High-Efficiency Long-Wavelength Fluorescent Hyperbranched Polysiloxanes: Synthesis, Emission Mechanism, Information Encryption, and Film Preparation.

Unconventional fluorescent polymers possess the advantages of excellent biocompatibility, environmental friendliness, and facile structural regulation; however, such polymers usually have low fluorescence intensity and quantum yields in the long-wavelength range. In this work, three kinds of high-efficiency long-wavelength emissive hyperbranched polysiloxanes are obtained by introducing aromatic amino acids. These functionalized hyperbranched polysiloxanes have high fluorescence intensity and quantum yields in green, yellow, and red emission regions. Experimental results and density functional theory calculations reveal that the long-wavelength emission comes from the enhanced electronic communication among the conjugated π bonds, electron-rich atoms, and -Si(O) and other functional groups. Especially, the conjugated π bonds efficiently enlarge the spatial electronic delocalizations, resulting in the high-efficiency long-wavelength emission. Moreover, the prepared polymers show excellent applications in information encryption and film preparation. This work could serve as a guide to develop high-efficiency long-wavelength unconventional fluorescent polymers.