tsuzuki, H., Shinkai, S. 1994. X-ray crystallographic studies of a 1,3-al-temate-calix[4]arene Na+ complex - Is the cation-pi interaction operative between the benzene rings and Na+ Tetrahedron Lett. 35 8417-8420. 

The cation-7t interactions were evidenced by Prodi, who studied the photophysical properties of calix[4]arene-crown and their complexes with alkali metal ions. The presence of these cation ions usually caused weak effects on the absorption spectra, but sometimes caused marked changes in the intensity and wavelength maxima of the fluorescence bands of the calixarenes. The fluorescence quantum yields of complexes with alkali metal follows a precise trend for both MC46 and MC7, decreasing from potassium to cesium. These changes were explained by cation-Tt interactions between the metal ion and the two aromatic rings pointing toward it.30... 

In water, the introduction of a counteranion (NOy) induces a stronger electrostatic interaction, which tends to draw the cations out of the mean plane of the crown ether loop. Simulations with cesium nitrate and the various calix[4]arene-biscrowns show that the best fit is obtained with BC8 and BC9.59... 

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