Utilization of Rhenium(I) Polypyridine Complexes Featuring a Dinitrophenylsulfonamide Moiety as Biothiol-Selective Phosphorogenic Bioimaging Reagents and Photocytotoxic Agents

We report herein a series of rhenium(I) polypyridine complexes featuring a 2,4-dinitrophenylsulfonamide (DNPS) unit as phosphorogenic bioimaging reagents and photocytotoxic agents. The biothiol-selective rhenium(I) polypyridine complexes [Re(N<<^>>N)(CO)(3)(py-DNPS)](CF3SO3) (py-DNPS=3-((2,4-dinitrophenylsulfonyl)aminomethyl)pyridine) and their DNPS-free counterparts [Re(N<<^>>N)(CO)(3)(pyridine)](CF3SO3) were synthesized and characterized. Upon photoexcitation, the DNPS complexes exhibited very weak luminescence as a result of photoinduced electron transfer (PET) from the excited rhenium(I) diimine moiety to the DNPS quenching unit. However, upon treatment with glutathione (GSH), the DNPS moiety was removed, resulting in emission enhancement of the solutions (I/I-o=12.6-22.2). After reaction of the DNPS complexes with GSH in living cells, intense intracellular emission and potent photocytotoxicity were both observed. Additionally, the modification of the diimine ligand with a tosylamide unit conferred on the complexes an endoplasmic reticulum (ER)-targeting ability, which can be exploited for selective bioimaging and photocytotoxic applications.

Automated summary

A series of rhenium(I) polypyridine complexes with 2,4-dinitrophenylsulfonamide (DNPS) units were synthesized and characterized for their phosphorogenic bioimaging and photocytotoxic properties. The complexes exhibited weak luminescence upon photoexcitation due to photoinduced electron transfer, but showed enhanced emission and potent photocytotoxicity after reaction with glutathione (GSH) in living cells. Additionally, modification with a tosylamide unit enabled the complexes to selectively target the endoplasmic reticulum (ER) for bioimaging and photocytotoxic applications.