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Title: Metallosupramolecular chain-like assemblies
Author: Davis, Lisa J.
ISNI:       0000 0001 3416 6920
Awarding Body: Nottingham Trent University
Current Institution: Nottingham Trent University
Date of Award: 2007
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One-dimensional molecules that display magnetic exchange between metal centres remain relatively scarce and few have been studied that possess a combination of both magnetic and electrochemical properties. This thesis addresses the area using a novel approach employing a combination of molecular magnetism methodologies and supramolecular coordination chemistry, which consists of preparing a series of finite and infinite one-dimensional chains of supramolecular magnetic helicates. This thesis reports the synthesis, structural characterisation and magnetic properties of a series of novel chain-like assemblies, which are formed tlmough the metal-directed self-assembly of transition metal ions and the appropriately designed polytopic ligands. This is tackled via two approaches. The first is the synthesis of organic ligands capable of coordinating contiguous spincoupled paramagnetic metal centres into large helical structural motifs via metaldirected self-assembly reactions. This produced dinuclear helicates of the novel ligand l,4-his(2,2'-bipyridine-6)-l,4-diamino-2,3-diazahuta-l,3-dienyl with a range of transition metals where complexes of manganese, cobalt and nickel displayed antiferromagnetic behaviour, with nickel showing the strongest interaction (J = -11.3cm⁻¹, g = 1.87). The ligand system was successfully extended to give a novel series of trinuclear, tetranuclear and pentanuclear manganese helicates. All the cations are approximately 10 Å in diameter and range from 11-26 Å in length with a pitch of approximately 10Å and twist angles of approximately 60° (Nbpy-N) and 70° (Nbipy-Nbipy), demonstrating the uniformity of the series. The second approach is through the synthesis of small magnetic helical building blocks that can be used as supramolecular synthons to construct extended one-dimensional chains, where biacetylhydrazone-azine (BHA) and hiacetyl oxime azine (H2BOA) both fomi isostructural dinuclear helicates in good yields. The isostructural nickel complexes of the respective ligands place the oxime and amine terminal groups in an approximate C3 symmetry with a tripodal alignment, necessary for the desired directional hydrogenbonding, and display antifeiTomagnetic behaviour (J = -4.6 cm⁻¹ and -11.0 cm⁻¹) so hence have the potential to be used as functional supramolecular synthons.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available