Preparation Of Fluorescence-functionalized Composite Materials And Their Applications In Analytical Chemistry

Composite materials composed of two or more than two types of materials through physical or chemical methods,usually have some unique properties.Various materials complement each other in performance based on synergistic effects,making composite materials have better performances than the individual material.Fluorescent composite materials,an important branch of composite materials that mainly include inorganic fluorescent materials,organic fluorescent light-emitting materials and metal organic frameworks,have received much attention in recent years.Novel fluorescent composite materials are widely used in chemistry,biology,medicine and life science.In the field of analytical chemistry,fluorescent composite materials can be designed as fluorescent probes to detect trace substances.It is of great significance to explore new and green fluorescent nanomaterials with strong fluorescence and simple synthesis technology,aiming at the recognition of metal ions and small molecules.This thesis mainly includes the preparation of fluorescence functionalized composite materials and their applications in analytical chemistry.In chapter 1,the definition and classification of composite materials were first briefly introduced.Then some concepts related to metal organic frameworks(MOFs)and recent advances in MOFs,especially,their FL sensing applications were introduced.And then the concepts and applications of Au nanoclusters and carbon dots(CDs)were concisely reviewed.Finally,the significance of this study and research purposes were mentioned.Chapter 2 includes the preparation and application of a new type of functional MOFs.Nitrogen and sulfur co-doped CDs(N,S-CDs)with strong blue light emission were encapsulated into red light-emitting europium metal-organic frameworks(Eu-MOFs)to form a new type of two color-light emitting nanohybrids(Eu-MOFs/N,S-CDs).The prepared Eu-MOFs/N,S-CDs were characterized by IR,XRD,fluorescence,N2 absorption measurements.In organic solvents,the encapsulated N,S-CDs are aggregated and confined in the cavities of the Eu-MOFs,exhibiting only very weak photoluminescence(PL)signal.Therefore,the nanohybrids show red light emission of the Eu-MOFs.On the contrary,as the Eu-MOFs/N,S-CDs are dispersed in water,the encapsulated N,S-CDs are released into solution while the red light emission of the Eu-MOFs are quenched due to the effect of O-H oscillators.The nanohybrids are used as the fluorescent probes for the water content in organic solvents.In chapter 3,a new type of carbon composite RB-lys-CDs with dual fluorescence emissions were prepared using rhodamine B,L-cysteine and citric acid as raw materials.The obtained RB-lys-CDs could generate two emissions respectively at the wavelengths of 445 nm and 580 nm under the excitation of a 365 nm UV light.Since Fe3+ could effectively quench the fluorescence of the composite while phosphate-containing metabolites were able to recover the fluorescence by complexation.On the basis,the obtained RB-lys-CDs were designed as chemical sensor to detect Fe3+ as well as ATP.In chapter 4,glutathione-functionalized Au nanoclusters(GSH-AuNCs)with bright and red fluorescence were prepared.The fluorescence of the nanoclusters could be quenched by free chlorine(ClO-)due to the redox reaction between glutathione and ClO-.Therefore,a simple,fast and effective sensing method for the detection of ClO~- was established.