This thesis details the silver(I) coordination chemistry of thirty four alkene-containing ligands. The synthesis of thirty two of these ligands is described of which fifteen are unreported compounds. The ligands were designed to fully explore the potential of the silver(I)-alkene synthon in metallosupramolecular chemistry. Five series of ligand were designed each exploring a different facet of ligand design. Three series explored different ligand cores which included benzene, naphthalene and single atoms such as carbon, oxygen and nitrogen. Another series explored ligands of higher denticity including tri-, tetra- and hexa-substituted benzenes. The last series investigated ligands with functional groups in addition to olefins, in particular, heterocyclic nitrogens. A metal-centred ligand was created from a bifunctional ligand subunit. The silver(I)-alkene synthon has been used to create a range of assemblies. Polymeric structures were favoured with a variety of one-dimensional polymers with linear, ladder, helical and necklace type structures. Two-dimensional networks were formed, with some showing porosity. Three-dimensional metallopolymers were formed, including an interpenetrated three-dimensional network. Discrete complexes are commonly of the type Ag2L2 but with the occasional formation of Ag2L. It is shown that silver(I)-alkene interactions can coexists with other stronger interactions such as silver(I)-nitrogen. The deliberate use of bifunctional ligands allowed the formation of many interesting assemblies including an Ag3L2 heterotopic helicate. A Cu(I) complex with copper(I)-alkene interactions was identified. Techniques used to characterise the ligands and complexes include NMR, mass spectrometry, elemental analysis and X-ray crystallography. The crystal structures of seven organic compounds and forty six complexes are discussed.

This study investigates the metallosupramolecular chemistry of functionalised 1,2-diazole ligands, by the preparation and characterisation of a range of first-row transition metal coordination polymers and discrete assemblies. To this end, twenty-six ligands containing 1,2-diazole functionality have been synthesised, twenty-one of which have not previously appeared in the coordination chemistry literature. Utilising these compounds, forty new coordination compounds have been prepared and characterised by single-crystal X-ray crystallography and other analytical techniques, and their solid-state structural features discussed in the search for reproducible new diazole-based synthons for the designed synthesis of new functional materials. Particular attention is paid to the contribution of the second nitrogen atom on the diazole ring, which participates in structure-directing hydrogen bonding interactions, or acts as a synthetic handle to easily append further functionality to the ligand system. The design of the ligands is separated into two primary categories, representing the different approaches adopted for the synthesis of the metallosupramolecular architectures. The combination of 1H-pyrazole and carboxylic acid functionality in mixed-ligand assemblies was investigated with the combination of bis-pyrazole and bis-carboxylic acid ligands, and with the preparation of ligands containing both functional groups. This approach was extended to the related heterocyclic species indazole, with all five possible isomers of indazole-carboxylic acid synthesised and used in coordination chemistry for the first time. The 1H-diazole-carboxylate synthon was employed in the synthesis of fourteen coordination polymers and three discrete assemblies. Heteroaryl substitution at the 1-position of pyrazole or indazole compounds was employed to generate chelating ligands containing pyridine or benzimidazole functionality, which were used to form nineteen discrete complexes, including dinuclear helicates and metallocycles, and five coordination polymers. The effect of flexibility and distance between coordination sites in bis-bidentate ligand systems was examined, in conjunction with studies into the effect of steric bulk and variation of the electronic nature of the coordinating groups. While this study is primarily concerned with the solid-state structural chemistry of 1,2-diazole coordination compounds, attention is paid where appropriate to solution-based measurements such as NMR and UV/Visible studies, and the pertinent behaviour of functional materials, such as thermogravimetric analysis for solvated species and gas uptake studies for stable void-containing materials.

