Molecular Design of Alkali Metal Ion Probes for Use in Aqueous Media

本文研究了碱金属离子在对称-（烷基）（2-羟基-5-硝基苄氧基）二苯并-16-冠-5（1）胶束水溶液中的选择性比色法。发现胶束表面电荷对比色行为有很大影响，在含有亲脂性DB 16 C5色离子载体的阴离子胶束溶液中，Na^+可被选择性比色。通过在DB 16 C5骨架中引入芘甲酰胺单元（2），可以预期与Na^+结合的荧光响应。结果表明，Na^+离子的结合促进了荧光离子载体中羧酰胺基团的质子解离，从而导致了从供体羧酰胺阴离子到芘受体的内部电荷转移（ICT），从而产生了有效的比率发射。Li^+或Cs^+的存在不会诱导荧光反应。因此，荧光离子载体2在4：1的1，4-二氧六环-水（v/v）中表现出具有高Na^+选择性的双重发射响应。苯并-15-冠-5（B15 C5）荧光离子载体3可以被分类为光诱导电子转移（PET）传感器。基于B 15 C5部分在非水溶液中1：1的络合物形成能力，获得了对3的中等Na^+选择性。与此相反，发现3在γ-CyD存在下作为一种新型离子探针工作，即使在Na^+存在下，它也能实现对K^+的高灵敏度和选择性。结果表明，在γ-CyD存在下，3形成了对K^+具有高选择性的2：1络合物，并且在水中同时显示单体和二聚体发射。

A selective colorimetry of alkali metal cations in aqueous micellar solution containingsym-(alkyyl)(2-hydroxy-5-nitrobenzyloxy)dibenzo-1 6-crown-5 (1) has been examined. Colorimetric behavior were found to be strongly affected by the surface charge of micellar species and a selective colorimetry of Na^+ was performed in the anionic micellar solution containing lipophilic DB 16C5 chromoionophore. By introducing pyrenecarboxamide unit into DB16C5 skeleton (2), a fluorescent response for Na^+ binding is expected. It was found that proton dissociation of the carboxamido moiety in fluoroionophore was promoted by Na^+ binding, which resulted in an efficient ratiometric emission due to internal charge transfer (ICT) from the donorcarboxamido anion to the pyrene acceptor. No fluorescent response was induced by the presence of Li^+ or Cs^+. Thus fluoroionophore 2 exhibited a dual emission response with high Na^+ selectivity in 4 : 1 1 , 4-dioxane-water (v/v). The benzo-15-crown-5 (B15C5) fluoroionophore 3 can be classified as a photoinduced electron transfer (PET) sensor. A moderate Na^+ selectivity is obtained for 3 based on a 1 : 1 complex formation ability of the B 1 5C5 moiety in a non-aqueoussolution. In contrast, 3 was found to work as a novel ion probe in the presence of gamma-CyD, and it achieved high sensitivity and selectivity for K^+ even in the presence of Na^+. The results revealed that 3 formed a 2 : 1 complex with high selectivity for K^+ in the presence of gamma-CyD, and it exhibited both monomer and dimer emission in water.