New strategies towards the development and understanding of self-assembled polyoxometalate building blocks

Cameron, Jamie McDougall (2014) New strategies towards the development and understanding of self-assembled polyoxometalate building blocks. PhD thesis, University of Glasgow.

Abstract

The work presented herein covers a broad range of polyoxometalate (POM) chemistry, exploring a variety of addenda, template and heterometal species as part of a fundamental study into the development of new POM ‘building blocks’. Whilst the isolation of new POM species capable of serving as platforms for the realisation of new functional materials remains a key goal, a clear gap in our existing knowledge of the processes by which these species assemble in solution has been identified as a significant obstacle to continued progress in the field. A firm emphasis is thus placed on understanding, either by careful empirical observation or direct analytical measurement, the route by which these clusters form and transform under the conditions in which they are synthesised.

The synthesis and characterisation of a new class of lacunary, lanthanide substituted [LnV12O32(Cl)]2- polyoxovanadate clusters is reported by employing a previously unknown coordination driven structural rearrangement. The electrochemical, magnetic and photoredox properties of these cage type clusters is studied and their use as the first ever lacunary oxovanadium building blocks is demonstrated in the one pot and stepwise syntheses of di substituted {Gd2V12} and {GdErV12} species, respectively.

The template effect of lone pair containing pyramidal heteroatoms has emerged recently as a powerful new strategy to isolate complex, self assembled POM clusters though this primarily one pot strategy currently suffers from a lack of a coherent and rational synthetic approach. Efforts to synthesise a series of five new POM clusters, each related by the same transient {Se2W12} building block are presented and a comparative study is presented between these new species and their known tungstophosphate analogues. A similar approach is also employed to isolate the highest nuclearity Pd substituted POM clusters reported thus far and this system is found to contain an unusual example of POM isomerism over the nanoscale.

Lastly, mass spectrometric techniques have been explored as an analytical tool with unparalleled resolving power for the real time study of the in situ speciation, assembly and formation of TMSP species. In this way, it has been possible for the first time to elucidate direct mechanistic information relevant to the formation of a series of complex Fe substituted POM species. Further to this, ion mobility spectrometry – mass spectrometry (IMS MS) has been used detect the supramolecular aggregation of azobenzene functionalised hybrid POMs and to quantitatively detect the extent of any photoisomerisation induced structural response in the gas phase.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Polyoxometalates, inorganic synthesis, mass spectrometry
• Subjects: Q Science > QD Chemistry
• Colleges/Schools: College of Science and Engineering > School of Chemistry
• Supervisor's Name: Cronin, Professor Leroy
• Date of Award: 2014
• Embargo Date: 4 September 2018
• Depositing User: Mr Jamie M Cameron
• Unique ID: glathesis:2014-5473
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 10 Sep 2014 08:17
• Last Modified: 16 Oct 2017 15:56
• URI: https://theses.gla.ac.uk/id/eprint/5473