A highly sensitive fluorescent probe with different responses to Cu and Zn.

We report a highly sensitive fluorescent probe based on p-dimethylaminobenzoyl derivatives (probe L) for the detection of Cu and Zn. In this work, the probe L exhibited a fluorescent turn-on sensing model to Cu and Zn with a distinct fluorescent color change from colorless to green and yellow respectively. Probe L exhibited high selectivity as a fluorescent Cu/Zn probe with a limit of detection (LOD) of 45 nM/17 nM. The results of H NMR titrations revealed that the response of L to Cu and Zn was triggered by the interaction of the thiophene unit and the metal ion. Furthermore, the fluorescence titrations and Job's plot curves displayed the binding ratio of 1:2 for Cu and 1:1 for Zn metal-L complex formation respectively. Density functional theory calculation also demonstrated the possibility of molecular luminescence and the process of metal-L complex formation. Additionally, fluorescent test strips have been prepared for convenient detection of Cu and Zn, which means the convenient and rapid assay in real samples can be achieved.