Novel fluoroionophores incorporating diaryl-1,3,4-oxadiazole and aza-crown ring. Potentially sensitive Mg2+ ion sensor

Abstract Synthesis of fluoroionophores MOX and BOX incorporating one and two monoaza-15-crown-5, respectively, on photoemittive diaryl-1,3,4-oxadiazoles is reported. Neither absorption nor emission spectra of MOX and BOX were significantly altered in the presence of alkali metal ions. However, alkaline-earth metal ions, Mg 2+ , Ca 2+ and Ba 2+ produced high fluorescence enhancements, the order of enhancement being Mg 2+  > Ca 2+  > Ba 2+ . BOX , which is a poor emitter ( Φ f  = 0.039) than MOX ( Φ f  = 0.065) experienced the highest emission revival by 24-folds upon Mg 2+ complexation. Potential, therefore is available in BOX to function as a sensitive Mg 2+ sensor in biological systems.