(258g) Rapidly Exfoliation of Layered Covalent Triazine-Based Frameworks into Quantum Dots for Selective Detection of Cu2+ Ions

Carbon quantum dots (CQDs) have attracted numerous attentions due to their unique physicochemical properties and a wide range of potential applications. The top-down strategy is widely used to prepare CQDs with low cost and simple operation. However, the starting materials are still limited to a few kinds of carbon structure, such as activated carbon, graphite, carbon nanotubes, graphene oxide, graphitic carbon nitride and so on. Very recently, fluorescent covalent organic framework (COF) have been synthesized by selectively choosing the fluorophore unit as the building blocks (such as pyrene, porphyrin and phthalocyanine). But most of them are insoluble bulk powers, which hinder their further applications in some promising field. Herein, we reports at the first time that the layered covalent triazine-based frameworks (CTF-1) could be developed as a potential candidate for the top-down fabrication of N-doped CQDs (CTFQDs). When exposed into the mixed solution of H₂SO₄ and H₂O₂, CTF-1 can be rapidly exfoliated into fluorescence nanosheets within several minutes. The obtained CTFQDs is approximately 50nm in lateral sizes and 1nm in thickness. The whole synthetic route only involve low-cost precursor and requires no hydrothermal treatment, which means that the production of CTFQDs can be easy scale-up. The as-prepared CTFQDs not only emitted intrinsic visible emission around 410 nm, but also showed a high fluorescent quantum yields (QY) of 21% (using Quinine sulfate as the reference) and large Stokes shift of 180 nm. Because of the unique PL properties and the good water solubility, the CTFQDs were further utilized as a photoluminescence probe for rapid, sensitive and selective detection of Cu²⁺ ion. The whole detection process can be completed in 1 min with a detection limit as low as 1 μM and a dynamic range from 1 to 50 μM. We expect that our effort will benefit future research on employing various kind of COFs for the CQDs preparation and applications.