Development of functional dye with redshifted absorption based on Knoevenagel condensation at 1-site in phenyl[b]-fused BODIPY

Integrating ring-fused modification with π-conjugated extension is an effective approach for designing, synthesizing, and application for novel borondipyrromethene (BODIPY) structures. In this work, based on phenyl[b]-fused BODIPY, we made reasonable modification of the methyl group at 1-site to generate dye NBDP. NBDP possessed near-infrared region (NIR) absorption and emission properties, and the intramolecular charge transfer (ICT) resulted in low fluorescence. Whereas, heat energy is evidently released in the presence of light, which can be exploited for intracellular photothermal therapy via the cell apoptosis process, reducing the inflammatory side-effects induced by necrosis. This research provides a crucial foundation for the novel molecule via BODIPY multi-directional alteration and its potential application in anti-tumor phototherapy.