A novel tryptanthrin-based “on–off-on” probe for sequential sensing Cu2+/S2− in water samples

Copper ions (Cu2+) and sulfide (S2−) play essential roles in many physiologies and pathologic processes. Herein, a new “on–off-on” tryptanthrin-based probe TR-1 (TR-1) has been designed and synthesized in a facile and economical way. TR-1 exhibited highly selective and sensitive response to Cu2+ without any interference over 14 competitive metal ions and the detection limit downs to 24 nM, which is far below the Chinese standard of fishery water quality (157 nM). The ‘in situ’ prepared complex TR-1 + Cu2+ could also be applied to detect S2− with the detection limit of 62 nM. Further, TR-1 was potentially applied for the analysis of copper ions in water samples.