This study concerns halogen bonding between small molecules. Except where otherwise stated herein this investigation was performed exclusively using the M06-2X density functional, in conjunction with the 6-31+G* basis set except for iodine and astatine which were treated using the aug-cc-pVDZ-PP basis set with relativistic pseudopotentials. All calculations were performed in the gas phase. The counterpoise procedure was employed for all full geometry optimisations. Statistical analysis of the Cambridge Structural Database, wherein the frequency of structures as a function of halogen bond angle and distance constituted the sole part of this study not to be based on density functional theory. Except in chapter 5, all halogens from fluorine to astatine are investigated. In chapter 3, halogen bonding between halobenzene and a single water molecule is discussed. Competition between R – X•••OH2 halogen bonding and R – X•••H-O-H hydrogen bonding interactions is described. This system is analogous to the more elaborate microsolvated 1- methyl-5-halouracil system described in chapter 4. In this latter system one 1-methyl-5- halouracil molecule interacts with either one or two water molecules. A central feature of the investigation into this system is competition between R – X•••OH2 and R=O•••H-O-H hydrogen bonding. In chapter 5, halogen bonding is discussed in the context of the thyroid system. In particular halogen bonding between a thyroxine iodine atom and the protein backbone as well as crystal water molecules is the subject of this chapter. The effect of substitution of the iodine atom with an astatine atom is presented. Chapter 6 is concerned with halogen bonding in halogenated DNA base pairs. Interaction energies are compared with those of the canonical base pairs, and the effect of halogen bonding on geometry is also discussed. For each system, halogen bonding was found to become stronger and more tolerant of non- linear bond angles going down the halogen group.

Doctor of Philosophy / Department of Chemistry / Christer B. Aakeroy / A methodology for estimating hydrogen-bond preferences and binding affinities in solution, based on molecular electrostatic potential surfaces (MEPS), is presented using tritopic hydrogen bond acceptor and a series of aromatic carboxylic acids. The plot of calculated MEPS values against experimentally determined binding constants produces a goodness-of-fit of over 0.93 and a similar positive correlation is obtained between MEPS values and binding enthalpies. A series of tritopic N-heterocyclic compounds were synthesized and subjected to systematic co-crystallizations with selected multi-topic aliphatic and aromatic carboxylic acids to determine if ditopic and tritopic donors formulate assemblies with desired stoichiometries. The co-crystals formed contained the COOHᐧᐧᐧBzim synthon, and we observe vacant sites on the acceptor molecules. A series of co-crystallizations between tritopic N-heterocyclic compounds and perfluoroiodoarenes were carried to map out structural landscapes. At least one potential binding site on the acceptor is left vacant on all the four structures obtained. The absence of halogen bonds to all sites can be ascribed primarily due to deactivation of the σ-hole on the iodo-arene donors and partially due to steric hindrance. Four nonsteroidal anti-inflammatory (NSAID) drugs were chosen due to the presence of the COOH moiety, to establish if aqueous solubility can be modulated by systematic solubility measurements of the complex. Two different solids were obtained with a 1:1 and 1:3 stoichiometry. The solubility of the 1:1 co-crystal decreased by 12-fold compared to pure aspirin (3mg/mL at 20 °C) indicating that co-crystals can offer promising new solid forms of pharmaceutically relevant compounds. A series of hydrogen- and halogen bonding Tröger’s base derivatives were synthesized using aromatic N-heterocycles and the iodoethynyl functionality, followed by a series of co-crystallization between aliphatic dicarboxylic acids and symmetric ditopic acceptors. The results suggest that reducing the number of binding sites from three to two facilitates the formation of co-crystals with the desired stoichiometry. The results indicate that directed assembly can be achieved more easily when the molecular building blocks are conformationally rigid.

CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / O presente trabalho trata do estudo, construÃÃo e teste de um forno tubular rotativo, para a calcinaÃÃo e obtenÃÃo de Ãxidos metÃlicos a partir do processo sol-gel protÃico convencional. A abordagem da pesquisa visa aumentar a eficiÃncia energÃtica com o propÃsito de reduzir o dispÃndio de energia e de tempo na obtenÃÃo de nanopartÃculas, utilizando-se 6(seis) lÃmpadas halÃgenas de tungstÃnio de base bilateral com 1000W/220V cada uma. Este forno à capaz de realizar sÃntese com boa homogeneizaÃÃo pela rotaÃÃo do pà durante a calcinaÃÃo com o diferencial do uso de lÃmpadas halÃgenas, que possibilitam um elevado aquecimento e resfriamento da amostra. Os componentes foram capazes de resistir a elevadas temperaturas, dotados de difÃcil oxidaÃÃo, e os isolantes tÃrmicos eficientes por sua baixa condutividade tÃrmica a fim de obter baixas perdas de calor pelas paredes do forno. O processo de montagem foi marcado por vÃrias melhorias em relaÃÃo ao projeto original, visto que a princÃpio o forno nÃo contava com o sistema de refrigeraÃÃo e sua utilizaÃÃo melhorou a eficiÃncia e conservaÃÃo das lÃmpadas halÃgenas. Os resultados da pesquisa evidenciam a eficiÃncia do forno de lÃmpadas halÃgenas em relaÃÃo ao forno a resistÃncia quanto ao tamanho da partÃcula e sua homogeneizaÃÃo, bem como quanto a perda de calor. Neste Ãltimo item atingindo um rendimento melhor em torno de 50% comparado ao forno a resistÃncia elÃtrica. / This paper deals with the study, construction and testing of a rotary tube furnace for calcinations and obtaining metal oxides from the conventional sol-gel protein process. The research approach aims to increase energy efficiency in order to reduce the expenditure of energy and time to obtain nanoparticles, using 6 (six) bilateral basis tungsten halogen lamps with 1000W/220V each one. This furnace is able to perform synthesis with good mixing by rotation of the powder during calcination with the differential use of halogen lamps, which enables a high heating and cooling of the sample. The components were able to withstand high temperatures, equipped with hard oxidation, and the efficient thermal insulation by low thermal conductivity in order to obtain low heat loss through the walls of the oven. The assembly process was marked by several improvements over the original design, since the beginning, the oven did not have the cooling system and its use has improved efficiency and conservation of halogen lamps. The research results show the better efficiency of the furnace of halogen lamps in comparison to the resistance furnace on the particle size and its homogeneity, as well as the loss of heat. In this last item reaching a better yield around 50% compared to electric resistance furnace.

Este projeto teve como finalidade construir uma fonte de luz baseada em lâmpadas halógenas que apresentasse características técnicas adequadas para aplicações em fotobiologia e fotomedicina, versátil e comercialmente viável. Foram analisadas as características de diferentes lâmpadas halógenas e realizados os experimentos com duas lâmpadas escolhidas, das quais utilizamos a lâmpada de menor divergência luminosa. Foi analisado também o material do corpo da fonte, com relação a características de aquecimento e peso, sendo escolhido um corpo de alumínio produzido industrialmente. Foram avaliadas as características ópticas das lentes, sendo escolhidas as lentes de vidro utilizadas em retroprojetores. Foram analisados os materiais e a construção de filtros térmicos para diminuir o aquecimento do objeto sob irradiação, sendo que escolhemos construir um filtro térmico próprio, que utiliza a água como absorvedor de calor. Medimos e avaliamos as características: espectrais, térmicas, a potência radiante (irradiância) e sua distribuição espacial de três protótipos, onde cada um recebeu modificações de modo a torná-los mais adequados para aplicações na fotoquimeoterapia. Foram também realizados testes preliminares de fotocitotoxicidade do protótipo final com o composto fotossensibilizador de nome comercial Photogem® aplicado em células tumorais de adenocarcinoma de colo retal humano (HT29), cujo resultado foi a ativação do composto fotossensibilizador e indução da morte celular. / The aim of this work was to produce a light source based in halogen lamps. This source should have appropriated technical characteristic for application in photobiology and photomedicine, it has easy operation and be commercially viable. The characteristics of different halogen lamps were evaluated and the lamp of smaller luminous divergence was chosen. We also have evaluated the material of the source holder, especially heating characteristics and weight; finally we chose an aluminum holder. Then, the lenses optical characteristics were studied, and we decided that the glass lenses used in projectors were the best. The materials and the construction of thermal filters were evaluated in order to reduce the heating of the object under irradiation, and we preferred to construct a thermal filter, that uses water as an heat absorber. The spectral and thermal characteristics, the radiant power (irradiance) and its space distribution of three prototypes were measured and evaluated, each one received modifications to become more appropriated to applications in photochemotherapy. We also made preliminaries tests of photocytotoxicity and the final prototype was used with the photosensitizer (Photogem®) in human colon carcinoma cell lines HT-29, resulting in the photosensitizer activation, that induced cellular death.

