Photochemical processing potential of a novel Schiff base as a fluorescent probe for selective monitoring of Al3+ ions and bioimaging in human cervical cancer HeLa cells

A novel efficient fluorescent probe 1,1'-((1E,1'E)-((4,5-dimethyl-1,2-phenylene)bis(azaneylylidene))bis(methaneylylidene))bis(naphthalen-2-ol) (PAMN) for the recognition of Al3+ was synthesized and extensively characterized using various physicochemical techniques. Free PAMN fluoresced weakly, but when aluminium added, it fluoresced dramatically against various metal ions. The recognition process was relied mainly on the chelation-controlled C=N isomerization combined with an inhibition of the excited-state intramolecular proton transfer (ESIPT). The energies of both HOMO and LUMO for PAMN and PAMN-Al3+ complex were estimated by DFT calculations to elucidate the configuration of the complex. PAMN coordinated with Al3+ in [1:1] stoichiometry with an association-constant of 2.18 x 10(5) M-1. Upon coordination with Al3+ ions, PAMN displayed a good linear relationship in extremely low concentrations with a limit of detection of 7.05 x 10(-9) M. The living-HeLa-cell imaging displayed that the probe had excellent cell membrane permeability, with great potential for intracellular Al3+ ion tracing via the fluorescence imaging technique.

Automated summary

A novel efficient fluorescent probe PAMN was synthesized for the recognition of Al3+ ions, showing strong fluorescence through chelation-controlled C=N isomerization and inhibition of ESIPT mechanism. The complex of PAMN-Al3+ exhibited high association constant and low detection limit, making it suitable for intracellular Al3+ ion tracing.