Calix-n-arenes

Cavity design using calix[n]arenes with heterocyclic fragments 97CRV1713. 

Other recent works in this field, studies on the transport of alkali and alkaline earth cations with p-zerr-butyl calix[n]arene esters and amides, were carried out by Arnaud-Neu et al. [20] and Casnati et al. [21]. They prepared 1,3-alternate calix[4]arene-crown-6 as a new class of cesium selective ionophore. 

Yosida et al. [41] found that p-t< rr-butylcalix[6]ar-ene can extract Cu from the alkaline-ammonia solution to the organic solvent. Nagasaki and Shinkai [42] described the synthesis of carboxyl, derivatives of calix-[n]arenes ( = 4 and 6) and their selective extraction capacity of transition metal cations from aqueous phase to the organic phase. Gutsche and Nam [43] have synthesized various substituted calix[n]arenes and examined the complexes of the p-bromo benzene sulfonate of p-(2-aminoethyl)calix[4]arene with Ni, Cu , Co-, and Fe. ... 

Deligoz and Yilmaz [52] reported that the selective liquid-liquid extraction of various alkali and transition metal cations from the aqueous phase to the organic phase as carried out by using p-tert-h iy calix[4]arene (1), p-tert-b x. y calix[6]arene (2), tetra-ethyl-p-tm-butylcalix[4]arene-tetra-acetate (3), tetra-methyl-p-/< /-/-butyl calix[4]arene-tetraketone (4), calix[n]arenes ( = 4 and 6) bearing oxime groups on the lower rim (5 and 6) and a polymeric calix(4]arene (8). It was found that compounds 5 and 6 showed selectivity towards Ag, Hg, Hg, Cu, and Cr and the order of the ex-tractability was Hg > Hg > Ag > Cu > Cr. The polymeric calix[4]arene (8) was selective for Ag, Hg, and Hg , unlike its monomeric analog. 

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 water-soluble calix[n]arenes 6.3 (n = 4, 6 and 8) containing trimethylammonium groups act as efficient inverse phase-transfer catalysts in the nucleophilic substitution reaction of alkyl and arylalkyl halides with nucleophiles in water (Eq. 6.19).40 In the presence of various surfactants (cationic, zwitterionic and anionic), the reactions of different halides and ketones show that the amount of ketone alkylation is much higher and that the reactions are faster in the presence than in the absence of surfactant aggregates.41 The hydrolysis of the halide is minimized in the presence of cationic or zwitterionic surfactants. 

Chiorboli C, Indelli MT, Scandola F (2005) Photoinduced Electron/Energy Transfer Across Molecular Bridges in Binudear Metal Complexes. 257 63-102 Coleman AW, Perret F, Moussa A, Dupin M, Guo Y, Perron H (2007) Calix[n]arenes as Protein Sensors. 277 31-88... 

The induced circular dichroism and Cotton effect have been investigated for quaternary ammonium ions with N anchored on an asymmetric C, when hosted in calix[n]arene molecules (215, n = 4, 6, 8)430. 

Calix[n]arenes (n=4,6,8) are cyclic condensation products of ap-substituted phenol and formaldehyde [58]. Gutsche and co-workers [59,60] have developed procedures for the synthesis of calixarenes and caHxarene derivatives. 

Photophysical studies have been conducted on a number of lanthanide complexes of calix[n]arenes, and a significant number of these are discussed in a recent review (79). The first europium and terbium calixarene complexes showed promising photophysical properties, with terbium luminescence lifetime of 1.5 ms and quantum yield of 0.20 in aqueous solution (80). 

A study48 of the direct upper-rim alkylation of calix[n]arenes has shown that, with n = 8, reaction with isopropyl chloride in 1,2-dichloroethane with AICI3 gives isopropylation, whereas when n = 4 hydroxyisopropylation is observed. With n = 6 there is a mixture of products, indicating overall an increase in phenolic behaviour as n increases from 4 to 8. 

More recently, thiacalix[ ]arenes were synthesized, in which methylene bridges of calix[n]arene are replaced by sulfur atoms.15 This replacement leads to... 

Extraction by Phosphine Oxide (Grafted on the Narrow-Rim of) Calix[n]arenes... 

Ikeda, A. and Shinkai, S. Novel Cavity design using calix[n]arene skeletons towards molecular recognition and metal binding , Chem. Rev., 1997, 97, 1713-1734. 

Since the preparation of 6.97, an enormous range of carcerand and hemicarcerand species have been prepared based upon both [n]resorcarenes and calix[n]arenes (n = 4,5), all of which exhibit interesting binding behaviour and intra-cavity reactivity, as we will see in the next sections. 

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