Phosphorogenic sensors for biothiols derived from cyclometalated iridium(III) polypyridine complexes containing a...

Area of Science:

• Coordination Chemistry
• Bioinorganic Chemistry
• Chemical Sensing

Background:

• Cyclometalated iridium(III) polypyridine complexes are widely studied for their photophysical properties.
• Developing selective and sensitive intracellular sensors for biologically relevant thiols remains a challenge.

Purpose of the Study:

• To synthesize and characterize novel cyclometalated iridium(III) complexes incorporating a 2,4-dinitrophenyl ether moiety.
• To evaluate these complexes as intracellular sensors for biothiols, focusing on their luminescence response and cellular applications.

Main Methods:

• Synthesis and characterization of three iridium(III) polypyridine complexes with varying dinitrophenyl ether linkages.
• Photophysical studies to assess luminescence properties and quenching mechanisms.
• Confocal imaging experiments to evaluate cellular uptake and sensing capabilities in live cells.

Main Results:

• The synthesized iridium(III) complexes exhibited weak emission due to the quenching effect of the dinitroaromatic moiety.
• Reaction with biothiols (e.g., glutathione) led to the displacement of the dinitroaromatic unit and a significant "turn-on" of luminescence.
• Complex 1a demonstrated non-cytotoxicity, facile cellular uptake, and effective phosphorogenic sensing of biothiols in cellular environments.

Conclusions:

• The developed iridium(III) complexes function as effective phosphorogenic intracellular sensors for biothiols.
• The "turn-on" luminescence mechanism is driven by the removal of the dinitroaromatic quenching group upon reaction with thiols.
• Complex 1a shows promise for real-time monitoring of biothiols like glutathione within living cells.