9,10-Azaboraphenanthrene-Containing Small Molecules and Conjugated Polymers: Synthesis and Their Application in Chemodosimeters for the Ratiometric Detection of Fluoride Ions
Wei-Dong Zhang, Guoping Li, Letian Xu, Yue Zhuo, Wen-Ming Wan, Ni Yan, Gang He
The introduction of main group elements into conjugated scaffold is emerging as a key route to novel optoelectronic materials. Herein, an efficient and versatile way to synthesize polymerizable 9,10-azaboraphenanthrene (BNP)-containing monomer by aromaticity-driven ring expansion reaction between high antiaromatic borafluorene and azides is reported, and corresponding conjugated small molecules and polymers are developed as well. BNP-containing small molecules and conjugated polymers showed good air/moisture stability and notable fluorescence properties. Addition of fluoride ions to the BNP-based small molecule and polymers induced a rapid change in the emission color from blue to green/yellow, respectively, accompanied by strong intensity changes. The conjugated polymers showed better ratiometric sensing performance than small molecules due to the exciton migration along the conjugated chains. Further experiments showed that the sensing process is fully reversible. The films made by solution-deposition of BNP-based compounds in the presence polycaprolactone also showed good ratiometric sensing for fluoride ions.