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

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, Mg2+, Ca2+ and Ba2+ produced high fluorescence enhancements, the order of enhancement being Mg2+ > Ca2+ > Ba2+. BOX, which is a poor emitter (Φf = 0.039) than MOX (Φf = 0.065) experienced the highest emission revival by 24-folds upon Mg2+complexation. Potential, therefore is available in BOX to function as a sensitive Mg2+sensor in biological systems.