A highly selective “turn-on” fluorescent chemosensor based on hydroxy pyrene–hydrazone derivative for Zn2+

A new hydroxypyrene-based sensor 1 was designed and synthesized as a Zn2+ selective colorimetric and fluorescent chemosensor. This chemosensor showed a new UV–vis absorption peak (λmax = 498 nm) with Zn2+, which can be attributed to an internal charge transfer (ICT) mechanism. In addition, Zn2+ induced a highly selective “turn-on” fluorescence enhancement at long wavelength (λmax = 588 nm) in a buffered system. A significant fluorescence enhancement was observed upon the addition of Zn2+. The combination of two phenol groups on the pyrene and phenyl moieties as well as a conjugated hydrazone group can generate a binding pocket for Zn2+. These results also demonstrate that 1-hydroxypyrene-2-carboaldehyde can be a unique platform to introduce various ligands for the colorimetric and fluorescent recognition of metal ions.

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► A new hydroxy pyrene–hydrazone derivative 1 was synthesized as a selective fluorescent chemosensor for Zn2+.
► Chemosensor 1 showed a new UV–vis absorption peak with Zn2+ via the internal charge transfer (ICT) mechanism.
► In addition, Zn2+ induced a highly selective “turn-on” fluorescence enhancement.