<p> Investigations on the stability and reactions of various isomers of the benzohomotropylium/bridged [11]-annulene system are presented in this thesis. As 1,6-methano-[11]-annulenium cations are isomeric with benzohomotropylium cations in principle it is possible for these systems to be interconverted by a circumambulatory migration of the 'bridging' methano group. If this reaction were to proceed to equilibrium it would allow the examination of the thermodynamic stability of the various isomers.</p> <p> Homotropylium cations with two methyl groups at C8 are known to undergo facile circumambulatory rearrangements. Thus in this work the 1-hydroxy 8,8-dimethyl-2,3-benzohomotropylium and 1-hydroxy 8,8-dimethyl-4,5-benzohomotropylium cations have been prepared by protonation of the corresponding 2,3- and 4,5- benzohomotropones in FSO3H. On the basis of their 1H NMR spectra it is concluded that they can properly be regarded as homoaromatic cations. The thermal isomerizations of these cations have been studied in detail. The thermal isomerization of these cations led to the formation of a series of products but does not yield the corresponding [11]-annulenium isomer. In addition the barriers to ring inversion in these cations were found to be much lower than those of other homotropylium cations. This suggests that the former cations have a very open structure. Besides this experimental approach, the relative stability of these isomers has been explored using MNDO calculations. The calculated heats of formation (ΔHf) showed that the 1-benzohomotropylium cation is more stable than the corresponding [11]-annulenium ion by 21 kcal/mol.</p> / Thesis / Master of Science (MSc)

Mass spectrometry has frequently been employed in the analysis of biologically relevant molecules; however, mass spectrometry alone may not always be sufficient for the differentiation and characterization of isomeric and isobaric ions. In this work, infrared multiple photon dissociation (IRMPD) spectroscopy and ion mobility spectrometry (IMS) were evaluated as complementary techniques for the characterization and separation of isomeric and isobaric ions of biological relevance. In the first project, analysis of experimental IRMPD spectroscopy data shows that this technique is useful in the differentiation of hydroxyproline isomers. Absorption bands allow for the differentiation of three isomeric species: 1640 cm-1 (trans-4-hydroxyproline), 1718 cm-1 (cis-4-hydroxyproline), and 1734 cm-1 (cis-3-hydroxyproline). In the second project, theoretical CCS and IR spectroscopy predictions of isobaric modified amino acids and isomeric drugs have been carried out as predictions of IMS and IRMPD spectroscopy suitability. Preliminary IMS measurements suggest that the CCS predictions are at least qualitatively useful.

Anthradithiophene (ADT) derivatives have proven to be a front-runner in the world of small molecule semiconductors for organic electronics and optoelectronics. This is mainly due to the improved stability, easy tuning of chemical and physical properties, and impressive device performance that these molecules possess, especially in organic field effect transistors (OFET) and organic photovoltaics (OPV). The second chapter of this dissertation shows that reducing the amount of alkylsilylethynyl groups, used for functionalizing and solubilizing the ADT backbone, does alter the chemical, physical and crystallographic properties of ADTs. These changes offer the opportunity to study and observe different intermolecular interactions as well as monitoring their influence on sulfur scrambling in solid state. Additionally, from the early days ADTs and functionalized ADTs have been synthesized as isomeric mixtures. In chapter three, I demonstrate a new and simple method that can separate the syn and anti isomers of the F-TES-ADT and F-TEG-ADT chromatographically. The effects of isomeric purity on crystal packing and field effect transistor performance were studied extensively. Chapter four of this dissertation reveals a new generation of acceptor (electron poor) ADT derivatives obtained by attaching cyanide as electron withdrawing group (EWG) to the ADT chromophore. An extensive study was conducted on CN-ADT (acceptor) molecules in small molecule (F-TES-ADT) donor/ small molecule (CN-ADT) acceptor binary BHJ blends as well as P3HT/CN-ADT/PCBM ternary BHJ blends. Photophysical studies of the Donor/ acceptor blends (interface, domains, and crystal orientation) were conducted to obtain a better understanding of the film morphology and its effect on solar cell performance. Finally, the last part of the dissertation, Chapter five, focus on studying singlet fission in ADT derivatives, as well as the effect of varying the size of the alkylsilylethynyl functional group (used for solubilizing the ADT backbone) on altering the electronic couplings and how can that potentially affect the singlet fission rate in these molecules. We also tried to inspect the extent of the correlation between long-range order in crystal packing and singlet fission by monitoring singlet fission rate and efficiency for ADT derivatives with different thin film morphologies.

