Persistent organic pollutants (POPs) are toxic chemicals that can be found in various matrices in all corners of the planet, including remote areas such as the Arctic.  Several POPs are known and monitored but given the abundance of new chemicals in commerce about which little is known, chemicals that may be new POPs are constantly being screened for. The use of flame retardants, particularly brominated flame retardants (BFRs), has been increasing for decades. PBDEs and HBCDDs are two types of BFRs that have historically been used in large volumes but recently faced legislative restrictions. However, in order to meet fire safety standards, these BFRs have been replaced by a variety of emerging flame retardants (EFRs) about which little is known especially concerning their toxicity, production volumes, and environmental behavior. The main purpose of this thesis was to investigate the occurrence and fate in indoor and outdoor environments of several EFRs and compare them with PBDEs, HBCDDs, and legacy POPs. Several indoor environments in the city of Stockholm, Sweden were sampled for dust, indoor air, and ventilation system air (Paper II).  Results from these samples revealed a number of EFRs that humans are exposed to and that are emitted from buildings through ventilation systems. These included DDC-CO, DBE-DBCH, PBT, HBB, EHTBB, and BEH-TEBP. PBDE levels seem to be declining compared to previous studies in Stockholm.  Outdoor air and soil were sampled across transects of Stockholm (Paper II) and Birmingham, United Kingdom (Paper III).  Results from these samples showed the presence of many of the same EFRs in the outdoor environment that were found in indoor environments.  Urban pulses in air were discovered for PBDEs in both cities and for some EFRs in Stockholm, indicating that the cities are sources of EFRs to the outdoor environment.  Atmospheric deposition samples were taken at two sites in northern Sweden (Paper I).  Three EFRs (DDC-CO, DBE-DBCH, and BTBPE) and two current-use pesticides (trifluralin and chlorothalonil) were identified, indicating these compounds’ potential for long range transport and global contamination.  Other legacy POPs such as HCH, PCBs, and PBDEs were measured in the deposition samples as well.  The bulk of deposition was comprised of HCH and PCBs with only minor contributions from PBDEs, chlordanes, and emerging compounds.  Finally, passive and active air sampling methods were compared for BFRs in offices in Beijing, China.  Some EFRs were identified in indoor air from China; however, BDE-209 was the most predominant compound found (Paper IV).  Air samples collected with passive samplers generally had measured FR concentrations within a factor of 2-3 of those collected with active samplers. The use of a GFF in the passive samplers resulted in concentrations of particle-bound contaminants such as BDE-209 that were more comparable to those in active samples. The positioning of the PUF in the passive samplers affected the sampling rates for gaseous compounds and particle retention on PUFs was shown to be a large source of uncertainty in passive sampling. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p><p> </p>

