A novel HBT-based Schiff base for colorimetric detection of aluminum: Synthesis, characterization, spectral and DFT computational studies

A novel Schiff base L was easily synthesized by the condensation reaction of 2-aminophenol and p-hydroxyphenylbenzothiazole (p-HBT) and could be used for detection of aluminum in ethanol as well as in aqueous solution. Among the detected metal ions, only Al3+ ion can induce a significant enhancement in fluorescence intensity. The lowest detection limit and the dissociation constants Kd for Al3+ are determined to be 8.24 × 10−9 M and 3.00 × 10−5 M, respectively. In addition, the binding details of L-Al3+ complex were investigated by means of infrared spectra, 1H NMR titration and DFT computational studies, implying the fluorescence intensity enhanced by the inhibition of the ESIPT process in L, and further the formation of a large π-electron conjugation system.