AIE-Active Supramolecular Dendrimer Enabling Sequential Two-step FRET for Efficient Aqueous Light-Harvesting System and Co ²⁺ -Selective Detection/Adsorption

Developing high-performance artificial light-harvesting systems (LHSs) that integrate cascade energy transfer and multifunctional capabilities for simultaneous heavy metal detection and remediation remains a significant challenge. In this work, we designed and synthesized two quinoline-cored poly(aryl ether) dendrons, QPD-D1 and QPD-D2, both of which exhibit typical aggregation-induced emission enhancement (AIEE) in aqueous solution. Using these dendritic assemblies as the energy donor, and employing NiR and Ce6 as the first and second cascade acceptors, respectively, we successfully constructed a supramolecular sequential two-step LHS. The system achieved energy transfer efficiencies of 87% for the first step and 40% for the second step, accompanied by a stepwise reduction in fluorescence lifetime from 13.73 to 3.73 ns and finally to 1.70 ns, thereby demonstrating efficient cascade energy transfer. Notably, the QPD-D2 assemblies exhibited highly selective fluorescence quenching toward Co 2+, with a quenching efficiency of 98.3% and a detection limit of 5.04 × 10 –7 M, outperforming most reported Co 2+ fluorescent probes. Notably, the QPD-D2 -NiR-based LHS further enhanced the sensitivity for Co 2+ detection, achieving a quenching efficiency of 99.6%. Furthermore, the material showed excellent Co 2+ adsorption performance, achieving a removal efficiency of 93.9% and a maximum adsorption capacity of 436.8 mg/g, along with good recyclability over four cycles. Overall, this work provides a feasible strategy for constructing aqueous supramolecular dendritic LHSs and develops a promising multifunctional material for the highly efficient and selective detection and adsorption of Co 2+, holding great potential for the environmental remediation of heavy metal pollution.