| Aza-heterocyclic compounds are of great interest to the researchers of pharmaceutical chemistry owing to their various biological activities.In the process of developing efficient synthetic methods for new aza-heterocycles and studying the biological activities of synthesized new aza-hetereocycles,the research group of the thesis advisor found that pentasubstituted tetrahydropyrimides(THPs),the products of a new developed multicomponent reaction,have very strong aggregation-indudec emission(AIE)characteristic.Organic small molecular fluorophores have been used in wide application areas such as quantitative and qualitative analysis,chemical/biological fluorescent probes and imaging owing to their high sensitivity,high selectivity and easyly detectable signals.Conventional fluorescent compounds usually show a high fluorescence efficiency in dilute solution,but a fluorescence decrease or enven quencheing in concentrated solutions or aggregation,which is often called aggregation-caused quenching(ACQ).Since fluorescent compounds are usually applied in a certain concentration or aggregated state,ACQ effect greatly limits the use of fluorescent compounds.AIE is exactly the opposite of ACQ,that is,fluorescent compounds show no emission in solution but emit strong fluorescene upon aggregation.AIE phenomenos is found and named in 2001 by professor TangBenzhong's research group.Over the past decade,compounds with AIE properties have shown great advantages in wide application areas,especially in chemical/biological detection and imaging analysis.Professor Tang's group found that AIE compounds usually contain ??conjugated systems connected with more than one aryl rotors.The molecular structure of THPs is completedly different from those of reported AIE compounds.Although THPs have a very low conjugated structure that has no aryl groups in ?-conjugated systems,their fluorescence quantum yields are up to 93%.Unique molecular structures usually lead to unique properties and applications.The thesis focuses on the research about the optical properties and applications of THPs via design and synthesis.In addition,the thesis investigates the optical properties and applications of 1-alkyl-3-alkylamino maleimides(MIs),another kind of aza-hetereocycles with no aryl group on ?-conjugated system but high emission in solution and aggregation state.This thesis consists of five chapters.This thesis consists of five chapters.The first chapter is the introduction to aggregation-caused quenching(ACQ)phenomenon of organic small molecule fluorescent compounds and the molecular structure characteristics,mechanism and application limitaion of ACQ;novel aggregation-induced emission(AIE)phenomenon found in 2001 by professor Tang's group as well as its molecular structure characteristics,mechanism and advantages in many application areas;the purpose,contents and significance of this essay.The second chapter is about the application of THPs as fluorescence probes for determination of the critical micelle concentration(CMC)of ionic surfactants.We designed and synthesized 16 THPs for the study of the structure influence on CMC and sensitivity.THPs are products synthesized by a five component reaction that we developed in 2011.They show strong aggregation-induced emission(AIE)characteristics,that is,show almost no light in the solution,but emit a strong fluorescence upon aggregation.One of THPs was found to be used as a unique and sensitive surfactant CMC fluorescent-turn-on probe,that is,the CMC value is determined by the inflection point with the strongest fluorescence intensity.Other reported fuorescent probes for CMC based on change in fluorescent intensity are fluorescent-turn-off probes,that is,the CMC value is determined by the inflection point with the weakest fluorescence intensity..After investigation into the structure-sensitivity relationship of 16 THPs,it was found that all the synthesized 16 THPs can be used as CMC fluorescent-turn-on probe;4-CF3 group is a effect subsituent enhancing the sensitivity of THPs as CMC probes(the concentration of THPs with 4-CF3 group used as CMC probes decreased to 0.7 ?M).The third chapter is about the fluorescent thermo-response of THP-1 and their uses as thermometers.Temperature is probably the most important parameter influencing physical,chemical and biological processes.Therefore,the simple and accurate methods of temperature measurement are needed in various areas,The temperature sensors were approximately 75-80%in the world sensor market.With the rapid development of molecular biology,proteomics,scientific instruments and techniques,the researches on the deseases and biological processes have gone deep into the microscopic dynamics process,such as the study of cellular and molecular biological changes.These developments raise the temperature measurement a new challenge:real-time and remote measurement of temperature and temperature distribution in the micro-environment.The traditional temperature sensors based on thermal expansion and contraction of the volume of material changes,the Seebeck effect,and so on,are unable to