Pyrene is a simple aromatic molecule, and it can easily form dynamic and static excimer in solution, which shows long wavelength fluorescence emission. Owing to the different fluorescence emission wavelengths of pyrene monomer and excimer, pyrene is often used as fluorophore for the synthesis of various fluorescent sensors. The progress of pyrene-based fluorescent chemosensors, including the molecular design, mechanism and their application to single-cation, dication as well as anion recognition are summarized. The developing prospect of this type of fluorescent chemosensor is envisaged in this review.

Contents
1 Introduction
2 Fluorescence sensors for single-cation
2.1 Fluorescent sensors for Hg²⁺ 2.2 Fluorescent sensors for Cu²⁺ 2.3 Fluorescent sensors for Zn²⁺ 2.4 Fluorescent sensors for Ag⁺ 2.5 Fluorescent sensors for other single-cation 3 Fluorescence sensors for dication
3.1 Fluorescent sensors for Hg²⁺,Cu²⁺ 3.2 Fluorescent sensors for Hg²⁺,Pb²⁺ 3.3 Fluorescent sensors for other dication
4 Fluorescent sensors for anion
5 Conclusion