Preparation Of Halogen-Doped Graphene Quantum Dots@Metal-Organic Framework Composites And Their Application In Fluorescence Sensing

Graphene quantum dots（GQDs）are novel zero-dimensional nanomaterials with quantum size effect.Compared with conventional semiconductor nanocrystals,GQDs have been widely used in various fields because of their unique optical properties,excellent thermal/electrical conductivity,low toxicity and good biocompatibility.Halogen-doped GQDs（X-GQDs）will improve their photoluminescence properties and p H stability,and enhancing the practicability of GQDs.Metal organic frameworks（MOFs）are crystalline porous materials with large specific surface area and porosity,which are an excellent carrier for encapsulated nanoparticles.By combining GQDs and MOFs,the synergistic effect between them can achieve complementary advantages,resulting in the enhanced performance of composites.In this paper,based on the advantages of X-GQDs@MOFs composite materials,ratiometric fluorescent probes were obtained and applied to fluorescence sensing.The relevant research contents are as follows:（1）Using julolidine and cetylpyridine chloride as carbon sources,acetic acid and ethanol were added and reacted under high pressure at 210℃for 14 h via a solvothermal reaction to obtain yellow light-emitting Cl,N-GQDs.Then,the prepared Cl,N-GQDs reacted with the precursor of Eu BTC（europium nitrate hexahydrate and 1,3,5-benzenetricarboxylic acid）at 120℃for 48 h.Thus,Cl,N-GQDs@Eu BTC was obtained and characterized.Cl,N-GQDs@Eu BTC was used as a ratiometric fluorescent probe to detect trace amounts of water in organic solvents.In ethanol,the linear detection range of water was 0.1～5 v%,and the detection limit was 0.018 v%.In tetrahydrofuran,the linear detection range of water is 0.1～3v%,and the detection limit is 0.04 v%.（2）The blue light-emitting F-GQDs were prepared by solvothermal method using（trifluoromethyl）benzene as the carbon source.Then,the prepared F-GQDs were encapsulated into Tb BTC by one-step synthesis method to synthesize blue-green dual-emitting F-GQDs@Tb BTC composites,and the structure and optical properties were characterized.The F-GQDs@Tb BTC was used as a fluorescent probe to detect the Bacillus anthracis marker 2,6-pyridinedicarboxylic acid（DPA）,and the DPA showed a good linear relationship with the fluorescence intensity ratio(I₅₄₇/I₄₀₅)in the concentration range of 1～100μM and the detection limit is 0.32μM.In addition,the fluorescent probe showed a strong selectivity and sensitivity.