"The simultaneous degradation of five organic contaminants: 1,4 dioxane, n-nitrosodimethylamine, tris-2-chloroethyl phosphate, gemfibrozil, and 17β estradiol, was investigated using a 1 L batch water-jacketed UV photoreactor utilizing titanium dioxide (TiO2) nanoparticles (Degussa P-25) as a photocatalyst. The primary objectives of this research were: (1) to experimentally assess the feasibility of heterogeneous photocatalysis as a promising alternative for the degradation of organic compounds in water; and (2) to model the chemical reactions by the application of two different approaches based on adsorption – surface reactions (Langmuir–Hinshelwood) and its simplification to a first order rate reaction. These objectives were motivated by the lack of information regarding simultaneous degradation of organic compounds in different categories as found in real aqueous matrices, and generation of specific intermediates that could eventually represent a potential risk to the environment. Contaminants were chosen based on their occurrence in water sources, their representativeness of individual sub-categories, and their importance as part of the CCL3 as potential contaminants to be regulated. Contaminant degradation was evaluated over time, and the TiO2 concentration and solution pH were varied under constant UV irradiation, oxygen delivery rate, mixing gradient, and temperature. 

 Specific accomplishments of this study were: (1) reaction kinetics data were obtained from the UV/TiO2 experiments and showed the potential that this UV/TiO2 process has for effectively removing different types of organic compounds from water; (2) a good fit was obtained between photocatalytic reaction kinetics models and the contaminant data using pseudo first-order and Langmuir-Hinshelwood (L-H) models; (3) results of the analytical methods developed in this study were validated by measurements performed by a certified laboratory; (4) the reaction kinetic parameters obtained in this study were normalized to electrical energy per order, reactor volume and surface area of the photocatalyst in order to provide rate constants with wider applicability for scale-up to more complex systems; and (5) degradation intermediates from the oxidation process and from interaction among compounds were identified and possible pathways for their formation suggested. This research has provided a better understanding of the photocatalytic process for the removal of organic contaminants from complex aqueous matrices."

Patients with keratoconus exhibit a biomechanically weakened cornea which loses its proper shape and thereby loses its refractive power. It is usually progressive, beginning with poor visual acuity and eventually necessitating corneal transplant. The cause is likely multifactorial, but involves the weakening of the collagen structure of the corneal stroma, resulting in characteristic thinning and conical distortion. Collagen cross-linking is the first treatment to demonstrate efficacy in halting the progression of the disease. UVA radiation is used to activate riboflavin and photochemically induce cross-linking reactions among collagen and proteoglycans within the stroma, thereby stiffening and strengthening the tissue, and preventing further loss of shape. The current standard treatment, which gained FDA approval less than one year ago, has proven to be efficacious, but has been modified very little since pioneering experiments. Optimization aims to maximize clinical effect while maintaining safety and reducing total treatment time. Major procedural modifications involve increasing light intensity over a reduced exposure duration, and varying the method of delivering riboflavin to the stroma. Theoretical modeling, informed by and scaled to experimental results, has the potential to predict clinical effect as a function of treatment parameters, enabling tailoring of individual treatments to the specific needs of each patient.

Este trabalho é parte de um projeto destinado a criar um equipamento médico, para ser aplicado com o protocolo de crosslinking de colágeno corneano, para o tratamento do ceratocone, do qual resultou o desenvolvimento de um sistema de irradiação UV-A de córneas para a aplicação clínica oftalmológica. O sistema desenvolvido neste trabalho consiste de um circuito de malha fechada, que estabiliza a potência luminosa emitida (com erro global, após a calibração, menor que 20% durante a emissão), possibilita seu ajuste até 5 mW (6,366 mW/\'CM POT. 2\') e permite selecionar a duração da emissão entre 10 s - 30 min. O sistema irradia com pico em 365 nm \'+ OU -\' 15 nm sendo que o design óptico proporciona spots homogêneos para três diâmetros selecionáveis: 10 mm; 8 mm; e 6 mm. O software desenvolvido tem a função de controlar todo o procedimento médico do crosslinking corneano, além de detectar falhas no sistema. Os resultados obtidos neste trabalho possibilitaram a criação de um equipamento robusto, flexível e estável, capaz de competir diretamente com os produtos internacionais comercializados mundialmente. Até a presente data tem-se conhecimento de apenas dois produtos, para mesma finalidade, comercializados em todo mundo, sendo ambos de empresas européias. Desta maneira, o sistema descrito nesta dissertação integra hoje o único aparelho de crosslinking totalmente projetado e produzido com tecnologia nacional. / This work is part of a project to create a medical device to be applied with the protocol for corneal collagen crosslinking for the treatment of keratoconus, which resulted in the development of an UV-A system for corneas irradiation for ophthalmic clinical application. The developed system consists of a closed loop circuit, which stabilizes the emitted light power (with global error, after calibration, less than 20% over the issue), allows its adjust up to 5 mW (6.366 mW/\'CM POT.2\') and allows to select the emission duration between 10 s - 30 min. The system irradiates with a peak wave length at 365 nm \'+ OU -\' 15 nm and the optical design provides homogeneous spots for three selectable diameter: 10 mm, 8 mm and 6 mm. The developed software has the function of controlling the medical procedure of corneal crosslinking, and detect system failures. The results of this work enabled the creation of a robust equipment, flexible, and stable that can compete directly with international products marketed worldwide. Until the present date, there has been aware of only two products for the same purpose, marketed worldwide, both from European companies. Thus, the system described in this dissertation integrates now the only unit of crosslinking completely designed and produced with national technology.

