Immobilization of a Water-Soluble Host Molecule by Polyion Complexation with a Polymer

大环化合物与水中客体分子的络合反应一直是人们研究的热点，因为它可以模拟生物体系中的基本分子识别过程。虽然改性环糊精在水介质中的包合、识别和催化等方面已经得到了广泛的研究，但其结构的通用性有限。相反，水溶性杯芳烃环番化合物在分子设计方面具有很大的优势。如果这些水溶性主体分子能够在不改变其性质的情况下从水溶液中被固定下来，将有利于它们作为具有类似酶功能的实用材料的应用。1n为了实现固定化杯芳烃作为新型功能材料，必须满足以下要求：它们不溶于水，因为它们应该在水界面上发挥全部功能。作为第二种，固定化后应该保持离子性质，因为静电相互作用和疏水相互作用对客体分子的识别起着决定性的推动作用。具有长烷基链的阳离子杯[6]芳烃氯化铵与阴离子硫酸软骨素形成多离子络合物，导致水溶液中的沉淀。络合物在有机溶剂中溶解后，蒸发形成不溶于水的透明膜。该膜具有足够强的手感，并显示出甲基橙分子的结合，表明它保留了母体主体分子的基本功能。阴离子磺化杯[6]芳烃的固定化也可以通过与阳离子聚(二烯丙基二甲基氯化铵)形成多离子络合物来实现。由该络合物制备的膜具有结合苯酚蓝分子的能力，这表明结合位置仍然保留在多离子络合物膜中。

Complexation of macrocyclic compounds with guest molecules in water has always attracted a major interest since it can mimic the molecular recognition which is a basic process in biological systems. Although modified cyclodextrins have been extensively investigated in terms of inclusion, recognition, and catalysis in aqueous media, versatility of their structure is limited. On the contrary water-soluble calixarenes cyclophanes have a great advantage of molecular design. If these water-soluble host molecules could be taken out from the aqueous solution without altering their properties by immobilization, it would facilitate their application as practical materials exhibiting enzyme-like functions. 1n order to accomplish immobilized calixarenes as novel functional materials, the following requirement must be satisfied ; they are not dissolved in water because they are supposed to give full function at the water interface. As the second the ionic character should be remained after immobilization because electrostatic interaction as well as hydrophobic interaction plays a decisive role as a driving force for recognition of the guest molecules. Formation of polyion complex between a cationic calix[6]arene ammonium chloride which has a long alkyl chain and an anionic chondroitin sulfate results in the precipitate in the aqueous solution. After dissolving the complex in a organic solvent, evaporation of this solution gives rise to the water-insoluble transparent film. The film is strong enough for handling and shows a binding of Methyl Orange molecule, indicating that it retains a fundamental function of the parent host molecule. Immobilization of an anionic sulfonated calix[6]arene can also be achieved by formation of polyion complex with a cationic poly (diallyldimethylammonium chloride). The film prepared from this complex exhibits the ability to incorporate Phenol Blue molecule, which suggests that the binding site still remains in the polyion complex film.