Supramolecular chemists can be thought of as architects, who combine individual non-covalently bonded molecular building blocks, designed to be held together by intermolecular forces to create functional architectures. Perhaps the most important assets of a supramolecular chemist, however, are imagination and creativity, which have given rise to a wide range of beautiful and functional systems. For years, analytical chemistry has taken advantage of supramolecular assemblies in the development of new analytical methods. The role of synthetic supramolecular chemistry has proven to be a key component in this multidisciplinary research. As such, the demand for synthetic receptors is rapidly increasing within the analytical sciences. The field “supramolecular analytical chemistry” involves analytical applications of synthetic organic and inorganic chemical structures that display molecular recognition properties and self-assembly but also signal these events. Chapter 1 presents an introduction to the background literature relevant to the central themes of the research presented in this thesis. The nonthermal production of visible light by a chemical reaction leads to the term “cool light”, and the process is called chemiluminescence. Although chemiluminescent reactions are not rare, the production of “cool light” holds such fascination for both chemists and nonchemists that demonstrations of chemiluminescent reactions are always well received. A glow assay technology for the detection of a chemical warfare simulant is presented in Chapter 2, which is based on modulating the peroxyoxalate chemiluminescence pathway by way of utilizing an oximate super nucleophile that gives an off-on glow response. As an alternative to highly analyte-specific synthetic receptors, trends in chemical sensing have shifted to the design of new materials and devices that rely on a series of chemo- or biosensors. The research relevant to Chapter 3 focuses on investigating the use of a single receptor, for sensing two different analytes; thiols and metal ions, utilizing a squaraine as the receptor in a sensor array format. The data is interpreted with principal component analysis. Finally Chapter 4 discusses an attempt to design and synthesize a chemosensor based on the luminophore-spacer-receptor format by incorporating the two concepts photoinduced electron transfer and peroxyoxalate chemiluminescence. / text

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Typescript (Photocopy) / Includes bibliographies / x, 157, A.xxxi : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Summary: Studies the complexation of various monovalent metal ions by the diaza-crown ether C21 and the cryptands, C211 and C22C5 to form cryptates in various solvents, and investigates the kinetics for the interaction of the pendant arm ligand 1,4,8,11-tetrakis (2-hydroxyethyl)-1,4,8,11-tetraazacyclotetradecane (THEC) with the divalent metal ions Cd2+, Hg2+ and Pb2 / Thesis (Ph.D.)--Dept. of Physical and Inorganic Chemistry, University of Adelaide, 1993

Thesis (Ph. D.)--University of Adelaide, Dept. of Pathology, 1986. / Includes bibliographical references (leaves 211-260).

Thesis (Ph.D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Huang, Ching-Hua; Committee Member: Kim, Jaehong; Committee Member: Pavlostathis, Spyros; Committee Member: Stack, Andrew; Committee Member: Yiacoumi, Sotira

Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xiv, 141 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 135-141).

Thesis (Ph. D.)--University of Hong Kong, 2006.

Mechanistic aspects of phosphorylation, dephosphorylation, pyrophosphorylation and depyrophosphorylation reactions that mimic phosphorylases, dephosphorylases, pyrophosphorylases and depyrophosphorylases have been studied in the biologically important middle pH region. The different systems monitored are; (a) the reactions between [{CoN4(OH)(OH2)}]2+ and [HPO4]- for 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to [HPO4]2- ratios. (b) the reactions between [{CoN4PO4] and [O2NC6H4O]- (abbreviated as NP-) for 1:1, 2:1 and 3:1 [{CoN4PO4] to [O2NC6H4O]- ratios. (c) the reactions between [{CoN4(OH)(OH2)}]2+ and [O2NC6H4PO4]2- (abbreviated as NPP2-) for 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to [O2NC6H4PO4]2- ratios. (d) the reactions between [{CoN4(OH)(OH2)}]2+ and [H2P2O7]2- for 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to [H2P2O7]2- ratios. (e) the reactions between [{CoN4P2O7}]- and [O2NC6H4O]- for 1:1, 2:1 and 3:1 [{CoN4P2O7}]- to [O2NC6H4O]- ratios. Significant phosphorylation was noted for systems containing 1:1 molar ratio [{CoN4PO4] and [O2NC6H4O]-. Enhanced phosphorylation was depicted for system containing 1:1 molar ratio of [{CoN4(OH)}2PO4]+ and [O2NC6H4O]-. Pyrophosphorylation was noted for reactions of 1:1 molar ratio of [{CoN4P2O7}]- and [O2NC6H4O]-. The rate of pyrophosphorylation was substantially reduced for systems that were 2:1 in molar ratio of [{CoN4P2O7}]- and [O2NC6H4O]-. No appreciable pyrophosphorylation was noted for systems, which has a 3:1 molar ratio of [{CoN4P2O7}]- and [O2NC6H4O]-. Specific mechanistic features and the possible roles metal ions play in phosphorylase, dephosphorylase and pyrophosphorylase are highlighted from results of UV-Visible spectroscopy, 31P {1H} NMR spectroscopy and Surface Enhanced Raman Scattering (SERS) studies / Chemistry / D.Phil. (Chemistry)

