Upper rim

This is simUar to (a) except that it is provided with a ring neck, which increases the mechanical strength, prevents breakage when a stopper is inserted, and provides a means for wiring a stopper in place. The upper rim is ground flat. 

A large metal tank, preferably lagged to within 5 cm. of the upper rim. 

To support a polystyrene onto the upper rim of ca-lix[4]arene (phenolic-O- of calix[4]arene) and 25,26,27-tribenzoyloxy-28-hydroxy, calix[4]arene was treated with chloromethylated polystyrene in the presence of K2CO3 (Scheme 7). Polymeric calix[4]arene (3a) thus obtained was hydrolyzed in the benzoyl groups prior to use for the extraction process. 

Figure 29 (a) Synthesis route of the molecule (b) (i) S8, NaOH, tetraethyleneglycol dimethyl ether, heat, (28%). (b) Adamantane upper rim derivative based on the thiacalix[4]arene platform. (c,d) The carboxylic acid and ester derivative of adamantane can also be used as substituents. Taken from Ref. [109] with permission. 

Alternatively, the Sn2 nucleophilic substitution reaction between alcohols (phenols) and organic halides under basic conditions is the classical Williamson ether synthesis. Recently, it was found that water-soluble calix[n]arenes (n = 4, 6, 8) containing trimethylammonium groups on the upper rim (e.g., calix[4]arene 5.2) were inverse phase-transfer catalysts for alkylation of alcohols and phenols with alkyl halides in aqueous NaOH solution to give the corresponding alkylated products in good-to-high yields.56... 

The results of unsymmetrical 7r-acid bidentate ligands, e.g., (81), have in the hydroformylation of ra-octenes was described. The preparation of seven such ligands was described. Thus, [Rh-(acac)(cod)]-catalyzed hydroformylation of ra-octene in the presence of a phosphinite ligand gave 94% ra-nonanal.295 A new upper-rim phosphacalix[4]arene 5,17-bis(diphenylphosphinomethyl)-25,26,27,28-tetrapropoxycalix[4]arene has been prepared. It reacted with [(cod)RhCl]2 to give a dirhodium complex that is an active catalyst for the hydroformylation of 1-octene and styrene.296 Rhodium complexes of [l-propyl-3-methylimidazolium+]2 [PhP(C6H4SO%)2] dissolved in the... 

It has been shown that upper-rim substitution of some dithiocarbamoyl-derivatized calix[4]arenes affects selectivity of Ptr extraction.327,329 Some selectivity over Pb, Hgn, and Ptn has been achieved by the introduction of 2-pyridyl-A-oxide groups on the lower rim, but Sn11, Ag1, Pd11, and Au111 were still extracted to a greater extent.32... 

Since the first examples of lower and upper rim glycocalixarenes were obtained in 1994 by Marra el al.,106 employing the Mitsunobu reaction or copper(II)-catalyzed glycosylation, the development of efficient synthetic methodologies has allowed the emergence of several examples of ()-, N-, or C-glycosyl calix arenes, and these have recently been reviewed (101-106, Fig. 8).107,10X... 

In this context, divalent presentation of this promising candidate has been investigated by the authors using the fixed cone conformation of calix[4]arene to allow introduction of the molecules onto the upper rim, and their projection into the same portion of space, thus mimicking, to some extent, a small portion of the natural cell-surface ganglioside. The synthesis of the divalent neoglycoconjugate was based on initial functionalization of the corresponding diacid with an aminated spacer and further introduction of squaric acid moieties. 

A. Marra, M.-C. Schermann, A. Dondoni, A. Casnati, P. Minari, and R. Ungaro, Sugar calixarenes Preparation of calix[4]arenes substituted at the lower and upper rims with O-glycosyl groups, Angew. Chem. Int. Ed., 33 (1994) 2479-2481. 

U. Schadel, F. Sansone, A. Casnati, and R. Ungaro, Synthesis of upper rim calix [4] arene divalent glycoclusters via amide bond conjugation, Tetrahedron, 61 (2005) 1149-1154. 

