Multichromophoric Macrocycle Nanoparticles for Mitigating Cyanine Limit and Efficient Aqueous Photocatalysis via Sequential Energy Transfer

ABSTRACT Cyanine dyes, despite their strong near‐infrared (NIR) absorption, often undergo symmetry‐breaking Peierls’ transitions in water known as the “cyanine limit,” resulting in suboptimal optical properties. In this work, we present a strategy to overcome this limitation by entrapping cyanine dye ( Cy746 ) within the micellar nanoparticle ( Np@M1‐Cy746 ) of a bichromophoric [1+1] macrocycle M1 comprising of perylene diimide (PDI) and aza‐BODIPY (Aza) that exhibits Förster resonance energy transfer (FRET), formed from an amphiphilic polymer 1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐N‐[methoxy(polyethylene glycol)]. This approach not only stabilizes the cyanine dye but also enables two‐step FRET from PDI to Aza of the macrocycle to Cy746 , resulting in panchromatic absorption, enhanced NIR emission, and achieved near‐white light emission. The micellar FRET assembly Np@M1‐Cy746 also serves as a ratiometric temperature sensor with a sensitivity of 0.0379%°C −1 and was utilized as a supramolecular photocatalyst in aqueous‐phase photocatalytic Knoevenagel condensation of benzaldehyde and malononitrile. The two‐step FRET process in Np@M1‐Cy746 enabled its superior photocatalytic performance compared to the micelle of only M1 ( Np@M1 ), which shows one‐step FRET. This study offers a distinct approach for constructing multichromophoric macrocycle nanoparticles in aqueous media, leveraging upon its sequential energy transfer to achieve efficient and scalable photocatalytic transformation.