Research On The Synthesis And Properties Of Several Novel Fluorescence Molecule Probes

This dissertation is divided into two stages.The first part of the studies are on the design, synthesis and properties of several DPA-type organic fluorescent molecule probes under the Hunan University"985" special fund project; and the second part of the studies are on the synthesis,properties and biomedical applications of quantum dots under the State Scholarship Fund in the United States as a joint PhD student.Section OneIn the first section, we reviewed the research history and recent development of the fluorescence probes, and focused on the application of this kind photo-introduced electron transfer reactions.Molecular fluorescence has many remarkable advantages, such as high sensitivity of detection down to the single molecule, rapid "on-off’ response, feasibility studies of human-molecule communication, subnanometer spatial resolution with submicron visualization and submillisecond temporal resolution. Compared to other materials, organic materials have the advantage of being designed and modified easily, and the investigation of new organic materials has attracted a lot of attention due to their potential application in chemical fluorescence probes.The design, synthesis and characterization of organic molecules have become an active and interesting subject. Highly developed organic chemistry, deep understanding of molecular recognition and increasing skills on molecular design provided the solid foundation for our research works herein.Except following the general rules of designing a new fluorescent molecular, we also emphasized the volatilities of preparation and derivation, especially. Then, the research goal of this dissertation is determined to develop fluorescent molecule probes with high quantum yield and investigate their application in many fields.Thus,in this section, several kinds of fluorescence probes based on chemical sensors,in which different metal ions was detected, were designed and synthesized by the organic coupling method. The selectivity and sensitivity of the new probes to the target ions were carefully studied.(1)Pyrene is an aromatics organism with strong fluorescence activity. The fluorescence properties and photosensitive of Pyrene plays an important role in the photochemical reaction.Moreover, it is easy to synthesis of various derivatives,such as the hydrophilic of fluorescent molecule probe is increased by the reductive amination reaction with connecting DPA group.The open structure of DPA group can rapidly complex with metal ions and ensure the real-time detection.Not only facilitate molecules in aqueous solution, but also provide the reactive groups on the application of molecular probe for further derivative and load.There may be fixed on polyester, polyether, and olefins copolymer on the sensors device.Based on the principle of PET process,a kind of pyrene-DPA fluorescent molecule probe is designed and synthesized. As the polarity medium of fluorescent probe, it is rapidly complex ability of metal ions and protected the real-time detection.Zn2+ and Cd2+ are obviously superior to the other metal ions in the 300 nM level detection.The detection limit is 0.26μg/L in the range of 0～0.40μM, and it is good single selective response for Zn2+.The affect of the pH value is not sensitivity, so this fluorescent molecule probe can avoid the external stimuli and have the development prospects for the biological system.(2)Stilbene is a common conjugate bridge for its good planar and conjugation. The fluorescent molecule probe of this structure has relatively smaller molecules,both the lipophilic and hydrophilic character, and the determination possibility in different environment. Based on the principle of ICT process,a kind of stilbene-DPA fluorescent molecule probe is designed and synthesized.The stokes shifts is 74-130 nm, so the emission spectrum can avoid the jamming of absorption spectrum.Then, the detection sensitivity and accuracy is improved.Cu2+ and Cu+ express an excellent sensitivity for this fluorescent probe molecular in the system of DMSO/H2O (10/90, v/v) and MeCN/H2O (10/90,v/v). The detection limit is 25 nM in the range of 0-0.50μM, and it is good single selective response for copper ion.It prompts the fluorescent molecular sensors and detection becoming truly a kind of technology for the conventional water detection.