Controllable Secondary Through-Space Interaction and Clusteroluminescence

Nonconjugated clusteroluminogens (CLgens), such as proteins and polystyrene, have become increasingly important in photophysics. They show many advantages over traditional conjugated dyes with fused aromatic rings in biological applications. However, CLgens have historically been unheeded because of their weak visible emissions in the aggregate state, namely clusteroluminescence (CL). Changing the electronic structures of CLgens by precisely regulating the intramolecular through-space interaction (TSI) to improve their photophysical properties remains an enormous challenge. Herein, we propose a general strategy to construct a higher-level intramolecular TSI, namely secondary TSI constructed by the primary TSI and a TSI linker, in multi-aryl-substituted alkanes (MAAs). By introducing methyl and phenyl into 1,1,3,3-tetraphenyl-propane, the modified MAAs show efficient CL with high luminescence quantum yield (∼40%) and long emission wavelength (∼530 nm). Then, comprehensive experiments and theoretical studies demonstrate that molecular rigidity and overlap of subunits play pivotal roles in improving these hierarchical TSIs. This work not only provides a feasible strategy to achieve controllable manipulation of hierarchical TSIs and CL but also establishes comprehensive TSI-based aggregate photophysics.