We utilized the tripodal ligand (tris-(3,5-di-tert-butyl-2-hydroxy-phenyl)- phosphine) H3[O3P] to react with 1 equiv of AlR3 (R = Cl, Me, Et, iBu and OiPr). From NMR and X-ray data proved, we could give the stable Al(III) complexes [O3P-H]AlR (R = Cl, Me, Et and iBu). [O3P-H]AlR is a zwitterionic complexes. Because the phenolato phosphine ligand bond a proton at the phosphorous, and Al(III) coordinated three RO- (tris phenolate group) and one alkyl- substituent group. So the Al(III) metal could be carried -1 charge and the phosphorous could be carried +1 charge. When H3[O3P] reacted with AlR3, the original trisphenolato phosphine ligand ([O3P]3-) was changed into a trisphenoato phosphonium ligand ([O3P-H]2-). The [O3P-H]AlMe in the trisphenoato phosphonium group has a proton, and we attempted to use a bese to deprotonate the acidic proton. We chose n-BuLi to react with [O3P-H]AlMe, and successfully gave {[O3P:]AlMe}- ionic complexe. In the {[O3P:]AlMe}- complexe, the lone pair electron of phenolato phosphine group is a nucleophile,It reacted with MeOTf of electrophile. The product of the reaction could give [O3P-Me]AlMe.In this reactions, the original trisphenoato phosphonium ligand ([O3P-H]2-) was changed into a new methyl trisphenoato phosphonium ligand ([O3P-Me]2-). We could utilize H3[O3P] to react with 1 equiv MeOTf in diethyl ether, and gave a new tripodal ligand {H3[O3P-Me]}OTf. Also, we utilized the {H3[O3P-Me]}OTf to react with 1 equiv of AlR3 (R = Cl, Me, Et and iBu). We gave that Al(III) complexes [O3P-Me]AlR (R = Cl, Me, Et and iBu).

Tripodal borate ligands, including Tp and Tm, are some of the most widely used in organometallic chemistry and were originally prepared, as anions, from the reaction of the relevant heterocycle with an alkali metal borohydride. However, an alternate route, allowing access to zwitterionic, charge-neutral, scorpionates was recently developed within the Bailey group using tris(dimethylamino)borane as the boron source. This thesis describes the expansion of the borane synthetic route to create new, charge-neutral, zwitterionic, tris(methimazolyl)borate (ZTm) ligands containing B-N, B-O and B-C coordinate bonds. Unusual reactivity with isonitrile donors is also presented which has allowed access to boron substituted anionic Tm ligands from the charge-neutral starting material, (HNMe2)ZTm. Attempts to control the helical chirality of ZTm complexes, by using chiral imidazoline donors on the central boron are also described. The borane synthetic route has allowed access to the novel ligand ZThp, the first example of a tripod based on 2-hydroxypyridine ligand arms. As with Tm, this ligand exhibits helical chirality upon complexation and demonstrates how individual atom hybridisation within the ligand arms affects the helicity and thus the chirality of flexible scorpionate ligands. Coordination studies of both zwitterionic and boron-substituted anionic Tm ligands have shown a tendency for the formation of ‘sandwich’ complexes of the form L2M with some metal precursors, whilst the formation of the corresponding ‘half-sandwich’ complexes of these ligands with ruthenium and rhodium was found to be disfavoured.

Research into inorganic supramolecular chemistry is burgeoning, in particular that which focuses on the formation of capsular molecules and the effects that these unique environments have on catalytic reactions. With the aim of producing new ligand designs that could not only support reactive metals, but also partake in supramolecular aggregation to provide a capsular microenvironment, new tripodal ligands and wide span imines and amines have been synthesised. Furthermore, the exploitation of hydrogen-bonding motifs formed through pyrrole-imine tautomerisation upon metallation of these ligands has been explored, with the aim of enhancing reactivity and stabilising reactive intermediates. In Chapter one, the concept of covalent and non-covalent capsules is introduced, and includes the different aspects affecting the encapsulation of molecules and their use as nanoreactors. The use of secondary interactions, e.g. hydrogen-bonding in metal complexes of tetrapodal and tripodal ligands is discussed. Chapter two describes the synthesis of a tripodal pyrrole-imine ligand and the formation of its multi-metallic complexes of Group one metals, transition metal and the f-block elements. The complete and partial tautomerisation of this ligand upon metal complexation is also examined. In Chapter three, the formation of hangman complexes of the tripodal pyrrole-imine ligand is described and is extrapolated to the chemistry of a new pyrrole-amide ligand. The synthesis of this latter ligand and its properties with regards to anion binding are also explored. Chapter four describes the formation of wide span diamine and diimine ligands and their propensity to form adducts with cobalt and zinc chlorometallates and unusual multimetallic palladium complexes. The final conclusions of the work presented in this thesis are drawn in Chapter five. Chapter six presents experimental details and characterising data for all of the new compounds presented in this thesis.

