Highly sensitive and selective rhodamine Schiff base “off-on” chemosensors for Cu2+ imaging in living cells

Three new rhodamine Schiff base sensors 1a-1c have been designed and synthesized as highly sensitive and selective “off-on” chemosensors for Cu2+ detection via the rhodamine ring-opening approach. The sensors display remarkably Cu2+-selective orange fluorescence and pink color switch over a wide range of tested metal ions. Fluorescent imaging of Cu2+ in living cells is also successfully demonstrated.