Synthesis And Application Of Calix[4]arene And Its Derivatives

Calixarenes, which are basket-shaped macrocyclic compounds of potential interest for host-guest complexation studies, represent the new type of receptor after cyclodextrins and crown ethers. In this paper, p-tert-butylcalix[4]arene(l) is readily accessible which provides the starting point for the present investigation. The removal of the p-butyl groups from 1 has been shown to proceed smoothly to afford calix[4]arene(2), and this compound would appear to be perfectly adapted to functionalization in the aryl ring at the positions para to the hydroxyl groups. Excessive benzoyl chloride in the presence of pyridine reacts with calix[4]arene yields only a tribenzoate(3) which is easily accessed affords a means for the selective functionalization of a calixarene. The synthesis of the tribenzoate of calix[4]arene provides the possibility of preparing mono-nitrocalix[4]arene via normal nitration route. Treatment of the tribenzoate with 65% nitric acid gives a high yield of pure5-nitro-25-hydroxy-26, 27, 28-tribenzoyloxycalix[4]arene(4). The benzoyl groups can be removed to yield the mono-nitrocalixarene(5). This compound can easily be reduced by SnCl₂.2H₂O to produce the mono-amidocalix[4]arene(6). Treatment of themono-amidocalix[4]arene(6) with acrylic chloride in the presence of a small amount triethylamine is a conventional method for producing 5-acrylamido-25, 26, 27, 28-tetrahydroxycalix[4]arene(7) which can be used to polymerized with itself or other monomers to obtain a new kind of material with special functions. To our surprise, if the portion of the benzoyl chloride was reduced and under these conditions which were used in above, 25, 27-dibenzoyloxy-26,28-dihydroxycalix[4]arene(10) was easily yielded from calix[4]arene(2). This unexpected but easy access to the bisbenzoate affords a means for the synthesis of bis-substitution in the upper rim of a calixarene. 5, 17-dinitro-26, 28-dibenzoyloxy-25,27-dihydroxycalix[4]arene(11), 5, 17-dinitro-25, 26, 27, 28-tetrahydroxycalix[4]arene(12), 5, 17-amino-25, 26, 27, 28-tetrahydroxycalix[4]arene(13), and 5, 17-diacrylamido-25, 26, 27, 28-tetrahydroxycalix[4]arene(14) were readily synthesized under the almost same but little modified conditions respectively which were used in the synthesis of mono-substituted calixarene derivatives with reasonable yields. All calixarene derivatives were characterized by IR, NMR and EA.Liquid membrane transport of K⁺ ion by means of bubbling pseudo-emulsion liquid membrane system with p-tert-butylcalix[4]arenes and its derivatives as carriers was investigated. Ten kinds of calixarenes as carriers in three different conditions were experimented, which is to say, the value of pH of the source phase and receiving phase were changed to look into the liquid membrane transport in the different pH gradient between the source phase and receiving phase. A comparison between the ten kinds of calixarenes about their transport ability of K⁺ ion was made and the reasons of different transport ability from their molecular structures were analyzed. Evidence shows:(1) The larger the ApH, the larger the net transport of K⁺ ion, which shows the pH gradient between the source phase and receiving phase, namely A pH, is the critical factor of transport of K⁺ ion for p-tert-butylcalix[4]arenes and its derivatives. The driving force for the transport is the pH gradient between the source phase and receiving phase.(2) Preserving phenolic hydroxyl in the lower rim of calixarenes molecular could enhance calixarenes' transport ability of K⁺ ion.(3) If the substituted functional group in the lower rim of calixarenes molecular made steric hindrance, calixarenes' transport ability of K⁺ ion would fall off.(4) If the substituted functional group in the upper rim of calixarenes molecular had electron-withdrawing conjugative effect, the transport ability of K⁺ ion would fall off; if it had electron-repulsive conjugative effect, the transport ability of K⁺ ion would be enhanced.