Organic Clusters With Well‐Defined Structure via Scaffold Confinement

ABSTRACT Organic clusters composed of heteroatoms and functional groups have been extensively employed to rationalize the intrinsic luminescence of nonconventional luminophores lacking aromatic structures. Nevertheless, in marked contrast to well‐studied metal clusters, their structures and sizes remain poorly delineated, substantially impeding rigorous mechanistic understanding and rational performance optimization. Here, we successfully overcome this limitation by employing 3D‐shaped cyclic hydrocarbon scaffolds to confine electron‐rich moieties, in analogy to the ligand–metal coordination motif in metal clusters, thereby suppressing inter‐cluster extended through‐space conjugation (TSC) networks. This strategy enables, for the first time, the construction of organic clusters with a programmable and precisely defined number of electron‐rich units (e.g., oxygen atoms). Our findings demonstrate that organic clusters with as few as four oxygen atoms can generate excitation‐dependent emission with green afterglow, implying the presence of multiple emissive species with varied TSC even within these well‐defined isolated clusters, likely associated with the intrinsic complexity and sensitivity of through‐space electronic interactions. This strategy thus establishes a robust platform for excluding impurity‐induced emission, precisely identifying organic cluster structures/sizes, and moreover providing a basis for correlating chemical structure, electronic configuration, and photophysical properties in nonconventional luminophores.