Poly(azolyl)borate ligands have proven to be extremely popular ligands since their introduction by Trofimenko in the late 60´s. The basic skeleton of these ligands involves usually three heterocycle units linked to a central boron apex via the azole nitrogen atoms. These ligands have been applied in diverse research areas such as homogeneous catalysis, materials science and bio-inorganic chemistry. More than 2000 papers, including books and reviews regarding the properties of these compounds, have been published. However, only a few synthetic methods for the preparation of such ligands have been reported and only a few examples of chiral borate-centred ligands are known. This thesis deals with the development of a novel synthetic route to tripodal borate ligands using B(NMe2)3 as the boron source. The mechanism of the reaction of this borane with azole heterocycles has been established by exploring the reactivity of a range of azoles. One of the major features of this new synthetic protocol is that it allows the formation of chiral tripodal ligands where the chiral groups are located either at the forth position at the boron atom or at the azole heterocycles. Coordination studies of the ligands have been undertaken and the metal complexes have been studied by a combination of spectroscopic and X- ray diffraction techniques. Preliminary application of the most representative ligands in the Asymmetric Transfer Hydrogenation (ATH) of prochiral ketones has been undertaken in collaboration with Prof. Dieter Vogt at the Technical University of Eindhoven.

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De nos jours, un des objectifs importants de la recherche bioinorganique moderne est le développement d'enzymes artificielles. L'étude séquentielle des acides aminés présents dans le centre actif des métalloenzymes peut présenter une voie possible de la stratégie de modélisation enzymatique. Cependant, les peptides linéaires ont leurs limites lors de la reconstitution des centres actifs des métalloenzymes : ils ne possèdent pas la structure tridimensionnelle bien définie, par conséquent leur structure est vulnérable vis-à-vis de la coordination ou de l’hydrolyse des azotes amidiques. La capacité de coordination des métaux par des peptides linéaires peut être améliorée, par exemple, en les attachant à une plateforme tripodale. Les composés tripodaux peuvent assurer une organisation structurale rigide ou moins flexible pour des chaînes latérales des acides aminés, créant ainsi des sites de coordination pré-organisés pour les métaux. Dans cette thèse, la synthèse et la caractérisation des ligands peptidiques tripodaux contenant de l'histidine et la formation des complexes en présence de cuivre(II) et de zinc(II) sont présentées. Les propriétés acido-basiques ont été étudiées par potentiométrie et différentes techniques spectroscopiques ont été utilisées pour la caractérisation structurale (UV-Vis, CD, ESR, RMN et MS). Outre que la caractérisation thermodynamique et structurale, des propriétés catalytiques des complexes en réaction enzymatiques (oxydation du catéchol, dismutation du superoxyde) ont également été étudiées. Nos résultats ont démontré que les ligands peptidiques tripodaux sont capables d'améliorer la stabilité des complexes métalliques et qu'ils peuvent fournir des structures adéquates pour mimer efficacement les fonctions catalytiques des enzymes. Grâce aux études approfondies et systématiques des propriétés acido-basiques et spectroscopiques, nous avons mis en évidence les forces motrices de la coordination des métaux et établi l'impact de la structure tripodale sur la stabilité, la structure et les propriétés catalytiques des complexes formés. Nos résultats confirment l'effet bénéfique des plateformes tripodales durant la complexation des métaux, et soulignent les possibilités qui s’offrent aux peptides tripodaux dans le domaine de la biomimétisme / One of the most important directions of modern bioinorganic research is the development of artificial enzymes. One pathway of enzyme modeling strategy is the study of amino acid sequences present in the active centers of metalloenzymes. Linear peptides, however, have their limitations in reconstituting the active centers of metalloenzymes, since they do not possess the well-defined three dimensional structure, therefore their structure is vulnerable towards amide nitrogen coordination/hydrolysis. Improvement of metal binding capabilities of linear peptides can be obtained by e.g. their functionalization with tripodal ligands. Tripodal compounds may provide a rigid, less flexible platform for the coordinating amino acid side chains, creating pre-organized metal binding sites. In my thesis, I present synthesis and characterization of histidine containing tripodal peptide ligands and their complex formation in presence of copper(II) and zinc(II). Solution equilibrium was studied with pH potentiometric measurements, and several spectroscopic methods were used for structural characterization (UV-Vis, CD, ESR, NMR and MS methods). Beside thermodynamic and structural characterization, enzyme mimicking catalytical properties of the complexes have also been investigated (catechol oxidation, superoxide dismutation). Our results demonstrated that tripodal peptide ligands are capable of enhancing the stability of metal-peptide complexes, and they may provide convenient structures to efficiently mimic the catalytic functions of enzymes. With thorough and systematical solution equilibrium and spectroscopic studies, we uncovered the driving forces of metal coordination, and established the impact of the tripodal structure in stability, structure and catalytic properties of the forming complexes. Our findings confirm the beneficial effect of tripodal scaffolds in peptide-type ligand-metal complexes, and emphasize the possibilities lying within tripodal peptides in the field of enzyme mimicking

