Abstract
Whilst a great deal of research has been undertaken on transition metal self-assembled complexes and a whole plethora of different architecture and geometry have been established their uses are rather limited apart from some notable examples.[1–3] In this thesis two foci of anion- binding supramolecular structures are discussed: cytotoxic chemotherapies and pollutant removals. In terms of chemotherapeutic treatments, bis- bidentate ligands L1, L2 and L3 were seen to form dinuclear double helicate species upon reaction with the metal cations Zn2+ and Cu2+ in both solid and solution states. These complexes were then tested for their in vitro toxicity and selectivity towards different cancer lines in comparison to ‘healthy cells’, with pleasingly successful results shown with treatment of PSN-1 cancer cells with [(L2)2Zn2]4+. As the lead complex, [(L2)2Zn2]4+ was tested for in vivo efficacy against PSN-1 human pancreatic tumours as well as in ovo, testing demonstrating the drug to be well tolerated with 100% embryo survival at day 14 and induced a 67% decrease in tumour mean weight. Interestingly, complexes derived from L3, although not as toxics as L2-containing complexes, show that upon addition of sulphate dianions to the complexes, the selectivity significantly improves due ‘healthy cell’ inhibition increasing dramatically.Removal of phosphate from aqueous systems, including bacterial growth media, was explored using two different ligand metal complex species. L4 and L4a were synthesised, both containing a stereospecific cyclohexane central spacer unit and bis-bidentate pyridyl thiazole ligand strand with L4a also containing a long chain ester group on the pyridyl ring. Both species showed a strong affinity for phosphate and sulphate anions, and the long chain ester group allowed for solubility in aqueous media. A series of competitive experiments were conducted and illustrated that the selectivity of the species could be tuned through pH, allowing for a ‘recyclable’ process in which transfer of anions across a DCM membrane in a U tube experiment, charged with the [(L4a)2Zn2]4+ complex, between the source phase of KHPO4 and receiving phase of NaHSO4. L6 and L7 were both synthesised using previously reported bis tridentate ligand synthesis, with changes to the pyridyl substituents on the ligands through inclusion of differing phenyl groups. Both ligands, upon self- assembly with Cu2+ metal species, showed successful binding of phosphate anions, with the [(L6)2Cu2]4+ complex showing a much stronger selectivity in competitive experiments than the L7 complex. A dramatic drop in phosphate concentration in treatment of a known BG11 algae growth media with [(L6)2Cu2]4+ demonstrating that phosphate can be removed selectively and efficiently even when a whole host of other cations and anions are present. It was also shown that this depletion of phosphate had a dramatic effect on the growth rate of the blue-green algae Synechocystis.
| Date of Award | 13 Feb 2025 |
|---|---|
| Original language | English |
| Supervisor | Craig Rice (Main Supervisor) & Roger Phillips (Co-Supervisor) |