In the frame of this thesis different calix[4]resorcin- and calix[4]pyrogallolarene derivatives were used as platform for the synthesis of novel star polymers and dendritic structures. The objectives of this work can be portrayed under the following points: First: Synthesis and modification of calix[4]resorcin- and calix[4]pyrogallolarenes with a varying number and varying type of functional sites and their precise characterization by modern NMR techniques and single crystal X-ray diffraction. Second: Synthesis of well-defined star polymers and dendrimers with different number of arms and accordingly dendrons, based on calix[4]resorcin- and calix[4]pyrogallolarenes, via convenient polymerization and generation growth reactions and analysis of the obtained products by different methods (MALDI-TOF-MS, SEC-RI and SEC-MALLS, NMR).

Os ânions inorgânicos nitrato (NO3-) e nitrito (NO2-) por muito tempo foram considerados produtos finais inertes do metabolismo do óxido nítrico (NO) e constituintes indesejáveis da dieta. Entretanto, é crescente o interesse das potenciais reações que podem se processar em meio fisiológico e, que envolvem especialmente o íon nitrito mediadas por complexos de metais de transição. Ferro-heme presente em proteínas como a mioglobina podem formar complexos porfirínicos com NO, gerando espécies que podem atuar principalmente como catalisadores em diversas vias biológicos importantes. Complexos com NOx coordenado a ferro-heme estão envolvidos tanto no processo da cura da carne (pigmentação da carne), como em processos redox, nos quais são capazes de oxidar substratos indiretamente pela produção de espécies reativas ou diretamente por reações de transferência de átomo de oxigênio (TAO). Os lipídeos, constituintes celulares fundamentais na composição de membranas e lipoproteínas, podem servir como substratos para essas reações e, sua oxidação pode ocasionar danos ao organismo. Tióis, importantes antioxidantes e constituintes de proteínas, também podem participar desse tipo de reações e, conseqüentemente gerar danos ao organismo. Considerando que o mecanismo e os parâmetros cinéticos e termodinâmicos destas reações ainda não foram completamente estabelecidos para explicar a vasta funcionalidade destes complexos, o presente projeto de pesquisa visa proporcionar um melhor conhecimento das reações redox envolvendo NOx e mediadas por porfirinas de ferro em alimentos e sistemas biológicos. / For long time, the anions nitrate (NO3-) and nitrite (NO2-) were considered inert end products of nitric oxide (NO) metabolism and undesirable constituents of the diet. Currently, there is an increasing interest for potential reactions which may occur in physiological conditions involving specially the nitrite ion and mediated by transition metal complexes. Heme NOx iron complexes are involved in meat curing process (meat pigmentation) and are able to oxidize substrates indirectly generating reactive species or directly by oxygen atom transfer reactions (OAT). Lipids, fundamental cellular constituents of membranes and lipoproteins, and thiols, important antioxidants and protein constituents, may serve as substrates to OAT and their oxidation may promote damage to the organism Considering that the mechanism and kinetic and thermodinamic parameters of these reaction have not yet been fully elucidated to explain the varied functionality of these complexes, the present research project aim to bring a better understanding of redox reactions involving NOx mediated by iron porphyrins in foods and biological systems. Thiols, important antioxidants and protein constituents, may serve as substrates to OAT and their oxidation may promote damage to the organism. The present work aims to bring a better understanding of the mechanism, kinetic and thermodynamic parameters of the reaction involving nitrite mediated by iron-porphyrins in food and biological systems.