Os retardantes de chama são usados em diversos produtos, especialmente na indústria de eletroeletrônico. A irrevogável finalidade dos retardantes é proteger a vida das pessoas, reduzindo ferimentos e a destruição de propriedades. Contudo, devido à percepção dos riscos ambientais e toxicológicos presentes nas composições comerciais halogenadas e tóxicas, o seu uso está sendo proibido. Apesar da comum comercialização, novas pesquisas têm se desenvolvido visando à substituição destes retardantes, acompanhando medidas legais. Este trabalho visa estudar uma alternativa de aditivo retardante de chama livre de halogênio, tendo como matriz polimérica o copolímero de ABS, combinando aditivos: argila organofílica Cloisite 20A, argila Cloisite Na+ tratada com sal quaternário de fosfônio, polifosfato de amônio, melamina, partículas micrométricas e nanométricas de hidróxido de alumínio, dióxido de titânio e sílica formando assim um compósito. Para a caracterização foram realizados ensaios de térmicos de TGA e DSC, ensaios mecânicos de resistência à tração e resistência ao impacto Izod sem entalhe, avaliação da morfologia através de MEV e MEV-FEG, análise de difração de Raios-X (DRX), espectroscopia de infravermelho acoplado ao acessório de reflexão atenuada (FTIR-ATR), ensaios de retardância à chama com base na norma ASTM D635-10 e norma UL 94. Por meio dos resultados foi possível observar efeitos da adição dos aditivos na obtenção de compósitos de ABS com aditivos retardante de chama inertes, que atingiram classificação V-0 e V-2 na Ul 94, com redução da velocidade propagação da chama entre 18% e 80% conforme a ASTM D635. / The flame retardant are used in several products, specialty for electrical and electronics industry. The irrevocable finality from flame retardant is fires protection to help safeguard of people, reduce injury and reduce destruction of property. However, due the perception of environmental risk and toxicity in composites commercial with halogen and toxic, it has been prohibited. Despite the common commercialization news researches has been developing to substitute this flame retardant, together accompany the new position of law. This work wanted to study an alternative of additive free halogen flame retardant, with polymer matrix the ABS copolymer, combinations the additive: organoclay Cloisite 20A, organoclay Cloisite Na+ treated with quaternary phosphonium salt, ammonium polyphosphate, melamine, micrometric and nanometric particles of aluminum hydroxide, titanium dioxide and silica forming that a composite. To characterization was doing thermal test of TGA and DSC, mechanical test of tensile and impact Izod strength, morphologia available through of MEV and MEV-FEG, X-ray diffraction analysis(XRD), infrared spectroscopy with attenuated total reflectance accessory (FTIR-ATR), flame retardant test based the ASTM D635-10 norm and UL 94 norm. Although the result was possible to observe effects about the addition the additive to obtain the ABS composite with inert flame retardant additives, that achieved V-0 and V-2 on the Ul 94, with reduction of linear burning rate between 18% to 80% from ASTM D635.

The design, construction and optimization of a low power-high temperature heated ceramic sensor to detect leaking of halogen gases in refrigeration systems are presented. The manufacturing process was done with microelectronic assembly and the Low Temperature Cofire Ceramic (LTCC) technique. Four basic sensor materials were fabricated and tested: Li2SiO3, Na2SiO3, K2SiO3, and CaSiO3. The evaluation of the sensor material, sensor size, operating temperature, bias voltage, electrodes size, firing temperature, gas flow, and sensor life was done. All sensors responded to the gas showing stability and reproducibility. Before exposing the sensor to the gas, the sensor was modeled like a resistor in series and the calculations obtained were in agreement with the experimental values. The sensor response to the gas was divided in surface diffusion and bulk diffusion; both were analyzed showing agreement between the calculations and the experimental values. The sensor with 51.5%CaSiO3 + 48.5%Li2SiO3 shows the best results, including a stable current and response to the gas.