Alogliptina (ALG) é um hipoglicemiante oral, que inibe a enzima dipeptidil peptidase – 4 (DPP-4) com alta seletividade e aumenta a secreção de insulina prevenindo a hiperglicemia prandial. Como ALG não está descrita nas farmacopeias, este trabalho objetivou caracterizar a matéria-prima (Capítulo I), desenvolver métodos analíticos (Capítulo II) e avaliar sua estabilidade (Capítulo III), auxiliando no controle de qualidade. No capítulo I, a ALG foi caracterizada através de calorimetria exploratória diferencial (DSC), termogravimetria (TGA) e microscopia eletrônica de varredura (SEM) acoplada a espectrômetro de raios X por dispersão de energia (EDS). A compatibilidade entre a ALG e os excipientes presentes nos comprimidos foi avaliada por DSC, TGA, infravermelho com transformada de Fourier (FTIR), difração de raios-X de pó (XRPD) e microscopia com estágio de aquecimento. ALG apresentou pureza próxima a 99%, com faixa de fusão entre 179,4 e 187,2 °C (pico em 183,3 °C), seguida por decomposição que iniciou em 198,0 °C. Na SEM/EDS, os cristais de ALG mostraram-se predominantemente irregulares e foram detectados traços de impurezas (chumbo e cobre). Alterações na temperatura de fusão da ALG com manitol, estearato de magnésio e nos comprimidos comerciais foram observadas. A microscopia com aquecimento demonstrou que a interação entre manitol e ALG e nos comprimidos é devida à solubilização do fármaco no excipiente fundido, enquanto que na mistura com o estearato de magnésio é devida à fusão do excipiente e do fármaco que ocorrem separadamente, onde o excipiente funde antes que o fármaco. FTIR e XRPD das misturas não detectaram incompatibilidades, somente o aparecimento de bandas adicionais relacionadas aos excipientes. ALG foi compatível com todos os excipientes testados. Estes resultados são importantes para caracterizar, conhecer a estabilidade e a compatibilidade do fármaco. No capítulo II, foram desenvolvidos e validados métodos de cromatografia líquida (LC) indicativos de estabilidade utilizando dois detectores, ultravioleta (UV) e detector de aerossol carregado (CAD) para análise de ALG em comprimidos. Foi utilizada uma coluna C8 (250 mm x 4,6 mm, 5 μm) em modo isocrático, fluxo de 0,8 mL min-1, utilizando acetonitrila e tampão acetato de amônio 10 mM pH 3,5 ajustado com ácido acético (90:10, v/v) como fase móvel e detecção no UV em 275 nm. Os métodos foram lineares no intervalo de 25 - 200 μg mL-1 em ambos os detectores. Os limites de detecção foram de 2,65 e 6,25 μg mL-1 e os de quantificação de 8,84 e 20,85 μg mL-1, respectivamente, para UV e CAD. Os métodos foram precisos e exatos, com desvio padrão relativo menor que 3% e percentuais de recuperação próximos a 100%. Nenhum dos excipientes, ou produtos de degradação interferiu na detecção do fármaco durante os estudos de especificidade. No ensaio de robustez, pequenas alterações no fluxo de fase móvel, pH e concentração de solvente orgânico não afetou significativamente os resultados. O doseamento dos comprimidos obtido com ambos detectores não mostrou diferenças entre si. Os métodos podem ser considerados intercambiáveis e podem ser aplicados como ferramentas para o controle de qualidade de rotina de comprimidos de ALG. No capítulo III foi avaliada a estabilidade térmica da ALG utilizando TGA isotérmica e não isotérmica, e degradação em estufa, analisando as amostras por LC-UV. Na TGA isotérmica a ALG foi submetida a 150, 155, 160, 165, 170 °C, até perda de massa de 10% e os dados foram analisados pelo método de Arrhenius. Na TGA não isotérmica variaram-se as razões de aquecimento, utilizando 2,5, 5,0, 10,0 e 15,0 °C/min até 500 °C. Os dados foram analisados pelo método de Ozawa e de Kissinger. Na degradação em estufa o fármaco foi submetido as temperaturas de 130, 140, 150, 155, 160 e 170 °C. Os parâmetros cinéticos foram obtidos por Arrhenius. ALG segue degradação de zero ordem, onde a velocidade de degradação independe da concentração do reagente. A perda de massa está relacionada à perda química. Os parâmetros cinéticos variaram de acordo com o modelo matemático aplicado. A energia de ativação variou de 26 a 45 kcal/mol. O fármaco degradado demonstrou ser menos tóxico em ensaio de citotoxicidade em células CRIB do que o fármaco não degradado. Os métodos