A novel pyrene-based fluorescent probe for Al3+ detection

Based on the classical Schiff base reaction, fluorescent probe dimethyl 5-((pyren-1-ylmethylene)amino)isophthalate (PAI) is designed and synthesized through introducing Schiff base structure to pyrene unit for structural modification. The structure of the synthesized probe PAI is determined and characterized by FT-IR, 1H NMR, 13C NMR and HRMS. PAI is a type of "turn-on" probe which can specifically recognize Al3+ ion with high selectivity. The limit of detection is calculated to be 3.07 × 10−8 M, which proves the probe's high sensitivity and is lower than that of many efficient reported probes. The probe PAI is intrinsically non-fluorescent due to the photoinduced electron transfer (PET) process. However, the addition of Al3+ ion leads to the breakage of the carbon–nitrogen double bond of Schiff base in PAI resulting in the product without PET property, which shows a typical localized state with enhanced fluorescence and blue color. In addition, PAI can recognize Al3+ ion through test papers, which is in favor of the future research regarding to Al3+ ion sensing.