A Novel D-π-A Type Fluorescent Probe for Cu2+ Based on Styryl-Pyridinium Salts Conjugating Di-(2-picolyl)amine (DPA) Units.

ABSTRACT

A novel D-π-A type fluorescent probe L(NO3) for Cu (II) sensing was designed and fully characterized. The probe consists of a styryl-pyridine cation fluorescent group and a di-(2-picolyl)amine (DPA) receptor unit, which are linked by a phenyl group to form an electron donor-π-acceptor (D-π-A) conjugate system, especially the introduction of a nitrate counter anion for significantly enhanced water solubility of the probe. Fluorescence titration studies of the probe L(NO3) showed a higher selectivity for Cu2+ than other metal ions, and the emission spectrum was strongly quenched upon binding. The competitive binding assay and the low detection limit (0.932 µM) showed that the probe L(NO3) had strong anti-interference ability and excellent Cu2+ detection performance. The binding ratio of probe L(NO3) and Cu2+ was determined from Job's plot to be 11, which is consistent with the results obtained from X-ray crystal structures. Meanwhile, the probe showed instantaneous chemical reversibility when titrated with EDTA solution, indicating potential recycling properties of the probe. In addition, the design of inexpensive fluorescent test strips can perform the on-site and real-time detection Cu2+ with a color recognition application.