Fluorescence sensors for Zn2+ based on conjugated indole Schiff base

• Two novel fluorescence probes were designed and synthesized.
• Experiments and theoretical calculations showed that compounds have outstanding fluorescence properties.
• The probes exhibited excellent sensitivity and selectivity for Zn2+.

Two novel fluorescence probes based on conjugated Schiff base for the detection of Zn2+ were developed. Corresponding molecular geometries, orbital energies, electron contributions and absorption properties of the fluorescence probes were calculated at B3LYP/6-31G∗ by density functional theory. The fluorescence properties of the probes were investigated by UV–vis and fluorescence spectrometer. Results indicate that the probes exhibit excellent sensitivity and selectivity for Zn2+ compared with metal ions examined. For example, the enhancement efficiency of the compound 2 for Zn2+ is up to 846%. The detection limit of the sensor toward Zn2+ could low to 1.0 × 10−7 M. Moreover, mechanisms for the high selectivity and sensitivity of the probes to Zn2+ were studied.

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