(3) As a series of electroluminescent materials, benzothiazoles shows unique advantage for containing heteroatomic.Its structure is easy to adjust and the conjugate degree can be changed by the unsaturated groups and various fluorophores.Change the light wavelengths of the materials,and the range can cover the whole of visible light. So, it can derive more structure of fluorescent molecular probes. Based on the principle of ICT process,a kind of benzothiazole-DPA fluorescent molecule probe is designed and synthesized.Sn2+ and Fe3+ express good Fluorescence quenches for this fluorescent probe molecular in the system of MeCN/H2O (10/90,v/v). The detection limit is 134 nM in the range of 0～0.50μM,and it is good single selective response for Sn2+.This kind of fluorescent molecule probe has good application value and prospect for development. (4)Retinoids is a kind of alternating single drug molecule with the aromatic ring andπconjugate system. There exist is the degeneration for the alternating single structure.But the molecular conjugate shortcoming is lack the existence fluorophores on the terminal of terpene chain structure.Moreover, the total plane and molecular conjugate level is not very ideal.In addition, the classic alkynyl forming reaction tends to involve carboxyl protection and deprotection reactions.A directly copper-free Sonogashira coupling between halogenated aromatic acid and termial alkynyl molecules was developed so as to simplify the reaction procedure and improve the synthetic efficiency.This directly copper-free Sonogashira coupling is expand by the choice of several substrates.The advantages of this method are simple operation, high yield, processing convenience and the products are easy to separate and purify. By using this method, the acetylene-type retinoids drug molecule and acetylene-type DPA fluorescent molecule probe are synthesized.This method shows a good application prospect. Moveover, the novel retinoids-DPA molecule is designed and obtained, and the structurely characteristic of fluorescent molecule probes is studied. The strong ultraviolet absorption ability is preserved, but the compound is not happened the electronic warp by the detected of the absorption spectra and can not identify the metal ions.A crystal is obtained in the synthetic process,and the structure is determined by the X-ray diffraction analysis.Section TwoIn the second section, QDs as novel fluorescence probes have many excellent optical properties.Compared with traditional fluorescence dyes,QDs play more and more important roles in the fields of molecular biology, cell biology and medicine, et al.QDs are novel semiconductor nanocrystals with the significant advantages of narrow, size-tunable,highly stable photoluminescence, biocompatibility and QDs with different sizes can be excited at single wavelength over organic fluorephores.The preparation of QDs with high quantum yield and good monodispersity through improved’Green Chemistry’in organic system.The influence of reaction time, temperature,and solvent on the growth and performance of QDs is discussed. Compared to conventional organic dyes,sufficiently passivated QDs appeare to be less susceptible to photobleaching with much narrower emission spectra and tunable maximum emission wavelength, which have been sucessfully used as fluorescent QWss in imaging of biological samples and cells. If not well passivated, the luminescence of the QDs becomes very sensitive to their local environment, and detections of some inorganic ions,proteins,DNA conformations were developed based on this property.(5) The advantages of microwave irradiation technology are not only for faster reaction time, but also higher product yields, cleaner reactions,more green reactions. So microwave irradiation technology has been extensive applied in synthesis of organic and inorganic nanomaterials in recent years.CdSe semiconductor photoluminescent QDs are rapidly synthesized via microwave irradiation technology at controllable temperature (50℃～140℃), where glycerin served as heating medium, diesel oil as the resolver, oleic acid as the ligand, and whithout taking violently poisonous TOPO as Ligand. Different amount of reaction temperature, reaction time, molar ratio and microwave power are employed to investigate the relationship of photophysical properties in different reaction conditions.The as-prepared CdSe QDs exhibit excellent photophysical properties.Their quantum yields are up to 70% and FWHM of the photoluminescent emission specturm peck is only 28 nm.This method reduces the cost of materials,simplifies the experimental process, and realizes the environmentally green synthesis.These QDs would benefite for the synthetic technology of quantum dot CdSe and biological applications.(6) Using the coordination of the carboxyl group and Cu2+ion, the water-soluble polymer Mao-mPEG coated CdSe/CdS core-shell quantum dots as fluorescent probe is synthesized. Cu2+ion shows the high selectivity of quantitative determination in the other metal ions coexistence.The detection limit is 16 nM in the range of 0～0.50μM, and it is good single selective response for Cu2+. The quench of quantum dot fluorescence is analysis from the mechanism.Without the interference of blood components that largely emission light at 595 nm,the quantum dot fluorescence with better emission signals offer an attractive alternative to fluorescent particles containing organic fluorophors and luminescent QDs to analyze in biological samples and cells.