Thiol-chromene click chemistry: A coumarin-based derivative and its use as regenerable thiol probe and in bioimaging applications

The synthesis and characterization of a coumarin-chromene (8, 9-dihydro-2H-cyclopenta[b]pyrano[2,3-f]chromene-2,10(7aH)-dione) (1) derivative and its use for thiol chemosensing in water was reported. Experimental details showed 1 acts as a probe for the detection of thiols including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), whereas amino acids which do not contain thiols induced no changes in UV-vis spectra and fluorescence emission properties of 1. A possible detection mechanism is a nucleophilic attack of thiols to the a,p-unsaturated ketone in 1 that resulted in a fluorescent coumarin derivative. Further studies showed that 1-thiol derivatives can be applied to the design of regenerative chemodosimeters for Cu2+, Hg2+ and Cd2+ in water based on Mn+-promoted desulfurization and recovery of 1. Furthermore, the optical properties of the probe and its Cys-addition product were theoretically studied. The ability of probe 1 to detect thiols in living cells (HepG2 cells) via an enhancement of the fluorescence was proved. Moreover, the applicability of 1 for the direct determination of biorelevant thiols in a complex matrix such as human plasma was also demonstrated. (C) 2013 Elsevier B.V. All rights reserved.