Calix arenes nitration

Calixarene crown-6 compounds, which are neutral extractants like crown ethers, are able to coextract technetium with cesium. Tests carried out with several calix-arene-crown ethers (MC7, MC8, MC14, BC2, BC5, BC8, and BC10) show that the extraction of technetium, present in the aqueous phase at a concentration 10 5 M, is enhanced as the cesium concentration in the aqueous phase increases from 10 5 to 10-2 M. As expected, an increase of nitrate concentration prevents pertechnetate extraction in competition with nitrate anion. The extraction of technetium is only appreciable when the nitric acid does not exceed 1 M. Distribution ratios DCs (close to 8) are comparable for the various calixarenes. However, a decrease of extraction is observed for naphtho derivatives.88 89... 

A polymer-bound analog of the p-sulfonato-calix[6]arenes is described in a Shinkai patent [31,32], which states that the hexakis(carbetoxymethyl)ether of p-sulfonatocalix[6]arene was partially nitrated, ami-nated, and fixed on crosslinked chloromethylated polystyrene. This resin is stated to absorb 108 ixg of uranium... 

The silver(I) complexes with the tetrakis(methylthio)tetrathiafulvalene ligand have been reported, the nitrate salt presents a 3D structure with an unprecedented 4.16-net porous inorganic layer of silver nitrate,1160 the triflate salt presents a two interwoven polymeric chain structure.1161 The latter behaves as a semiconductor when doped with iodine. With a similar ligand, 2,5-bis-(5,5,-bis(methylthio)-l,3,-dithiol-2 -ylidene)-l,3,4,6-tetrathiapentalene, a 3D supramolecular network is constructed via coordination bonds and S"-S contacts. The iodine-doped compound is highly conductive.1162 (Methylthio)methyl-substituted calix[4]arenes have been used as silver-selective chemically modified field effect transistors and as potential extractants for Ag1.1163,1164... 

Regnouf-de-Vains, J. B. Dalbavie, J. O. Lamartine, R. Fenet, B. Quantitative solvent extraction from neutral aqueous nitrate media of silver(I) against lead(II) with a new calix-4-arene-based bipyridine podand. Tetrahedron Lett. 2001, 42, 2681-2684. 

Sachleben, R. A., Bonnesen, F. V., Descazeaud, T., Haverlock, T. J., Urvoas, A., Moyer, B. A., Surveying the extraction of cesium nitrate by 1,3-alternate calix 4-arene crown-6 ethers in 1,2-dichloroethane, Solv. Extr. Ion Exch., 17,1445-1459, 1999. 

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... 

Extraction of tetrahedral pertechnetate anion from aqueous solutions using several crown ethers is well known. The coextraction of cesium (or strontium) and technetium from nuclear waste by calix[4]arene-crown-6 has been reported from alkaline media. Although technetium in its common pertechnetate form does not complex directly with crown ethers, pertechnetate extraction may be facilitated by crown ethers as the coanion of sodium (for alkaline nitrate waste). Pertechnetate at trace levels in the waste may be more than a 1000-fold more extractable than the smaller nitrate anion in ion-pair extraction processes.87... 

Delmau, L. H., Lefranc, T. J., Bonnesen, P. V., Bryan, J. C., Presley, D. J., and Moyer, B. A. Fundamental Studies Regarding Synergism Between Calix[4]arene-bis(ferf-octylbenzo-crown-6) and Alcohol Modifiers in the Solvent Extraction of Cesium Nitrate, Solvent Extr. Ion Exch., in press. 

The anion binding properties of a series of highly cationic metallated calix[4]arenes have also been investigated. Host 33, in which the calix[4]arene is coordinated to four Ru(rf-p-cymene) units,was found (using H NMR titrations) to bind chloride (TC,=551 M1), bromide (1 =133), iodide (1 =51) and nitrate (K]=49) in aqueous solution [28]. No electrochemical data were reported. 

Another chromophore, 8-alkoxy-5-chloroquinoline, was appended to the narrower rim of a calix[4]arene triamide, 44a and 44b (see fig. 38). If Nd111, Er111, and Ybm nitrates are added to acetonitrile solutions of these receptors, quenching of the methoxy quinoline luminescence oc-... 

There is indirect evidence that in solution (see below) the 1,3-alternate conformer is in equilibrium with a cone conformer of idealized C4 symmetry (Fig. 15, a). The tetramer of Fig. 14 can be considered to be a metal analogue of a calix[4]arene [24], and this analogy includes also the propensity of this compound to coordinate metal ions. In fact, after further deprotonation of UrH- to the dianion Ur2-, the complex binds additional divalent cations to yield octanuclear species, [ (en)PtnM(Ur2, N(1),N(3),0(2), 0(4)) 4f+ with M = ds-(NH3)2Ptn, (en)Pt11, (H20)3Nin, (en)Pd11, and Cu11. The nitrate salts of these cations were isolated and the stmctures of the first... 

The first examples of urea-containing dimeric capsules were discovered independently by Rebek and Bohmer [165,166]. These are based on calix[4]arene ethers, in which the lower rim ether units help to fix the calixarenes in a cone conformation via intramolecular interactions. Figure 60 shows the generic structure of such systems. Synthetically, the urea calixarenes are readily prepared. The calixarenes are first nitrated, followed by a reduction of these groups into amines. The urea derivatives are fixed to the upper rim by reaction of the p-amino calixarenes with isocyanates. Many systems were studied using differently substituted ureas which contain either short alkyl chains or simple phenyl derivatives. Studies also involved the changing of the lower rim ether substituents. 

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