Submitted by Izabel Franco (izabel-franco@ufscar.br) on 2016-09-30T14:47:31Z No. of bitstreams: 1 DissVMV.pdf: 2967521 bytes, checksum: 9bebee517d7d20c1b36810aa5e5744df (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-04T17:34:08Z (GMT) No. of bitstreams: 1 DissVMV.pdf: 2967521 bytes, checksum: 9bebee517d7d20c1b36810aa5e5744df (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-04T17:34:16Z (GMT) No. of bitstreams: 1 DissVMV.pdf: 2967521 bytes, checksum: 9bebee517d7d20c1b36810aa5e5744df (MD5) / Made available in DSpace on 2016-10-04T17:34:24Z (GMT). No. of bitstreams: 1 DissVMV.pdf: 2967521 bytes, checksum: 9bebee517d7d20c1b36810aa5e5744df (MD5) Previous issue date: 2015-02-26 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / The enzymes involved in the conversion process of lignocellulosic biomass into second generation (2G) ethanol add a high cost to the process. Studies reported in the literature indicate that some metal ions, easily found in nature, improve the activity and stability of enzymes and the biomass saccharification process when added to the enzymatic cocktail. In this context, this work aimed to evaluate the strategy of addition of metal ions in the crude enzymatic extract in order to increase the enzyme activity and stability and to improve the saccharification process. For the production of (hemi)cellulase enzymatic complex step, a selected strain of Aspergillus niger was cultivated under solid-state fermentation (SSF), submerged fermentation (SmF) and sequential fermentation (FS). Enzyme production and thermostability were evaluated also considering the effects of pretreatment (using steam-explosion and liquid-hot-water) of the sugarcane bagasse used as carbon source and inducer. For endoglucanase and xylanase enzymes, cultivation under SSF favored production when using steam-exploded and liquid-hot-water pretreated bagasse (both washed). Removal of inhibitors from the pretreated biomass employed in the cultivation media was necessary, because the presence of phenolic compounds restricted fungal growth. The findings revealed that endoglucanase and β-glucosidase produced under SSF were less prone to thermal deactivation. From these results, enzyme complex produced by SSF using the hydrothermal bagasse was selected to evaluate the influence of the divalent metal ions Ca, Co, Cu, Fe, Mg, Mn, Ni, Zn in two concentrations (2 and 10 mM) on enzymatic activity and stability. Most of the ions influenced differently the enzymatic activity and stability, at both concentrations. The most favorable influence was obtained by the Mn+2 ion, increasing by 57% the endoglucanase activity and maintaining the enzyme stable for 72 hours, besides it also showed no negative effects on β-glucosidase and xylanase. The Mn+2 ion was then selected for the saccharification of sugarcane bagasse submitted to different pretreatments. The addition of Mn2+ ion (10 mM) in the saccharification process using enzymatic extracts produced "in house" proved to be very effective by increasing the release of glucose up to 120% when using the acid pretreated bagasse (Bác). The increase was 55% for the washed exploded bagasse (BEXL) and 70% for the liquid-hot-water pretreated bagasse (BHT). Therefore, it was possible to validate that the addition of metal ions is able to positively influence the activity and stability of enzymes, and also the process of enzymatic saccharification of lignocellulose biomass. / As enzimas envolvidas no processo de degradação da biomassa lignocelulósica para a produção do etanol de segunda geração (2G) agregam um alto custo