In the title monohydrate compound, 1a, and the methanol solvate compound, 1b, the tri­ethyl­benzene derivative, C35H51N5O, has three functionalized side arms and three ethyl groups, the former being located on one side of the central benzene ring, while the latter are directed to the opposite side. Both the crystals are constructed of structurally similar dimers of 1:1 host–guest complexes held together by N—H...O and O—H...N hydrogen bonds, and in 1a additionally by O—H...O hydrogen bonds. The structure of 1b contains additional highly disordered solvent mol­ecules. Thus, the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18] in PLATON was used to generate a modified data set, in which the contribution of the disordered mol­ecules to the structure amplitudes is eliminated. These solvent mol­ecules are not considered in the reported chemical formula.

Self-assembly processes were used to construct supramolecular architectures based on metal-ligand interactions. The structures formed strongly depend on the used metal ion, the ligand type, the chosen counter ion and solvent as well as on the experimental conditions. The focus of the studies was the design of multifunctional N-donor ligands and the characterization of their complexing and structural properties. This work was divided into three distinct main parts: The bis(2-pyridylimine), the bis(2-hydroxyaryl) imine and the tripodal imine / amine ligand approach. In the first part a series of bis(2-pyridylimine) derivatives having different linking elements were employed as building blocks for novel supramolecular architectures. Reaction of individual d-block metal salts with these ligands has led to the isolation of coordination polymers, a metallamacrocycle, double-stranded helicates, triple-stranded helicates as well as of circular meso-helicates. The nature of the spacer in the Schiff base ligands, the noncovalent weak interactions, such as hydrogen bond, face-to-face π-π and edge-to-face CH-π interactions, are all important factors influencing the architecture of the final products. Topological control of the assembly process of the hexanuclear meso-helicates is clearly associated with the bidentate coordination of the sulfate anion which directs the formation of a double- rather than a triple-stranded helicate around the octahedrally coordinated Cu(II). Surprisingly, the variation of the linker function in the ligands, which significantly changes the linking angle of the pyridylimine strands, has only a little influence of the resulting structure. Also the use of a mixture of ligands does not influence the meso-helicate topology; the result is the symmetrically mixed meso-helicate. The new iron(II) triple helicate [Fe2(L5)3](PF6)4 14 {L5 = bis[4-(2-pyridylmethyleneimino)phenyl]-1,1-cyclohexane} in its chloride form binds strongly to DNA as confirmed by induced circular dichroism signals in both the metal-to-ligand charge transfer (MLCT) and in-ligand bands of the helicate. The induced CD spectrum gives some evidence that [Fe2(L5)3]4+ interacts with the DNA in a single binding mode, which is consistent with major groove binding. The cytotoxicity of the new iron(II) triple helicate 14 was evaluated on human lung cancer A549 cells and compared with that of cisplatin and that of the previously reported iron(II) triple helicate [Fe2(L1)3]4+{L1 = bis[4-(2-pyridylmethyleneimino)phenyl]methane}. The first results show some distinguishing features for 14 obviously caused by the existing structural differences of the complexes. In the second part of the thesis, novel uranyl complexes of the bis(2-hydroxyaryl) imine ligands have been synthesized and characterized. 1D coordination polymers and mononuclear structures were formed. In all complexes a distorted hexagonal bipyramidal coordination geometry around the uranyl centre is observed. The imine nitrogen atoms of the ligands do not bind to the metal centre but interact strongly with the hydroxy group via H-bonding. DFT calculations made with L8 ( α,α’-Bis(salicylimino)-m-xylene) are in good agreement with the X-ray crystal structure data. Liquid-liquid extraction studies involving selected ligands and Eu(III) or U(VI) indicate remarkably high selectivity for U(VI) over Eu(III) at weak acidic pH conditions. We believe that the study made opens up new possibilities for uranyl ion extraction which could be interesting in view of the treatment of nuclear waste. In the third part of the thesis, a series of multifunctional tripodal ligands with different N-donor centres were used for U(VI) and lanthanide, Nd(III), Eu(III) and Yb(III), binding and extraction. Reaction of these metal ions with selected tripodal ligands afforded complexes which were characterized by ESI mass spectroscopy. The complex composition was found to be 1:1 in all cases. The extraction behaviour of the tripodal ligands towards Eu(III) and U(VI) was studied both in the absence and presence of octanoic acid as co-ligand using the extraction system Eu(NO3)3 or UO2(NO3)2–buffer–H2O/ ligand–CHCl3. These separation systems show a remarkably high selectivity for U(VI) over Eu(III). It is interesting to note that the addition of the octanoic acid to the extraction system leads to high synergistic effects. A series of Eu(III) extraction experiments were done to clarify the composition of the extracted complexes. The results clearly point to the formation of various species with changing composition.