Synthesis Of Bis-β-diketonate Rare Earth Complexes With Azobenzene Bridged And Studies Of Their Photo/Thermal Response Properties

The rare earth β-diketonate complex is one of the most widely studied molecular-based materials.This is mainly based on the β-diketone ligand as a classical chelate ligand,it can chelate with rare earth metal ions to form a stable six-membered ring by enol form and to give kinetic lability of rare earth complexes with certain stability.In the rare earth β-diketonate complexes,the β-diketone ligand can highly transfer its energy to the rare earth ions owing to its high molar absorption coefficients,and they can emit the characteristic fluorescence of rare earth ions when exposed with ultraviolet light.Hence,they have wide application prospects in the fields of fluorescent device materials,magnetic materials,catalysis,molecular recognitions and adsorption.Therefore,the development of novel rare earthβ-diketonate complexes and their performance research have important practical significance.In this paper,an azobenzene group with photoresponsive property was introduced into the bis-p-diketone ligand to construct a dual-core rare earth β-diketonate complex with photoresponsive property.It is desirable to develop rare earth β-diketonate complexes with multifunctional properties.The main contents of this paper are as follows:The first chapter is the introduction.The research progress of rare earthβ-diketonate complexes is elaborated from mono/bis β-diketone ligands two aspects.The important applications of β-diketonate rare earth complexes are briefly introduced.The basic profiles of rare earth P-diketonate complexes derived from azobenzene are introduced,and the research ideas and significance of this paper are present.In the second chapter,a novel bis-β-diketone ligand of 4,4’-(4,4,4-trifluoro-1,3-butanedione)azobenzene(L)and its Ln2L3(DMSO)4(Eu3+,Gd3+ and Tb3+)complexes were synthesized.The purity of the complexes was characterized by IR,1HNMR,elemental analysis and XRD.The stability of the complex was characterized by thermogravimetric analysis.And the single crystal structures of the complexes were obtained by X-ray single crystal diffraction.The structure of complexes is proved to be binuclear triple helix.In the third chapter,we discuss the photoisomerization behavior of 4,4’-(4,4,4-trifluoro-1,3-butanedione)azobenzene ligand(L)and its three bis-β-diketonate rare earth complexes Ln2L3(DMSO)4 in ethanol and acetonitrile,respectively.Their isomerization rate constants and photoisomeirzation yields were obtained.The thermo-isomerization property and their photoresponsiveness of the ligand and its complexes in the polymer polymethyl methacrylate film were discussed.Finally,we discuss the theoretical reason for the non-luminescence of these three bis-β-diketonate rare earth complexes.The fourth chapter gives a brief summary and prospect of the work of the dissertation.