Tetracoordinate Boron Materials for Biological Imaging

This chapter focuses on recent developments in boron-functionalized materials that show great promise for biological imaging applications, and introduces molecular design principles of bioimaging agents. Tetracoordinate boron complexes are commonly embedded in a matrix or are conjugated to a polymer for fluorescence applications. Chemical interactions aside, molecular size and weight also influence how small molecules and polymers interact with biological systems. Polymer interactions not only provide solubility, but also new opportunities for macromolecular assemblies. Polymers offer several advantages compared to their small molecule congeners. Energy-transfer polymers with boron dyes are more commonly prepared as semiconducting conjugated materials. D. T. Chiu and co-workers developed a series of BODIPY-modified dyes for Yamamoto polymerization to assemble conjugated polymers for bioimaging applications. Semiconducting polymers can be prepared as aggregation-induced emission (AIE) active materials. Y. Chujo and co-workers have investigated the synthesis and photophysical properties of AIE active boron diketonate materials for optical devices.