Two analogously structural triphenylamine-based fluorescent “off-on” probes for Al^sup 3+^ via two distinct mechanisms and cell imaging application

Two similar structural triphenylamine-based Schiff bases “off-on” fluorescent probes for detecting Al3+ through naked eye manner were prepared by changing their bridging groups, one via styrene (LW1), the other via phenethyl (LW2). This modification affected the performance remarkably in terms of selectivity, sensitivity and efficiency as well as recognition mechanism. The experimental results showed probe LW1 can selectively detect trivalent ion especially for Al3+ by hydrolysis-chelation-enhanced fluorescence with a detection limit of 1.22×10−7M. However, probe LW2 can only highly selectively detect for Al3+ by the direct chelation-enhanced fluorescence with a detection limit of 2.99×10−7M. Furthermore, benefiting from their good water solubility and biocompatibility, cell imaging and real-time monitoring of Al3+ in living HepG2 cells were successfully achieved.