A novel fluorescence probe based on triphenylamine Schiff base for bioimaging and responding to pH and Fe³⁺

A novel fluorescence probe 1 based on triphenylamine was synthesized and characterized by NMR, IR, high resolution mass spectrometry and elemental analysis. Its fluorescence was quenched when pH below 2. There was a linear relationship between the fluorescence intensity and pH value ranged from 2 to 7. And its fluorescence emission was reversibility in acidic and alkaline solution. Furthermore, it exhibited remarkable selectivity and high sensitivity to Fe³⁺ and was able to detect Fe³⁺ in aqueous solution with low detection limit of 0.511 μM. Job plot showed that the binding stoichiometry of 1 with Fe³⁺ was 1:1. Further observations of ¹H NMR titration suggested that coordination interaction between Fe³⁺ and nitrogen atom on C =N bond promoted the intramolecular charge transfer (ICT) or energy transfer process causing fluorescence quenching. Additionally, 1 was also able to be applied for detecting Fe³⁺ in living cell and bioimaging. - Graphical abstract: Triphenylamine based fluorescence probe can detect pH and Fe³⁺ simultaneously in aqueous solution and be applied for detecting Fe³⁺ in living cell and bioimaging. - Highlights: • The fluorescence probe is sensitive to pH in strong acid conditions. • The fluorescence chemosensor can detect pH and Fe³⁺ simultaneously. • The recognition is able to carry out in aqueous solution. • The probe can also be applied for detecting Fe³⁺ in living cell and bioimaging. • The sensor is synthesized easily with one step.