No description available.

No description available.

The class of compounds known as the dibenzotetraaza[14]annulenes have been of particular interest over the past 25 years, with the initial impetus for research being the relationship they hold with the naturally occuring porphyrins. The main aim of the work undertaken was to establish the potential of dibenzotetraaza[14]annulene type systems for the development of novel materials whose applicable behaviour was likely to fall into one of the following three categories; liquid crystals, organic conductors, and chelating systems. Additionally the chemistry involved with the synthesis of these types of materials was interesting in its own right and provided a platform for the author to increase his own knowledge of chemistry. The research undertaken may be broadly classified into the following areas: 1. The preparation of linear Schiff base polymers, 2. The preparation of dibenzotetraaza[14]annulenes (metal complexes and free ligands), 3. The preparation of 1-D and 2-D unsymmetrical macrocyclic complexes, and 4. The preparation of polymeric materials incorporating dibenzotetraaza[14]annulenes both as part of the polymeric backbone and as pendant side chains in a comb type polymer. 1. The preparation of linear Schiff base polymers. The Schiff base condensation of phenylenediamines with malondialdehydes has enabled the preparation of materials of the type illustrated below. [chemical formula]. Examination of the materials by differential scanning calorimetry has shown that many of the materials exhibit interesting thermal transitions from one crystalline state to another. However the use of thermal microscopy has not shown any of these phases to be liquid crystalline transitions. 2. The preparation of dibenzotetraaza[14]annulenes (metal complexes and free ligands). An extensive array of dibenzotetraaza[14]annulenes have been prepared, generally by a one step process involving the reaction of ortho-phenylenediamine and various 2-substituted malondialdehydes in the presence of a suitable acid catalyst and solvent. [chemical formula]. 3. The preparation of 1-D and 2-D unsymmetrical macrocyclic complexes. The introduction of unsymmetricality into the dibenzotetraaza[14]annulenes has been of interest since dipole-dipole interactions between molecules may lead to enhanced crystalline stacking, which in turn has a direct effect on any liquid crystalline or semiconducting properties the material may exhibit. Consequently the preparation of unsymmetrical dibenzotetraaza[14]annulenes has been undertaken, which has often required extended stepwise synthetic reaction pathways involving the use of protecting reagents. Small quantities of pure materials have been prepared and are believed to be the first of their type. 4. The preparation of polymeric dibenzotetraaza[14]annulenes. The incorporation of dibenzotetraaza[14]annulenes into a polymeric system has been examined in two ways. The initial study concentrated on the incorporation of the macrocycle directly into the polymer backbone and involved the reaction of suitably functionalised dibenzotetraaza[14]annulenes with linking groups such as para-phenylenediamine. The additional study has focussed on a method of forming polymers which include the macrocyclic complexes as pendant side chains in a comb type polymeric arrangement (illustrated below). [chemical formula]. At present the prepartion of a polymer of this type has not been achieved. However an extensive study into the attachment of groups to the macrocycles which are capable of undergoing polymerisation has been undertaken which has established the potential use of the Gabriel synthesis of amines and the Wittig reaction as potential methods of attachment.

No description available.

Doctor of Philosophy / Department of Chemistry / Christopher J. Levy / This work examines the synthesis of novel chiral Schiff-base complexes derived from (1R,2R)-cyclohexanediamine and (R)-[1,1’-binaphthalene]-2-2’-diamine structural backbones with quinoline, isopropyl-quinoline, and benzoquinoline structural side-arms. We incorporated some degree of flexibility in the ligands and complexes so they can accommodate the sterics of different substrates during a catalytic reaction. We successfully achieved this by reducing the imine bond in the ligands to the corresponding amine bond. Therefore, the successful reduction and metallation of some of these ligands to give structures of different symmetries is reported. We had difficulty reducing ligands with the binaphthalene backbone but were able to partially reduce the ligand through a one-pot reaction with a zinc(II) salt and NaBH4. The complete 1H NMR assignments of the complexes reported in this thesis serve as a valuable tool for use in the characterization of future complexes. The complete NMR characterization of compounds reported is a complex process because they are polycyclic aromatic systems and the coupling network similarity in different parts of the molecule usually results in severe overlap of their 1H resonances. To overcome this impediment, we took advantage of various 2D-NMR techniques (COSY, NOESY, ROSEY, HSQC, and HMBC) along with other 1D-NMR experiments (1H HOMODEC, 1H, and 13C) to completely assign the desired complexes. Subsequently we also studied the coordination chemistry of several meal cations with our ligand system with the goal of obtaining single stranded monhelices. The potential use of some of the complexes in the area of NMR discrimination and kinetic resolution of racemic mixtures was examined and shown to be promising. Several NMR experiments were conducted using the racemic olefins 3-buten-2-ol and 1-penten-3-ol to demonstrate the discriminating power of our silver(I) complexes. We discovered that sterics play an important role in this resolution experiment and the bulky nature of our complexes affect the overall efficiency of the NMR discriminatory process as it diminishes the contact between the reactive metal center and the olefins involved. Temperature also plays a vital role in the chiral recognition of racemic olefins as we examined the ideal temperature needed to reduce the various dynamic processes that take place in solution at room temperature.

No description available.