desenvolvidos e a caracterização realizada mostram-se úteis para o adequado controle de qualidade do fármaco. / Alogliptin (ALG) is an oral hypoglycemic agent, which inhibits the enzyme dipeptidyl peptidase - 4 (DPP-4) with high selectivity and increase insulin secretion, preventing postprandial hyperglycemia. ALG is not described in any pharmacopeia. In this context, this study aimed to characterize the active pharmaceutical ingredient (Chapter I), to developed assay methods (Chapter II) and to evaluate the stability (Chapter III), assuring the adequate quality control. In Chapter I, ALG was characterized by differential scanning calorimetry (DSC), thermogravimetry (TGA) and scanning electron microscopy (SEM) coupled with energy dispersive spectrometer X-ray (EDS). The compatibility between ALG and the excipients present in the commercial tablets was evaluated by DSC, TGA, Fourier transform infrared (FTIR), X-ray powder diffraction (XRPD) and hot stage microscopy. ALG presented purity close to 99%, with a melting range between 179.4 to 187.2 °C (peak at 183.33 °C), followed by decomposition which began at 198 °C. In the SEM/EDS the crystals of ALG were predominantly irregulars and it were detected traces of impurities (lead and copper). Alterations in melting temperature of ALG with mannitol, magnesium stearate and in tablets were observed. The hot stage microscopy showed that the interactions between mannitol and ALG and in the tablets were due to the solubilization of the drug in the fused excipient, and in the mixture with magnesium stearate, it was due to the melting of the drug and excipient separately, where the excipient started the melting prior of the drug. FTIR and XRPD of the mixtures did not detect incompatibilities, only the appearance of additional bands related to the excipients. ALG was compatible with all excipients tested. These results are important to characterize, to know the drug stability and compatibility. In Chapter II, liquid chromatography (LC) methods indicative of stability were developed and validated using two detectors, ultraviolet (UV) and charged aerosol detector (CAD) for ALG tablets. It was used a C8 column (250 mm x 4.6 mm, 5 um) in isocratic mode, flow rate of 0.8 ml min-1 using acetonitrile and ammonium acetate buffer 10 mM, pH 3.5 adjusted with acid acetic acid (90:10, v/v) as mobile phase and UV detection at 275 nm. The methods were linear in the range of 25 - 200 μg ml-1 in both detectors. Limits of detection were 2.65 and 6.25 μg mL-1, and of quantification were 8.84 and 20.85 μg mL-1, respectively, for UV and CAD. The methods were accurate and precise, with a relative standard deviation lower than 3% and recovery close to 100%. None of the excipients or degradation products showed interference in the drug detection during specificity studies. In the robustness test, small changes in the mobile phase flow, pH and organic solvent concentration did not significantly affect the results. The results for tablets obtained with both detectors showed no differences. The methods may be considered interchangeable, and they can be used as tools for routine quality control of ALG tablets. In Chapter III the thermal stability of the ALG was evaluated using isothermal and non-isothermal TGA, as well as oven, and samples were analyzed by LC-UV. In the isothermal TGA the ALG was subjected to 150, 155, 160, 165, 170 °C until a mass loss of 10% and the data were analyzed by the Arrhenius method. In non-isothermal TGA the heating rates were varied using 2.5, 5.0, 10.0 and 15.0 °C/min until 500 °C. Data were analyzed by the Ozawa and Kissinger method. In oven the drug was subjected to 130, 140, 150, 155, 160, and 170 °C. The kinetic parameters were obtained by Arrhenius. ALG follows zero-order degradation, where the rate of degradation is independent of the concentration of any reagent. Mass loss is related to chemical reactions. The kinetic parameters varied according to the applied mathematical model. The activation energy ranged from 26 to 45 kcal / mol. The degraded drug was shown to be less toxic in cytotoxicity assay using CRIB cells than the non-degraded drug. The methods developed and the characterization performed proved to be useful for adequate quality control tests of the drug.

