**4. Conclusions**

A series of silane-based poly(thioether)s and functionalized poly(thioether)s were synthesized via successive thiol click reaction. These poly(thioether)s exhibited excellent fluorescent properties in solutions and showed visible blue fluorescence in living cells. The responsiveness of poly(thioether)s to metal ions can be adjusted by end-modifying with di fferent sulfhydryl compounds. The functionalized poly(thioether)s showed high selectivity to Fe3<sup>+</sup> detection and still exhibited responsiveness to Fe3<sup>+</sup> ions in living cells. The synthetic route of poly(thioether)s described herein could be extended to synthesize novel organosilicone fluorescent materials, and their application in ion detection and cell imaging can extend the application field of poly(thioether)s.

**Author Contributions:** W.L. directed the research, Z.G. and Y.Z. designed the experiments, X.Z. and Z.G. performed the experiments, Z.G., Y.Z. and W.L. wrote the paper.

**Funding:** This work was financially supported by NSFC (21877048, 21472067, 21672083), Taishan Scholar Foundation (TS201511041), the startup fund of University of Jinan (309-10004, 160100332, 140200321), and Natural Science Foundation of Shandong Province (ZR2018BB022).

**Conflicts of Interest:** There are no conflict to declare.