Late transition metal complexes bearing nitrogen-containing ligands may act as catalyst in biotechnology or industrial catalysis. Imidazole is one of the most common biofunctional ligands that play critical roles in meta1loenzymes, since the imidazole moiety of the histidyl residues often constitutes all or part of the binding sites of various transition metal centers. In this work, some new zinc(II), copper(II) and nickel(II) complexes containing the imidazolate and pyridyl moieties incorporated in the imine (ImPyI) and amine (ImPyA) ligands were obtained. Different methods of crystallization yield crystals of complexes (2), (6), (8), (9), (10), (17) and (18). Subsequent structural analyses revealed their interesting structures. In zinc(II) and nickel(II) complexes, facial isomers were isolated while none of the meridional isomers were observed. Particularly interesting is the zinc(II) complexes where two facial complexes with different geometries were identified. The mixture of the different nitrogen donor groups in the same ligand provides handy comparison of these structural variations due to the different nature of these donor groups. One tridentate ligand with bromide substitution on the imidazolate and a tetradentate ligand with an additional pyridyl group were synthesized as an extension of this work. One crystal structure of each of the corresponding metal complex bearing these ligands is also discussed here. Most metal complexes are consolidated by extensive weak hydrogen bonds among them in the crystal lattices.

Neurodegenerative diseases have been shown to correlate positively with an ageing population. The most common neurodegenerative diseases are amyotrophic lateral sclerosis (ALS), Parkinson’s disease and Alzheimer’s disease. The cause of these diseases is believed to be the interaction between genetic and environmental factors, synergistically acting with ageing. BMAA (β-methylamino-L-alanine) is one kind of toxin present in our environment and might play an important role in the development of those diseases. BMAA was initially isolated from cycad seeds in Guam, where the incidence of ALS/Parkinsonism-dementia complex among the indigenous people was 50 – 100 times higher than the rest of the world in the 1950’s. BMAA can induce toxic effects on rodents and primates. Furthermore, it can potentiate neuronal injury on cell cultures at concentrations as low as 10 µM. BMAA was reported to be produced by cyanobacteria, and could bio-magnify through the food chain. In this thesis, work was initially focused on the improvement of an existing analytical method for BMAA identification and quantification using liquid chromatography coupled with tandem mass spectrometry.  Subsequently, the refined method was applied to environmental samples for probing alternative BMAA producer(s) in nature and to seafood samples for estimation of human exposure to this toxin. In Paper I, a systematic screening of the isomers of BMAA in a database was performed and seven potential isomers were suggested. Three of them were detected or suspected in natural samples. In Paper II, a deuterated internal standard was synthesized and used for quantifying BMAA in cyanobacteria. In Paper III, Diatoms were discovered to be a BMAA producer in nature. In Paper IV, ten popular species of seafood sold in Swedish markets were screened for BMAA. Half of them were found to contain BMAA at a level of 0.01 – 0.90 µg/g wet weight. In Future perspectives, the remaining questions important in this field are raised.