The potential effect of increased UV-B radiation on photosynthetic activity and related processes in a range of terrestrial Antarctic plant species was investigated; from a chlorophyte alga to a vascular plant (Deschampsia antartica). The relative contribution of the UV-B waveband to photosystem II (PSII) damage was used to construct an action spectrum for those species found to be sensitive to UV-B exposure. Investigation involved non-invasive measurements of photosynthesis using chlorophyll-a fluorescence emission coupled with polarographic measurement of oxygen and infra-red gas analysis of carbon dioxide. Compounds associated with UV-B protection were extracted, and analysed using high performance liquid chromatography. Different species exhibited differing sensitivity to UV-B exposure. Reduction in the efficiency of the light independent stage of photosynthesis and decrease in leaf length were found in D. antarctica. A decline in the potential activity of PSII (dark-adapted chlorophyll-a fluorescence) was found in some cryptogams, but no concurrent decrease in gas exchange parameters. Shorter wavelengths of UV-B were shown to be more effective in depression of PSII efficiency. The first action spectrum for terrestrial Antarctic plants would predict a higher weighted UV-B exposure under ambient ozone, but would expect less damage under stratospheric ozone depletion than the commonly used plant action spectrum. Some of the plants investigated contained increased amounts of UV absorbing flavonoids following UV-B exposure. The morphological changes found in D. antarctica should lower photosynthetic productivity, but are dependent on developmental stage. The action spectrum produced herein would still forecast increased damage to PSII due to early spring ozone depletion, but not as great as previously predicted. Moreover, current levels of UV-B radiation may be more damaging to some species than previously thought based on other plant action spectra.

Ce travail s’intéresse à évaluer l’efficacité de procédés d’oxydation avancée pour l’élimination de pesticides dans l’eau, plus particulièrement l’acide 2,4-dichlorophénoxyacétique (2,4-D), un herbicide largement répandu, qui a été récemment classé comme cancérogène possible pour l’homme. Ces procédés utilisent différents types de rayonnement – UV/visible, ultrasons, rayons gamma –, seuls ou en combinaison avec des oxydants et/ou catalyseurs (ozone, peroxyde d’hydrogène, réactif de Fenton). L'influence du pH, de la dose d'oxydant, du type et de la concentration du catalyseur, du spectre d'irradiation lumineuse, de la dose de rayons gamma et de la fréquence ultrasonore est également analysée, de façon à déterminer par plans d’expériences les plages de fonctionnement optimales pour la conversion et la minéralisation du polluant. Parmi les procédés individuels, seules l’ozonation et l’oxydation Fenton homogène d’une part, la photolyse et l’irradiation gamma d’autre part permettent d’éliminer plus de 25% du carbone organique total en 1 heure. La sonolyse (à haute fréquence) apparaît comme le traitement moins performant, avec une dégradation du 2,4-D inférieure à 15% sur la même durée. Par ailleurs, des effets synergiques marqués sont mis en évidence en associant les différents types de rayonnement avec H2O2 ou le réactif de Fenton. Dans le dernier cas, le polluant est décomposé en moins de 10 minutes, tandis que le rendement de minéralisation est plus que doublé par rapport aux procédés séparés. Il en est de même pour le procédé couplé UV/O3 par rapport à l’ozonation et la photolyse seules. Ramenés à leur consommation énergétique, les traitements les plus efficaces sont, respectivement en termes de conversion et de minéralisation, l’oxydation radio-Fenton et l’oxydation photo-Fenton utilisant une lampe UV à basse pression de mercure. Par ailleurs, contrairement à la photolyse, ce dernier procédé est également activé par une lampe à arc Xenon, dont le spectre d’émission est proche de celui de la lumière du soleil. Sur la base de ces résultats, un photo-réacteur solaire à recirculation est mis en œuvre pour traiter par oxydation photo-Fenton homogène des solutions de 2,4-D, préparées dans l’eau du robinet ou une eau résiduaire en entrée de station d’épuration. Dans les deux cas, la conversion du pesticide dépasse 95% en 1 heure et sa minéralisation 75% en 5 heures. Par ailleurs, l’eau ainsi traitée respecte tous les paramètres de qualité établis par la norme cubaine de rejet des eaux usées, en incluant une étape successive de neutralisation avec Ca(OH)2 et de filtration. Enfin, plusieurs parmi les meilleurs procédés sont évalués pour éliminer deux autres pesticides organochlorés, particulièrement toxiques et persistants dans l’environnement : le chlordécone et le bêta-hexachlorocyclohexane. Des résultats encourageants sont obtenus, avec une dégradation pratiquement totale des polluants en cinq heures, ce qui démontre l’intérêt des méthodes étudiées pour cette problématique.

