A new route to oligothiophene-PEO-block-co-polymers has been developed, in which well-defined a-oligothiophene blocks (from bithiophene to sexithiophene) alternate with poly(ethylene oxide) blocks. These materials show high solubility in common organic solvents. Sexithiophene derivatives with short PEO chains attached at the a-positions have been synthesised as model systems for the above sexithiophene polymer. PEO side-chains as short as pentaethylene glycol had a good solubilising effect on the otherwise insoluble sexithiophene. All compounds prepared exhibited surface activity, as shown by monolayer experiments on a Langmuir trough. Sexithiophene model compounds with short PEO side-chains could be compressed to form a two-dimensional condensed phase. X-ray diffraction of melt cast films of the oligothiophene polymers showed that a minimum oligothiophene block-length of five thiophenes (pentathiophene) was necessary to fully disturb PEO crystallisation. The sexithiophene polymer formed regions of crystalline/aggregated sexithiophene in the bulk. UV/Vis and fluorescence studies in solution indicated that the oligothiophene segments were molecularly dissolved in good solvents like chloroform. Aggregation of the oligothiophenes occurred in THF/water mixtures, which was consistent with observed shifts of the UV absorption maxima towards the blue and quenching of the fluorescence. An oligothiophene length of four thiophenes (quaterthiophene) was necessary to observe this aggregation phenomenon. A sexithiophene derivative with chiral pentaethylene glycol side chains showed a large circular dichroism effect in aqueous solution and no effect in chloroform solution, indicating the formation of a chiral superstructure upon aggregation.

Doctor of Philosophy / Department of Chemistry / Christer B. Aakeröy / A series of four bifunctional ligands based on β-diketonate moieties bearing methyl, chloro, bromo and iodo substituents and their corresponding Cu(II) complexes were synthesized and crystallographically characterized in order to explore the possibility of using relatively weak halogen…halogen contacts for the directed assembly of predictable architectures in coordination chemistry. The four ligands have characteristic O–H...O intramolecular hydrogen bonds, and the structures of the halogenated ligands contain extended 1-D architectures based on C-O...X halogen bonds, which can be explained on the basis of electrostatic considerations. The corresponding Cu(II) complexes show a constant coordination chemistry for all the ligands, wherein the metal ion sits in a slightly distorted square-planar pocket, without any coordinated or uncoordinated solvent molecules. Furthermore, the absence of halogen-bonds in the coordination complexes is due to the depleted charge on the potential halogen-bond acceptors. As a result, the halogen-bonds are unable to compete with the inherent close packing in the crystal lattice, and thus display a head to head close-packed motif for methyl, chloro, and bromo, substituted Cu(II) complexes. The enhanced polarizability of the iodine atom, produces a more electropositive surface which means that this structure cannot accommodate a linear head-to-head arrangement due to electrostatic repulsion, and thus a unique close-packed structure very different from the three iso-structural complexes is observed for the iodo substituted Cu(II) complex.(1) Oximes offer great opportunities in supramolecular chemistry (hydrogen-bond donors), as well as in coordination chemistry (strong coordinating ligands). Hence, we established a versatile and robust mechanochemical route to aldehyde/ketone–oxime conversions for a broad range of aldehydes(2) and ketones(3) via a simple mortar–pestle grinding method. The relative reactivity of aldehydes vs. ketones under these conditions was also explored, along with an examination of the possible connection between reactivity and electronic substituent effects. The growing interest in the oxime (RR′C═N–OH) functionality, and a lack of the systematic examinations of the structural chemistry of such compounds, prompted us to carry out analysis of intermolecular oxime···oxime interactions, and identify the hydrogen-bond patterns for four major categories of oximes (R′ = −H, −CH3, −NH2, −CN), based on all available structural data in the CSD, complemented by three new relevant crystal structures.(4) It was found that the oximes could be divided into four groups depending on which type of predominant oxime···oxime interactions they present in the solid-state: (i) O–H···N dimers (R22(6)), (ii) O–H···N catemers (C(3)), (iii) O–H···O catemers (C(2)), and (iv) oximes in which the R′ group accepts a hydrogen bond from the oxime moiety catemers (C(6)). In order to explore and establish a hierarchy between hydrogen (HB) and halogen (XB) bonds in supramolecular architectures, we designed and synthesized two ditopic HB/XB donors, and screened them with a series of 20 HB acceptors. IR was used as a preliminary and reliable tool to gather information on the presence/absence of HB/XB in the different cases. We were able to get the solved single-crystal data for three of the 40 reactions. In two out of two cases with symmetric ditopic acceptors, both HB and XB were present leading to 1-D infinite chains, which suggests that in a system of “equal opportunities”, both these interactions can be tolerant of each other. In the only case with asymmetric ditopic acceptor, the HB donor binds to the best acceptor, whereas XB donor binds to the second best acceptor. This selectivity can be rationalized on the basis of electrostatic considerations, where the HB donor was shown to have a higher molecular electrostatic potential than the XB donor. Finally, we designed and synthesized a versatile and dynamic metallomacrocycle based on the 2,2'-bipyridyl backbone capable of controlling the metal-metal distance within the macrocycle cavity. The macrocycle was synthesized by high-dilution method and characterized by several spectroscopic techniques (IR, NMR, Mass, UV-Visible). Also, the macrocycle:Cu(II) stoichiometric ratio was determined by Job’s continuous variation method using UV-Visible spectroscopy, and was found to be 1:2, respectively. (1) Aakeröy, C. B; Sinha, A. S.; Chopade, P. D.; Desper, J. Dalton Trans. 2011, 40, 12160. (2) Aakeröy, C. B.; Sinha, A. S.; Epa, K. N.; Spartz, C. L.; Desper, J. Chem. Commun. 2012, 48, 11289. (3) Aakeröy, C. B.; Sinha, A. S. RSC Adv. 2013, 3, 8168. (4) Aakeröy, C. B.; Sinha, A. S.; Epa, K. N.; Chopade, P. D.; Smith, M. M.; Desper, J. Cryst. Growth Des. 2013, 13, 2687.

