Probe formation by carbamate coupling between dichalcogenide secondary amines and PQ-chloroformate: The amine hydrochloride was suspended in DCM (50 mM). NEt3 (3.0 equiv.) was added, and the solution was added dropwise into a suspension of chloroformate PQ-OC(O)Cl in DCM (0.25 M). The resulting reaction was stirred for 1 h, concentrated in vacuo yielding a pale yellow crude oil, and typically, flash column chromatography provided the target probe carbamates in excellent purity without contamination by residual fluorescent PQ-OH. For the solubilised piperazinamide probes including RX1, additional purification by preparative HPLC was conducted.