Switching of C–C and C–N Coupling/Cleavage for Hypersensitive Detection of Cu²⁺ by a Catalytically Mediated 2-Aminoimidazolyl-Tailored Six-Membered Rhodamine Probe

Abstract

A robust six-membered rhodamine spirocyclic probe <b>1</b> containing a versatile 2-aminoimidazolyl moiety was elaborately designed and synthesized via an attractive C-C and C-N coupling strategy to improve the performance in the detection of ultralow transition metal ions. Probe <b>1</b> allowed the highly hypersensitive detection of Cu²⁺ with a superior picomolar limit of detection (35 pM) and nanomolar naked-eye performance (80 nM) via the switching of C-C and C-N cleavage by a catalytic hydrolysis mode.