An imidazole-containing core-substituted naphthalene diimide: Fluorescent sensing properties toward copper ion and optimized selectivity by tuning the solvent medium

A core-substituted naphthalene diimide (NDI-3) with long emission wavelength was synthesized. Due to the complexation of imidazole and copper ions, it can be used as a fluorescent probe toward Cu2+. More interestingly, the sensing behavior of NDI-3 could be well tuned by the solvent systems. After optimization, in DMF/HEPES, both the selectivity and sensitivity were enhanced largely. Furthermore, NDI-3 could serve as a practical fluorescence sensor by test strips and silica gel plates, also, it can be used for imaging of Cu2+ in living cells and in vivo potentially.