Fluorescent Zn Chemosensor Mediated by a 1,8-Naphthyridine Derivative and It's Photophysical Properties.

One of the greatest challenges in using fluorescent chemosensors for highly selective and sensitive transition-metal ions is finding an efficient and simple method for its synthesis. In this study, a highly efficient fluorescence chemosensor for Zn was developed from -Boc-proline modified 1,8-naphthyridine. The fluorescence intensity of the chemosensor was increased significantly only in the presence of Zn ion which provided a perceived color change for rapid visual sensing, while other metal ions showed fluorescence quenching or little changes. It was worth noting that the chemosensor distinguished Zn from Cd commonly having similar properties. The solvent effect and possible bonding mode for fluorescence enhancement have been also discussed. Results of this study indicated that the Boc-group in -proline significantly improved the sensitivity and selectivity for Zn detection performance, as confirmed by comparison experiments and time dependent-density functional theory (TD-DFT) calculations.