Bis(isoquinoline N-oxide) pincers as a new type of metal cation dual channel fluorosensor.

[structure: see text] A new type of donor-spacer-acceptor podand system has been synthesized and proved as an efficient dual channel fluorosensor for Li+, Mg2+, and Ca2+. The known ability for the N-oxide function to bind Lewis acids is the key step in the appearance of a new emitting charge-transfer (CT) excited state. The occurrence of this CT state for alkaline earth (Mg2+ and Ca2+) and not for alkaline metals (Li+) provided a new type of dual channel fluorosensors.