Gold Nanoclusters are of particular interest due to their many possible applications across a wide range of scientific fields. More specifically, nano-sized gold particles have potential to be used in drug delivery systems, cancer therapy and catalysis. This dissertation focuses on improving our understanding of ligated gold nanoclusters by examining the role of a variety of phosphine based ligands, novel methods to produce monodisperse solutions, and investigating the kinetics of water soluble ligated gold nanoclusters. The addition of ligands to solutions of Au have shown to produce small (< 20 Au atoms) clusters. All nanocluster solutions were prepared in a similar manner. Typically, a gold salt, either Chloro(triphenylphosphine) gold(I) (Au(PPh3)Cl), or Potassium gold (III) chloride (KAuCl4), were dissolved in various solvents. Next, an equal concentration of ligand was added to the solution and stirred until completely dissolved. Finally, all were reduced with 5X the concentration of borane-tert-butylamine (BTBC) after which were sonicated for ~20 minutes. The timing and method of adding the ligands and reducing agent varied depending on the solution and solubility of the ligands. Primarily we used Electrospray Ionization Mass Spectrometry (ESI-MS) and Ultraviolet – Visible Spectroscopy (UV-VIS) for the characterization of samples, however, occasionally Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and X-Ray Photoemission Spectroscopy (XPS) were used. The most recent research took advantage of the size selective nature of an alpha hemolysin (a-HL) nanopore to investigate the kinetics of thiol-ligated Au clusters ~2 nm in size. The relationship between ligand rigidity and solvent polarity and the size and dispersity of Au cluster suspensions was investigated. We observed the formation of stable monodisperse clusters with the shortest ligand, (L3), independent of solvent. With a longer flexible ligand, (L6), we observed primarily Au8-10 cores depending on the ratio of L6/PPh3. All other ligands yielded polydisperse distributions. These dispersions contained clusters with a nuclearity between 8 and 11, for example [Au10(PPh3)9]3+ in LBn and [Au8(PPh3)7]2+ in LBp, were observed in the initial stages, but they were not stable and precipitated out or plated the glass vial. We also observed that the polarity of the solvent did not play a significant role in the formation of MPC’s, however a correlation between the size of the solvent and MPC formation was observed. The growth and evolution of two unique gold structures was also observed via UV-Vis and ESI-MS. Solutions were prepared which contained Potassium gold (III) chloride and PPh2(CH2)3PPh2, i.e., 1,3-bis(diphenylphosphino)propane, denoted by L3, reduced with Borane tert-butylamine complex (BTBC) in a 1:1 diethyl ether:methanol mix, which yielded a stable [Au11(L3)5]+3. Starting with this known Au11 solution, the addition of Mn2+ has shown to lead to the formation of a stable diphosphine ligated Au8 and a new Au14 species. Additionally, we show that the co-reduction of NiCl2 and Au in the absence of the ligand (L3) does give us a simple method for the production of a monodisperse [Au9(PPh3)8]2+ cluster solution and via electroless deposition does give us a potential low temperature pathway to the formation of a AuNi nanoalloy particle.

Time-resolved spectroscopic studies of energy transfer between molecules in solution form a basis for both, our understanding of fundamental natural processes like photosynthesis as well as directed synthetic approaches to optimize organic opto-electronic devices. Here, coherent two-dimensional (2D) spectroscopy opens up new possibilities, as it reveals the correlation between absorption and emission frequency and hence the full cause-and-effect chain. In this thesis two optical setups were developed and implemented, permitting the recording of electronic 2D spectra in the visible and in the hitherto unexplored ultraviolet spectral range. Both designs rely on the exclusive manipulation of beam pairs, which reduces the signal modulation to the difference between the transition frequency of the system and the laser frequency. Thus - as has been shown experimentally and theoretically - the timing precision as well as mechanical stability requirements are greatly reduced, from fractions of the oscillation period of the exciting light wave to fractions of the pulse duration. Two-dimensional spectroscopy and femtosecond transient absorption (TA) as well as different theoretical approaches and simulation models were then applied to coupled multichromophore systems of increasing complexity. Perylene bisimide-perylene monoimide dyads were investigated in cooperation with Prof. Dr. Frank Würthner and Prof. Dr. Bernd Engels at the University of Würzburg. In these simplest systems studied, global analysis of six different TA experiments unequivocally revealed an ultrafast interchromophoric energy transfer in the 100 fs range. Comparison between the obtained transfer rates and the predictions of Förster theory suggest a breakdown of this point-transition-dipole-based picture at the donor-acceptor distances realized in our