Photoinduced electron transfer (PeT), a foundational mechanism for constructing stimuli-responsive fluorescent probes, faces persistent challenges including the lack of generalizable quantitative models, limited systematic case studies, signal interference, and synthetic complexity. To address these challenges, we propose a boron-centric PeT molecular engineering strategy that harnesses the unique tetrahedral coordination geometry of B(III) centers. This approach leverages the programmable nature of boron coordination chemistry to precisely tailor -dye electronic energy levels and photophysical properties. Using dipyrromethane as a core scaffold and modulating boronic acid coordination with diverse nucleophiles (such as alcohols, phenols, and carboxylic acids), we developed a modular, multicomponent one-pot synthesis platform for efficient assembly of B-PeT dyes. Extending this strategy to pyrrolyldipyrrin and dipyrrolyldipyrrin scaffolds achieved the synthesis of near-infrared (NIR) B-PeT dyes. A library of 75 B(III)-derivatives was synthesized and characterized to enable systematic elucidation and predictive modeling of structure-PeT activity relationships, providing mechanistic insights to guide mitigation of PeT signal interference. The engineered B-PeT probes exhibit superior performance in photoactivated imaging and lysosomal pH sensing, highlighting their translational potential. Our work establishes boron coordination chemistry as a modular toolkit for rational PeT probe design, offering scalable molecular platforms for next-generation sensors with enhanced functionality and synthetic efficiency.
Keywords: BODIPY * Photoinduced electron transfer * Tetra-coordinated boron fluorophore* Photocage * pH bio-sensor.
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