Design and syntheses of Mn-Anderson based compounds as functional hybrid materials

Rosnes, Mali Husby (2011) Design and syntheses of Mn-Anderson based compounds as functional hybrid materials. PhD thesis, University of Glasgow.

Abstract

This thesis focuses on the synthesis of hybrid organic-inorganic polyoxometales (POMs), more precisely Mn-Anderson based complexes; {MnMo6O18((OCH2)3-R)2}. A modular synthetic approach has been designed, resulting in an asymmetrically grafted Mn Anderson compound (compound 3a). Electrospray ionisation mass spectrometry (ESI-MS) was used to screen the batches from fractional crystallisation, identifying the pure material of the desired compound. Two additional symmetrically grafted Mn-Anderson compounds were synthesised containing the same organic ligands (compounds 1a and 2a). The Langmuir-Blodgett (LB) technique was used to deposit monomolecular films of the three isolated compounds on to solid substrates, and subsequently scanning force microscopy (SFM) was used to investigate the resulting architectures. Two of the compounds formed defined anisotropic fibre like structures, and it was found that the resulting surface architectures depend on the nature of the organic ligands employed.
For the Mn-Anderson complex which previously did not result in the formation of any defined structures cation exchange from tertbutylammonium (TBA) to dimethyldioctadecylammonium (DMDOA) was successfully performed (compound 1b). SFM investigations of LB deposited films showed perfectly shaped hexagonal nanocrystals. The nanocrystals are of high stability, although by thermal treatment self patterning occurs. Scanning capacitance microscopy (SCM) was carried out, and the hexagonal nanocrystals were found to exhibit fascinating capacitance behaviour.
The aforementioned work led to the design and syntheses of a range of organic ligands, along with the corresponding symmetrically grafted Mn Anderson complexes (compounds 1 12), with a diverse range of cations. Systematic SFM studies of LB deposited films of the resulting hybrid organic inorganic Mn-Anderson compounds were carried out with the results described and discussed.
Furthermore, the syntheses of three β-octamolybdate salts, along with their ESI-MS analyses, led to the proposal that the fragmentation of β-octamolybdate in solution is similar to that of α-octamolybdate, the traditional starting material for hybrid Mn Anderson compounds. Accordingly, three hybrid organic-inorganic Mn-Anderson compounds were successfully synthesised from the β-octamolybdate isomers (compounds C-J). These syntheses increase the understanding of the one-pot reaction mechanism, and might allow for the syntheses of Mn-Anderson compounds with new cations.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Polyoxometalates, Hybrid Mn-Anderson
• Subjects: Q Science > QD Chemistry
• Colleges/Schools: College of Science and Engineering > School of Chemistry
• Supervisor's Name: Cronin, Prof. Leroy
• Date of Award: 2011
• Embargo Date: 25 November 2015
• Depositing User: Miss Mali Husby Rosnes
• Unique ID: glathesis:2011-3035
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 29 Nov 2011
• Last Modified: 10 Dec 2012 14:03
• URI: https://theses.gla.ac.uk/id/eprint/3035