compounds. Furthermore, a model including conformational changes and an interchromophoric charge transfer has been derived to consistently describe the observed pico- to nanosecond dynamics and fluorescence quantum yields. A second collaboration with Prof. Dr. Gregory Scholes (University of Toronto, Canada) and Prof. Dr. Paul Burn (University of Queensland, Australia) addressed the photophysics of a series of uorene-carbazole dendrimers. Here, a combination of 2D-UV spectroscopy and femtosecond ansiotropy decay experiments revealed the initial delocalization of the excited state wave function that saturates with the second generation. In room temperature solution, disorder-induced localization takes place on the time scales comparable to our instrument response, i.e. 100 fs, followed by energy transfer via incoherent hopping processes. Lastly, in tubular zinc chlorin aggregates, semi-synthetic analogues of natural lightharvesting antennae that had again been synthesized in the group of Prof. Dr. Frank Würthner, the interchromophoric coupling is so strong that coherently coupled domains prevail even at room temperature. From an analysis of intensity-dependent TA measurements the dimensions of these domains, the exciton delocalization length, could be determined to span 5-20 monomers. In addition, 2D spectra uncovered efficient energy transfer between neighboring domains, i.e. ultrafast exciton diffusion. / Zeitaufgelöste spektroskopische Untersuchungen zu Energietransferprozessen zwischen Molekülen in Lösung bilden die Grundlage nicht nur für unser Verständnis elementarer natürlicher Vorgänge wie der Photosynthese, sondern auch für gerichtete Synthesen zur Optimierung organischer opto-elektronischer Bauteile. Die kohärente zweidimensionale (2D) Spektroskopie eröffnet hier neue Möglichkeiten, da sie - durch Aufdeckung der Korrelation zwischen Absorptions- und Emissionsfrequenz - die konventionelle transiente Absorption (TA) um die Offenbarung der Ursache erweitert. Im Rahmen dieser Arbeit wurden zwei optische Aufbauten entworfen und umgesetzt, die die Aufnahme von elektronischen 2D Spektren im sichtbaren und im bis dahin unerschlossenen ultravioletten Spektralbereich ermöglichen. Beide Designs beruhen auf dem Prinzip der ausschließlich paarweisen Strahlführung, wodurch die Modulation des Signals auf die Differenz zwischen Übergangsfrequenz des Systems und Laserfrequenz reduziert wird. Damit verringern sich - wie theoretisch und experimentell gezeigt - die Anforderungen sowohl an die mechanische Stabilität der Laborumgebung als auch an die Genauigkeit der verwendeten Verzögerungsbühnen erheblich, von Bruchteilen der Oszillationsperiode des anregenden Lichts auf Bruchteile der Laserpulsdauer. Sowohl die 2D Spektroskopie als auch die transiente Absorption sowie unterschiedliche theoretische Ansätze und Simulationsmodelle wurden in den weiteren Teilen dieser Arbeit auf gekoppelte Multichromophor-Systeme unterschiedlicher Komplexität angewandt. Im einfachsten dieser Systeme, einem Perylen-basierten Heterodimer, einer Kooperation mit Prof. Dr. Frank Würthner und Prof. Dr. Bernd Engels an der Universität Würzburg, konnte durch globale Analyse von sechs verschiedenen TA-Messungen ein ultraschneller Energietransfer im 100 fs Bereich zweifelsfrei identifiziert werden. Ein Vergleich mit Vorhersagen aus der Förster-Theorie legt einen Zusammenbruch dieser auf punktförmigen Übergangsdipolen beruhenden Theorie bei den vorliegenden Interchromophor- Abständen nahe. Darüber hinaus wurde für die Piko- bis Nanosekunden-Zeitskalen ein Schema vorgestellt, das Konformationsänderungen sowie einen Ladungstransfer beinhaltet und das die beobachtete Dynamik wie auch die gemessenen Fluoreszenz-Quantenausbeuten konsistent beschreibt. In einer weiteren Kooperation wurden in Zusammenarbeit mit der Gruppe von Prof. Dr. Gregory Scholes (University of Toronto, Kanada) Fluoren-Carbazol-Makromoleküle untersucht, die in der Gruppe von Prof. Dr. Paul Burn (University of Queensland, Australien) synthetisiert worden waren. In diesen sogenannten Dendrimeren konnte durch die Kombination von 2D Spektroskopie und Femtosekunden-Anisotropie-Zerfalls-Experimenten eine anfängliche Delokalisierung der Wellenfunktion des angeregten Zustands abgeleitet werden, die mit der zweiten Generation saturiert. Die Umgebungsunordnung in Raumtemperatur-Lösung führt hier zu einer ultraschnellen Lokalisierung innerhalb der Zeitauflösung des Experiments, gefolgt von inkohärenten Energietransfer-Prozessen. In tubularen Zink Chlorin Aggregaten schließlich, semisynthetischen Analoga zu den Lichtsammelantennen natürlicher Chlorosome, die ebenfalls von Prof. Dr. Frank Würthner's Gruppe bereitgestellt wurden, ist die Kopplung zwischen den einzelnen Molekülen so stark, dass kohärent gekoppelte Segmente selbst bei Raumtemperatur Bestand haben. Die Ausdehnung dieser kohärenten Domänen, die Exzitonen-Delokalisierungslänge, konnte aus der Intensitätsabhängigkeit des transienten Absorptionssignals auf 5-20 Monomere bestimmt werden. 2D Spektren zeigten dabei den effizienten Energietransfer zwischen benachbarten Domänen im Aggregat, also einen ultraschnellen Exzitonen-Diffusionsprozess.

