Synthesis And Properties Study Of Emission-tunable Carbon Quantum Dots

Carbon quantum dots?CDs?,a new class of fluorescent carbon nanomaterials,have drawn increasing attention in recent years owing to their multie merits,such as excellent optical properties,robust chemical inertness,low toxicity,biocompatibility and cost-effective preparation.Based on these remarkable properties,CDs have already been apied widely in various fields,including fluorescent probes,biomedical imaging,catalysis and light-emitting devices.The main work of this paper is to prepare CDs with different optical properties by a sime one-step route using thousands of starting materials,and study their optical apications in detection and cell imaging.The main points are as follows:1.Solvent-dependent emitting CDs?o-CDs?were synthesized by one-step hydrothermal treatment of o-phenylenediamine.The as-prepared o-CDs exhibited different emission different emission colors in different solvents.Multi-color emissive o-CDs/polymer films were achieved through integrating the o-CDs with different polymer matrices.In addition,our experimental results demonstrated that the emission peak of the as-prepared o-CDs was sensitive to the water in organic solvents.Based on this discovery,this novel o-CDs were used as a probe for visual and quantitative detection of water in different organic solvents.2.N-doped CDs?N-CDs?with a quantum yield of 50%were synthesized by one-step solvothermal process using citric acid and 3,4-Diaminobenzoic acid.The obtained N-CDs are spherical with an average particle size of 3.6 nm.N-CDs emit bright blue photoluminescence under 400 nm light,and they have excellent water solubility and stability.Finally,the N-CDs can be apied as probes toward Fe³⁺detection with high selectivity and sensitivity,and the calibration curve disayed a linear region over the range of 1-25?mol/L with a detection limit of 0.21?mol/L.3.A facile solvothermal method for preparing green emissive CDs?m-CDs?with a quantum yield of 65.1%was achieved using m-phenylenediamine.as the carbon precursor,of which show optimal emission wavelength at 513 nm.In addition,the m-CDs exhibit low toxicity and high photostability.Chemical composition analysis results showed that there exist hydroxyl and carboxylic groups on the surface of the m-CDs,which results in excellent solubility and biocompatibility of m-CDs in water.,m-CDs were used as fluorescent probes for the detection of Fe³⁺in water and cell imaging,by virtue of their high solubility,high quantum yield and abundant groups on the surface of the m-CDs,the detection of Fe³⁺with two linear ranges of 0-2.2 mmol/L and 2.2-17 mmol/L.