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

由于大环化合物与客体分子在水中的络合作用可以模拟生物系统中的基本分子识别过程，因此一直引起人们的极大兴趣。虽然改性环糊精在水介质中的包合、识别和催化方面已经得到了广泛的研究，但其结构的多功能性是有限的。而水溶性杯芳烃环烷具有很大的分子设计优势。如果这些水溶性宿主分子能够在不改变其性质的情况下从水溶液中分离出来，将有助于它们作为具有类酶功能的实用材料的应用。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作用。由于静电相互作用和疏水相互作用作为识别客体分子的驱动力起着决定性的作用，因此固定后离子特性应保持不变。具有长烷基链的阳离子杯状[6]芳烃氯化铵与阴离子硫酸软骨素之间形成多离子络合物，导致水溶液中沉淀。将络合物溶解在有机溶剂中后，该溶液的蒸发产生不溶于水的透明薄膜。薄膜的强度足以处理，并显示出甲基橙分子的结合，表明它保留了母体宿主分子的基本功能。阴离子磺化杯芳烃的固定化也可以通过与阳离子聚二烯基二甲基氯化铵形成多离子配合物来实现。由该络合物制备的膜显示出结合酚蓝分子的能力，这表明结合位点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.