Thesis (M.S.)--Florida State University, 2006. / Advisor: Armen Zakarian, Florida State University, College of Arts and Sciences, Dept. of Chemistry. Title and description from dissertation home page (viewed Sept. 19, 2006). Document formatted into pages; contains xiv, 120 pages. Includes bibliographical references.

Thesis (M. Sc.)--University of Canterbury, 2006. / Typescript (photocopy). "July 2006." Includes bibliographical references (leaves 69-72). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

This thesis describes the synthesis of macrocyclic and interlocked receptors which exploit halogen- and hydrogen-bonding intermolecular interactions for anion recognition. <strong>Chapter One</strong> introduces the field of supramolecular chemistry, with particular focus on applications of host–guest chemistry to anion coordination and anion templation in the construction of mechanically interlocked molecules. <strong>Chapter Two</strong> details the synthesis of a series of cyclic and cage-like porphyrin-based receptors which bind anions through halogen- and hydrogen-bonding interactions. The ability of these receptor systems to bind and sense anionic guest species is investigated and comparisons between hydrogen- and halogen-bonding are discussed. <strong>Chapter Three</strong> reports anion-templated pseudorotaxane assemblies stabilised by both halogen- and hydrogen-bonding. The related catenanes are also prepared and their affinity for anions is investigated. The first examples of interpenetrated and interlocked architectures constructed by a single charge-assisted halogen bond are also reported. <strong>Chapter Four</strong> describes the synthesis of a 1,3-dialkyl-1,2,3-triazolium-containing threading component, whose anion binding properties are studied and compared with other threading molecules. The ability of this novel thread to form pseudorotaxanes is investigated and the preparation of the related rotaxane species is outlined. <strong>Chapter Five</strong> discusses attempts to prepare rotaxanes with improved anion binding affinities through increasing the lipophilicity of the anion binding clefts. Several novel rotaxanes are described and their anion binding properties are probed. <strong>Chapter Six</strong> describes the experimental procedures used in this work and the characterisation of compounds presented in chapters two to five. <strong>Chapter Seven</strong> summarises the conclusions of this thesis.

A radioisotope of rubidium, 82Rb is used in positron emission tomography. Neutral crown ethers and cryptands have been studied as carrier ligands for Rb+ but exhibit low ion carrying capacity and high toxicity. The present study involved investigating a lariat ether containing an ionizable phosphoryl moiety and a lipophilic sidearm. This kind of molecule is expected to be ionized at physiological pH. It should be able to form neutral complexes with Rb+ and may be able to cross the blood-brain barrier. Molecular modeling of crown ether-alkali metal cation complexes indicates that a macrocycle containing more than 18 but less than 21 atoms can incorporate Rb+ ion in its cavity. Molecular modeling of some of the complexes of phospho-lariat ethers with rubidium using the Spartan'02 software package revealed that a lariat ether containing 20 member macrocycle will probably form the most stable complex with Rb+ion. Also, it was thought that more flexibility could be imparted to the macrocycle if it contains propyleneoxy units instead of ethyleneoxy units which form most crown ethers. Molecular modeling of two phospho-lariat ethers with 16 and 20 membered rings revealed that 20 membered macrocycle may be a better choice due to the side arm's participation in the complexation with Rb+ to a greater extent. Molecular modeling was used to find the bond angles and bond distances in this molecule. The synthesis to obtain ionizable phospho-bipodands was performed using subsequent benzylation, phosphorylation and hydrogenation steps. The characterization of products was done using HPLC, NMR and ESI-MS techniques. The synthetic scheme used was demonstrated to be plausible and could be used to obtain ionizable phoshobipodands. Extraction using solid phase anion exchange columns proved to be a good clean up procedure for obtaining pure bipodand. This bipodand could be used as a precursor for synthesizing an ionizable 20 membered lariat ether.

No description available.