Pastaraisiais dešimtmečiais atliktų tyrimų rezultatai rodo, jog gyventojų mitybos įpročiai palaipsniui blogėja, mažiau kreipia dėmesį į suvartojamų riebalų, kalorijų kiekį. Tai įtakoja nutukimą, sergamumą širdies ir kraujagyslių ligomis, cukriniu diabetu, skatina onkologinių ligų atsiradimą. Pasaulio sveikatos organizacija (PSO) rekomenduoja, kad trans riebalų rūgštys sudarytų mažiau nei 1 proc. nuo bendrojo energijos suvartojimo kiekio. Darbo tikslas: Įvertinti lietuviškų gaminių saugumą riebalų rūgščių trans izomerų atžvilgiu. Tyrimo uždaviniai: 1. Literatūros apie riebalų rūgščių trans izomerų susidarymą jūrinių žuvų gaminiuose apžvalga. 2. Nustatyti riebalų rūgščių trans izomerų kiekius ir įvertinti jų atitikimą Lietuvoje reglamentuojamiems dydžiams skirtingų gamintojų silkės, lašišos, skumbrės gaminiuose. 3. Atlikti riebalų rūgščių trans izomerų kiekio lietuviškuose tirtuose žuvies gaminiuose monitoringą, palyginti su kitų tyrėjų duomenimis, įvertinti gaminius saugos aspektu. 4. Apdoroti gautus duomenis statistiškai, suformuoti išvadas. Išvados: 1. Žuvies ir jos gaminiuose dažniausiai nustatomos šios riebalų rūgščių trans izomerai elaidino ( C18:1n9t ) ir linolo ( C18:2n6t ). 2. Riebalų rūgščių trans izomerų buvo aptikta net 60 proc. ( % ) iš visų tirtų mėginių, o likusiuose nebuvo rasta. Riebalų rūgščių trans izomerų kiekiai svyravo nuo 0,1 iki 1,86 proc. ( % ). 3. Vertinant žuvies gaminius daugiausiai riebalų rūgščių trans izomerų marinuotoje Atlantinių silkių... [toliau žr. visą tekstą] / Purpose: to evaluate the safety of Lithuanian products trans fatty acid isomers against. Tasks: 1. Literature on trans fatty acid isomers formation of marine fish products review. 2. The set fatty acid trans isomers and assess their compliance with Lithuania regulated sizes from different manufacturers herring, salmon, mackerel products. 3. Perform trans fatty acid isomers in Lithuanian studied in fish monitoring in comparison with data of other researchers, to assess product safety. 4. Process received data statistically to form conclusions. Research. Fatty acids - saturated, unsaturated, monounsaturated, poliansaturated and trans izomer were analyzed in fish products: in salmon, herring, mackerel and technologically processed fish products. The research was performed in Chemistry laboratory of Food Institute of Kaunas University of Technology. Investigations were carried out in 2010 september – 2013 february. Results. Trans fatty acid isomers were found as much as 60 percent of all samples tested. most fatty acids, trans isomers were found smoked herring 1,86±0,35 proc. ( % ) and smoked scomber 0,60±0,01 proc. ( % ). Trans isomers depends on the technology and technology process. Chilled salmon were no found trans isomers. Fish products are safe if they are used about as little as possible heat-treated. Fish is high in saturated fatty acids, polyunsaturated fatty acids and monounsaturated fatty acids. trans isomers of fatty acids is undesirable in fish. Conclusion... [to full text]

Inherited hyperbilirubinemias are a group of metabolic disorders, characterized by increased levels of total serum bilirubin or its conjugated fraction. Most of these hyperbilirubinemias are inherited autosomal recessively and are manifested in young age. Increased bilirubin reflects the genetic disturbances in one of the enzymes of heme degradation pathway, the defect of bilirubin conjugation (UGT1A1 gene) or its transport (ABCC2, OATP1B1, OATP1B3). All of these proteins are involved not only in elimination of bilirubin, but various substrates; therefore the performed studies have a great pharmacogenomics impact. We have studied the molecular pathology of hereditary hyperbilirubinemias in Caucasian and Roma population and to compare the clinical and biochemical results with the molecular genetic data. We described the impact of compound defect of c.-3279T>G and g.175492_175493insTA on total serum bilirubin and calculated the linkage disequlibrium of these two variants in promoter region of UGT1A1 gene. We also verified, that the population distribution of both variants is in concordance with the literature. In our second study, we have described the rare conjugated hyperbilirubinemia Dubin-Johnson type among 7 Roma families. We have found a novel variant NG_011798.1:c.[1013_1014delTG] together with...

