Pre-Assembled Coumarin-Rhodamine Scaffold for Ratiometric Sensing of Nitric Oxide and Hypochlorite

A new pre-assembled ratiometric sensing platform was constructed from a coumarin donor and a rhodamine acceptor designed for through-bond energy transfer (TBET). A phenylacetylene linker was installed to disrupt the planarity of the extended conjugated system but retaining the efficient energy transfer between the donor and acceptor motifs. To demonstrate its versatility as a sensing platform, we conjugated recognition motifs through amide coupling reactions to yield two TBET chemosensors capable of sensing either endogenously produced NO and ClO^- . Both probes possessed high selectivity for their analytes, exhibited good stability under physiological conditions, and performed well as bioimaging probes in living cells.