Im ersten Teil dieser Arbeit wurde die erfolgreiche Synthese einer Serie von bisTriarylamin (bisTAA) Verbindungen vorgestellt. Zum einen wurde das Substitutionmuster an der Benzol Brückeneinheit in Form einer meta- bzw. para-Ständigkeit der Redoxzentren (pX bzw. mX), und zum anderen die energetische Lage der Brückeneinheit durch zwei elektronen-schiebende oder ziehende Substituenten X (mit X = OMe, Me, Cl, CN, NO2) in 2,5-Position variiert. Im Falle der meta-Serie wurden auch einige in 4,6-Position substituierte Verbinungen hergestellt (mX46). Die neutral Verbindungen wurden bezüglich ihrer elektrochemischen und photophysikalischen Eigenschaften untersucht. Durch Oxidation konnten die gemischt valenten (MV), kationischen bisTAA-Verbindungen erzeugt werden. Der thermisch induzierte Lochtransfer (HT) wurde durch temperatur-abhängige ESR-Spektroskopie untersucht. Während die HT-Rate k und HT-Barriere ΔG in mX unbeeinflusst von den Substituenten X sind, steigen gleichzeitig k und ΔG in der pX-Serie mit zunehmenden Elektonenschub von X an. Diese zunächst widersprüchliche Beobachtung konnte durch einen ansteigenden Einfluss von Lösungsmitteleffekten und dadurch resultierend, einer zusätzlichen effektiven Barriere erklärt werden. Der optisch induzierte Lochtransfer wurde mittels UV/Vis/NIR-Spektroskopie untersucht. Die pX-Serie zeigte eine Zuhname der elektronischen Kopplung V und dementsprechende eine Abnahme von ΔG, mit Anstieg des elektonenschiebenden Charakters von X. Für mX war eine spektroskopische Bestimmung dieser Parameter nicht möglich. Die mX46-Serie zeigte ein intermediäres Verhalten, wobei MV-Verbindungen mit stark elektronenschiebenden X eine ähnliche hohe Kopplungen wie pX aufwiesen, was mit Hilfe von DFT-Rechnungen bezüglich der Molekülorbitale erklärt werden konnte. Im zweiten Teil dieser Arbeit wurde die Synthese einer Serie von Verbindungen mit Triarylamin (TAA) als Donor und Naphthalindiimid (NDI) als Akzeptor vorgestellt. Auch hier wurde zum einen das Substitutionmuster an der Benzol-Brückeneinheit in Form einer meta- bzw. para-Ständigkeit der Redoxzentren (pXNDI bzw. mXNDI) variieiet und die energetische Lage der durch X (mit X = OMe, Me, Cl, CN, NO2) in 2,5-Position variiert. Außerdem wurde die in 4,6-Position substituierte Verbinungen mOMe46NDI hergestellt. Alle Verbindungen wurden bezüglich ihrer elektochemischen und photophysikalischen Eigenschaften untersucht. Die Elektronentransferprozesse der Ladungsseparierung (CS) und Ladungsrekombination (CR) dieser Verbindungen sollten mittels transienter Absorptionsspektroskopie (TA) in Toluol untersucht werden. Für die Nitroverbindungen p-/mNO2NDI war dies nicht möglich, da sich diese unter Bestrahung zersetzten. Die CR von pXNDI waren nicht im ns-Bereich detektierbar, weshalb sich auf die mXNDI-Serie (mit X = OMe–CN) konzentriert wurde. Die CS wurde mittels fs-TA untersucht. Nach optischer Anregung konnte die Bildung eines CS-Zustandes detektiert werden, dessen Bildungsgeschwindigkeit hin zu elektronen-ziehenden Substituenten X steigt. Die CR wurde mit ns-TA untersucht. Sie findet in der Marcus invertierten Region statt und zeichnet sich wird durch ein biexponentialles Abklingverhaten, was durch ein Singulet-Triplett Gleichgewicht im CS-Zustand zustande kommt, aus. Durch Anlegen eines externen Magnetfeldes ließ sich das Abklingverhalten entscheidend verändern und es konnte eine Singulett-Triplett Aufspaltung nachgewiesen werden. Dieser Befund konnte weiterhin durch Simulation der Abklingkurven bestätigt werden. In beiden Teilen dieser Arbeit konnte ein entscheidender Einfluss der Benzolbrücke auf die auftretenden Ladungstransferprozesse gezeigt werden. Für den HT in Grundzustand der MV bisTAA Verbindungen, sowie der ET im angeregten Zustand der Donor-Akzeptor-Verbindungen, wurden die höchsten ET-Raten für die para-Serien pX und pXNDI gefunden, während die meta-Serien mX und mXNDI deutlch kleine Transferraten aufwiesen. In beiden Studien zeigten die meta46-Verbindungen mX46 und mOMeNDI46 ein intermediäres Verhalten, zwischen denen der para- und meta-Verbindungen. / In the first part of this thesis, the synthesis of a series of bistriarylamine (bisTAA) compounds was presented. On the one hand, the substitution pattern of the TAA at the benzene bridging unit was varied from meta- to para-position (pX and mX), on the other hand, the energetic position of the bridging unit was tuned by use of two electron-donating or electron-accepting substituents X (with X = OMe, Me, Cl, CN, NO2) in 2,5-position. In case of the meta-series, compounds with X in 4,6-position were synthesized (mX46). The photophysical and electrochemical properties of the neutral compounds were investigated. The cationic mixed valence (MV) bisTAA compounds could be generated by oxidation. Thermally