This thesis describes the preparation of a series of compounds containing π-excessive, five-membered, heterocyclic rings with peripheral aryl substituents, designed to investigate their oxidative cyclodehydrogenation and/or photocyclisation to form curved, fused aromatic systems with a heterocyclic atom at the core of the compound. The ability of these compounds to undergo oxidative cyclodehydrogenation was investigated using a range of conditions, including the use of Lewis acidic transition metals, organic reagents and light as catalysts to carry out the desired carbon-carbon bond forming reactions. Two backbone linked 2,2’-biimidazole ligands were prepared to investigate their coordination chemistry with a range of different metal ions and counter ions. Two families of model compounds, including ten previously unreported compounds, were prepared and subjected to various conditions for oxidative cyclodehydrogenation and photocyclisation resulting in the isolation of compounds with one carbon-carbon bond formed between the peripheral aryl rings in the same position on the heterocyclic ring, nineteen previously unreported compounds were isolated. Additionally, in one case oxidative cyclodehydrogenation resulted in the formation of two carbon-carbon bonds, producing a highly strained aromatic compound containing a heterocyclic ring. Photocyclisation of one family of compounds resulted in the formation of a different heterocyclic core dependent upon the substituent on the nitrogen atom. Five pentaarylpyrrole compounds, three of which were previously unreported, were also prepared after the exploration of various synthetic routes towards the pentaarylpyrrole motif. Photocyclisation also resulted in the formation of one carbon-carbon bond. The compounds resulting from oxidative cyclodehydrogenation and photocyclisation were characterised by NMR spectroscopy, UV/vis spectroscopy and fluorometry, where possible X-ray crystallography was also used. The coordination chemistry of backbone linked 2,2’-biimidazole ligands to various metal ions could be controlled by the length of the backbone linker. The ethyl linked 2,2’-biimidazole ligand formed bridging and monodentate coordination compounds with various metal ions, the metallosupramolecular assemblies produced with silver ions could be controlled by the anion present. Discrete coordination complexes were usually formed, but in two cases metallopolymers were produced. The propyl linked 2,2’-biimidazole ligand formed exclusively discrete, chelating complexes with copper (II) metal ions. Eighteen coordination complexes were prepared during the course of this study characterized by X-ray crystallography, and NMR spectroscopy where appropriate.

Metallosupramolecular self-assembly has fast expanded as a field due to the possibility for relatively facile construction of large assemblies through reversible non-covalent interactions, compared to their more synthetically challenging covalent counterparts. Not least, it provides a fast and often quantitative route to the construction of three-dimensional structures with a cavity. These internal spaces have been shown to be effective for a variety of applications, including but not limited to catalysis, drug delivery, use as a noncovalent protecting group, a separations material etc. Thermodynamic processes, with the inherent advantages of atom efficient, high-yielding reactions, usually control these systems. However this can also be a double-edged sword, with these systems susceptible to changes to specific ambient conditions, and are thus often not kinetically stable. Herein, we report the expansion of a method utilising the one electron oxidation of high spin d7 cobalt(II) to low spin d6 cobalt(III) as a molecular locking mechanism as part of the assembly process. This allows for the formation of species under thermodynamic control in the CoII manifold, with the kinetic stability of these assemblies in the oxidised CoIII and has been used to synthesise a variety of tetrahedra and helicates with a series of bis-bidentate N,N’-chelate ligands, which have shown to be stable away from their thermodynamically preferred conditions for long periods of time. These containers can be made both water and organic soluble via counteranion exchange, and a series of guests have been shown to bind in the tetrahedral species. Alongside on going biological viability tests, these guests show promise for a variety of applications including fluorescent tagging and radio-diagnostic agents. Novel switching methods have also been demonstrated for transformations between these species going both energetically down and up hill.

No description available.

