A naphthalimide–rhodamine chemodosimeter for hypochlorite based on TBET: High quantum yield and endogeous imaging in living cells.

Graphical abstract In this article, a naphthalimide-rhodamine fluorescent turn-on probe RHSNO with red emission for hypochlorous acid based on dual reaction linkage induce through-bond energy transfer (TBET) system was designed and synthesized, and had been applied to the detection of endogenous and exogenous ClO−. Highlights • A naphthalimide-rhodamine probe RHSNO with red emission for ClO− based on dual reaction linkage induce TBET. • ClO− triggered intramolecular desulfurization cyclization and the fluorescence of rhodamine enhanced up to 260-fold. • The efficiency of energy transfer was calculated to be 86%, and the quantum yield of rhodamine moiety is 0.64. • The probe RHSNO had been employed for endogenous and exogenous imaging in MCF-7 cell for ClO−. Abstract A naphthalimide-rhodamine fluorescent turn-on probe RHSNO with red emission for hypochlorous acid based on dual reaction linkage induce through-bond energy transfer (TBET) system was designed and synthesized. Rhodamine B thiohydrazide and naphthalimide -N,N- dimethylthiocarbamate (DMTC) were linked to form a structure of monothio-bishydrazide. In addition, introduce dimethylthiocarbamoyl chloride as another reaction site of ClO−, and it acts to quench the fluorescence of naphthalimide. In the presence of ClO−, RHSNO exhibits high selectivity toward ClO− at trace levels over other anions/ROS based on ClO−-triggered intramolecular desulfurization cyclization of rhodamine-thiohydrazide, the spiro ring of rhodamine was opened and meanwhile desulfurization hydrogenation happened at DMTC of naphthalimide moiety. These dual linkage reaction happened simultaneously made a typical TBET process took place from naphthalimide donor to rhodamine acceptor, an obvious increase of rhodamine emission at 590 nm and enhanced up to 260-fold gradually after adding ClO− with the increase of the concentrations. The efficiency of energy transfer was calculated to be 86%. And the quantum yield of rhodamine moiety is 0.64. Besides, the chemodosimeter RHSNO for ClO− with high sensitivity, a dramatic color change from colorless to brightly pink among 2 s after the addtion of ClO−. The detection limit was determined to be 22.1 nM and works excellently within a wide pH range of 5–10. Moreover, RHSNO had been employed for endogenous imaging in MCF-7 cell for ClO−. The results indicated that the probe could permeated into the cells and reacted with the intracellular ClO−. It is excellent to design fluorescence sensor RHSNO as a quick and effective method for detecting excess ClO− in living cell, for maintaining the balance of hypochlorite in the body and ensure normal life activities. [ABSTRACT FROM AUTHOR]