Multicomponent\nDiversity-Oriented Access to Boronic-Acid-Derived\nPyrrolide Salicyl-Hydrazone Fluorophores with Strong Solid-State Emission

Fluorescent molecular platforms are highly sought after\nfor their\napplications in biology and optoelectronics but face challenges with\nsolid-state emission quenching. To address this, bulky substituents\nor aggregation-induced emission luminogens to restrict intramolecular\nmotion are used to enhance the brightness. Here, we have successfully\nengineered a novel class of boron complexed pyrrolide salicyl-hydrazone\nfluorophores named BPSHY. These dyes were synthesized through a diversity-oriented\ncondensation of pyrrole and salicylaldehyde derivatives combined with\nvarious aromatic boronic acids. The resulting 3D structures, owing\nto bulky boron axially substituted aryl groups, impart excellent solubility\nin a variety of solvents. Significantly, the BPSHY dyes exhibit strong\nabsorption in the visible region and remarkably large Stokes shifts.\nCrucially, they demonstrate intense emission in aqueous solutions\ndue to aggregation-induced emission effects. In solid-states, these\ndyes achieve high quantum yields, reaching up to 58%. Further expanding\ntheir utility, we developed two new BPSHY probes: one incorporating\nmorpholine and another containing triphenylphosphine salt. Both of\nthem are found to specifically label subcellular organelles such as\nlysosomes and mitochondria within live cells. Notably, these probes\ndemonstrate exceptional staining efficacy and two-photon fluorescence\nfeature. This highlights the considerable promise of BPSHY fluorophores\nfor monitoring and visualizing the dynamic transformations of organelles.