The smaller p -tert-butyl-calix [4] arenes have a rich coordination chemistry as well (65). Of these, however, only the upper-rim modified calixarenes seem to support metal complexes with confined binding sites (66), except in those cases where the lower-rim substituents form an appended cavity. Thus, Matt and coworkers have reported (67) a pocket-shaped calix[4]arene ligand L2 bearing two lower-rim [([Pg.410]

The placement of four pyridyl groups on the upper rim of the resorcin[4]arene cavitands was followed by the addition of Pd(II) ions to generate a monomeric molecular receptor with hydrophobic binding sites <00TL3113>. The treatment of 2,4,6-rm[(4-pydrinyl)methyl-sulfanyl]-l,3,5-triazene (tpst) with silver to form a single-stranded one-dimensional coordination polymer, [Ag7(tpst)(C104)2(N03)5(dmf)2] , which contains nanotubes... 

Calixarene and their resorcinarene relatives are similar to CDs with respect to their ability to form a concave cavity in which guests can bind. Calixarenes are conformationally more flexible than the resorcinarenes, and depending on the substituents attached to their wider upper rim or to the narrower lower rim they may exist in a highly-symmetric bowl-shaped, so-called cone conformation or in several other conformations that do not exhibit an as perfect cavity as does the cone conformation (Scheme 9). Cationic guests, such as alkali metal or ammonium ions. 

Fig. 5.15. Sample vial filled with analyte. The bright spot halfway between the tip of the tweezers and upper rim of the vial is the piece of solid material to be analyzed. Use of more sample does not have any advantage it only causes ion source contamination.

As described above, cavitand 13 is able to extract efficiently silver(I) ion. For a guest to host ratio G/H>2 a new species was formed and recovered in quantitative yield and was identified as the 2 4 complex 132-(AgPic)4. The X-ray crystal structure of the 132-(AgPic)4 complex showed a supramolecular assembly made of two cavitands linked by their upper rim with four silver cations through P=S...Ag...S=P coordination (Fig. 9) [70]. 

The stability of the polypyridyl rhenium(I) compounds mentioned above stimulated applications of this coordination chemistry. Thus, new heterotopic bis(calix[4]arene)rhenium(I) bipyridyl receptor molecules have been prepared and shown to bind a variety of anions at the upper rim and alkali metal cations at the lower rim. A cyclodextrin dimer, which was obtained by connecting two permethylated /3-cyclodextrins with a bipy ligand, was used for the preparation of a luminescent rhenium(I) complex. The system is discussed as a model conipound to study the energy transfer between active metal centers and a bound ditopic substrate. The fluorescence behavior of rhenium(I) complexes containing functionalized bipy ligands has been applied for the recognition of glucose. ... 

Calixarene derivatives involving crown ethers like 233 exhibit complexation ofalkali or ammonium cations typical of crown ethers that is especially effective in the partial cone conformation [26]. By a proper functionalization selective synthetic receptors for specific hosts have been developed. For instance, two 2,4-diaminotriazine groups at diametrical positions of the upper rim of a... 

The use of the upper rim of calix 4 arcncs, blocked in the cone conformation, as convenient platforms for the introduction of metal ion binding sites is well documented [26e,291. Table 5.9 shows the catalytic performances of regioisomeric vicinal 21-Ba2 and distal 22-Ba2, and of the m-xylylene derivative 17-Ba2 in the basic ethanolysis of esters 14 and 23-25 [30]. 

The septum nut, septum, and retainer nut of the GC were removed, and the liner containing the sample was inserted into the inlet of the GC on top of the Teflon 0-ring. When the retainer nut was tightened above the upper rim of the liner, a seal was formed between the base of the inlet and the lower rim. After the inlet was closed with the septum and septum nut, the carrier gas was forced to flow through the sample. This assembly has been previously described (15). 

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