satisfy the needs of the development of these disciplines.In this repect,thermo-senstive fluorescent materials possessing advantages of high sensitivity(to detect a single molecule),fast response speed(10-8-10-10 s),high spatial resolution(submicron)has attracted a great concern.For organic fluorophores,thermo-stimuli sensitive and reversible solid-state fluorescence-on-off/-color switching is rare.We found that two polymorphs(lb and lc)of diethyl 1,2,3,6-tetrahydro-1,2,3-triphenylpyrimidine-4,5-dicarboxylate(THP-1)show such thermo-stimuli fluorescence changes.The highly emissive polymorph 1b/1c shows sensitive thermo-stimuli dynamic solid-state fluorescence-color/-on-off switching in different temperature ranges when excited at different red-edge excitation wavelengths and can be used as new type of fluorescent thermometers in wide T-range.The fourth chapter is the study on the fluorescence properties of 1-butyl-3-(butylamino)-1 H-pyrrole-2,5-dione(MI-1).Organic small molecule fluorescent compounds generally have conjugated structures containing aromatic groups.Maleic acid is a kind of widely existing in nature,and has good biological activity and fluorescence properties.It has been widely used in biological fields and luminescent materials.Like other organic small molecule fluorescent compounds,MIs fluorescent compounds generally have conjugated structures containing aromatic groups.Only O'Reilly study group reported a class of molecules that did not contain an aromatic group of MIs.And the optical properties of the compound in solution were simply reported,and the optical properties of the compound were not reported.In the course of the development of multicomponent reactions,we found that the 1-butyl-3-(butylamino)-1H-pyrrole-2,5-dione in the thin layer plate made a very bright fluorescence,which can be observed under the sun.Why is it so simple,conjugated system does not contain aromatic group of small molecules will be made so strong fluorescence it?The optical properties of MI-1 in different solutions and solid are studied in detail in this paper.The luminescence mechanism of single crystal structure,structure design and synthesis were studied.MI-1 has good solubility in different solvents,the fluorescence quantum yield of is up to 70%in the non proton solvent,but only about 0.1%in the proton solvent.We found that MI-1 can be used for the determination of trace amounts of water in organic solvents.This is because in the organic solvent water content within the range of 0-0.5%,MI-1 fluorescence intensity and emission wavelength with the water content increase were significantly reduced with redshift respectively,and with water content into good phenomena.According to the experimental results,it can be speculated that the solid fluorescence of MI-1 is mainly produced by the intermolecular N-H...O hydrogen bond formed by the two polymer;fluorescence in nonpolar solvents was generated by the intramolecular N-H...O and C-H...O formation of the rigid fused ring structure;while in the proton solvent fluorescence sharp decrease because of the intramolecular N-H...O and C-H...O hydrogen bond is destroyed.The characteristics of structure,the mechanism of production,and the advantages in many application fields,as well as the research purpose and significance of the thesis.The fifth chapter is on investigation into the application as fluorescent probes for CMC and Fe3+ of Mis with only aliphatic group on ?-conjugated system in molecular structure.Surfactants have many characteristics,such as wetting,washing,corrosion resistance,dissolution,dispersion,anti-static,etc.and hence are widely used in many fields,such as medicinal chemistry,synthetic chemistry,material science,biology and so on.Under a certain concentration,that is,CMC,surfactants prefer forming thermodynamicly stable micelles,at the same time,a variety of properties have changed significantly.Therefore,the determination of CMC has very important significance in practical application and interested researchers of physical chemistry and analytical chemistry.Metal ions are widely used in chemical,biomedical,and environmental sciences.Wherein the iron content in the crust is the second multi-metal elements,but also one of the essential trace elements.Iron is mainly in Fe2+ and Fe3+ ions form in the body,whereas Fe3+ plays an important role in the metabolic processes of organisms and many enzymes involved in the iron and oxygen metabolic reactions,electron transport and mitochondrial respiration are related with Fe3+.In view of the good solubility of alkyl substituted amino MIs in various solvents and the high emission both in solution and aggregates,the applications of alkyl substituted amino MIs as fluorescent probes for CMC and Fe3+ ion were studied in this essay.It was found that 3-(benzylamino)-l-butyl-1H-pyrrole-2,5-dione(MI-4)can be used as a dual indicator of fluorescence intensity and emission wavelength for CMC;(3-(2-hydroxyethylamino)-1-(2-hydroxyethyl)-1H-pyrrole-2,5-dione)(MI-5)can be used as Fe3+ fluorescence probe. |
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