Text

theses

Metal organic frameworks (MOFs), also known as porous coordination polymers (PCPs), are frameworks composed of metallic centers and multidentate organic ligands. In this thesis, the author focuses mainly on synthesizing new MOFs as yellow phosphors for white light emitting diodes (WLEDs) and the study of their adsorption properties for gas storage and separation. A critical aspect in the research and development of white light-emitting diodes (WLEDs) is the discovery of highly efficient phosphors free of rare-earth elements. In chapter 2 and 3, the author has designed and synthesized a new type of rare-earth-free, blue-excitable yellow phosphors, obtained by combining a strongly emissive molecular fluorophore with a second linker as a bandgap modulating co-ligand, in three-dimensional networks. Compound 1 [Zn6(btc)4(tppe) 2(DMA)2] (btc = benzene-1,3,5-tricarboxylate, tppe = 1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)ethene, DMA = dimethylacetamide) and compound 2 are both composed of zinc metal center, btc and tppe linkers, but with different structures. Compound 1 contains both primary building unit (PBU) and secondary building unit (SBU), while 2 is constructed on two different primary building units (PBUs). Compound 3 is made of zinc metal center, fdc and tppe linkers (fdc=9-Fluorenone-2,7-dicarboxylate). All three compounds (air stable sample of 1 , outgassed samples of 2 and 3 ) emit bright yellow light (540, 535, 540 nm for 1 , 2 and 3 respectively) when excited by a blue light source. These studies show that the title compounds represent a promising series for use in phosphor-conversion WLEDs. Gas adsorption and separation is another important application of MOFs as mentioned previously. Commensurate adsorption is an interesting phenomenon, in which the location and orientation of adsorbates are commensurate to the crystal symmetry of adsorbents. Commensurate adsorption is helpful to understand the interaction between adsorbates and adsorbents and usually indicates high selectivity of commensurate adsorbed molecules over incommensurate ones. In chapter 4, the commensurate to incommensurate transition of hydrocarbons (C2 to n-C7 alkanes/alkene) adsorptions on Ca(sdb) has been investigated by simulation, adsorption and single crystal analyses, conducted by author and collaborator. The commensurate adsorption of selected hydrocarbons on [Zn 2(bpdc) 2(bpe)]·2DMF was studied as well in Chapter 4 by both simulation and adsorption methods.

ETD_5849

Ph.D.

Includes bibliographical references

by Qihan Gong

doi:10.7282/T3NK3CGT

ETD doctoral

The author owns the copyright to this work.