The Synthesis and Characterisation of Polyhedral Oligomeric Silsesquioxane Bound Chromophores

Author: David John Clarke

Clarke, David John, 2008 The Synthesis and Characterisation of Polyhedral Oligomeric Silsesquioxane Bound Chromophores, Flinders University, School of Chemistry, Physics & Earth Sciences

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Abstract

This research involved the synthesis and characterisation of a range of optically active polyhedral oligomeric silsesquioxane (POSS) compounds. POSS precursor compounds containing functional groups required for subsequent attachment of the desired functional groups have been synthesised. Examples of such precursor compounds include mono-functionalised POSS compounds with periphery aldehyde, azide, amino and pyridyl functional groups. A variety of POSS compounds, functionalised with a range of optical functionalities, including optical limiters such as fulleropyrrolidine and iminofullerene, and dyes and pigments, including naphthalene, biphenyl, perylene, pyrene and porphyrin have been synthesised. The reaction of mono-functionalised POSS aldehydes with fullerene (C60) in the presence of N-methylglycine yielded the desired POSS fulleropyrrolidines, whilst reaction of mono-functionalised POSS azide with C60 yielded POSS iminofullerenes. All POSS fullerene compounds were characterised by power limiting measurements, exhibiting comparable power limiting to that of parent C60. The microwave condensation of mono-amino POSS with a range of mono- and bis-anhydrides yielded the POSS imide compounds, which were characterised by UV-Vis and fluorescence spectrophotometry. The perylene POSS imide derivative was further characterised by single crystal x-ray crystallography. The naphtha and biphenyl POSS imides exhibited extremely weak fluorescence, whilst the perylene ii POSS imide displayed particularly strong fluorescence, with a quantum yield approaching unity. The incorporation of a pyridyl group on the periphery of a mono-functionalised POSS cage allowed for the synthesis of the first porphyrin functionalised POSS compound. Mono-porphyrin POSS exhibited comparable absorption properties to other pyridyl ligated ruthenium porphyrins. Mono-functionalised pyrene POSS compounds were prepared through the reaction of 1-pyrene acid chloride with mono(3-aminopropyl)POSS. This synthetic pathway offered a convenient route to mono-functionalised pyrene POSS, in preference to the multi-substitution associated with Heck coupling. Mono-pyrene POSS was determined to be strongly fluorescent, exhibiting a high quantum yield of fluorescence

Keywords: silsesquioxane,POSS,fullerene,fulleropyrrolidine,iminofullerene,pyrene,perylene,porphyrin
Subject: Chemistry thesis

Thesis type: Doctor of Philosophy
Completed: 2008
School: School of Chemical and Physical Sciences
Supervisor: Janis Matisons