A novel tetrahydroquinazolin-2-amine-based high selective fluorescent sensor for Zn2+ from nopinone

2-[[5, 6, 7, 8-Tetrahydro-4-phenyl-7, 7-dimethyl-6, 8-methanoquinazolin-2-imino] methyl] phenol (3) is a novel tetrahydroquinazolin-2-amine-based high selective fluorescent sensor for Zn2+ and was successfully synthesized from nopinone. Its optical properties have been investigated with UV-vis absorption spectra, fluorescence emission spectra and confocal fluorescence imaging, respectively. The sensor could enhance fluorescence after adding some Zn2+ and emitted green light in ethanol. A linear relationship between Zn2+ concentration (Zn2+, 0.5-13×10−6 M) and fluorescence intensity was obtained for determining the content of Zn2+ with a detection limit of 2.35×10−6 mM, y=76.567x+18.469, R2=0.9956. A grinding method was used to detect the presence of Zn2+ in a solid state. Two clear confocal fluorescence images of watermelon peel veins were provided by adding compound 3 into the watermelon peel slices containing Zn2+ ion, and the new method could be used to detect Zn2+ in fruits. Thus, compound 3 synthesized from nopinone is a fluorescent probe and fluorescence imaging agent.

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