This study investigates the self-assembly of ligands consisting of sterically hindered backbones. Ligands synthesised in this study took advantage of the twisted nature of benzil-2,3-dihydrazone brought about by the steric repulsion between two neighbouring phenyl groups. Synthesis of all ligands used a simple imine condensation reaction, where benzil-2,3-dihydrazone was combined with a chosen aromatic aldehyde. Coordination studies were conducted using first row transition metals and described in text are the solid state structures of twelve new discrete supramolecular complexes, characterised by single crystal X-ray crystallography. Chapter 1 outlines an introduction to the topics discussed in this text, while providing examples drawn from literature and nature. Chapter 2 details the modified synthesis of bis-2-pyridyliminohydrazono-1,2-diphenylethane, L1, and the in-depth background of previous studies with the ligand. The complexes of L1 with Mn(II), Fe(II), Co(II), Cu(I) and Zn(II) determined by single X-ray crystallography are presented, noting the structural effects different metal ion sources have upon L1. In chapter 3 the modified synthesis and characterisation of bis-2-imidazolyliminohydrazono-1,2-diphenylethane, L2, is presented. Crystallographically characterised complexes from the combination of L2 with Mn(II), Ni(II), Co(II) and Zn(II) show the formation of interesting topologies which are compared to structures previously determined. Chapter 4 begins with a brief introduction to clusters, followed by the synthesis and characterisation of a recently synthesised ligand, bis-2-salicyliminohydrazono-1,2-diphenylethane, L3,. The formation of a Ni(II) cluster with L3 is further discussed in detail, and outlines the future scope for the work with these ligands. The synthesis and characterisation of L4, and the discussion of mononuclear complex formed between L4 and Cu(II) is also introduced. The chapter concludes with a discussion with the potential future direction of this work with these ligands and their related compounds. Chapter 5 concludes the results and discussion with a brief summary of these results. Chapter 6 outlines the synthesis and characterisation of all ligands and complexes used in this study as well as potential ligands for future studies.

This thesis details the synthesis and coordination chemistry of twenty-five nitrogencontaining heterocyclic ligands, nineteen of which were previously unreported compounds. These ligands were designed for use as synthons for the formation of molecular cages, so contain multiple coordination sites capable of bridging multiple metal atoms. The majority of molecular cages in the literature are formed by rigid bridging ligands, whereas the ligands studied in this research incorporate a higher level of flexibility, thereby lessening the degree of control over the self-assembly process and increasing the number of possible structures that can be formed upon reaction of these ligands with meal salts. Three of the new ligands synthesised were two-armed bridging ligands, which were reacted with a wide variety of metal salts to investigate what self-assembly products were formed. The complexes characterised include a M₃L₃ cyclic trimer, a range of coordination polymers of varying dimensionality, a range of dimeric products and a series of M₄L₆ cage-like molecular squares. However, the majority of ligands studied were three-armed, potentially tripodal compounds, which were envisaged as potential components of M₃L₂ or M₆L₄ molecular cages. The products of self-assembly of these ligands with various metals salts were shown to include a variety of discrete tri- and tetranuclear complexes, a range of coordination polymers of varying dimensionality and interpenetration, and a complex M₆L₄ assembly that appears to be a collapsed coordination cage. Unfortunately some of the ligands synthesised were shown to decompose in the presence of various metal salts, a phenomenon already identified in the literature. Analogues of these decomposition products were synthesised deliberately to identify the potential of a known tridentate ligand as a metallosupramolecular synthon. ¹H NMR spectroscopy, mass spectrometry, elemental analysis, thermogravimetric analysis and X-ray crystallography were used to study the compounds synthesised. The crystal structures of five ligands and fifty-one complexes are discussed.

This thesis details the synthesis and coordination chemistry of twenty-five nitrogencontaining heterocyclic ligands, nineteen of which were previously unreported compounds. These ligands were designed for use as synthons for the formation of molecular cages, so contain multiple coordination sites capable of bridging multiple metal atoms. The majority of molecular cages in the literature are formed by rigid bridging ligands, whereas the ligands studied in this research incorporate a higher level of flexibility, thereby lessening the degree of control over the self-assembly process and increasing the number of possible structures that can be formed upon reaction of these ligands with meal salts. Three of the new ligands synthesised were two-armed bridging ligands, which were reacted with a wide variety of metal salts to investigate what self-assembly products were formed. The complexes characterised include a M₃L₃ cyclic trimer, a range of coordination polymers of varying dimensionality, a range of dimeric products and a series of M₄L₆ cage-like molecular squares. However, the majority of ligands studied were three-armed, potentially tripodal compounds, which were envisaged as potential components of M₃L₂ or M₆L₄ molecular cages. The products of self-assembly of these ligands with various metals salts were shown to include a variety of discrete tri- and tetranuclear complexes, a range of coordination polymers of varying dimensionality and interpenetration, and a complex M₆L₄ assembly that appears to be a collapsed coordination cage. Unfortunately some of the ligands synthesised were shown to decompose in the presence of various metal salts, a phenomenon already identified in the literature. Analogues of these decomposition products were synthesised deliberately to identify the potential of a known tridentate ligand as a metallosupramolecular synthon. ¹H NMR spectroscopy, mass spectrometry, elemental analysis, thermogravimetric analysis and X-ray crystallography were used to study the compounds synthesised. The crystal structures of five ligands and fifty-one complexes are discussed.

