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Title: Metal-based function in [2]rotaxanes : from molecular-level motion to dipolar interactions
Author: Gonzales Cabrera, Diego
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2007
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Two novel mechanisms for inducing shuttling in hydrogen-bond assembled architectures have been developed. In the first example, a metal chelating group is attached to the preferred binding site for a benzylic amide macrocycle via a methylene spacer within a two-station rotaxane. Metal ion complexation followed by deprotonation of the carboxamides nitrogen nearest the chelate group results in simultaneous binding of the metal ion both to the stopper and, crucially, to the high affinity station, thus inducing translocation of the macrocycle to the second binding site through competitive binding effects. In the second example, the same metal chelating group is directly attached to the high affinity station. In this architecture, simple metal complexation (CuII or CdII) to the stopper greatly attenuates the affinity of the adjacent binding site for the macrocycle due to sterics. This allosteric effect causes the macrocycle to move to a second station, distant from metal-binding site. in both molecular shuttles, this large-amplitude motion can be reversed by removal of the metal ion. In addition, a novel strategy for the assembly of hydrogen-bonded rotaxanes containing paramagnetic species in the macrocycle and the thread using the CuI-catalysed terminal alkyne-azide cycloaddition reaction is demonstrated. As a result, a range of unique homo- and mixed- metal-coordinated rotaxanes were prepared in very good yields. These systems were then utilised to establish and investigate dipolar interactions between the two paramagnetic metal centres using continuous wave electron paramagnetic resonance. The new synthetic strategy was then extended to synthesise rotaxanes with octamethylferrocene stoppers and metal-containing macrocycles. These systems were used to investigate and quantify the effects of dipolar interactions on the redox behaviour of the octamethylferrocene unit via cyclic and square-wave voltammetry measurements.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available