A highly sensitive and fast responsive naphthalimide-based fluorescent probe for Cu2+ and its application†
Abstract
A novel naphthalimide-based Cu2+ fluorescent probe containing diglycolamine, which served as a water solubility group and provided the coordination ability to Cu2+, was designed and successfully synthesized. The response of the probe L to Cu2+ is reversible and very fast (20 s). The low detection limit of 49 nM for Cu2+ detection was sufficient for the detection of the maximum allowed copper levels in dietary and environmental sources. The stoichiometry of binding between L and Cu2+ was 1 : 1, as supported by fluorescence spectra and ESI-MS. L has been used for the imaging of Cu2+ in MCF-7 cells with satisfying results. The sensor L can be analyzed with a molecular logic gate. It was also found that the fluorescence of L-Cu2+ can be regulated by a photoacid.