In molecular magnetism, rational design and serendipity have played complementary roles in the synthesis of complexes which display a breadth of interesting physical characteristics. These range from the basic understanding of magneto‐structural correlations, to more complicated phenomena such as slow relaxation of the magnetisation, spin frustration effects, and tuning magnetic interactions with a view to spintronics. The inherent physical properties of these complexes has already afforded molecules which can behave as single‐molecule magnets, singlechain magnets, single‐ion magnets, magnetic metal‐organic frameworks, magnetic refrigerants, and molecular qubits. Even when the building blocks are well known, the rational design of magnetic clusters can be extremely difficult, with the shape and nuclearity often dominated by several internal and external factors. Metallosupramolecular processes proffer an attractive strategy to the rational design of these clusters by making use of structurally‐rigid precursors which, when combined in the correct stoichiometric ratio, can be used to construct various predefined discrete two‐ and three‐dimensional polygons and polyhedra. In particular, the use of metalloligands as structurally‐rigid precursors is appealing, not only because of their often‐straightforward synthesis, but because of their ability to be easily modified in order to create comparable building blocks with different chemical and physical properties. It is therefore surprising that there are limited examples of magnetic architectures built through this approach. Each chapter of this thesis aims to exploit the use of acetylacetonate‐based paramagnetic metalloligands for the synthesis of structurally analogous magnetic coordination capsules, with inherently different magnetic properties. Chapter 2 describes the structural and magnetic studies of fourteen tetradecanuclear coordination cubes, synthesised using the paramagnetic metalloligand [MIIIL3] (MIII = Cr, Fe; HL = 1‐(4‐pyridyl)butane‐1,3‐dione). The heterometallic [MIII8MII6L24]n+ (MII = Co, Ni, Cu, and Pd; n = 0‐ 12) cubes formed from the reaction of [MIIIL3] and a “naked” MII salt are all topologically similar, with the MIII ions occupying the corners of the cubes and the MII ions occupying the faces. Excluding the PdII‐based cube, all of the complexes display magnetic exchange interactions at low temperatures. Due to the enormous size of these clusters and their resulting matrices, the magnetic fitting was done using the process of statistical spectroscopy. Chapter 3 describes the structural and magnetic studies of five [MIII2MII3L6]n+ (MIII = Cr, Fe, and Al; MII = Co, Zn, and Pd; HL = 1‐(4‐pyridyl)butane‐1,3‐dione; n = 0‐6) trigonal bipyramids, built using the diamagnetic and paramagnetic metalloligands [MIIIL3]. [FeIII2CoII3L6Cl6] represents the first magnetic trigonal bipyramid synthesised through the pyridyl‐based metalloligand approach. SQUID magnetometry studies show a weak antiferromagnetic exchange interactions between the FeIII and CoII ions, while EPR spectroscopy measurements demonstrate a small increase in the zero‐field splitting parameter of the FeIII ion upon coordination of [FeIIIL3] to a MII ion. Complete active space self‐consistent field (CASSCF) calculations show the axial zero‐field splitting parameter of CoII to be ≈‐14 cm‐1, which is consistent with the magnetothermal and spectroscopic data. Chapter 4 describes the synthesis and characterisation of six magnetic trigonal bipyramids, synthesised through dynamic covalent reactions of the metalloligand [FeIIILNH23] (HLNH2 = 1‐(4‐ aminophenyl)butane‐1,3‐dione) with either a dialdehyde or diacyl dichloride. The three [FeIII2MII3Lim3]n+ (MII = Co, Ni; n = 0‐6) imine‐based cages are formed from the reaction of the metalloligand with 2,6‐pyridinedicarboxaldehyde in the presence of a templating MII salt and a catalytic amount of acid, whereas the three [FeIII2Lam3] amide‐based cages are formed from the reaction of the metalloligand with isophthaloyl chloride in the presence of a base. The [FeIII2NiII3Lim3]n+ trigonal bipyramid displays weak antiferromagnetic interactions between FeIII and NiII ions, with JFe‐Ni = ‐0.12 cm‐1 and DNi = 8.93 cm‐1, while the [FeIII2Lam3] amide‐based cages display interesting configurational features dominated by the enthalpic gain from a series of intermolecular interactions.

