A Novel “Turn-on” Triphenylamine-Based Fluorescent Probe for Ultrasensitive Detection of Al3+ and Its Application on Test Strips

Abstract A triphenylamine-based “turn-on” fluorescent chemosensor, (E)-3-(benzyloxy)-N′-{[4′-(diphenylamino)-4-hydroxy[1,1′-biphenyl]-3-yl]methylidene}benzohydrazide (BDHBMB), containing a 3-benzyloxybenzohydrazide moiety was successfully synthesized. It showed high selectivity, excellent anti-interference performance, and remarkable sensitivity for Al3+ ions in methanol solution. After the addition of Al3+, BDHBMB exhibited strong fluorescence emission (18 times enhancement) at λ 573 nm due to the formation of a rigid conjugate structure based on chelation-enhanced fluorescence (CHEF) mechanism. A great linearity with a correlation coefficient R2 of 0.99 was observed in the concentration range 0–60 μM. The binding constant and the limit of detection (LOD) for Al3+ were calculated to be 1.48×103 M–1 and 8.94×10–8 M, respectively. The “turn-on” fluorescent probe was successfully applied to visual detection of Al3+ in test paper.