Orientador: Marcos Nogueira Eberlin / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-16T12:58:37Z (GMT). No. of bitstreams: 1 BenassiNeto_Mario_D.pdf: 12057357 bytes, checksum: 9c84e704ca7f0f4d824a37e0c4f45b55 (MD5) Previous issue date: 2010 / Resumo: É proposto um método absoluto para diferenciação de isômeros constituicionais por espectrometria de massas, utilizando a reatividade em fase gasosa de fragmentos iônicos diagnósticos de estrutura (FIDE), gerados a partir de precursores isoméricos. Com apenas um espectro de massas é possível fazer a atribuição de configuração de um isômero, sem a necessidade de comparação com outros espectros de massas. Para provar o príncipio foram testadas as seguintes classes de isômeros: acetonaftonas, alquilanilinas, carbetoxipiperidinas, metiltiofenos, ácidos ciclohexeno carboxílicos e metilpiperidinas. Os precursores foram submetidos a EI a 70 eV, e o comportamento dissociativo foi estudado com o intuíto de se identificar o FIDE. É desejável que o FIDE tenha as seguintes características: i) seja formado por todos os isômeros dentro do conjunto, ii) mantenha a informação estrutural da molécula precursora, iii) seja estável em fase gasosa e iv) os FIDE¿s formados por cada um dos precursores devem ter estruturas diferentes e estes não podem interconverter-se. Para cada classe de isômeros foi selecionado a m/z do FIDE e este íon foi submetido à dissociação induzida por colisão (CID), esperando que sua dissociação seja distinta dependendo do precursor, e à reações íon/moléculas, esperando que FIDEs de precursores diferentes formem diferentes produtos iônicos. Foi utilizado um espectrômetro de massas pentaquadrupolar que permite experimentos de MS/MS/MS, que permitiu caracterizar os produtos iônicos formados nas reações, através de CID. / Abstract: Herein, it¿s described an absolute method for structure assignment of constitutional isomers exploring the gas phase behavior of a structurally diagnostic fragment ion (SDFI) generated by each one of the precursor molecules within an isomeric set. This method allows the unequivocally assigning of the configuration of a precursor isomer with only one mass spectrum. To prove the principle the following isomeric sets were tested: acetonaphthone, alkylanilines, carbetoxypiperidines, methylthiophenes, cyclohexene carboxylic acids and methylpiperidines. All of the precursor isomers were submitted to 70 eV electron ionization (EI) with the intent of identifying the proper SDFI for each of the isomeric sets. Ideally, the SDFI should have the following characteristics: i) must be formed by all the isomers within the isomeric set, ii) retain the structural information of the precursor molecule, iii) be stable (long lifetime) and iv) the SDFI generated from different precursors must have different structures and must not interconvert into one another. The m/z of the SDFI is selected and then submitted to collision induced dissociation, hoping that the dissociative behavior is different depending on the precursor molecule, and ion/molecule reactions, hoping the bimolecular chemistry is different due to the formation of different ion products. For all the experiments it was used a pentaquadrupole mass spectrometer that allows MS/MS/MS, therefore allowing characterization of the ion products generated by ion/molecule reactions through collision induced dissociation. / Doutorado / Quimica Organica / Doutor em Ciências