ao processo. Estudos já reportados na literatura indicam que alguns íons metálicos, facilmente encontrados na natureza, ao serem adicionados ao coquetel enzimático atuam na melhoria da atividade e estabilidade das enzimas e no processo de sacarificação da biomassa. Nesse contexto, este trabalho teve como objetivo avaliar a estratégia de adição de íons metálicos ao extrato enzimático bruto com o intuito de aumentar a atividade e estabilidade enzimática e a melhoria na conversão do processo de sacarificação. Para a etapa de seleção do complexo (hemi)celulásico foi utilizada uma cepa selecionada de Aspergillus niger cultivada em fermentação em estado sólido (FES), fermentação submersa (FSm) e fermentação sequencial (FS). A produção de enzimas e a termoestabilidade foram avaliadas considerando os efeitos do pré-tratamento (explosão a vapor e hidrotérmico) do bagaço de cana-de-açúcar utilizado como fonte de carbono e indutor. A produção de endoglucanase e xilanase foi favorecida pelo cultivo em FES a partir do bagaço explodido e hidrotérmico (submetidos ao processo de lavagem). A remoção de inibidores da biomassa prétratada mostrou-se necessária, pois a presença de compostos fenólicos restringiu o crescimento fúngico em FES. Os resultados revelaram que endoglucanase e β-glicosidase produzidas sob FES foram menos propensas à desativação térmica. A partir desses resultados, foi selecionado o complexo enzimático produzido por FES utilizando o bagaço hidrotérmico lavado, para avaliação da influência dos íons metálicos bivalentes Ca, Co, Cu, Fe, Mg, Mn, Ni, Zn em duas concentrações (2 e 10 mM) na atividade e estabilidade enzimática. A maioria dos íons metálicos utilizados influenciou, de forma distinta, a atividade e estabilidade enzimática em ambas as concentrações para as enzimas estudadas. O íon Mn2+ se destacou, propiciando um aumento de 57% na atividade de endoglucanase e mantendo a enzima estável por 72 horas, além disso não apresentou efeito negativo para β-glicosidase e xilanase. Assim, o íon Mn2+ foi selecionado para o estudo da sacarificação dos bagaços de cana submetidos a diferentes pré-tratamentos. A adição do íon Mn2+ (10 mM) no processo de sacarificação utilizando extratos enzimáticos produzidos “in house” mostrou-se bastante eficaz no aumento da liberação de glicose, com ganhos percentuais de até 120% para o bagaço pré-tratado em meio ácido (Bác). Para o bagaço explodido lavado (BEXL) o aumento foi de 55 % e para o hidrotérmico (BHT) foi de 70%. Desse modo, foi possível validar que a adição de íons metálicos é capaz de influenciar positivamente tanto a atividade e estabilidade, como o processo de sacarificação enzimática da biomassa lignocelulósica.

Tridentate benzimidazole-based ligands, bis((1H-benzimidazol-2-yl)methyl)sulfide (BNSN) and bis((1H-benzimidazol-2-yl)methyl)amine (BNNN), along with dinonylnaphthalene sulfonic acid (DNNSA) as a synergist, were investigated as potential selective extractants for Ni2+ from base metals in a solvent extraction system using 2-octanol/Shellsol 2325 (8:2) as diluent and modifier. However, extraction studies show a lack of pH-metric separation of the later 3d metal ions with bis((1-octylbenzimidazol-2-yl)methyl)sulfide (BONSN) and bis((1- decylbenzimidazol-2-yl)methyl)amine (BDNNN) as extractants, but extractions occurred in the low pH range with an opportunity for back extraction. This investigation suggested that tridentate ligands (at least those of the nature investigated here) are not feasible extractants for separation of base metal ions due to their lack of stereochemical “tailor-making.”