Secondary Through-Space Interactions: Achieving Single-Molecule White-Light Emission from Clusteroluminogens with Isolated Phenyl Rings

Clusteroluminogens (CLgens) refer to some non-conjugated molecules that show visible light due to the formation of aggregates and unique electronic properties with through-space interactions (TSI). Although mature and systematic theories of molecular photophysics have been developed to study conventional conjugated chromophores, it is still challenging to endow CLgens with designed photophysical properties by manipulating TSI. Herein, three CLgens with non-conjugated donor-acceptor structures and different halide substituents with secondary TSI are designed and synthesized. These molecules show multiple emissions and even white-light emission in the crystalline state and the intensity ratio of these multiple emission peaks is easily manipulated by changing the halide atom and excitation wavelength. Experimental and theoretical results successfully disclose the electronic nature of these multiple emissions: through-space conjugation for short-wavelength fluorescence, through-space charge transfer based on secondary TSI for long-wavelength fluorescence, and room-temperature phosphorescence. The introduction of secondary TSI to CLgens not only enriches their varieties of photophysical properties but also inspires the establishment of novel aggregate photophysics for clusteroluminescence.