- Fluorogenic Sensors of Heavy Metal Ions Based on Calix[4]arenes Functionalized by 1,3-Dipolar Cycloaddition Reactions

Figure 7.1 The two rims of calix[4]arenes. Sensors that give fluorescence enhancement upon binding with metal ions are preferred for biological imaging over those

that respond to metal ion with a fluorescence quenching. We have developed a method of attaching aryl isoxazoline or isoxazole units onto the upper or lower rims of calix[4]arenes by 1,3-dipolar cycloadditions. Furthermore, novel capping of calix[4]arenes us-ing double cycloaddition reactions between bisdipoles and bisdi-polarophiles was successfully carried out. Arrays of calix[4]arenes

containing various bifunctional groups were obtained after ring-opening reactions of the attached isoxazoline or isoxazole groups, furthermore, fluorophores can be appended near the bifunctional groups making them useful as fluorescent sensors.