Design,Synthesis And Fluorescence Properties Of Novel Coumarin Derivatives

Coumarin derivatives are important organic oxygen-containing heterocyclic compounds with 1,2-benzopyrone ring as the skeleton.As an important phenolic compound in natural products,coumarin derivatives have significant biocompatibility,remarkable medical activity,anti-cancer,anti-neurological disease,anticoagulant,analgesic,anti-inflammatory and anti-Oxidation many other biological activities.In addition,coumarin derivatives have strong fluorescence in visible light region because of the large conjugated system formed by C=C and C=O double bonds in their structures.Meanwhile,the rigidity of molecular skeleton structure is enhanced by the lactone structure of the molecule.Coumarin derivatives have mang excellent optical properties,such as high fluorescence quantum yield,large Stokes shift,good photostability and adjustable fluorescence,etc.They are widely used in the development of fluorescence sensors in molecular recognition,organic chemistry,analytical chemistry and material chemistry.In this thesis,guided by the good fluorescence properties of coumarin derivatives,4-methylumbelliferone was selected as the raw material to synthesize the oxygen-containing bidentate system and nitrogen-oxygen bidentate system coumarin derivatives with fluorescence properties respectively.In addition,in view of the fact that oxygen-containing bidentate compounds are beneficial to form complexes with inorganic metals and non-metals through coordination bonds,the oxygen-containing bidentate compounds are used as organic ligands and combined with boron to design and synthesize two boron spiral ring complexes with rigid structure,and then,using boron spiral ring complex as fluorescence sensors,six kinds of boron screw ring metal complexes were constructed to identify alkali and alkaline earth metals.The specific content is divided into the following:Three coumarin derivatives(compounds 1-3)of oxygen-containing bidentate system with fluorescence properties were designed and synthesized by using 4-methylumbelliferone as raw material.The oxygen-containing bidentate system compounds and their intermediate products were systematically characterized,and the UV absorption and liquid fluorescence properties of the system compounds were studied.The structure optimization and frontier molecular orbital of the oxygen-containing bidentate system compounds are carried out.Through theoretical calculations,the internal charge transfer characteristics of the compound’s luminescence and the stability of the compound structure are explored.Four coumarin derivatives(compounds 4-7)of oxygen-containing bidentate system with fluorescence properties were designed and synthesized by using 4-Methylumbelliferone as raw material.The nitrogen-oxygen bidentate system compounds were systematically characterized,and the UV absorption and liquid fluorescence properties of the system compounds were studied.Compared with imine fluorescent compounds,the nitrogen-oxygen bidentate system compounds themselves have good fluorescence properties due to the carbon-nitrogen double bond in the molecular structure are reduced and inhibiting the isomerization of C=N double bonds.The structure optimization and frontier molecular orbital of the nitrogen-oxygen bidentate system compounds are carried out.Through theoretical calculations,the internal charge transfer characteristics of the compound’s luminescence and the stability of the compound structure are explored.Two boron spiral ring compounds(compounds 8 and 9)with rigid structure were constructed by using oxygen-containing bidentate componds(componds 1 and 2)as organic ligands and introducing boron element.Then two boron spiro ring compounds were used as fluorescent sensors to introduce alkali metals and alkaline earth metals,constructed six cases of boron spiro ring metal complexes(complexes 10-15),carring out the identification study of alkali metals and alkaline earth metals.The boron spiro ring compound and its metal complexes were systematically characterized,and the ultraviolet absorption and liquid fluorescence properties of the boron spiro compound and its metal complexes were studied.The liquid fluorescence properties of organic ligands,boron spiro compounds and their metal complexes are compared,and the reasons for their fluorescence intensity and luminescence mechanism changes are analyzed and speculated.In addition,the structure optimization and frontier molecular orbital of the boron spiro ring compounds(compounds 8 and 9)were carried out,and the internal charge transfer characteristics of the boron spiro compound luminescence were explored through theoretical calculations.