Luminescent Metal Complexs/LDHS Supramolecular Materials: Fabrication And Fluorescent Property Regulation

In this dissertation, a series of functional organic/inorganic hybridmaterials have been fabricated by using layered double hydroxides （LDHs）as host material and luminescent metal complexes tris（8-hydroxyquinoline-5-sulfonate） aluminum（AQS）, bis（8-hydroxyquinoline-5-sulfonate） zinc（ZQS）, bis（8-hydroxy quinolinate） zinc（Znq2）and bis[2-（2-benzothiazoly）phenolato] zinc（Zn（BTZ）₂） as guest molecules.The hybrid materials posses the properties of single/double color emission,polarized fluorescence and pH-responsive fluorescence. By stepwiseself-assembly way, small molecules anions and neutral molecules wereincorporated into the interlayer of LDHs to fabricate multilayer film,which will provide a new idea for the development of optical functionalmaterials and extend the LDHs-based assembly method. The relationshipbetween the supramolecular structure, host-guest interaction, guest-guestinteraction and the aggregation degree, packing mode of the metalcomplexs with the optical properties of the hybrid materials wereinvestigated. The effect of preparing condition, external circumstance to their luminescence was also detected. The main research contents are asfollows:1. DDS–AQS（x%）/LDHs material （DDS means dodecyl sulphonateanion） were prepared by a hydrothermal method, and their luminescenceshifted to450nm in comparison to that at495nm for AQS.DDS–AQS（66.67%）/LDHs exhibit the strongest fluorescence. NMR, IRand DFT calculation show that the obvious fluorescence change was dueto the isomer transition from mer-AQS to fac-AQS inducing by thepositive-charged LDHs nanosheet through electrostatic interaction. Theconfinement effect of two-dimensional LDHs plate can stabilize thefac-AQS configuration, which solves the problem for preparing thefac-AQS blue luminescence materials.2. ZQS and DDS were co-intercalated into the LDHs host by aco-precipitation method, denoted with DDS–ZQS（x%）/LDHs （Mg2Al,Mg3Al, Zn2Al, Zn3Al）. The lattice orientation effect of LDHs and theincorporation of the second guest DDS play the role of the isolation anddispersion of fluorescent molecules, which will lead the maximumemission wavelength, quantum efficiency and lifetime of the productcontinuously adjusted from464nm to497nm,2.3%to24.4%and10.5ns to22.8ns, separately. The results reveal that the LDHs layer chemicalcomposition and metallic proportion, complex content will influence theintercalated product fluorescence properties. 3. Metal complexes small anion–polyanions/LDHs film: metalcomplex small anions are difficulty to be assembled into the film withexfoliated LDHs nanosheet due to the less charges and driving forcebetween them. We present a new method to solve the problem byco-assembly the small anion and polyanions. Small anion and polyanionare pre-mixed to form the negative-charged mixture through П-Пinteraction and intertwining, then assemble with the positive-chargedLDHs nanosheets through layer-by-layer assembly to prepare the（AQS–polyanion/LDH）nmultilayer ultrathin films. The（AQS–polyanion/LDH）nfilm is continuous, uniform and possesinorganic–organic ordered structure. Furthermore, their luminescence canbe precisely tuned.4. Neutral metal complex@block copolymer/LDH film: Neutralmetal complex can be incorporated into micellear core formed from blockcopolymer through hydrophobic interaction. So, Znq2@PTBEM micelles(PTBEM: poly（tert-butyl acrylate-co-ethyl acrylate-co-methacrylic acid）with uniform size of15nm were prepared. Compared with thefluorescence emission of545nm and lifetime of5.32ns for Znq2solution,the micelles exhibit a fluorescence enhancement characterize with theiremission blue shifted to494nm, lifetime increased to24.71ns. Themicelles and LDH nanosheets were further assembled into theZnq2@PTBEM/LDH film which exhibited the polarized luminescence. 5. Based on the research of4, Zn（BTZ）₂@PS-b-PAA micelles(PS-b-PAA: poly（styrene-b-acrylic acid） and（Zn（BTZ）₂@PS-b-PAA/LDH）nfilm with pH-modified fluorescenttransition were prepared: pH=6or acidic atmosphere, the luminescence ofmicelles and film located at460nm, pH=9or alkaline atmosphere, theirluminescence turn to510nm. PS-b-PAA micelles can reversiblycontraction/expansion induced by pH change which will cause the changeof the molecular packing mode for Zn（BTZ）₂incorporated in PS-b-PAAmicellar core. The Zn（BTZ）₂@PS-b-PAA micelles are highly stable andtheir pH-modified fluorescent transition process was reversible. Moreover,the （Zn（BTZ）₂@PS-b-PAA/LDH）nfilm has good light resistance.