Organic Letters 2010-09-03

Squaramide-based reagent for selective chromogenic sensing of Cu(II) through a zwitterion radical.

Elena Sanna, Luis Martínez, Carmen Rotger, Salvador Blasco, Jorge González, Enrique García-España, Antoni Costa

Index: Org. Lett. 12(17) , 3840-3, (2010)

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Abstract

A minimalist squaramide-based chemodosimeter for Cu(2+) is described. Upon selective chelation to 2, Cu(2+) induces the formation of a highly colored zwitterionic radical, which is kinetically stable for hours. The presence of a radical is confirmed by EPR and ESI-MS. It is then possible to use reagent 2 for visual and selective sensing of Cu(2+) at neutral pH.