Acridine‐Cored Supramolecular Dendron for Smart Artificial Light Harvesting: PH‐Responsive Two‐Step Energy Transfer and Photocatalysis in Aqueous Solution

ABSTRACT Artificial light‐harvesting systems (ALHSs) featuring dynamic and efficient sequential energy transfer have attracted considerable attention, yet the development of ALHSs with acid‐base responsiveness remains a critical and unmet challenge. Herein, we design and synthesize a dendritic molecule APD‐G1 that self‐assembles in aqueous media to form well‐defined nanostructures with prominent aggregation‐induced emission (AIE) characteristics. By employing APD‐G1 assemblies as the energy donor, we construct a two‐step sequential ALHSs employing NiR and the near‐infrared dye MTSIC as cascaded acceptors, achieving remarkably high FRET efficiencies of up to 96.0%. Notably, the APD‐G1 ‐based ALHS exhibits reversible and robust acid‐base responsive fluorescence switching upon alternating stimulation with trifluoroacetic acid (TFA) and triethylamine (TEA). The fluorescence intensity remains recoverable after four cycles with only slight attenuation, enabling dynamic modulation of energy transfer efficiency and fluorescence emission behavior. Furthermore, the APD‐G1 ‐NiR assembly serves as an efficient photocatalyst for the aerobic cross‐dehydrogenative coupling (CDC) reaction, affording an excellent isolated yield of 92% with broad substrate scope and good functional group tolerance. This work establishes a multifunctional dendritic platform that integrates AIE‐guided self‐assembly, pH‐responsive sequential energy transfer, and aerobic photocatalysis, offering a bioinspired strategy for the design of adaptive optoelectronic materials, sustainable photocatalytic systems, and smart stimulus‐responsive luminescent materials.