| According to the electron transition rules, the4f-4f transitions of lanthanide ions are parity-forbidden, which results in the free lanthanide ions have a low absorbance coefficient in intensity and their direct excitation yields merely weak luminescence efficiency. In order to improve the luminescence efficiency of lanthanide ions, scientific researchers have screened organic ligands with specific structure, which can coordinate with lanthanide ions. The problem of weak light absorption can be overcome by the so-called antenna effect, upon irradiation more light can be absorbed by the organic ligands, subsequently, the excitation energy can be transferred from the organic ligands to the lanthanide ions by non-radiative transitions. The lanthanide complex has some excellent properties, such as high color purity, long lifetimes, large Stokes shift and so on. However, the lanthanide complex still has low photostability, limited thermal stability and poor mechanical properties, which limits its applications in practice, In recent years, people have been paying their attentions to the research of luminescent hybrid materials based on lanthanide complex, incorporating the lanthanide complex into a stable matrix to get excellent hybrid light-emitting materials. Up to now, there are many matrices used as the host materials, such as sol-gel, titania, ionic liquid, mesoporous silica, organic polymer, zeoliet and other functional nano-particles. Based on the previous work of our group, we used the polymer and SiO2nano-particles as host materials to fabricate the lanthanide complex composite hybrid luminescent materials. Also we studied the luminescence properties of the two materials and the behavior of the intra-molecular energy transfer.The thesis can be concluded as follows:1. The summary of lanthanide luminescent complex properties and the research progress of lanthanide hybrid luminescent materials classified by type of substrate.2. The preparation of lanthanide complexes hybrid luminescent materials based on PMMA polymer matrix.(1) Herein, the lanthanide complex Na[Eu(tta)4] has been attached to attapulgite (Atta) via ion-pairing interactions, where Htta is2-thenoyltrifluoroacetonate. Moreover, efforts have been made to produce plastic attapulgite materials by utilizing poly(methyl methacrylate) (PMMA) matrix and discuss the impact of matrix on the luminescent properties of complex.(2)The synthesis of carboxylic acid ligand and its ternary complex, incorporating the complexes into PMMA polymer matrix to form a complex-containing polymer/film. The results show that the films lead to significant photostability and machinability. By adjusting the ratios of the doping complexes, the emission color of hybrid materials changes from red to green. Moreover we also discussed the luminescent properties of hybrid materials and the way of energy transfer between complexes in the hybrid materials.3. The design and synthesis of a rhodamine donor, fabricating its functional lanthanide luminescent materials based on SiO2nanoparticles by the way of grafting. All the materials and the ligand have been characterized and analyzed by1H NMR,13C NMR, UV-Visible spectroscopy, IR, XRD,TEM, fluorescence spectra. The results obviously show that this rhodamine analog can sensitize the lanthanide ions (Tb, Nd, Er, Yb). Furthermore, the excitation spectra of the materials containing Nd(Ⅲ),Yb(Ⅲ) extend to the visible-light range, so following the visible-light excitation, the materials show the characteristic NIR-luminescence of the corresponding Ln(Ⅲ). And this has inspired the visible-near infrared emission properties of SiO2nanoparticles hybrid materials, are expected to have potential applications in the field of bio-medical imaging. |
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