Heating promoted fluorescent recognition of Cu2+ with high selectivity and sensitivity based on spiropyran derivative.

A spiropyran derivative containing an ethyl group (SPEt) was applied for fluorescent recognition of Cu2+. With Cu2+ addition, the SPEt-contained solution using a mixed solvent of DMF/H2O (9/1, v/v) showed a very strong characteristic emission peak with high quantum yield which is 4.3 times that of the pure SPEt solution. As a result, Cu2+ was successfully picked out from totally 17 kinds of common metal ions and a detection limit as low as 14.9 fM had been achieved in using this assay system. Particularly, the recognition process was temperature- and time-dependent and could be effectively promoted by heating. In addition, SPEt had been used to image and detect Cu2+ in mussels. Thus, our results in this study provided an exclusive Cu2+ recognition via fluorometry in wide temperature, time, and dynamic ranges of assay, enabled a femtomolar scale detection of Cu2+ by spiropyran derivative, and showed a promising imaging ability of Cu2+ in marine living organisms.