This work investigated the use of large tetradentate mixed nitrogen and oxygen donor macrocycles as potential ligands for titanium(IV).These large ligands are capable of encapsulating the metal ion, thereby protecting it from reacting further. In addition, titanium complexes of this type had not been reported previously.Molecular modelling was utilised to evaluate and predict the coordinating potential of the macrocycles investigated.An alternative synthetic strategy was needed to achieve coordination complexes with titanium. This involved the use of a benzene based solvent system and rigorously dry reaction conditions.The final part of the work involved a detailed study of the kinetics of the hydrolysis of the titanium complexes investigated. / Doctor of Philosophy (PhD)

With the goal of developing Schiff base macrocycles with conjugation extended over multiple aromatic rings, new phenanthrene and triphenylene-containing bis(salicylates) were synthesized. A convenient route to 3,6,9,10-tetraalkoxy-2,7-diiodophenanthrene was developed. This compound has been found to be a useful precursor for Pd-catalyzed cross-coupling reactions. Macrocycles were synthesized by Schiff base condensation of the phenanthrene and triphenylene precursors. Reaction of smaller phenanthrene and triphenylene bis(salicylates) with 1,2-dialkoxy-4,5-phenylenediamine afforded macrocycles in poor yield and purity, but formation of the macrocycle was confirmed by mass spectrometry. Condensation of larger phenanthrene ethynylene bis(salicylates) with phenylenediamines formed [3+3] Schiff base macrocycles in good yield and could be purified through recrystallization. These two large macrocycles were weakly luminescent, and showed decrease in intensity of emission in solution over time. Addition of nitroaromatic compounds to solutions of the macrocycles caused quenching of luminescence, but Stern-Volmer constants could not be determined. One of the macrocycles aggregates in solution and shows some order in the solid state. Association constants for self-assembly of this macrocycle in chloroform were determined, and aggregation was found to be enthalpically driven and entropically disfavoured. Both large macrocycles can complex metals, but low solubility prevents thorough characterization of the metal complexes. Phenanthrene-containing poly(phenyleneethynylene)s (PPEs) and poly(phenylenevinylene)s (PPVs) were synthesized via the Sonogashira and Heckcouplings, respectively. The PPEs had high molecular weight and both polymers were extremely luminescent with OF = 70% for the PPE and OF = 59% for the PPV. These polymers show potential for use in solar cells and nitroaromatic sensors . Dithienylsalphen monomers were made using 4-(2-thienyl)salicylaldehyde and 5-(2-thienyl)salicylaldehyde. These monomers were coordinated to Ni(II), Cu(II) and vanadyl, and tested for electropolymerization. Conjugated dithienylsalphen monomers polymerize poorly, while non-conjugated dithienylsalphen monomers form good films through electropolymerization. Ultraviolet-visible spectroscopy confirmed extended conjugation in N,N '-phenylenebis(4-(2-thienyl)salicylideneimine).

In this article, we examined different synthetic approaches with varying adding starting materials for the thiol containg schiff-base complex [ZnL1]2(L1=o-C6H4(SH)(CH=NC6H4SH-o)). We found that the key step for successful synthesis of [ZnL1]2 is the formation of zinc aldehyde intermediate. We also break the [ZnL2]2 dimer by adding chelating agent, TMEDA, to obtain the Zn(L1)(TMEDA) monomer. It¡¦s single crystal X-ray structure confirmed, the structure of the target ligand L1. We also synthesized [NiL1]2 by transmetalation of [ZnL1]2 - an easier synthetic approach. We further reduced the imine part on L1 of [ZnL1]2 and Zn(L1)(TMEDA) to get [ZnL2]2(L2=o-C6H4(SH)(CH2NHC6H4SH-o)) and Zn(L2)(TMEDA) respectively for future reactivity studies.

Anion binding has emerged as an important field of study due to the role that anionic species play in nature. As a consequence, considerable effort has been focused on the generation of anion receptors. These receptors have been designed to recognize anions through interactions, such as hydrogen bonding, donor-acceptor, and hydrophofic effects, in order to achieve higher sensitivity and selectivity. Another approach involves ion pair recognition, wherein the anions and cations are bound to the same system. Specifically, receptors bearing both hydrogen bonding donor and cation coordination sites have been of great interest as systems that lead to anion recognition and enhanced anion selectivities. Chapter 1 of this dissertation describes efforts to develop systems on the basis of modified Schiff-base calixpyrroles. This modification was achieved by incorporating a “strap” across the macrocycle to produce the so-called strapped Schiff-base calixpyrroles. The strap bearing amides are known to act as hydrogen bonding donors that can isolate the binding site from the medium. On the other hand, Schiff-base calixpyrroles have been widely studied as multidentate ligands for metal cation coordination. Therefore, the synthetic combination of these two moieties might provide a system wherein an ion pair complex is formed. Strapped Schiff-base calixpyrrole palladium complex were found to bind selectively cyanide anions. The effects of direct substitution on one meso position on the optical and photophysical properties of porphycenes was recently found to be dependent of the electronic properties of the substituten (e.g., electron donor or electron withdrawing group). However, the effects on the electronic and optical properties properties as a result of substitution through a conjugated spacer are as yet unknown. This led to the synthesis of four meso substituted etioporphycenes, which are described in Chapter 2. Here, the substitution through an ethenyl group was stablished by analytical and structural means. This chapter provides of a description of the spectroscopic, structural and voltamperometric features of these compounds. Experimental procedures and characterization data are reported in Chapter 3. / text