Duisburg, Universiẗat, Diss., 1998. / Dateiformat: zip, Dateien in unterschiedlichen Formaten.

Wuppertal, Universiẗat, Diss., 2001.

No description available.

Cyclodextrins, a family of compounds formed from a cyclic array of glucose monomers, contain a hydrophobic cavity which displays selective complexation of size specific guests. This selective molecular recognition is critical to the development of successful chemosensors. A selection of cyclodextrin-conjugates have been designed to report complexation of guests into the cyclodextrin cavity by optical and electrochemical means. Alkylated cyclodextrins containing a single linker group have been synthesised allowing the development of two cyclen-appended cyclodextrin conjugates and their lanthanide complexes. The tetraamide ligand (25) displayed a high rigidity, assessed by (^1)H NMR and luminescence methods. The Tb complex of the monoamide ligand [Tb.26] displayed long lived luminescence arising from energy transfer from cyclodextrin-complexed napthalene to the lanthanide. The association constant, K(_11), between naphthalene and the cyclodextrin [Tb.26], was calculated as 10,200 M(^-1). K(_11) between the Gd complex [Gd.26] and GdDOTAPh (40) was determined to be 1740M(^-1) by NMRD. These association constants are ca 14 and 7 times greater respectively than for the corresponding complexes with β-cyclodextrin (1). Bromonaphthalenes exhibit long lived phosphorescence when complexed within cyclodextrins. Four bromonaphthalene-appended cyclodextrins (57-60) were designed to form inframolecular self-complexes. Competitive complexation of optically transparent guests was expected to reduce the lifetime of phosphorescent emission. The four conjugates were successfully synthesised, although luminescence studies revealed no evidence for complex formation and no response upon competitive guest complexation was observed. The rotaxane (95) and corresponding thread (92) of a hydrophilic ferrocene- cyclodextrin conjugate were made and structurally assessed by CD, (^-1)H NMR and MALDI-TOF MS. The hydrophilic per-O-ethyl conjugates (93 & 100) were also synthesised. A lipophilic quinoline-cyclodextrin conjugate (94) was made, which, when incorporated into an optode membrane, allowed the detection of acetylcholine at micromolar concentrations.

Universiẗat, DIss., 2002--Bonn.

No description available.

Inspired by the performance and evolutionarily-optimised natural molecular machines that carry out all the essential tasks contributing to the molecular basis of life, chemists aim towards fabricating synthetic molecular machines that mimic biological nanodevices. The use of rotaxanes as a prototype for molecular machines has emerged as a result of their ability to undergo translational motion between two or more co-conformations. Although biological machines are capable of complex and intricate functions, their inherent stability and operational conditions are restricted to in vivo. Synthetic systems offer a limitless number of building blocks and a range of interactions to be manipulated. Transition metal-ligand interactions are utilised as one strategy to control the directional movement of submolecular components in artificial machines due to their well-defined geometric requirements and significant strength. This thesis presents new externally addressable and switchable molecular elements for transition metal complexed-molecular machines involving an acid-base switch. The proton input that induces changes to cyclometallated platinum complexes can be exploited to control exchange between different coordination modes. The development of the pH-switchable metal-ligand motif for the stimuli-responsive platinum-complexed molecular shuttle has also been explored. The metal-directed self-assembly of tubular complexes were studied in order to develop self-assembled rotaxanes. A series of metal building blocks was explored to extend the scope for a tube self-assembly.