Amphiphilic polymers are a class of polymers that self-assemble into different types of microstructure, depending on the solvent environment and external stimuli. Self assembly structures can exist in many different forms, such as spherical micelles, rod-like micelles, bi-layers, vesicles, bi-continuous structure etc. Most biological systems are basically comprised of many of these organised structures arranged in an intelligent manner, which impart functions and life to the system. We have adopted the atom transfer radical polymerization (ATRP) technique to synthesize various types of block copolymer systems that self-assemble into different microstructure when subject to an external stimuli, such as pH or temperature. The systems that we have studied are: (1) pH responsive fullerene (C60) containing poly(methacrylic acid) (PMAA-b-C60); (2) pH and temperature responsive fullerene containing poly[2-(dimethylamino)ethyl methacrylate] (C₆₀-b-PDMAEMA); (3) other responsive water-soluble fullerene systems. By varying temperature, pH and salt concentration, different types microstructure can be produced. In the presence of inorganic salts, fractal patterns at nano- to microscopic dimension were observed for negatively charged PMAA-b-C60, while such structure was not observed for positively charged PDMAEMA-b-C60. We demonstrated that negatively charged fullerene containing polymeric systems can serve as excellent nano-templates for the controlled growth of inorganic crystals at the nano- to micrometer length scale and the possible mechanism was proposed. The physical properties and the characteristics of their self-assembly properties will be discussed, and their implications to chemical and biomedical applications will be highlighted. / Singapore-MIT Alliance (SMA)

Liquid chromatography is an analytical technique that is constantly facing new challenges in the separation of small molecules and large biomacromolecules. Recently the development of ultra high pressure liquid chromatography has increased the demand on sturdy particles as stationary phase. At the same time the particle size has decreased to sub-2 µm and packed into shorter analytical columns. This thesis deals with the development of new ways of preparing particulate polymer materials using divinylbenzene (DVB) as crosslinker. It includes a novel procedure for synthesizing monodisperse polymer particles by photoinitiated precipitation polymerization. A 150 W short arc xenon lamp was used to initiate the polymerizations. The synthesized particles are monodisperse and have an average particle size ranging from 1.5 to 4 μm depending on reaction conditions and have subsequently been used as grafting templates. The surface of DVB particles contains residual vinyl groups that serve as anchoring points for further functionalization via a variety of grafting schemes. Copolymerization with incorporation of 2,3-epoxypropyl methacrylate yielded pendant oxirane groups on the particle surface. Atom transfer radical polymerization (ATRP) was used to graft methacrylates from the surface resulting in a core-shell type material. A “grafting to” scheme was used to attach pre-made sulfopropyl methacrylate telomers onto particles containing oxirane rings. / Populärvetenskaplig sammanfattning på svenska: Vätskekromatografi är en analytisk kemisk teknik som ständigt står inför nya utmaningar när det gäller att separera allt från små organiska föreningar till stora makro¬molekyler. Denna avhandling beskriver tillverkning av polymera partiklar med exceptionellt jämn storleksfördelning och ytmodifiering av dessa, för användning som stationärfas i kromatografi¬kolonner. Polymeriserings¬tekniken som används är utfällnings¬polymerisering där lösningen UV-bestrålas av en 150 W xenonlampa. Monomeren (byggstenen) löses tillsammans med en intiator i ett lösningsmedel och efterhand som polymeriseringen fortskrider faller polymerpartiklarna ut. Polymerpartiklarna är gjorda av monomeren divinylbensen som fungerar som en tvärbindare, dvs att den länkar ihop flera kedjor till ett hårt litet nystan. Partiklarna växte till en storlek på 1,5 till 4 µm under två till fyra dygn. Efter tillverkningen är partiklarnas yta täckta av vinylgrupper som kan användas för att fästa funktionella polymerkedjor. Genom att tillföra monomeren 2,3-epoxipropyl¬metakrylat i polymeriseringen kunde man desutom få en partikelyta som innehöll epoxigrupper. Epoxigrupperna användes för att fästa positivt laddade polymerkedjor av bestämd längd. Materialet packades i en kromatografikolonn och användes för att separera en testlösning bestående av fyra proteiner. Partiklarna användes även som bas för ymppolymerisering där den vinyltäckta ytan fått reagera med vätebromid. Detta gör att partiklarna blir stora makroinitiatorer som kan användas för att på ett kontrollerat sätt låta polymerkedjor växa från ytan. I en undersökning ympades 2,3-epoxypropylmetakrylat från ytan på partiklarna och resultatet blev ett tjockt ytskikt. Epoxigrupperna kunde sedan hydrolyseras till dioler vilket gjorde partiklarna mer hydrofila.

