Synthesis Of Doped Carbon Quantum Dots And Their Application In The Detection Of Molecules

Carbon dots(CQDs)have with excellent optical properties,simple engineering process and low cost.They have been widely used in drug transport,ion probes,optoelectronic devices and other fields,showing excellent and good practical application value.The main research contents of this topic are as follows:Firstly,N,O-CQDs was prepared with 4-cyanopyridine as raw material,ethanol as solvent,at 220 ℃ and 14 h under the best reaction conditions,with blue light emission,and its optical quantum yield reached 0.19(quinine sulfate as the standard reference).It shows good optical and chemical stability.Due to the high sensitivity of N,O-CQDs to tetracycline(TC)and methyl orange(MO),the addition of TC and MO to N,O-CQDs solution can induce the corresponding fluorescence response.Therefore,a signal response detection probe(fluorescence mode)can be established using N,O-CQDs as an optical responder.Interestingly,when TC was added consecutively,it was easy to observe a change in fluorescence color from blue to yellow,with a gradual decrease in fluorescence intensity.These color changes can occur within tens of seconds and are easily discerned by the naked eye.The limit of detection(LOD)was up to 6 n M.In addition,the designed probe has high selectivity for TC and MO,and has been used to the detection of TC and MO in tap water,with flying colors.Secondly,three kinds of blue,green and red fluorescent nitrogen doped carbon dots(B-NCQDs,G-NCQDs and R-NCQDs)with high fluorescence quantum yields were synthesized by one-step solvent method using 4-Pyridinecarboxaldehyde and N,N-dimethyl-p-phenylenediamine as raw materials and ethanol as solvent.Then,the synthesized NCQDs were characterized as G-NCQDs,and their optical properties and lysochromic properties were explored.It was found that the synthesized NCQDs had good optical properties,stable chemical properties,lysochromic properties and showed sensitivity to water.Therefore,based on the characteristics of G-NCQDs sensitivity to water,a fluorescence quenching method was designed to detect the water content in organic solvents,showing the advantages of 0-100% wide range and low detection line.The actual sample of alcohol in Erguotou was detected,showing a satisfactory recovery rate,which has practical application value.At the same time,in order to expand the application of G-NCQDs,the preparation of G-NCQDs/PVP membrane,fluorescence filter paper and highlighter pen were carried out,which has certain market application value.Finally,the yellow fluorescent R-NCQDs/silica gel powder was successfully prepared by using the characteristics of forming intermolecular hydrogen bonds between R-NCQDs and silica gel.The solid fluorescence emission center was at 610 nm,which possess very fine and excellent fluorescence performance.