A substitution-dependent light-up fluorescence probe for selectively detecting Fe3+ ions and its cell imaging application

Deliberate design of specific and sensitive molecular probes with distinctive physical/chemical properties for analyte sensing is of great significance. Herein, by taking advantage of the position-dependent substituent effects, an aggregation-induced emission featured iron (III) probe from ortho-substituted pyridinyl-functionalized tetraphenylethylene (TPE-o-Py) is synthesized. It displays high sensitivity and selectivity toward iron (III) detection. The recognition arises from the position isomer of ortho-substitution, and the fact that TPE-o-Py has a low acid dissociation constant (pKa) that is close to that of hydrolyzed Fe3+. Importantly, TPE-o-Py as a light-up fluorescence probe could be employed for Fe3+sensing in living cells with a pronounced red-shift in fluorescence emission.