Preparation And Circularly Polarized Luminescence Properties Of Chiral SURMOFs Thin Films

Circularly polarized luminescence（CPL）has attracted great interest in 3D display,optical sensing,information storage and biological probes,which has been widely concerned by scientists.So far,many chiroptical materials have been reported for CPL,such as metal complexes,small organic molecules,polymers,self-assembled supramolecules and so on.However,obtaining CPL materials with high luminous efficiency and asymmetric factor is still great challenging.Metal-organic frameworks（MOFs）have unique advantages due to their large porosity,diverse structures,tunable pores size and shape,and high thermal stability.Particularly,Chiral MOFs（Chir MOFs）have a wide range of applications in asymmetric catalysis,enantioselective adsorption/separation and nonlinear optics.However,the preparation of Chir MOF thin films or membranes for CPL is still a challenging task,which provides hug potential on chiral optical applicantion.In this thesis,liquid-phase epitaxial（LPE）layer-by-layer（lbl）growth methods were applied for high quality Chir MOFs thin films on functionalized substrates（Surface-coordinated chir MOFs thin films,SURchir MOFs）,and then layer by layer loaded with Ln complexes and modified with dyes for the study of CPL performance.In this thesis,two kinds of SURchir MOFs materials were designed and synthesized,which were used to study the CPL properties.As follows:1.We prepared chiroptical materials by using host-guest assembly strategy with LPE lbl loading method,in which using lanthanide complexes Eu（acac）₃,Tb（acac）₃ and Gd（acac）₃ as guests and SURchir MOFs Ln（acac）₃@Zn₂（D/Lcam）₂dabco（Dcam=（1R,3S）-（+）-camphorate or Lcam=（1S,3R）-（-）-camphorate;dabco=1,4-Diaza[2.2.2]bicyclooctane）as the host.It is found that these thin films not only exhibit strong fluorescence properties and chiral features,but also have CPL performances with large dissymmetry factor(g_lum).In addition,due to the lanthanide complexes Eu（acac）₃,Tb（acac）₃ and Gd（acac）₃ exhibit strong red,green and blue emission fluorescence.We idealized them as three primary colors for fluorescence regulation,and then achieved different CPL emission.In addition,the compared CPL and fluorescent lifetime results showed that the advantage of this preparation strategy could effectively achieve energy transfer from Ln（acac）₃ to SURchir MOFs,resulting in an excellent CPL performance.This work provides a simple and effective strategy to obtain tunable CPL thin film materials.2.We selected D/Lcam and 2-aminopyrazine（Pr-NH₂）as organic linkers and zinc ions as metal nodes to prepare a new SURchir MOFs by LPE lbl growth method.Subsequently,we grafted fluorescent molecules with carboxylate groups to assemble SURchir MOFs possessing stronger fluorescent properties.Further investigation exhibited that the obtained chiroptical thin films had improved CPL property.