Orientador: Marcos Nogueira Eberlin / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-15T19:01:40Z (GMT). No. of bitstreams: 1 Lalli_PriscilaMicaroni_M.pdf: 4223184 bytes, checksum: 852704419d68edf5bd13623379abf7b4 (MD5) Previous issue date: 2010 / Resumo: Na espectrometria de mobilidade iônica, íons de diferentes tamanhos ou conformações espaciais em fase gasosa são separados de acordo com o tempo que levam para atravessar um gás sob a influência de um campo elétrico. O acoplamento dessa técnica à espectrometria de massas (IMMS) resulta numa ferramenta extremamente versátil, capaz de investigar a estrutura molecular e separar amostras complexas, incluindo isômeros. No capítulo I, diferentes gases foram utilizados na separação dos isômeros N-butil anilina e p-butil anilina a fim de investigar a interação íon/molécula durante o processo de mobilidade iônica. Mostramos que as moléculas do drift gas não atuam apenas como barreiras físicas que atrasam os íons, como geralmente são consideradas, mas podem interagir quimicamente com os íons. No caso desses isômeros, gases mais polarizáveis como eteno e CO2 mostraram melhorar consideravelmente a separação. Acredita-se que a grande diferença de polarizabilidade entre os isômeros esteja relacionada com este fato, pois o gás mais polarizável interagiria melhor com o isômero também mais polarizável atrasando-o numa intensidade maior. Gases mais massivos e pressões maiores também ajudam a melhorar consideravelmente a separação de isômeros. No capítulo II, a IMMS foi usada para determinar pela primeira vez a mobilidade intrínseca de uma série de agregados catiônicos e aniônicos de líquidos iônicos na fase gasosa. Os resultados são condizentes com as medidas feitas em solução por RMN, que mostram uma aparente anomalia em que os cátions, mais volumosos, viajam mais rápido do que os ânions. Esse comportamento ainda não é muito bem compreendido, entretanto, pode estar relacionado à orientação dos íons pelo campo ou a diferença de dureza entre cátions e ânions / Abstract: Ion mobility spectrometry separates ions with different sizes or spacial conformations in gas phase according to the time they take to travel through a gas under the influence of an electrical field. Coupling this technique to mass spectrometry provides an extremely versatile tool, able to investigate molecular structure and separate complex samples, including isomers. In Chapter I, different gases were used to separate the isomers N-butyl aniline and p-butil aniline in order to investigate the ion/molecule interaction during the ion mobility process. We have shown that drift gas molecules don¿t act only as physical barriers that slow down the ions, as they are usually considered, but they may interact chemically with them. In the case of these isomers, more polarizable gases such as ethene and CO2 have shown to improve considerably the isomer separation. We believe that the large difference of polarizability between both isomers is related to this fact, because more polarizable gases would interact better with the more polarizable isomer slowing it down more intensively. More massive gases and higher pressures also help improve isomer separation. In Chapter II, IMMS was used to perform the first measurements of the intrinsic mobility of a series of gaseous cationic and anionic aggregates of ionic liquids. Results confirm previous mobility measurements by NMR, which show an apparent anomaly in which the bulkier cations travel faster than respective anions. This behavior isn¿t well understood yet, however, it may be related to the ions orientation by the field or to the hardness difference between cations and anions / Mestrado / Quimica Analitica / Mestre em Química

Doctor of Philosophy / Department of Physics / Carlos A. Trallero / Ultra-fast spectroscopy has become a common tool for understanding the structure and dynamics of atoms and molecules, as evidenced by the award of the 1999 Nobel Prize in Chemistry to Ahmed H. Zewail for his pioneering work in femtochemistry. The use of shorter and more energetic laser pulses have given rise to high intensity table-top light sources in the visible and infrared which have pushed spectroscopic measurements of atomic and molecular systems into the strong-field limit. Within this limit, there are unique phenomena that are still not well understood. Many of such phenomena involve a photoionization step. For three decades, there has been a steady investigation of the single ionization of atomic systems in the strong-field regime both experimentally and theoretically. The investigation of the ionization of more complex molecular systems is of great interest presently and will help with the understanding of ultra-fast spectroscopy as a whole. In this thesis, we explore the single ionization of molecules in the presence of a strong electric field. In particular, we study molecular isomer pairs, molecules that are the same elementally, but different structurally. The main goal of this work is to compare the ionization yields of these similar molecular pairs as a function of intensity and gain some insight into what differences caused by their structure contribute to how they ionize in the strong-field limit. Through our studies we explore a wavelength dependence of the photoionization yield in order to move from the multi-photon regime of ionization to the tunneling regime with increasing wavelength. Also, in contrast to our strong-field studies, we investigate isomeric molecules in the weak-field limit through single photon absorption by measuring the total ionization yield as a function of photon energy. Our findings shed light on the complexities of photoionization in both the strong- and weak-field limits and will serve as examples for the continued understanding of single ionization both experimentally and theoretically.