Development of Artificial Materials which Selectively Bind and Separate the Nitrate Ion from Environmental Water

为了开发可用于环境水体中硝酸根离子选择性分离的人工材料，用吡啶或丁氨基对环糊精和环寡糖进行化学修饰，然后将其修饰为可在有机介质中溶解或固定在聚合物上。1)将单-[6-(1-吡啶)-6-脱氧]-环糊精过苯甲酰化，得到可溶于氯仿的主体化合物。在氯仿中，定量评价了宿主结合包括硝酸根离子在内的无机阴离子的能力。2)将单-[6-(1-吡啶)-6-脱氧]-环糊精固定在桥型或悬挂型聚合物上，考察了硝酸根离子在水溶液中的吸附情况。硝酸根离子在主体聚合物上的吸附符合朗缪尔型吸附等温式。3)用丁氨基取代了环糊精的所有C(6)-OH基团，考察了聚合物在酸性水溶液中与硝酸根离子的结合能力。宿主-硝酸根离子体系的结合常数很小，但约为未经修饰的环糊精-硝酸根离子体系结合常数的50倍。另一方面，在酸性水溶液中，宿主与硫酸盐离子结合非常强烈。

In order to develop artificial materials available for the selective separation of the nitrate ion from environmental water, cyclodextrins, cyclic oligosaccharides, were chemically modified with pyridinio or butylamino groups, and the host compounds were further modified to be solubilized in organic media or to be immobilized on polymers.1) Mono-[6-(1-pyridinio)-6-deoxy]-cyclodextrin was perbenzoylated to give a host compound soluble in chloroform. An ability of the host to bind inorganic anions, including the nitrate ion, was uantitatively evaluted in chloroform. The nitrate ion was bound to the perbenzoylated host much more strongly than other inorganic anions common in environmental water.2) Mono-[6-(1-pyridinio)-6-deoxy]-cyclodextrin was immobilized on bridge type or pendant type polymers, and the adsorption of the nitrate ion on the host polymers was examined in an aqueous solution. The nitrate ion was strongly adsorbed on the host polymers with the Langmuir-type adsorption isotherm. However, the maximum amount of adsorption was less than the polymer are not always exposed to the nitrate ion in water.3) All the C(6)-OH groups of cyclodextrins were replaced with butylamino groups, and an ability of the resulting hosts to bind the nitrate ion was examined in an acidic aqueous solution. The binding constant for a host-nitrate ion system was unsatisfactorily small, though it was about 50 times that for a unmodified cyclodextrin-nitrate ion system. On the other hand, the host bind the sulfate ion very strongly in an acidic aqueous solution.