induced hole transfer (HT) in the groud state was investigated by temperature depending ESR spectroscopy. While the HT rate k and HT barrier ΔG in mX are unaffected by the substituents X, k and ΔG in the pX series increase simultaneously with increasing electron-donating strength of X. This, at first contradictory observation can be explained by an increasingly important solvent dynamic effect and an additional, effective barrier. The optically induced HT was examined by UV/Vis/NIR spectroscopy. The pX-series revealed an increase of the electronic coupling V, and correspondingly a decrease of ΔG, with an increase of the electron donating character of X. For mX, a spectroscopic determination of these parameters was not possible. mX46 showed an intermediate behavior, MV compounds with strong electron-donating X, obtained coupling of similar magnitude as pX, which could be explained by means of DFT calculations, with regard to the molecular orbitals. In the second part of this work, the synthesis of a series of dyads with triarylamine (TAA) as a donor and naphthalene diimide (NDI) as an acceptor was presented. Again, the substitution pattern of the redox centers at the benzene bridging unit was varied in the form of a meta- or para-position (pXNDI or mXNDI) and the energetic position of the bridging unit was varied by X (with X = OMe, Me, Cl, CN, NO2) attached in the 2,5-position. Additionally, compound mOMe46NDI with methoxy substitution in 4,6-position was synthesized. The photophysical and electrochemical properties of these compounds were investigated. The electron transfer (ET) processes of charge separation (CS) and charge recombination (CR) of these were investigated by means of transient absorption (TA) spectroscopy in toluene. This was not possible for the nitro-compounds p-/mNO2NDI, since they decomposed under irradiation. In addition to that, the CR of pXNDI was not detectable by ns-setup, which is why the focus was given to the mXNDI series (with X = OMe–CN).The CS was examined by fs-TA spectroscopy, where the formation of a CS state could be detected. The rise time of the CS states decreases with increasing electron-withdrawing substituents X. CR was examined with ns-TA spectroscopy and shows a biexponential decay behavior, which is caused by singlet-triplet equilibrium in the CS state. By applying an external magnetic field, the decay behavior was decisively changed and the singlet-triplet splitting could be determined. This finding could also be confirmed by simulating the decay curves. In both parts of this work, the decisive influence of the benzene bridging unit on the appearing ET processes became obvious. For the HT in the ground state of the MV compound, as well as for the ET in the exited states of the DA compounds, the highest transfer rates were found for the para-series pX and pXNDI, and much smaller rates for the meta-series mX and mXNDI. The meta46-compounds mX46 and mOMeNDI46 showed an intermediate behavior in both parts of this work.

There is currently no published method for the analysis of the herbicide quizalofop-p-tefuryl or its matabolite quizalofop in biological matrices. Quizalofp-p-tefuryl is a relatively new herbicide with apparent low toxicity and is readily degraded. Its metabolite also has herbicide activity. Quizalofop-p-tefuryl is a aryloxyphenoxypropionate and is a post emergence herbicide used for pulses and vegetables. This work reports on a method for the analyses of this pesticide residue and its metabolite in soybean using HPLC on a C-18 column with UV detection at 332 nm. Several methods are tried including some involving the use of solid phase extractors like silica, Florisil and strong cationic exchange cartridges. The main method developed uses an extraction solvent hexane: acetone: acetic acid for extracting the quizalofop-p-tefuryl and quizalofop from the ground soybean. The extracts are then made alkaline with NaOH and this deprotonates the quizalofop separating it from the hexane phase which contains the quizalofop-p-tefuryl. The hexane phase is extracted with ACN and quizalofop-p-tefuryl partitions into this phase. The quizalof-p-tefuryl is repartitioned into a fresh diethyl ether: hexane phase by adding a large quantity of H2O and NaCL to the ACN layer. The organic phase is washed and evaporated to dryness before being made up to volume with ACN for direct analysis by UV detection or by derivatising it to methoxychloroquinoxaline for fluorescence detection. Using the method that directly detects the analytes, for quizalofop-p-tefuryl and quizalofop at spike levels, the method has average recoveries. The precision of recoveries for both compounds is about 9%. The method is fairly robust. Time of analysis per analyte is about 2 hrs. / Master of Science