The potential use of renewable, bio-based polymers in high-technological applications has attracted great interest due to increased environmental concern. Cellulose is the most abundant biopolymer resource in the world, and it has great potential to be modified to suit new application areas. The development of controlled polymerization techniques, such as atom transfer radical polymerization (ATRP), has made it possible to graft well-defined polymers from cellulose surfaces. In this study, graft-modification of cellulose substrates by ATRP was explored as a tool for tailoring surface properties and for the fabrication of functional cellulose surfaces. Various native and regenerated cellulose substrates were successfully graft-modified to investigate the effect of surface morphology on the grafting reactions. It was found that significantly denser polymer brushes were grafted from the native than from the regenerated cellulose substrates, most likely due to differences in surface area. A method for detaching the grafted polymer from the substrate was developed, based on the selective cleavage of silyl ether bonds with tetrabutylammonium fluoride. The results from the performed kinetic study suggest that the surface-initiated polymerization of methyl methacrylate from cellulose proceeds faster than the concurrent solution polymerization at low monomer conversions, but slows down to match the kinetics of the solution polymerization at higher conversions. Superhydrophobic and self-cleaning bio-fiber surfaces were obtained by grafting of glycidyl methacrylate using a branched graft-on-graft architecture, followed by post-functionalization to obtain fluorinated polymer brushes. AFM analysis showed that the surface had a micro-nano-binary structure. It was also found that superhydrophobic surfaces could be achieved by post-functionalization with an alkyl chain, with no use of fluorine. Thermo-responsive cellulose surfaces have been prepared by graft-modification with the stimuli responsive polymer poly(N-isopropylacrylamide) (PNIPAAm). Brushes of poly(4-vinylpyridine) (P4VP) rendered a pH-responsive cellulose surface. Dual-responsive cellulose surfaces were achieved by grafting block-copolymers of PNIPAAm and P4VP. / QC 20100804

We reported a non-crosslinking approach to synthesize nitroxide radical polymer brushes for thin-film electrodes via surface-initiated atom transfer radical polymeization (SI-ATRP), which was effective to yield the organic radical polymer brushes with high grafting density and to attain a uniform surface. As mentioned above, the covalent bonding of nitroxide polymer brushes to the conducting substrate not only prevented the polymer dissolution into organic electrolyte solution but improved the cycle life performance of batteries. Moreover, they can be the potential application in microbatteries by using microcontact printing to produce the patterned nitroxide polymer brushes on a conducting substrate. Even though the organic radical polymer brushes provided a new approach to syn-thesize thin-film electrodes, they still existed many problems that needed to study and to figure out. We discussed the morphology and electrochemical performance about ni-troxide radical polymer in the thesis. In the measurement of surface properties, we used the contact angle, electron spectroscopy for chemical analysis (ESCA) and atomic force microscopic (AFM) to proceed. Another, in the measurement of electrochemical analysis, we used the cyclic voltammetry(CV), alternating current (AC) impedance and charge-discharge to understand the regarding mechanism in this polymer layer during the electrochemical reaction. In chapter 4, we discussed the oxidative problem in the polymer brushes. It should be well controlled during the oxidation reaction, because the oxidation level may affect the diffusion of electron that resulted the capacity better or not. In chapter5, we controlled the density of polymer brushes to construct the possible mechanism during the electro-chemical reaction, and found out the possible factors that affected the electrochemistry. In chapter 6, we applied the better results from the front chapter to the organic radical battery, and compared their electrical performance.

In this study, ethyl methacrylate was polymerized by free radical polymerization at 600C, 700C, 800C at open atmosphere / atom transfer radical polymerization, (ATRP), at 800C in vacuum and in gamma irradiation in vacuum. The polymer obtained was white, hard material. The kinetic curves for free radical polymerization and ATRP by gamma radiation were S-type. However, the curve for polymerization by gamma irradiation raises more smoothly. For ATRP by thermal initiation gives a lineer change of conversion with time. It was observed that the molecular weight can be controlled and low molecular weight polymer could be obtained by ATRP method. The characterization of polymers were made by FTIR, DSC, 1H and 13C NMR techniques.

