Acridino-Diaza-20-Crown-6 Ethers: New Macrocyclic Hosts for Optochemical Metal Ion Sensing

Acridino-diaza-20-crown-6 ether derivatives as new turn-on type fluorescent chemosensors with an excellent functionality and photophysical properties have been designed and synthesized for metal ion-selective optochemical sensing applications. Spectroscopic studies revealed that in an acetonitrile-based semi-aqueous medium, the sensor molecules exhibited a remarkable fluorescence enhancement with high sensitivity only toward Zn2+, Al3+ and Bi3+, among 23 different metal ions. Studies on complexation showed a great coordinating ability of logK > 4.7 with a 1:1 complex stoichiometry in each case. The detection limits were found to be from 59 nM to micromoles. The new ionophores enabled an optical response without being affected either by the pH in the range of 5.5-7.5, or the presence of various anions or competing metal ions. Varying the N-substituents of the new host-backbone provides diverse opportunities in both immobilization and practical applications without influencing the molecular recognition abilities.

Automated summary

New acridino-diaza-20-crown-6 ether derivatives have been designed and synthesized as turn-on type fluorescent chemosensors, showing remarkable fluorescence enhancement only towards Zn2+, Al3+, and Bi3+ among 23 metal ions. These sensors exhibit high sensitivity and excellent coordinating ability, with detection limits ranging from 59 nM to micromoles, and are not affected by pH or competing ions. The N-substituents variations in the host-backbone provide diverse opportunities for immobilization and practical applications without compromising molecular recognition abilities.