Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.693942
Title: Branched organometallic complexes for molecular electronics
Author: Inkpen, Michael Stephen
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2013
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Abstract:
To date, investigations concerning single or small groups of molecules for molecular electronics have largely focussed upon the transfer of electrons from donor to acceptor (electrodes or redox centres), through a single molecular pathway (bridging ligand or linear structure). Herein is described the synthesis and electrochemical properties of some branched and macrocyclic compounds containing {FeCp 2 } and {Ru(dppe) 2 } centres, with phenylene ethynylene backbones and pyridyl-termini for surface binding (Chapters 2 and 5 , respectively). Such systems provide two well-defined molecular pathways for electron transfer, facilitating the study of quantum interference effects and other phenomena resulting from concurrent, and ultimately convergent, electron transport. In addition, the large-scale 'oxidative purification' of 1,1?-diiodoferrocene ( 1 ) is presented (Chapter 2) , its usefulness as a starting material being further enhanced by an investigation into the optimisation of its (typically low-moderate yielding) reactions with terminal alkynes under Sonogashira cross-coupling conditions (Chapter 3) . As part of this study, attempts to synthesise 1,1?-bis[(4-thioacetylphenyl)ethynyl]ferrocene from 1 and 4-ethynylphenylthioacetate unexpectedly produced a cyclic trimer (15) of the latter. This observation afforded an explanation as to why the Fc?C?C?C6H4?SAc motif may not be formed using this approach, and resulted in the realisation of a new route to ?-phenylthioketones in general. The linear complex Ru(dppe)2(C?C?C5H4N)2 (17) has also been prepared - a synthesis complicated by the bifunctional nature of the 4-ethynylpyridine ligand (Chapter 4). It is hoped that future conductance studies of this and extended structures will complement recent work by others on analogous complexes with isonitrile and thiolate-termini. Experiences with protecting the pyridyl nitrogen of 4-ethynylpyridine, and the moderate success of employing N-methyl-4- ethynylpyridinium triflate (19) as a ligand, are detailed. Finally, 'mixed-valence' complexes of the type [{M(L) n}2(?-BL)] (?-BL = bridging ligand) are discussed and evaluated in light of recently observed correlations between their measured ?E1/20 values (the difference between sequential redox events, ?E1/20 = E20 - E10) and IR triple bond frequencies of analogous {M(L) n}?R (R = C?O, ?C?N?C?C?Ph) complexes (a indicator of electron density at {M(L) n}) (Chapter 6). Trends in individual contributions to the free energy of comproportionation are explored for complexes of the type [{M(L) n}2(?-C?C?C?C)].
Supervisor: Albrecht, Tim ; Long, Nicholas Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.693942  DOI: Not available
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