Chapter 1 presents an overview of the synthetic methods and properties of phthalocyanines, focusing on the unsymmetrical analogues, side-strapped derivatives, and crown ether-containing phthalocyanines. The use of these compounds in photodynamic therapy and their supramolecular chemistry are also reviewed. / Chapter 2 reports the synthesis of a series of unsymmetrical "3+1" zinc(II) phthalocyanines via a one-pot cyclization-transesterification procedure in different alcoholic solvents. Their photophysical properties and in vitro photodynamic activities toward HT29 human colorectal adenocarcinoma cells and HepG2 human hepatocarcinoma cells are also reported. One of the compounds, a zinc(II) phthalocyanine substituted with two polyethylene glycol chains, can form surfactant-free nanoparticles in water and in the culture media. These phthalocyanine-containing nanoparticles exhibit a high photocytotoxicity toward HepG2 cells showing that the polymeric substituents may serve as an effective carrier system. / Chapter 4 reports the synthesis and spectroscopic properties of a side-strapped bis(17-crown-5)-containing zinc(II) phthalocyanine. In contrast to the previously reported benzo-fused crown ether-appended phthalocyanines, the ether rings of this molecule are orthogonal to the phthalocyanine plane. As a result, this compound forms J-aggregate in chloroform. Upon addition of alkali metal ions, these aggregates are disrupted forming a linear supramolecular structure, which has been inferred by absorption and fluorescence spectroscopic methods. / Chapter 5 describes the synthesis and spectroscopic properties of two side-strapped zinc(II) phthalocyanines, which have one and two benzo-25-crown-8 moieties, respectively. The bis(crown ether) analogue favors the formation of J-aggregate in non-coordinating solvents. In CHCl 3, the aggregation of these compounds is promoted by the addition of 1,2-bis(pyridinium)ethane bis(hexfluorophosphate). The aggregation of these compounds can also be induced by the oxonium ions generated by the addition of organic acids such as trifluoroacetic acid and acetic acid. After neutralization with Et3N, the aggregate is disrupted and the phthalocyanines are converted back to their original nonaggregated state. For the symmetrically substituted compound, this acid-base switched aggregation-disaggregation process can be recycled for more than 8 times. / The synthesis, spectroscopic characterization, photophysical properties, aggregation properties, and in vitro photodynamic activities of several side-strapped phthalocyanines are described in Chapter 3. Pentaerythritol, having four hydroxyl groups, has been used as the linker to connect hydrophilic oligoethylene glycol chains or hydrophobic alkyl chains to the phthalocyanine core. The aggregation tendency of these compounds, which depends on their amphiphility, has been studied by absorption spectroscopy. The relationship of this property with the in vitro photocytotoxicity has also been revealed. / This thesis reports our studies on several novel series of phthalocyanines including a series of "3+1" unsymmetrical phthalocyanines formed by a one-pot cyclization-transesterification procedure, and several side-strapped phthalocyanines having an amphiphilic character or containing crown ether units. The applications of these compounds in photodynamic therapy and supramolecular chemistry have also been explored. / by Bai, Ming. / "September 2007." / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4745. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Zhao Xiaoli. / "July 2005." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 178-194). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese.

Thesis (Ph. D.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. 3 MPEG files (not linked from research.pdf file). Title from title screen of research.pdf file viewed on (Feb. 27, 2007). Vita. Includes bibliographical references.

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Nanostructures, molecular assemblies at the nanometer scale, are currently influencing diagnostics, imaging, and therapeutics. Many nanostructures are built using supramolecular chemistry principles, where hydrogen bonding between simple building blocks causes the formation of specific morphologies. Here we hypothesize that a six stranded DNA nanotube can be generated by tethering triaminopyrimidine and cyanuric acid building blocks as bases on the natural DNA backbone. We also hypothesize that cyanuric acid, a secondary oxidation product of guanine, will form complex architectures with adenine, its natural hydrogen bond complement. To test these hypotheses, we used multi-step synthetic strategies to generate DNA strands of cyanuric acid and triaminopyrimidine. The synthesis of the cyanuric acid DNA strand is complete and preliminary self-assembly studies with adenine DNA strands have been performed. The synthesis of the triaminopyrimidine DNA strand is ongoing. This thesis provides the groundwork for incorporating supramolecular building blocks into DNA to generate complex DNA architectures.