Novel An Efficient Fluorescent Probe Based on Calix[4]triazacrown-5 With Naphthalimide Group for Co2+, Cd2+ and Dopamine Detection

A novel naphthalimide-substituted calix[4]triazacrown-5 ( Nap-Calix ) at cone conformation was designed and synthesized to employ as a fluorescent probe, which enables the simultaneously detection of Co 2+ and Cd 2+ metal ions as well as dopamine (DA). 1 H-NMR, 13 C-NMR, ESI–MS and elemental analysis techniques were carried out to characterize its structure. Cation binding property of Nap-Calix against various metal ions such as Ba 2+ , Co 2+ , Ni 2+ , Pb 2+ , Zn 2+ , and Cd 2+ exhibited that the sensor selectively binds to Co 2+ and Cd 2+ metal ions with a remarkable affinity. Introduction of Co 2+ and Cd 2+ metal ions to a solution of Nap-Calix in DMF/water (1:1, v/v) resulted with a new emission band at 370 nm when excited at 283 nm. In addition, the fluorescence sensing affinity of the probe Nap-Calix against a catecholamine neurotransmitter (dopamine) was investigated in a wide range of concentration of DA (0–0.1 mmol L −1 ) in 50% DMF/PBS (pH = 5.0). The fluorescence intensity of Nap-Calix , with excitation/emission peaks at 283/327 nm, is highly enhanced by DA. It was also observed that Nap-Calix exhibits excellent fluorescence behavior towards DA with a very low detection limit as 0.21 µmol L −1 .