Βασικός στόχος της παρούσης Διπλωματικής Εργασίας ήταν η μελέτη της κρυσταλλικής μηχανικής συμπλόκων ενώσεων του CuII με το 2-φαινυλοϊμιδαζόλιο ως υποκαταστάτη. Η κρυσταλλική μηχανική μπορεί να θεωρηθεί ως ο κλάδος της υπερμοριακής χημείας στη στερεά κατάσταση. Η υπερμοριακή χημεία (supramolecular chemistry) είναι μια από τις πλέον δημοφιλείς και γρήγορα αναπτυσσόμενες περιοχές της πειραματικής χημείας. Χαρακτηρίζεται ως η χημεία των ασθενών διαμοριακών δυνάμεων και εστιάζει στη δομή και λειτουργία χημικών συστημάτων με υψηλή πολυπλοκότητα (υπερμόρια) που προκύπτουν από το συνδυασμό δύο ή περισσοτέρων διακριτών χημικών ειδών (μορίων, ιόντων) και συγκρατούνται με ασθενείς (και αντιστρεπτές) διαμοριακές δυνάμεις (π.χ. αλληλεπιδράσεις π-π, δεσμούς υδρογόνου, υδρόφοβες αλληλεπιδράσεις, δυνάμεις van der Waals, αλληλεπιδράσεις διπόλου-διπόλου, δεσμούς ένταξης μετάλλου-υποκαταστάτη κλπ). Ένα σημαντικό πεδίο της υπερμοριακής χημείας είναι αυτό της κρυσταλλικής μηχανικής (crystal engineering) που αναφέρεται στη στρατηγική σχεδιασμού ενός κρυσταλλικού υλικού με επιθυμητές ιδιότητες και βασίζεται στην κατανόηση και τον έλεγχο των διαμοριακών αλληλεπιδράσεων των μορίων στην κρυσταλλική κατάσταση. Καταρχήν, πραγματοποιήθηκε η σύνθεση συμπλόκων ενώσεων με γενικό τύπο ΜΙΙ/Χ-/L, όπου ΜΙΙ = CuII, X- = Cl-, NO3-, ClO4-, SiF62-, SO42- και L = 2-φαινυλοϊμιδαζόλιο. Από τις συνθετικές παραμέτρους που μεταβάλλαμε -γραμμομοριακή αναλογία μετάλλου:υποκαταστάτη, πολικότητα του διαλύτη (MeOH, EtOH, MeCN, DMF, CH2Cl2), συνθήκες θερμοκρασίας και μέθοδο κρυστάλλωσης– απομονώσαμε και χαρακτηρίσαμε τα σύμπλοκα: (LH)+(NO3)- (1), [CuCl2L2] (2), [Cu2(OMe)2(L)4(NO3)2]∙2MeOH (3∙2MeOH), [Cu(L)4](NO3)2 (4), [Cu2(OMe)2(L)4](ClO4)2 (5), [Cu(L)4](ClO4)2 (6), [Cu2(OMe)2(L)4]SiF6 (7) και [Cu2(SO4)2(L)4] (8). Με τη βοήθεια της κρυσταλλογραφικής ανάλυσης με ακτίνες Χ των ανωτέρων συμπλόκων, διαπιστώθηκε ότι οι διαμοριακές αλληλεπιδράσεις που είναι υπεύθυνες για την υπερμοριακή οργάνωση των δομών τους είναι ισχυροί και ασθενείς δεσμοί υδρογόνου και αλληλεπιδράσεις τύπου π-π. Αναλυτικότερα: • Σταθερά μοτίβα διαμοριακών αλληλεπιδράσεων (συνθόνια) σχηματίζονται μεταξύ των τεκτονίων N-H των ιμιδαζολικών δακτυλίων και των ανόργανων ανιόντων X- (Cl-, NO3-, ClO4-, SiF62-, SO42-) ή/και πλεγματικών μορίων διαλύτη, οδηγώντας σε 1D, 2D και 3D υπερμοριακές δομές. • Οι δομές σταθεροποιούνται περαιτέρω μέσω ενδομοριακών (σύμπλοκα 4, 5 και 6) και διαμοριακών (σύμπλοκο 2) αλληλεπιδράσεων τύπου π-π. • Το μέγεθος και το φορτίο των ανιόντων δεν επηρεάζουν τους δομικούς πυρήνες των μορίων, σε αντίθεση με την