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
[Zn
2(SO
4)
2(3535Bp)]
4- with large 1D channels of about 1nm dimension have been formed
from DMF. As prepared it is believed these have organic [NMe
2H
2]
+ cations derived from
DMF hydrolysis, these can be exchanged for inorganic cations. Using potassium chloride the
novel phase K
3[Zn(3535Bp)]Cl.xH
2O 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 K
3[Ln(2,6-PDA)
3]xH
2O
followed by partial exchange with (R)-2-amino-3-phenylpropan-1-ol affording rhombohedral
crystals of K[R-2-NH
3-3-Ph-PrOH]
2[Δ-Ln(2,6PDA)
3].7H
2O, 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-.
Post a Comment