| Rare earth ions possess the characteristics of abundant energy levels and special 4f electronic transition.These features make the rare earth ions have rich performances in optical spectra and luminescence.Luminescent materials which activated or sensitized by rare earth ions show many advantages,such as narrow optical spectra lines,good mono chromaticity,and a wide range of absorption or emission wavelength which contains ultraviolet to infrared region.In addition to the high energy conversion efficiency and long luminescent life of luminescent materials,their stable physical and chemical properties are also attractive.All these properties make rare earth materials have wide applications in many fields like luminescence,display,medicine,biology and so on.Nitrogen heterocyclic rare earth complexes attract the attention of many researchers in the fields of application on rare earth materials.The design and synthesis of organic ligands with novel structure,multi-functional coordination groups,and efficient energy transfer to lanthanide ions have attracted great attention in the fields of organic chemistry,coordination chemistry,medicinal chemistry,analytical chemistry.Seven nitrogen heterocyclic pyridyl ligands and an azobenzene compound have been synthesized.We have also studied the luminescent properties of nitrogen heterocyclic pyridyl ligands and the photoisomerization properties of azobenzene compound.The luminescent properties of complexes of europium and samarium which containing hexafluoroacetylacetone(short for hfac),phenanthroline(short for phen),2,2’-(2,6-pyridinedyl)bis(1-phenyl)-1H-benzimida-zole(short for L)and four binary complexes of europium and samarium were compared.The interaction between the azobenzene compound,nitrogen heterocyclic pyridyl ligands,several rare earth complexes and bovine serum albumin were studied by means of fluorescence spectroscopy.This paper includes 4 parts as follow:1.Literature review.Introduction of nitrogen heterocyclic ligands,photoluminescent rare earth complexes and their mechanics,researches on the interactions of rare earth complexes containing nitrogen heterocyclic ligands and biomacromolecules.2.Design and synthesis of nitrogen heterocyclic pyridyl ligands and azobenzene compound.P-methoxyaniline was used as original material,azobenzene compound(1)was prepared by diazotization coupling reaction and ullmann coupling reaction.Using 2-nitro-N-phenyl-benzenamine and 2,6-pyridinedicarboxaldehyde as original materials,nitrogen heterocyclic ligands 2,2,-(2,6-pyrridyl)bis(1-phenyl)-1H-benzimdazole(2)were synthesised by reduction reaction and ring closing reaction.Using pyridine-2,6-dicarboxylic acid,pyridine-2-carboxylic acid as original materials,under the catalysis of phosphoric acid,reacting with o-phenylene diamine,ortho-aminophenol,2-amino-thiophenol respectively,2,2’-(2,6-pyridyl)-bis-1H-benzimidazole(3),2,2,-(2,6-pyridyl)-bis-lH-benzoxazole(4),2,2 ’-(2,6-pyridyl)-bis-1H-benzothiazole(5),2-(2-pyridyl)-1 H-benzimidazole(6),2-(2-pyridyl)-1H-benzoxazole(7),2-(2-pyridyl)-1 H-benzothiazole(8)were synthesised and characterized by 1HNMR,LC-MS,IR,UV-Vis,fluorescence spectroscopy.3.Preparation and characterization of rare earth complexes.Six single complexes and four binary complexes of europium and samarium were prepared and characterized by IR,TG-DTA,fluorescence spectroscopy,their thermostability and luminescent properties were studied.The experimental data suggests that the thermal decomposition temperature of all rare earth complexes is over 270℃,particularly the thermal decomposition temperature of EuL2 and SmL2 is over 400 ℃.All europium and samrium complexes emit characteristic fluorescence of Eu3+ and Sm3+,except Sm(hfac)3.Among these rare earth complexes,the ratio of luminescent intensity of 5D0→7F2/5D0→7Fi of Eu(hfac)3L is 11.36,while the ratio of luminescent intensity of 4G5/2→6H9/2/4G5/2→6H7/2 of Sm(hfac)3L is 2.65.4.The interactions and mechanism between nitrogen heterocyclic pyridyl ligands,azobenzene compound,rare earth complexes and bovine serum albumin was analysized by fluorescence technique.The binding constants,number of binding sites,form of the binding forces were obtained by the Stern-Volmer equation and Scatchard equation.According to experimental data and calculation,it can be inferred that the interaction between Eu(hfac)3,Sm(hfac)3 and BSA is not obvious by the fluorescence spectrum of BSA which nearly has no change because of the hexafluoroacetyactone has no absorption in ultravilet.2-(2-pyridinediyl)-1H-benzoxazole(7)can enormously enhance the fluorescence of BSA,all the other ligands and rare earth complexes can quench the fluorescence of BSA.The calculation of thermodynamic parameter shows that the interaction between EuL2,Eu(hfac)3L and BSA is electrostatic force;the interaction between Sm(phen)3L,Sm(hfac)3L,2-(2-pyridiediyl)-1 H-benzimidazole(6),2-(2-pyridinediyl)-1 H-benzo-thiazole(8)and BSA is hydrophobic force;the interaction between Eu(phen)3,Eu(phen)3L,SmL2,Sm(phen)3,azobenzene compound,L ligand,2,2’-(2,6-pyridine-diyl)-bis-lH-benzimidazole(3)and BSA is hydrogen bonding and van der waals force;According to the calculation of the combination of distance between all the above compounnds,all the quenching type belongs to non-radiation energy transfer of static quenching. |
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