Os ânions inorgânicos nitrato (NO3-) e nitrito (NO2-) por muito tempo foram considerados produtos finais inertes do metabolismo do óxido nítrico (NO) e constituintes indesejáveis da dieta. Entretanto, é crescente o interesse das potenciais reações que podem se processar em meio fisiológico e, que envolvem especialmente o íon nitrito mediadas por complexos de metais de transição. Ferro-heme presente em proteínas como a mioglobina podem formar complexos porfirínicos com NO, gerando espécies que podem atuar principalmente como catalisadores em diversas vias biológicos importantes. Complexos com NOx coordenado a ferro-heme estão envolvidos tanto no processo da cura da carne (pigmentação da carne), como em processos redox, nos quais são capazes de oxidar substratos indiretamente pela produção de espécies reativas ou diretamente por reações de transferência de átomo de oxigênio (TAO). Os lipídeos, constituintes celulares fundamentais na composição de membranas e lipoproteínas, podem servir como substratos para essas reações e, sua oxidação pode ocasionar danos ao organismo. Tióis, importantes antioxidantes e constituintes de proteínas, também podem participar desse tipo de reações e, conseqüentemente gerar danos ao organismo. Considerando que o mecanismo e os parâmetros cinéticos e termodinâmicos destas reações ainda não foram completamente estabelecidos para explicar a vasta funcionalidade destes complexos, o presente projeto de pesquisa visa proporcionar um melhor conhecimento das reações redox envolvendo NOx e mediadas por porfirinas de ferro em alimentos e sistemas biológicos. / For long time, the anions nitrate (NO3-) and nitrite (NO2-) were considered inert end products of nitric oxide (NO) metabolism and undesirable constituents of the diet. Currently, there is an increasing interest for potential reactions which may occur in physiological conditions involving specially the nitrite ion and mediated by transition metal complexes. Heme NOx iron complexes are involved in meat curing process (meat pigmentation) and are able to oxidize substrates indirectly generating reactive species or directly by oxygen atom transfer reactions (OAT). Lipids, fundamental cellular constituents of membranes and lipoproteins, and thiols, important antioxidants and protein constituents, may serve as substrates to OAT and their oxidation may promote damage to the organism Considering that the mechanism and kinetic and thermodinamic parameters of these reaction have not yet been fully elucidated to explain the varied functionality of these complexes, the present research project aim to bring a better understanding of redox reactions involving NOx mediated by iron porphyrins in foods and biological systems. Thiols, important antioxidants and protein constituents, may serve as substrates to OAT and their oxidation may promote damage to the organism. The present work aims to bring a better understanding of the mechanism, kinetic and thermodynamic parameters of the reaction involving nitrite mediated by iron-porphyrins in food and biological systems.

No description available.

The first project in this dissertation presents a simplified and efficient protocol for synthesizing pyrrolines through 5-exo iminyl radical cyclizations. The microwave irradiation of O-Phenyloximes tethered to alkenes causes N-O homolysis resulting in iminyl radical generation, which subsequently undergoes 5-exo-trig cyclizations furnishing pyrrolines. This eliminates the need for toxic radical initiators (AIBN, benzoyl peroxide), propagating agents (Bu3SnH, (Me3Si)3SiH), and expensive catalysts or single-electron transfer (SET) cycles. We explored the scope of diverse traps and substrates for iminyl radical cyclizations. The iminyl radical cyclizations formed versatile pyrrolines with moderate to excellent yields. The diastereoselectivity also ranged from low to high. Moreover, these versatile pyrrolines were further transformed via various reactions, such as hydrogenation, allylation, dihydroxylation, and cross-metathesis. The second part of this project extends the scope of the non-redox iminyl-radical based approach to γ-C(sp3)−H ketone activation. The sequence of N-O homolysis triggered by microwave irradiation of O-phenyloximes, 1,5-hydrogen atom transfer (HAT), trapping of the radical intermediate, and in situ imine hydrolysis, ultimately leads to the formal γ-C–H functionalization of ketones. We achieved both C-O and C-C bond formation by using diverse O-phenyloxime substrates. This work's notable achievement was accomplishing γ-C–H activation of 1o carbon atoms, a feat that has not been attained using SET-based iminyl radical chemistry. The third part of this dissertation focuses on the influence that dehydroamino acids have on secondary structures. This project describes the synthesis of incipient 310 helical tetrapeptides containing dehydroamino acids. A bulky dehydroethylnorvaline-containing tetrapeptide was synthesized. Based on our published data, we speculated that dehydroethylnorvaline might increase peptide proteolytic stability.