Tetracoordinated organoboron dyes exhibiting strong fluorescence in either solution or the solid state are currently receiving much attraction in view of their photovoltaic, optoelectronic, and biological applications. Herein, a series of aromatic-ring-fused BOPPY dyes have been developed by one-pot condensation of formylated isoindoles or indoles and pyridinylhydrazine followed by subsequent borylation coordination. The facile synthesis provides excellent diversity of these unsymmetrical α-benzoand β-benzothiophene-fused BOPPY dyes with intriguing photophysical properties owing to their rigid and planar structure and extended πconjugation while containing a reactive site. They display intense green to orange fluorescence in solution and red-to-near-infrared emission in the solid state, with high fluorescence quantum yields up to 92 and 21%, respectively, relatively large Stokes shifts, and excellent photostability. Furthermore, two representative benzofused BOPPY probes with morpholine or benzenesulfonamide groups were developed and used to selectively "light up" the subcellular organelles such as lysosomes and endoplasmic reticulum under ultralow concentration, respectively.

Hydrazine inserted pyrrole-based bisboron fluorophores showcasing strong fluorescence in either solution or solid state have attracted wide applications in biomedicine and optoelectronic materials science. The growing demand calls for multiple strategies for generating novel fluorophores to solve the problems of small Stokes shifts and poor solid fluorescence. By changing the frameworks, BOPHY, BOPPY, BOPYPY, BOPAHY and BOAPY has recently been developed as increasingly valuable classes of bisboron fluorophores owing to its tunable structures and promising spectroscopic properties, high photostability and low LUMO energy level and the electron-deficient bisBF2 groups. This review mainly highlights the key synthetic strategies of these hydrazine inserted pyrrole-based bisboron fluorophores BOPHY, BOPPY and BOAPY in our group and their superior properties. Moreover, significant photophysical data of these fluorophores in solution and solid states are also inside the scope of this review. The facile functionalization of these fluorophores’ platforms allows a practically structural modification and generate novel versatile dyes with excellent chemical and photophysical properties. We believe that these fluorophores will hold promise to make an important contribution to various applications.