A highly selective ‘off–on’ fluorescence chemosensor for Cr(III)

An ‘off–on’ fluorescence chemosensor for the selective signalling of Cr(III) has been designed exploiting the guest-induced inhibition of the photoinduced electron transfer signalling mechanism. The system shows an approximately 17-fold Cr(III)-selective chelation-enhanced fluorescence response in tetrahydrofuran and the system is highly selective against the background of environmentally and biologically relevant metal ions.