The use of a chemical template to control the spatial arrangement of reactants revolutionized the synthesis of mechanically interlocked molecules. The recently developed ‘active metal template’ strategy, in which transition metal ions act as both the template to guide interlocking and as the catalyst for the covalent bond forming reaction that captures the interlocked structure, has several advantages in comparison with traditional ‘passive template’ approaches. In contrast with passive template approaches the active template strategy is more efficient, completing the assembly of the interlocked structure in one step instead of two and in some cases requiring only a substoichiometric amount of metal template. In addition, fewer permanent recognition sites are required and in certain cases the active template reaction can shed light on mechanistic details of related metalcatalyzed processes and act as a conduit for reaction discovery. This Thesis will discuss the expansion of this new methodology in two main directions: firstly, exploration of new active metal template reactions, specifically the application of a novel Ni catalyzed sp3–sp3 C–C bond forming reaction, and secondly, the application of previously developed active template reactions to the synthesis of agrochemical-based [2]rotaxanes and other architectures, macrobicyclic [3]rotaxanes, [2]catenanes and a trefoil knot.

This thesis describes the synthesis of acyclic, macrocyclic and, in particular, interlocked anion and ion-pair receptors and sensors. <strong>Chapter One</strong> will introduce the field of supramolecular chemistry with particular emphasis on areas which are pertinent to this thesis, including anion receptor design and templated synthesis of interlocked structures. <strong>Chapter Two</strong> focuses on the synthesis of new heteroditopic macrocycles functionalised with both cation and anion recognition sites and their incorporation into interlocked architectures. The affinity for a range of anions and ion-pairs is explored via ¹H NMR and UV-visible spectroscopy as well as by X-ray crystallography. <strong>Chapter Three</strong> details the incorporation of d- and f-metal luminescent reporter groups into an isophthalamide motif in order to construct acyclic, macrocyclic and [2]rotaxane receptors. <strong>Chapter Four</strong> investigates the synthesis of complex higher-order interlocked structures through post-synthetic modification of lower-order interlocked structures. <strong>Chapter Five</strong> explores the potential for fluorescent gold nanoparticle conjugates to act as luminescent and colourimetric sensors for chemical warfare agents (CWAs) by employing a fluorescent displacement assay technique.

Within living organisms in the natural world, highly complex systems have evolved over billions of years to carry out the specific synthetic functions required to support and propagate life. Nature's use of biological machines for the synthesis of functional molecules has inspired synthetic chemists from a broad range of specialisms to design artificial molecular machines and systems capable of facilitating non-trivial synthetic tasks. A core strategy employed in attempting to emulate biological machines for synthesis has been to mimic Nature's ability to compartmentalise discrete aspects of a synthetic process. Rotaxanes are favourable architectures around which to design molecular machines as their mechanically-interlocked nature provides the chemist with a unique means by which to achieve compartmentalisation and to control the effective molarity of non-covalently linked components. The research presented in this thesis investigates the design, synthesis and operation of novel, rotaxane-based molecular machines for the non-trivial assembly of individual amino acid building blocks into information-rich oligopeptides. The artificial devices described herein each endeavour to emulate (in a primitive manner) one of Nature's most remarkable machines for synthesis: the ribosome. Information is programmed into these 'synthetic ribosomes' through their careful design and modular assembly; upon operation of the artificial molecular machine, this transcribed information is translated into a pre-defined oligopeptide product. The research presented in this thesis is laid out as follows:Chapter 1 reviews the current state of the art in biomimetic molecular machines and systems capable of promoting non-trivial synthetic tasks;Chapter 2 describes a molecular machine capable of non-proteinogenic oligopeptide synthesis via the sequence-specific assembly of beta-homo amino acid building blocks;Chapter 3 presents a device which operates upon a polymer to assemble individual leucine units into a homo-oligopeptide. This product forms a secondary alpha-helical structure capable of asymmetric organocatalysis in the Juliá-Colonna epoxidation of chalcone derivatives;Chapter 4 details a novel mode of amide-bond-forming catalysis for rotaxane-based molecular machines with a view to assembling an advanced peptidic precursor to Penicillin G.Chapters 2 and 3 are presented as manuscripts which have been compiled for peer-review publication and which represent the collaborative efforts of the Author and the researchers indicated at the beginning of each chapter. The Author's contributions are also outlined at the beginning of each chapter. These manuscripts have been modified only to ensure consistency with the other chapters contained in this thesis.