Although a number of rhodamine-based Cu2 þ chemosensors have been developed during these years, most of them worked in near neutral aqueous media [3,10–19]. Taking all above spectro- scopic results together, the properties of RhB-Im almost meet the basic requirements of a chemosensory reagent. It could be used as a ‘‘turn-off’’ fluorescence chemosensor for Cu2 þ in an acidic aqueous solution though some properties are not outstanding compared with other rhodamine-based Cu2 þ chemosensors