A new fluorescent and colorimetric probe for Cu2+ in live cells.

Based on a change in structure between spirocyclic (non-fluorescent) and ring-open (fluorescent) forms of rhodamine-based dyes, a new fluorescent and colorimetric Cu(2+) probe was designed and synthesized. Upon treatment with Cu(2+), the weakly fluorescent probe exhibited a strong fluorescence response with high selectivity. In addition, the turn-on fluorescent probe upon the addition of Cu(2+) was applied in live cell imaging.