This thesis documents the successful syntheses of six novel 2,2':6',2"-terpyridine-amine based polydentate ligands and a range of mono-, di-, and polynuclear complexes derived from them. The ability of some dinuclear complexes to affect the rate of hydrolysis of the phosphate diester group in the DNA model compound, bis-p-nitrophenyl phosphate (BNPP) has also been explored. Owing to the presence of two potential ligating groups in each polydentate ligand, a number of dinuclear, tetranuclear and serendipitous supramolecular architectures have been produced and characterised during this research.
The polydentate ligands were synthesised by stepwise functionalisation of the progenitor ligand, 4'-(2"'-toluyl)-2,2':6',2"-terpyridine (L2.1), at its ortho methyl position via free radical bromination, and where various amine groups were appended by nucleophilic substitution reactions. The detailed ligand syntheses, and characterisation are discussed in Chapter 2, along with the crystal structures of some ligands.
Chapter 3 describes coordination chemistry of 4'-(2"'-toluyl)-2,2':6',2"-terpyridine with transition metal ions. Thirteen new complexes of Ni(II), Cu(II), Zn(II) and Ag(I) are reported, where Ag(I) produced a striking spiral shaped polymer with L2.1 having unusual „hyperdentate‟ nitrogen atoms.
Two polydentate ligands, 4'-[2"'-{(2-pyridylmethyl)aminomethyl}phenyl]-2,2':6',2"-terpyridine, L2.3, and 4'-[2"'-{bis(2-pyridylmethyl)aminomethyl}phenyl]-2,2':6',2"-terpyridine, L2.4, produced six different dinuclear and tetranuclear metal complexes (Chapter 4).
The Zn(II) dinuclear complexes were used to study kinetics of hydrolysis of BNPP, and the enhanced rates were reported compared to the analogous mononuclear complexes. The detailed experimental methodology and results are discussed in Chapter 5.
The most interesting outcome of this research was formation of the box and wheel shaped complexes, where the ligand L2.3 binds with different metal ions via different coordination modes. The box shaped tetranuclear complexes were synthesised deliberately via structural control over the coordination chemistry of terpyridine-type site of L2.3, where the coordination flexibility of the pendent picolylamine-type site of the ligand was used to bind with other metal ions.
The tetranuclear [M¹₂M²₂(L2.3)₄X₂]⁶⁺ box shaped complexes were formed when two divalent M¹ ions bridge between the ligands to produce octahedral bis-terpyridine type complex M¹(L2.3)₂, and then two divalent M² ions link two M¹(L2.3)₂ units together through picolylamine binding sites, where X = Cl⁻, Br⁻, CH₃COO⁻; M¹ = Fe(II), Zn(II), Ni(II); M² = Zn(II), Cu(II).
The bis-bidentate bridging ligand terephthalate was also deliberately encapsulated in the middle of Fe₂Zn₂L2.3 box to produce the complex where X₂ = terephthalate. These structures invite speculation that it may be possible to bind and react molecules within these boxes.
In a more fortuitous outcome, Ni(II) ions were found to bind to both sites of L2.3 to give, exclusively, an unprecedented decanuclear wheel-shaped structure. A halide ion occupies the central position in the wheel, with Br⁻ being preferred over Cl⁻. The detailed crystal structures, and properties of the wheels shaped Ni₁₀(L2.3)₁₀ complexes are discussed in Chapter 6.
| Identifer | oai:union.ndltd.org:canterbury.ac.nz/oai:ir.canterbury.ac.nz:10092/9945 |
| Date | January 2014 |
| Creators | Kaur, Gurpreet |
| Publisher | University of Canterbury. Chemistry |
| Source Sets | University of Canterbury |
| Language | English |
| Detected Language | English |
| Type | Electronic thesis or dissertation, Text |
| Rights | Copyright Gurpreet Kaur, http://library.canterbury.ac.nz/thesis/etheses_copyright.shtml |
| Relation | NZCU |
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