Preparation Of Novel Sulfur-containing Non-metallic Fluorescent Quantum Dots And Their Fluorescence Sensing Behavior

The detection of Cr₂O₇^2-and Fe³⁺plays a very important role in various fields such as industry,biological life,medicine,etc.Therefore,the design of simple,sensitive,highly reproducible,and low-level probes has attracted more and more people’s interest.Organic fluorescent probes are cumbersome to prepare and difficult to purify.Heavy metal quantum dots（Ge Te,Ge S,Cd Se etc.）fluorescent probes have high biological toxicity.Therefore,new inorganic non-metal quantum dot luminescent materials have been developed to replace organic fluorescent probes and metal quantum dot fluorescent probes.Needles became a better choice.In this thesis,two new non-metal quantum dot fluorescent probes are designed and synthesized to detect Cr₂O₇^2-and Fe³⁺ions in the water,and the actual water body is tested.（1）We used sublimated sulfur powder as the raw material to synthesize sulfur quantum dots（SQDs）by top-down solvothermal method,and purify them by over-chromatography,and SQDs can be stored for half a year at room temperature.SQDs have blue fluorescence and are uniformly dispersed in water environment and have good fluorescence performance.The quantum yield is 3.8,and the fluorescence stability is good.It is a promising electrodeless luminescent material that can be used for optical sensing.The Cr₂O₇^2-ion was qualitatively and quantitatively detected.SQDs exhibit fluorescence quenching in Cr₂O₇^2-water solution.The reason is the internal filtering effect.Therefore,SQDs can be designed as fluorescent probes to detect Cr₂O₇^2-.The detection process has fast response speed,high sensitivity,and detection limit.（LOD）low（0.16μM,0-300μM（R²=0.94095））characteristics.Tests on actual water samples have proved that our SQDs can avoid interference factors in the actual environment to achieve efficient detection of Cr₂O₇^2-.（2）We synthesized a new type of phosphorous-sulfur quantum dots（PS QDs）fluorescent probe with blue-green fluorescence by solvothermal method using cheap phosphorous pentasulfide（P₂S₅）as raw material,and purified PS QDs solid by column chromatography.Powder,its aqueous solution exhibits strong blue-green fluorescence,and its relative quantum yield can reach 0.37.PS QDs can be used as fluorescent probes for detecting Fe³⁺in water.The detection process is simple,rapid fluorescence response,and good repeatability.Fe³⁺ions have a good linear relationship in the range of 0.2-3.2 m M,and have strong anti-interference it has been successfully applied to the detection of actual water samples.By bean sprouts in vitro,PS QDs fluorescent probes have been successfully labeled with organisms.These experimental results show that the prepared new PS QDs fluorescent probes have good biocompatibility and low toxicity,and can be used for biological imaging and biomedical diagnosis.With the good luminous efficiency of PS QDs fluorescent probes in solvents of different polarities,we have successfully applied PS QDs fluorescent probes to the surface of different substrates,such as rubber pads,plastic plates,glass plates,cardboard and iron.Board and so on.These studies show that PS QDs fluorescent probes have very good application value in the future.