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: This investigation comprises the synthesis and characterisation of new macrocyclic ligands with pendant arms appended to the nitrogen donor atoms of 1,5,9-triazacyclododecane (12aneN3) and their coordination to various transition metal ions. The five macrocyclic ligands, 1,5,9-tris[(2S)-2-hydroxypropyl]-1,5,9-triazacyclododecane (THPTACD), 1,5,9- tris(2-hydroxy-2-methylpropyl)-1,5,9-triazacyclododecane (THMPTACD), 1,5,9-tris[(2S)-2- hydroxy-2-phenylethyl]-1,5,9-triazacyclododecane (THPETACD), 1,5,9-tris[(2S)-2- hydroxybutyl]-1,5,9-triazacyclododecane (THBTACD) and 1,5,9-tris(2-mercaptopropyl)- 1,5,9-triazacyclododecane (TMPTACD) were prepared by addition of pendant arms that contain alcohol or thiol end groups to a preformed 12aneN3 macrocycle. The 12aneN3 was synthesised from simple starting materials using 1,3-propanediol and bis(3-aminopropyl)- amine. The macrocycles with oxygen donor atoms on the pendant arms were prepared from the corresponding epoxides whereas for the one that contained sulphur donor atoms, propylene sulphide was used. The reaction progress was followed by 13C and 1H NMR spectroscopy and the final macrocyclic ligands were further analysed by mass spectrometry and in some instances, elemental analysis was also performed. Protonation constants of the free ligands were determined using potentiometric titrations at 25 oC and the ionic strength was kept constant at 0.1000 mol dm-3 using NaNO3. The log K1 values were 11.47, 10.96 and 10.47 for THPTACD, THBTACD and THMPTACD, respectively, whereas the corresponding values of 5.81, 6.02 and 5.94 were obtained for log K2. THPTACD is the most basic mainly due to less steric hindrance whereas THMPTACD is the least basic owing to high steric hindrance to both solvation and formation of strong hydrogen bonds of the protonated species to solvent molecules during the solvation step in a Born Haber-type cycle of the complete process. Protonated THBTACD is the most basic of the three mono-protonated ligands, a result that may be explained in terms of better correlation between inductive and steric effects. The second protonation constant is mostly influenced by inductive effects unlike the first protonation constant which is mostly determined by steric effects. The third protonation constant could not be established because of lack of sensitivity of the glass electrode in very high acidic medium. The complex stability constants of Co(II), Zn(II), Cd(II) and Pb(II) cations were similarly determined using potentiometric titrations at 25 ¡ÆC in 0.1000 mol dm-3 NaNO3. Log K values with THPTACD are 15.45, 21.22, 14.03 and 16.11 for Co(II), Zn(II), Cd(II) and Pb(II), respectively. THBPTACD has corresponding values of 13.93, 20.02, 13.55 and 15.01, whereas for THMPTACD the values of 14.63, 18.08, 12.91 and 14.36 log units were obtained. The Zn(II) 1:1 complexes are the most stable and those of Cd(II) the least stable. A crystal structure determination of [Zn(THPTACD)]2+ shows that optimal interaction between the Zn(II) metal ion and the donor atoms with their short Zn(II)-N bond lengths occurs. The short Zn(II)-N distances indicate that the metal ion is situated very close to the macrocyclic hole. On the other hand, each half of the hydrogen-bonded dimeric molecular structure of [Cd2(THPTACD)2]4+ has long Cd(II)-N bond lengths. Although metal nitrates, perchlorates and acetates were used in attempted crystal structure determinations, only metal nitrates formed suitable crystals. THPTACD complexes with Co(II), Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II) were subjected to such determinations. Each central metal ion in these complexes is six coordinate to the three N atoms of the parent macrocyclic ring on one plane and the three O atoms of the pendant hydroxypropyl arms forming another plane on the other face of the metal ion. The geometry of all six molecular structures is pseudo octahedral with the Cu(II) complexes being the most twisted towards a trigonal prismatic arrangement. The change towards trigonal prismatic can be attributed to packing forces overriding octahedral crystal field stabilisation effects. The overall chirality of the isomorphic complexes of Zn(II), Co(II), Mn(II), Ni(II) and Cu(II) with THPTACD is [¥Ë((2¥ë.)¥ä.¥ä)] whereas the overall chirality of each half of the dimeric [Cd2(THPTACD)2]4+ complex is [¥Ë(¥ë.(2¥ä.)¥ä)]. The Cu(II) complex with THPETACD has the same overall chirality as the Cu(II) complex with THPTACD but is less twisted towards trigonal prismatic geometry. Both Cu(II) complexes exhibited strong evidence of Jahn-Teller tetragonal distortion in the solid state with tetragonality parameter values of 0.87 and 0.81, respectively. The structure of a new di-¥ì-chloro bridged binuclear complex of Cd(II)-12aneN3 was also determined. The molecule contains an inversion centre coinciding with the crystallographic centre of symmetry. Finally, the molecular structure of the protonated 1,5-bis[(2S)-2- hydroxybutyl]-1,5,9-triazacyclododecane shows that the oxygen donor atoms of the two pendant arms are pre-organised for meridional coordination. The hydrogen bond network in this structure emphasises the important role that such weak interactions play in stabilising the proton even in solution during determination of protonation constants in triazamacrocycles with pendant arms carrying oxygen donor atoms.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Hybrid macrocycles, which chimerically integrate multiple chemical compositions and architectures, provide an effective way to impart new properties to polymers that are not found in their linear or homocyclic analogues. This dissertation addresses the incorporation of hydrophilic blocks into hydrophobic polymer, as either a poly(dimethyl siloxane)-block-poly(oxyethylene) (PDMS-POE) tadpole with a hydrophobic head and a hydrophilic tail or as a diblock poly(styrene)-block-diethylene glycol (PS-DEG) hydrophobic-hydrophilic macrocycle. The supramolecular association properties of both kinds of cycles were studied: the PDMS-POE tadpoles in forming micelles, and the PS-DEG macrocycles in threading with linear polymer to form polyrotaxanes. For the PDMS-POE macrocycle, linear alpha,omega-dihydroxy PDMS was cyclized under dilute conditions with dichloromethylhydrosilane as a linking group to produce hydrosilane-functionalized cyclic PDMS. This was joined to alpha-methoxy,omega-allyl POE via a free radical hydrosilylation reaction to produce the hybrid tadpole macrocycle, which was analyzed by GPC, DSC, and 1H, 13C, and 29Si NMR spectroscopy. Supramolecular aggregation consisting of the formation of micelles under both polar and nonpolar conditions was studied by surface tensiometry and quasielastic light scattering. For the PS-DEG macrocycle, linear alpha,omega-dihydroxy PS was prepared by ATRP polymerization of styrene, followed by reaction with KOH to give hydroxyl endgroups. The linear PS was then cyclized under dilute conditions with diethylene glycol ditosylate, and the product was analyzed by GPC, MALDI-TOF MS, DSC, and 1H, 13C and DOSY NMR spectroscopy. The macrocycle was then statistically threaded with linear PS to give the supramolecular structure poly(styrene)-rotaxa-cyclo[poly(styrene)-block-diethylene glycol]. Characterization was performed with DOSY NMR to verify that the product was threaded, and 1H NMR was collected to determine that the product was 13% macrocycle by weight. DSC showed only one Tg, indicating that the linear and cyclic species were present in the same phase.

Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.