Core-Shell Structures Govern Through-Space Interactions in Triblock Copolymers toward Deep-Red Clusteroluminescence

Green fluorescent protein (GFP) and its derivatives have transformed biological imaging, yet fluorophores that simultaneously combine biocompatibility, structural programmability, and intrinsic long-wavelength luminescence remain scarce. Here, we develop a controllable one-pot polymerization strategy to construct nonconjugated triblock copolymers that can self-assemble into core-shell clusters. By modulating the hydrophilic-hydrophobic balance of copolymer chains, the core-to-shell ratio, chain packing, and electronic through-space interactions within the clusters can be precisely regulated, enabling tunable clusteroluminescence (CL) that extends to the deep-red and near-infrared emission region. Ultrafast spectroscopy further uncovers the excited-state dynamics of these core-shell clusters and reveals how the coupled evolution of electronic states and structures governs CL generation. Moreover, the core-shell clusters enable in vivo angiography under two-photon excitation, highlighting their potential as biocompatible nanofluorophores. These findings establish core-shell engineering as a general design principle for efficient clusteroluminogens, deepen the mechanistic understanding of CL, and pave the way for next-generation nanofluorescence technologies.