Extended tetrapodal perylene diimde with enhanced radical stability for selective photothermal antibacterial treatment

Perylene diimide (PDI) radical anions are attractive for near-infrared (NIR) photothermal applications, but strong aggregation in aqueous media severely limits their biomedical utility. Here, we report an extended tetrapodal PDI dye, PDI-4PPy-1 ⁴⁺ , featuring four elongated 4-phenyl-pyridinium pendants that provide substantial steric hindrance and significantly suppress chromophore aggregation. This structural design stabilizes PDI radical anions under reductive conditions and enables efficient NIR photothermal conversion. Compared with conventional PDIs, PDI-4PPy-1 ⁴⁺ exhibits markedly enhanced bio-reduction-driven photothermal activity, allowing selective and effective antibacterial treatment. These findings demonstrate the critical role of deliberate structural tailoring in modulating aggregation and functional performance of organic dyes, offering a general strategy for designing non-aggregating, highly isolated chromophores for targeted biomedical photothermal applications.