Reflexivity and the process of maturation of students in a work-based learning programme

This thesis presents the outcomes of a five-year ethnographic research project of a work-based learning programme, the BA in Social Pedagogy (hereafter, the BA), which was provided in partnership with a university by a residential school for vulnerable children and young people (hereafter, the School) to its workers. The aim of the research was to develop an understanding of how the organisational fields of the School influenced learning practices and identities of workers undertaking the BA (hereafter, students). Two theoretical frameworks, of Pierre Bourdieu and Margaret Archer, were applied consecutively in the analysis of collected data. Bourdieu’s theory of practice, applied first, allowed an investigation of the conditioning by the School’s organisational fields of students’ dispositions and actions, as well as of a function of the BA in the mechanism of social reproduction of the School’s communities. Limitations of Bourdieu’s theoretical framework in examining students’ personal transformations in the course of their work and studies prompted a turn to Archer’s Morphogenetic Approach and theories of reflexivity and personal development. Re-analysis of collected data indicated that the expansion of the BA curriculum triggered and then sustained cultural and structural changes in the School. Such changes created enabling conditions for the process of maturation of students, with the BA educational practices and School work practices facilitating this process. This research project contributes to the field of applied sociological studies. Firstly, it develops an explanatory theory of processes at a work-based learning programme and its hosting institution. Secondly, it demonstrates that Archer’s theoretical framework presents methodological and analytical advantages, compared to Bourdieu’s theory of practice, for the investigation of social phenomena both on the level of an institution and on the level of individual actors, in particular when the institution undergoes cultural and structural changes and the individuals are progressing in their maturational development

Metaphors of Work-based Vocational Education for Residential Care

Within an ethnographic study of effects of organisational cultures on work-based learning, two students’ practice portfolios and interviews were analysed applying Bourdieu’s theoretical tools. Analysis pointed to two types of habitus, one being characterised by the student’s propensity to immerse herself in the “lifespace” of her local community and to cultivate a sense of belonging and trust, and the other by a disposition on the other student’s part to establish “boundaries” in her interaction with colleagues and to attain a “balcony view” of the turbulent events in the wider organisation. Metaphors used by the students in their writing indicated transformation of students’ habitus on their trajectories through the organisational fields

Metallosupramolecular assemblies : development of novel cyclometalated Pt(II) and Ir(III)-based capsules

Inspired by nature’s use of self-assembled systems to carry out virtually all biological processes, chemists have taken to building simplified synthetic systems that mimic the biotic world. Although transition metal-ligand interactions are rarely used for the purpose of biological self-assembly, they have several advantages over other weak noncovalent interactions, such as pronounced directionality and significant strength. These particular attributes have allowed chemists to construct a comprehensive library of self-assembled polygons and polyhedra, using different transition metal-ligand motifs. Many of these supramolecular assemblies possess cavities of defined shape and size, which are able to accommodate guest molecules. It has further been realised that isolation of guest species from the bulk phase can lead to many interesting functions, such as containment, sensing and catalysis. Herein, a new self-assembly strategy has been used to construct novel cyclometalated Pt cages and assembly of the first known [Ir(ppy)2]-based capsule has also been achieved. Chapter 1 includes an introduction to metallosupramolecular assemblies, followed by a comprehensive review of three-dimensional architectures with accessible cavities, their synthetic strategies and applications. Chapter 2 reports on the construction of novel Pt(II)-based trigonal prisms using an unusual, kinetically controlled protocol. By exploiting asymmetric cyclometalated 2-phenylatopyridine based platinum corner units that possess both labile and non-labile cis-coordination sites, trigonal prismatic stereoisomeric architectures have been selectively prepared by altering the sequence of addition of ditopic 4,4′-bipy (4,4′-bipyridine) and tritopic tpt (2,4,6-tris(4-pyridyl)-1,3,5-triazine) molecular structural components using a template free method. Collision-induced-dissociation mass spectrometry experiments were used to differentiate between the structural isomers due to their significantly different fragmentation profiles. Chapter 3 describes the synthesis and characterisation of the first molecular capsule based on an [Ir(ppy)2]+ 90° metallosupramolecular acceptor unit. Initial work focused on pyridine-based donor ligands from which an Ir2L2 metallamacrocycle was assembled. However, when the highly conjugated tpt “panels” were used, due to postulated constraints in the dihedral angle, self-assembly of the Ir6tpt4 octahedral was unsuccessful. The constraints in the dihedral angle were eliminated by swapping pyridine for nitrile-based ligands and following the development of a method to resolve rac-[(Ir(ppy)2Cl)2] into its enantiopure forms, homochiral Ir6tcb4 (tcb = 1,3,5-tricyanobenzene) octahedral capsules where realised. Photophysical studies on the Ircapsules have shown that the ensemble of cooperative, weakly coordinating ligands can lead to luminescence not present in the comparative mononuclear analogues. X-ray crystallographic analysis revealed that the Ir capsules possess cavities large enough to accommodate 4 triflate counterions. Through a series of titration experiments the ability of the capsules to act as anion sensors was also exposed. Further exploration into the host-guest chemistry of the Ir6tcb4 capsule is reported in Chapter 4. Subsequent experiments have shown that self-assembly is highly dependent on the counterions associated with the system. While a number of different anions (OTf-, BF4 -, ClO4 -, PF6 -) facilitate the formation of the same octahedral scaffold, when triflimide was employed as a bulkier counterion, no capsule was observed. On subsequent addition of smaller counterions, such as triflate, the same Ir6tcb4 cage assembles, demonstrating that the anions also act as templates. Kinetic stability experiments, undertook by monitoring the rate of scrambling of the Δ and Λ-[Ir(ppy)2]+ components within the preformed ensembles, show that the Ir capsules are up to 1.4×104 times more stable than their mononuclear analogues. The counter anions were also observed to play a crucial role in the capsule’s stability with measured scrambling half-lives ranging from 4.7 mins with tetrafluoroborate to as long as 4.5 days with triflate. In contrast, the rate of ligand exchange in simple mononuclear complexes, as ascertained using EXSY NMR experiments, was found to be approximately independent of the associated anion

