Metal organic frameworks (MOFs) are a new class of organic-inorganic hybrid materials which have attracted tremendous attentions over the past two decades. Their structural properties equip them with wide varieties of applications, such as gas storage and separation, selective sorption, ion exchange, catalysis, magnetism and luminescence. Chapter 1 introduces the ways of designing and tailoring MOFs, as well as a background to chiral lanthanide luminescence.

Chapter 2 focuses on the solvothermal synthesis and characterization of open yet stable MOFs based on biphenyl di-/tri-carboxylic acids and more than 20 new crystalline phase types are reported. The MOFs constructed by these biphenic acids were from different transition metals or lanthanides, and in some cases ancillary N-d...[ Read more ]

Metal organic frameworks (MOFs) are a new class of organic-inorganic hybrid materials which have attracted tremendous attentions over the past two decades. Their structural properties equip them with wide varieties of applications, such as gas storage and separation, selective sorption, ion exchange, catalysis, magnetism and luminescence. Chapter 1 introduces the ways of designing and tailoring MOFs, as well as a background to chiral lanthanide luminescence.

Chapter 2 focuses on the solvothermal synthesis and characterization of open yet stable MOFs based on biphenyl di-/tri-carboxylic acids and more than 20 new crystalline phase types are reported. The MOFs constructed by these biphenic acids were from different transition metals or lanthanides, and in some cases ancillary N-donor co-ligands such as 4,4’-bipy, bpane and bpene are also involved to extend the network.

Chapter 3 describes the further exploration of MOFs assembled from biphenyl-3,5,3',5'-tetracarboxylate, which provides a rich coordination chemistry. Ten new crystalline phases are reported; several with highly open 3D networks and interesting potential as ion exchangers. In particular two anionic frameworks [Zn(3535Bp)]^2- and [Zn₂(SO₄)₂(3535Bp)]^4- with large 1D channels of about 1nm dimension have been formed from DMF. As prepared it is believed these have organic [NMe₂H₂]⁺ cations derived from DMF hydrolysis, these can be exchanged for inorganic cations. Using potassium chloride the novel phase K₃[Zn(3535Bp)]Cl.xH₂O is formed, which undergoes cation or anion exchange.

Chapter 4 follows up some work in which phases of [Ln(2,6-PDA)₃]^3- were previously shown to have intense luminescence with high quantum yield. We determined to investigate whether chiral resolution of Δ- and Λ- forms of [Ln(2,6-PDA)₃]^3- was possible and if so examine their chiro-luminescence (CPL). Both direct one-pot solvothermal and exchange metathesis using chiral organic cations were attempted. Several resolved systems were obtained. The best method was the preparation of cubic phase K₃[Ln(2,6-PDA)₃]xH₂O followed by partial exchange with (R)-2-amino-3-phenylpropan-1-ol affording rhombohedral crystals of K[R-2-NH₃-3-Ph-PrOH]₂[Δ-Ln(2,6PDA)₃]．7H₂O, Ln = Tb, Eu. The resolved lanthanide complexes were shown to be stable in aprotic solvents based on solution CD spectra. The solids had intense luminescence, and measurable yet disappointing CPL in the solid and solution states. Solutions were then cast as thin films of PMMA composites from DMSO and found to show much enhanced CPL (g_lum of ca 0.2) over the bulk solid powders (g_lum ca 0.02). PXRD and SEM imaging showed that the rhombohedral phases were retained but with highly preferred orientation with platelets growing normal to the 3-fold axis. The molecules are all oriented with optimal chiral twist perpendicular to the crystal plane and show the maximal CPL for this complex type. The results show chiral Ln complexes can be prepared, resolved, stabilized and oriented to give intense circularly polarized luminescence.

Finally Chapter 5 summarizes some of the key findings and suggests some follow up stuidies of i) MOF frameworks most suitable for selective sorption, ii) ion exchange of the anionic MOFs formed and iii) further probing of CPL in [Eu(2,6-PDA]^3- and [Ln(CDA)]^3-.