Water-soluble cyclophanes

Shinkai and co-workers (145,146) have incorporated sulphonic acid groups into a calix [6] arene skeleton to produce the first water-soluble calixarenes 

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Tabushi, I. Yamamura, K. Water Soluble Cyclophanes as Hosts and Catalysts, 113,145-182 (1983). Takagi, M., and Ueno, K. Crown Compounds as Alkali and Alkaline Earth Metal Ion Selective Chromogenic Reagents. 121, 39-65 (1984). 

Tabushi, I., Yamamura, K. Water Soluble Cyclophanes as Hosts and Catalysts. 113,145-182(1983). 

Systematic analysis of stabilities of cyclic dimeric pseudorotaxanes, generated from complementary homoditopic molecules, has been shown<99ACIE143, 99CC789> A new class of water-soluble cyclophanes, pyrenophane, capable of encompassing a neutral cavity has been constructed<99JA14S2>. 

Because of their relatively young history, there are only a few examples of X-ray analyses of water-soluble cyclophanes. The macrocyclophanes are... 

Hydrophobic species bearing hydrocarbon chains present vitamin B12 or vitamin B6 type activity [5.37]. Such systems lend themselves to inclusion in membrane or micellar media. They thus provide a link with catalysis in more or less organized media such as membranes, vesicles, micelles, polymers [5.39-5.41] (see Section 7.4). Water soluble cyclophanes showing, for example, transaminase [5.42], acetyl transfer [5.43], pyruvate oxidase [5.44] or nucleophilic substitution [5.45] activity have been described. 

Design and Synthesis of a New Water-Soluble Cyclophane 1.1. Introduction... 

Water-soluble cyclophane 86145 exhibited a well-defined fluorescence band at 290 nm with a 210 nm excitation. The emission intensity was markedly increased by complexation with Zn2+ which forms a 2 1 (metal-ligand) complex. The fluorescence emission is pH-independent to pH 2. The fluorescence enhancement factor is 5.0 at pH 6 and 50 at pH 8.6 (due to the pH dependence of the free ligand). Ni2+ and Cu2+ ions quenched the ligand fluorescence via a PET mechanism. Furthermore, when cyclophane 86 was coordinated to Cu2+, the molar absorptivity of the transition band observed at 260 nm was increased by a factor of about 10. Such a large spectral change was not observed for the Zn2+ and Ni2+ complexes. In the Cu2+ complex, the two phenyl rings of the cyclophane are expected to be... 

C.S. Wilcox and his research team designed and synthesized chiral water-soluble cyclophanes based on carbohydrate precursors. These compounds are also dubbed as glycophanes and they are potentially valuable enzyme models. The key macrocyclization step utilized the Glaser coupling and the reaction was carried out in a thermal flow reactor at 80 °C in 67% yield. 

Bukownik, R. R., Wilcox, C. S. Synthetic receptors. 3,6-anhydro-7-benzenesulfonamido-1,7-dideoxy-4,5-0-isopropylidene-D-altro-hept-1-ynitol a useful component for the preparation of chiral water-soluble cyclophanes based on carbohydrate precursors. J. Org. Chem. 1988, 53, 463 67. 

Recently oxidative coupling reactions of a,a>-diethynyl compounds have been applied in the synthesis of cyclophanes, which are interesting functional host molecules. Whitlock and coworkers, - for example, have reported the synthesis of the water-soluble cyclophane (21), designed as an esterase mimic by the Eglington reaction of (20 Scheme 8). 

Cyclophanes are the class of synthetic receptors that have a hydrophobic cavity. Water-soluble cyclophane can make organic compounds soluble in water via the formation of inclusion complex. Anderson et al. synthesized rod-like organic compounds in water in the presence of water-soluble cyclophanes, and obtained corresponding rotaxanes. When oxidative coupling of an acetylenic derivative in the presence of a cyclophane, an oligorotaxane having an axle with a conjugated structure was dominantly obtained rather than non-complexed diacetylene.[187,188] (Scheme 31). This rotaxane is a prototype of insulated molecular wire that is expected as an electric wire in a molecular device. 

A water-soluble cyclophane receptor (Figure 58) has been reported to form intracavity complexes with adenine derivatives with association constants of the order of 100 M [81]. 

Figure 58 A water-soluble cyclophane receptor for adenine derivatives [811...

Figure 78 A chiral, water-soluble cyclophane for enantioselective binding [104]...

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