|dc.description.abstract||Isoreticulation is the “tweaking” of the structure of an already established metal-organic framework (MOF) to alter certain properties, while still maintaining the original parent topology. This work investigated the isoreticulation of the already established Li-MOF with the intention of enhancing gas uptake. The literature suggests that isoreticulation through the incorporation of Lewis basic sites (Chapter 2) and linear ligand extension (Chapter 3) are useful ways to enhance the uptake of gas.
A general overview of MOFs, i.e. what they are and specific design strategies is provided in Chapter 1. This is then followed by examples of isoreticulation, including the addition of Lewis basic sites and linear ligand extension. To this end, the versatility of the adamantane core is showcased, but the absence of literature methods describing the direct attachment of functionalised N-heterocycles is made known.
The utilisation of N-oxide chemistry and photochemistry towards the direct addition of N-heterocycles onto the adamantane core is discussed in Chapter 2. Both areas of investigation utilised a di-substituted adamantane precursor, 1,3-dibromoadamantane (1,3-DBA) or 1,3-carboxyadamantane (1,3-DCA), to facilitate the addition of two N-heterocycles. The N-oxide chemistry focused on the coupling of 1,3-DBA with various pyridine-N-oxide moieties. Many reaction conditions were tested, with each providing access to mono-substituted adamantane derivatives. The photochemistry explored light irradiation of 1,3-DCA with the N-heterocycles methyl nicotinate, methyl isonicotinate, 2-acetylpyridine and 5-methyl-2,2’-bipyridine carboxylate. The chemistry discussed provided access to both mono- and di-substituted adamantane derivatives. In both cases, access to the mono-substituted adamantane core proceeded with the retention of the unreacted precursor functional group, i.e. a bromine atom or carboxylic acid of 1,3-DBA or 1,3-DCA, respectively. Three robust compounds were synthesised using the photochemistry established: 1,3-bis(3-carboxypyridine)adamantane (L1), 1-carboxy-3-(3’-carboxypyridine)adamantane (L2) and 1-carboxy-3-(4-carboxypyridine)adamantane (L3).
Linear extension of 1,3-bis(carboxyphenyl)adamantane to the corresponding 1,3-bis(4-carboxyphenyl-4’-phenyl)adamantane (L4) is described in Chapter 3. Various synthetic routes towards the construction of L4 are discussed, all of which were successful.
Complexation of L1 and L4 with various metal salts is detailed in Chapter 4. When reacted with LiOH·H2O, both L1 and L4 provided isoreticulations of the previously established framework Li-MOF, referred to as IRLi-MOF and IRLi-MOF-L4, respectively. The complexation of L1 with Cu(BF4)2·H2O and Zn(OTf)2 provided a 2D3D interpenetrated framework (Cu-L1) and an infinite 1D zig-zag chain (Zn-L1), respectively.||