Chaotropic Effect Stabilized Radical-Containing Supramolecular Organic Frameworks for Photothermal Therapy

Radical-containing frameworks (RCFs) have emerged as promising functional materials in various fields due to the combination of the highly ordered frame structure and the fascinating property of organic radicals. Here, the first example of radical-containing supramolecular organic frameworks (SOFs) fabricated by the chaotropic effect between closo-dodecaborate cluster (B₁₂ H₁₂^2- ) and 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPT³⁺ ) is presented. The SOFs can be easily synthesized by stirring the B₁₂ H₁₂^2- and the TPT³⁺ in aqueous solution through self-assembly. Upon 435 nm light irradiation, the SOFs exhibits photochromic behavior from slight yellow (SOF-1) to dark purple (SOF-2). Electron paramagnetic resonance spectroscopy also reveals that stable radicals are generated in situ after light irradiation. Powder X-ray diffraction demonstrates the SOFs maintain their structural stabilities upon light irradiation. More interestingly, the radical-containing SOFs exhibit efficient photothermal effect under 660 nm light irradiation, which can be applied as photothermal agent for antibacterial application both in vitro and in vivo. This work highlights the construction of RCFs through supramolecular self-assembly, which may arouse applications in energy, catalysis, photoluminescence, and biomedical fields.