Photoinduced energy- and electron-transfer from a photoactive coordination cage to bound guests.

In a coordination cage which contains an array of twelve naphthyl chromophores surrounding a central cavity, photoinduced energy or electron-transfer can occur from the chromophore array to the bound guest in supramolecular host/guest complexes

Stepwise synthesis of mixed-metal assemblies using pre-formed Ru( ii ) ‘complex ligands’ as building blocks

Two families of heteronuclear coordination complexes have been prepared in a stepwise manner using pre-formed, kinetically inert [RuL3]2+ building blocks, in which L is a bis-bidentate bridging ligand with two pyrazole–pyridyl termini, coordinated at one end to the Ru(II) centre. These pre-formed ‘complex ligands’ – with three pendant binding sites – react with additional labile transition metal dications to complete the stepwise assembly of mixed-metal arrays in which labile [Co(II)/Cd(II)] or inert [Ru(II)] ions strictly alternate around the framework. When L = the thiophene-2,5-diyl spaced ligand Lth, the complex [Ru(Lth)3]2+ is formed in the expected 3[thin space (1/6-em)]:[thin space (1/6-em)]1 mer[thin space (1/6-em)]:[thin space (1/6-em)]fac ratio: reaction with labile Co(II) or Cd(II) ions completes formation of a heteronuclear square [Ru2Co2(Lth)6]8+ or one-dimensional coordination polymer {[CdRu(Lth)3]4+}∞, respectively. In these only the mer isomer of [Ru(Lth)3]2+ is selected by the self-assembly process, whereas the fac isomer is not used. When L = a 1,3-benzene-diyl spaced ligand (Lph), the complex ligand [Ru(Lph)3]2+ formed in the initial step is enriched in mer isomer (80–87% mer, depending on reaction conditions). Two quite different products were isolated from reaction of [Ru(Lph)3]2+ with Co(II) depending on the conditions. These are the rectangular, hexanuclear ‘open-book’ array [Ru3Co3(Lph)9]12+ which contains a 2[thin space (1/6-em)]:[thin space (1/6-em)]1 proportion of fac/mer Ru(II) metal centres; and the octanuclear cubic [Ru4Co4(Lph)12{Na(BF4)4}]13+ cage which is a new structural type containing all mer Ru(II) vertices and all fac Co(II) vertices. The cavity of this cubic cage contains a tetrahedral array of fluoroborate anions which in turn coordinate to a central Na(I) ion – an unusual example of a metal complex [Na(BF4)4]3− acting as the guest inside the cage-like metal complex [Ru4Co4(Lph)12]16+

Stepwise synthesis of a Ru4Cd4 coordination cage using inert and labile subcomponents: introduction of redox activity at specific sites.

The kinetically inert mononuclear complex [RuL3](PF6)2 (1 : 3 mixture of fac and mer isomers), with three pendant binding sites, reacts with labile Cd(ii) ions to complete the assembly of a Ru4Cd4 cubic coordination cage in which reversible redox behaviour has been introduced at the Ru(ii) sites