La famille des composés halogènes et inter-halogènes représentent des solides moléculaires adoptant des phases denses communes avec des solides moléculaires diatomiques comme l’azote et l’hydrogène. Parmi les transformations structurales et électroniques induites sous haute pression et observées dans ces solides, on note, entre autres, la dissociation moléculaire et la métallisation. De plus, l’étude des phases denses de l’iode a permis récemment l’observation d’une structure cristalline possédant une modulation dite incommensurable, c’est-à-dire une modulation possédant une périodicité différente de celle de la structure cristalline, jetant ainsi une lumière nouvelle sur le processus de dissociation moléculaire dans les solides halogènes. Dans ce mémoire, on propose d’étudier les changements structuraux dans monobromure d’iode (IBr), un composé inter-halogène possédant des propriétés structurales semblables à celles de deux composés halogènes, soit l’iode (I2) et le brome (Br2) sous leur forme solide. Des expériences de diffraction des rayons X de poudres en utilisant un rayonnement synchrotron ont été réalisées à température ambiante sur l’IBr en variant la pression jusqu’aux environs de 60 GPa. La nature chimique particulière du composé IBr a nécessité la mise au point de techniques de chargement d’échantillon destinées à préserver l’intégrité chimique de la substance utilisée. On rapporte également l’observation d’une phase de l’IBr présentant une modulation incommensurable. Les phases observées dans l’IBr permettent d’établir des parallèles avec les phases denses rapportées dans I2 et Br2 par le biais d’un modèle phénoménologique décrivant la séquence structurale des solides halogènes sous forme condensée.

Gegenstand der Arbeit ist ein neuer Atomemissionsdetektor (AED) für die Gaschromatographie (GC), der µ-ESD. In der vorliegenden Arbeit wird der Aufbau und das Funktionsprinzip des µ-ESDs vorgestellt. Untersucht wurde die Eignung des Detektors zur elementselektiven Bestimmung von Cl, Br, F, S und C im nahen Infrarot nach Optimierung einiger Betriebsparameter. Weiterhin wurden Möglichkeiten zur Korrektur spektraler und chemischer Interferenzen diskutiert. Die Charakterisierung des Detektors erfolgte anhand wichtiger Detektoreigenschaften wie Selektivität und Empfindlichkeit. Ein abschließender Vergleich des µ-ESDs mit einem kommerziellen AED und einem Elektroneneinfangdetektor anhand von Untersuchungen an einigen Umweltproben ermöglichte eine Einschätzung der Leistungsfähigkeit des neuen Detektors. Im direkten Vergleich zum kommerziellen AED wurden neben analytischen auch wirtschaftliche Aspekte betrachtet.

No description available.

The fully halogenated or hydrogenated B12X12²- (X = H, F, Cl, Br and I) clusters are confirmed to be icosahedral.Onthe other hand, the bare B12 cluster is shown to have a planar structure.Aprevious study showed that a transformation from an icosahedron to a plane happens when 5 to 7 iodine atoms are remained [P. Farràs et al., Chem. - Eur. J. 18, 13208–13212 (2012)]. Later, the transition was confirmed to be seven iodine atoms based on an infrared spectroscopy study [M. R. Fagiania et al., Chem. Phys. Lett. 625, 48–52 (2015)]. In this study, we investigated the effects of different halogen atoms on the opening of the B12 icosahedral cage by means of density functional theory calculations.We found that the halogen elements do not have significant effects on the geometries of the clusters. The computed infrared (IR) spectra show similar representative peaks for all halogen doped clusters. Interestingly, we found a blue-shift in the IR spectra with the increase in the mass of the halogen atoms. Further, we compared the Gibbs free energies at different temperatures for different halogen atoms. The results show that the Gibbs free energy differences between open and close structures of B12X7- become larger when heavier halogen atoms are presented. This interesting finding was subsequently investigated by the energy decomposition analysis.