υπερμοριακή οργάνωση που επηρεάζεται καθοριστικά και οδηγεί σε 2D και 3D αρχιτεκτονικές. / The main target of this diploma thesis was the crystal engineering studies of coordination compounds of CuII using 2-phenylimidazole as ligand. Crystal engineering may be regarded as the solid-state branch of supramolecular chemistry. Supramolecular chemistry is one of the most popular and rapidly developing areas of experimental chemistry. It may be defined as the chemistry of weak intermolecular forces and focuses on the structure and function of chemical systems of high complexity (supermolecules), resulting from the association of two or more discrete chemical species (molecules, ions) held together by weak (and reversible) intermolecular forces (e.g. π-π interactions, hydrogen bonds, hydrophobic interactions, van der Waals forces, dipole-dipole interactions, metal-ligand coordination bonds etc). Crystal engineering is an important field of supramolecular chemistry that refers to the design and synthesis of a crystalline material with desired properties, based on the understanding and exploitation of intermolecular interactions in the crystalline state. Initially the synthesis of coordination complexes with general formula ΜΙΙ/Χ-/L [ΜΙΙ = CuII, X- = Cl-, NO3-, ClO4-, SiF62-, SO42- and L =2-phenylimidazole] took place. By altering the parameters of synthesis –metal:ligand molar ratio, solvent polarity (MeOH, EtOH, MeCN, DMF, CH2Cl2), temperature, as well as crystallization method– we were able to isolate and study the following complexes: (LH)+(NO3)- (1), [CuCl2L2] (2), [Cu2(OMe)2(L)4(NO3)2]∙2MeOH (3∙2MeOH), [Cu(L)4](NO3)2 (4), [Cu2(OMe)2(L)4](ClO4)2 (5), [Cu(L)4](ClO4)2 (6), [Cu2(OMe)2(L)4]SiF6 (7) και [Cu2(SO4)2(L)4] (8). Based on the X-ray crystal structure determination of the above complexes, it was established that the intermolecular interactions responsible for the supramolecular organization of the structures are strong and weak hydrogen bonds, as well as π-π interactions. Specifically: • Supramolecular synthons between the N-H tectons of imidazole rings and the inorganic anions X- (Cl-, NO3-, ClO4-, SiF62-, SO42-) or/and lattice solvent molecules are formed, leading to 1D, 2D and 3D supramolecular structures. • The structures are further stabilized by intramolecular (complexes 4, 5 and 6) and intermolecular (complex 2) π-π interactions. • The size and charge of the anions X- used does not affect the structural core of the complexes, in contrast to their supramolecular organization which is decisively affected, leading to 2- and 3D architectures.