Development of Anion Receptors Utilizing Hydrophobic Space Formed by Dendrimer Structures

环境分析和临床分析领域对方便分析溶于水介质中的痕量阴离子有着强烈的需求。在这方面，我们设计了具有由苄基型树枝状大分子结构形成的疏水空间的分子，它可能能够在水-膜界面结合阴离子，产生足够的电响应作为离子选择电极。从同样的角度出发，还制备了可用作阴离子荧光传感器的高密度苯乙炔类树枝状大分子，制备了具有硫脲结合位的第一代至第四代的苯乙炔类树枝状大分子。通过核磁共振稀释实验，明确了它们在非极性溶剂中的聚集不足以干扰与阴离子的结合。根据紫外-可见光谱对磷酸二氢阴离子的滴定实验，确定了它们在氯仿中的结合常数为10~(-3)M^~(-1)~(-1)~(-1)，且与生成物的生成关系不大。在含有二氢磷酸根阴离子的聚氯乙烯膜上，没有一种树枝状大分子对磷酸二氢离子作为离子选择电极有反应，但它们对氢化硫酸根阴离子表现出了足够的响应。与第一代六乙基苯相比，树枝状大分子的荧光效率略有降低。由于还开发了树枝状单元的制备，因此为制备这种类型的更大的树枝状大分子奠定了基础。

There have been strong demands from the fields of environmental and clinical analyses to analyze conveniently trace anions dissolved in aqueous media. In this respect, we designed molecules having hydrophobic space formed by the benzyl type dendrimer structure, which may capable of binding anions at the water-membrane interface, producing sufficient electrical response as ion-selective electrodes. From the same points of view, preparation of highly dense dendrimers of phenylacetylene type, which may be used as fluorescence sensors for anions, was also carried out.The benzylic dentrimers of 1st to 4th generations having a thiourea binding site wee prepared. By the NMR dilution experiments, it was clarified that their aggregation in nonpolar solvents was not significant enough to disturb binding with anions. On the basis of the titration experiments with dihydrogenphosphate anion using UV-vis spectroscopy, the binding constants in chloroform were determined to be in the order of 10^3 M^<-1> and the values were not much dependent on the generation. Though none of the dentrimers responded toward dihydrogenphosphate anion as ion-selective electrodes using a PVC membrane containing them, they exhibited sufficient response toward hydrogensulfate anion, which is also known to be strongly hydrated.Dense phenylacetylene type dendrimers of 2nd generation was successfully prepared by using the protocol developed in our laboratory. The fluorescence efficiency of the dendrimer was slightly reduced compared with the 1st generation hexaethynylbenzene. Since the preparation of a dendron unit was also developed, the stage is set for preparation of larger dendrimers of this type.