Abstract
The research presented in this thesis is concerned with the design, synthesis and structural analysis of new platinum (II) pincer complexes with a view to developing new solid state and solution state molecular switches.Chapter 1 consists of a literature review that starts by introducing platinum and its numerous uses across a variety of fields. This review also considers the photophysics of platinum and considers the background theory for the observed spectral properties of Pt(II) complexes. The end of this chapter investigates the history and current research of Pt(II) complexes that are relevant to the research presented in this thesis. Chapter 2 is a description of the instrumental methods frequently used in this thesis. These include a description of single crystal X-Ray crystallography, solution state UV-Vis and emission spectroscopy, reflectance spectroscopy and NMR spectroscopy. Chapter 3 lays out the general research aim of this thesis, in addition to more
detailed aims for each of the chapters.
Chapter 4 is the first of the results chapters. It consists of a systematic study of a group of Pt(II) terpyridine complexes. The start of this chapter reviews the key literature in the area that inspired the research in this chapter. This study was designed to investigate the effects of ligand substitution and counter-ion sterics in a systematic way to assist in the development of a design methodology for ‘smart’ materials. This investigation focussed on the structural analysis of thirteen complexes, two of which had been previously published in the literature.
Chapter 5 shifted the focus from the use of terpyridine based ligands to N^C^N ligands. The central phenyl ring in this ligand increases the emissive properties of the Pt complexes. This chapter built on previous work within the Raithby group, utilising the same N^C^N pincer that had led to the discovery of a vapochromic complex. In this chapter, the ligand in the 4th position of the Pt coordination sphere was altered with ligands of various configurations and the spectral properties of the complexes were analysed using the techniques described in chapter 2. As a result a number of complexes were synthesised that displayed solvato and vapochromic capabilities and have potential uses in the field of chemical sensing.
Chapter 6 focussed on developing complexes for a specific purpose. In this instance photo-switching. The functional groups azobenzene and stilbene were used to establish a benchmark for future materials. These functional groups were substituted onto two different areas of the Pt complex, on the pincer and via an acetylide on the 4th co-ordination site of the Pt centre. Computational techniques were utilised to predict the orbital arrangements and solution state spectra of the complex and therefore whether they would undergo a cis/trans isomerisation. Once each of the complexes had been analysed it was found that the computational predictions were correct and with further development would be an invaluable tool in predicting the behaviour of these complexes.
Chapter 7 built on the research conducted in chapter 6 and used computational methods to predict whether a complex would be sensitive to changes in pH. In this instance the two different substitution patterns showed sensitivity to changes in pH, however the behaviour for each complex was unique. Three pH
sensitive complexes were discovered as part of the research in this chapter and show promise as solution and solid-state sensors.
The conclusions and potential future research is detailed in Chapter 8. Chapter 9 details the synthesis of each of the complexes discussed in this thesis.
| Date of Award | 24 Jun 2020 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Paul Raithby (Supervisor) & Chick Wilson (Supervisor) |