An oxazole-derived Schiff base as a multifunctional fluorescence sensor towards Al3+ and Ga3+ in different media

Abstract

A facile Schiff base derivative N′-(2, 3-dihydroxybenzylidene)-5-(naphthalen-1-yl)oxazole-4-carbohydrazide (G3) was constructed and synthesized through the reaction of 5-(naphthalen-1-yl)oxazole-4-carbohydrazide with 2,3-dihydrobenzaldehyde, which achieved the distinct recognition for two kinds of IIIA group metal ions (Al3+, Ga3+) in different media. G3 performed an enhanced blue luminescence upon addition of Al3+ in CH3OH/H2O buffer solution. As well, G3 exhibited a remarkable fluorescence enhancement toward Ga3+ with a color change from colorless to green in DMSO/H2O buffer solution. Therefore, G3 was applied as a multifunctional fluorescence sensor for Al3+ and Ga3+. The molar ratio for G3 towards Al3+ and Ga3+ was both verified to be 1:2, and the possible sensing mechanism was demonstrated by Job's plot, mass spectrometry titration and theoretical calculation. What’ more, G3 could be used to determinate target ions in real water samples with favorable recovery, which implied a wide prospect for application. And more importantly, the fine difference on microstructure causing the macroscopic performance of sensors in the buffer solution was revealed through the contrastive study of G3 and G1 in previous work.