Les éthers de cellulose (EC) sont des adjuvants couramment introduits dans les mortiers pour améliorer leurs propriétés. Malgré le retard d'hydratation du ciment engendré par ces polysaccharides, ils sont capables d'améliorer la maniabilité et la rétention d'eau des matériaux cimentaires.Cette étude a été initiée afin d'accroître les connaissances sur l'effet des EC sur la rétention d'eau des mortiers à l'état frais. L'objectif est double : identifier les paramètres physico-chimiques jouant un rôle clé et clarifier les mécanismes d'action de dérivés cellulosiques dans les matériaux cimentaires.Pour ce faire, grâce à un large panel d'EC, l'influence des paramètres structuraux des molécules a été élucidée. Les résultats ont démontré que la masse moléculaire était un paramètre primordial alors que les degrés de substitution des groupements greffés sur la molécule ont un impact négligeable sur la rétention d'eau des mortiers. Pour comprendre les mécanismes d'action des EC dans les phénomènes de rétention d'eau, deux pistes ont été explorées. La première a consisté à savoir s'il existait une relation entre le comportement rhéologique des mortiers et leur capacité à retenir l'eau lors d'un contact avec un substrat. L'étude rhéologique a montré que les EC sont des agents viscosants et que pour des EC ayant des degrés de substitution identiques, la viscosité et la rétention d'eau du mortier semblent aller de paire. Cependant, cette relation n'est pas aussi simple. En effet, des propriétés de rétention d'eau différentes ont été mesurées pour des mortiers ayant des consistances voisines. La capacité des mortiers à retenir l'eau ne peut donc pas être déterminée uniquement à partir de son comportement rhéologique. Par ailleurs, d'autres molécules telles que les dérivés de l'amidon, ont mis en évidence une évolution opposée de la rétention d'eau avec les propriétés rhéologiques. Ainsi, la consistance d'un mortier ne peut pas à elle seule expliquer les phénomènes de rétention d'eau des mortiers adjuvantés avec les éthers de cellulose.La seconde hypothèse souvent avancée pour expliquer les propriétés de rétention d'eau est que les dérivés cellulosiques forment une barrière de diffusion à l'eau dans le mortier. La capacité des polymères à former des films a été étudiée à l'aide de deux techniques de résonance magnétique nucléaire (RMN) : la RMN à gradients de champ et la relaxométrie RMN. A l'aide de ces deux techniques, il a été montré que les EC n'ont aucun effet sur le coefficient de diffusion de l'eau dans le volume et à la surface des solides. Une étude temporelle menée par relaxométrie a mis en avant l'importance de la quantité d'eau piégée transitoirement à la surface des solides.

Polybrominated diphenyl ethers (PBDEs) are synthetic chemicals that are added to a variety of consumer products as flame-retardants. The ubiquitous nature and endocrine disrupting properties of PBDEs are a public concern. A pilot study was performed to investigate whether in utero PBDE exposure, as measured in maternal hair, is associated with genitourinary tract malformations in male infants. In addition, we compared PBDE levels in maternal and infant hair and used segmental analysis to investigate how PBDEs varied along the shaft. Preliminary results suggest a trend toward an elevated PBDE body burden in mothers whose infants were born with genitourinary tract malformations; this was significant for some PBDEs. The sum of PBDEs (ΣPBDEs) in maternal hair did not correlate with infant hair levels; children had significantly greater levels. A significant increase in the ΣPBDEs was observed in distal hair suggesting hair PBDEs may be reflective of both internal and external exposure.

Reações de O-desmetilação oxidativa estão entre as várias oxidações realizadas pelas enzimas do citocromo P-450. Entretanto, poucos estudos de O-desmetilação catalisadas por enzimas do citocromo P-450 ou modelos químicos baseados em metaloporfirinas sintéticas têm resultado em dúvidas acerca do mecanismo da O-desmetilação destes compostos orgânicos. Neste trabalho, foi estudada a O-desmetilação oxidativa, com PhIO, do benzil metil éter e alguns de seus derivados para substituídos (com os grupos doadores de elétrons -OCH3 e -CH3 e os grupos retiradores -NO2 e -Cl) catalisada pelas Mn(III)P [Mn(TPP)]Cl, [Mn{T(4-N-MePy)P}](PF6)5, [Mn(TMP)]Cl, [Mn(TDCSPP)]Cl e [Mn(TFPP)]Cl para verificar o efeito destes diferentes catalisadores na conversão e seletividade de produtos da O-desmetilação oxidativa e avaliar o efeito dos diversos substituintes citados no mecanismo de O-desalquilação. Inicialmente, realizou-se o estudo das oxidações catalíticas do metil benzil éter. Todas as reações catalisadas pelas MnP se mostram seletivas, sendo que o benzaldeído foi o produto comum a todas as oxidações. A melhor condição encontrada foi 1:50:1224 (catalisador/oxidante/substrato). Em relação às reações com os substratos contendo os substituintes na posição -para, as reações de oxidações catalíticas do p-metóxibenzil metil éter por PhIO não se mostraram tão seletivas quanto as do metil benzil éter, mostrando claramente que o grupo metóxi alterou a reatividade do aril éter original. Mesmo assim, o p-metoxibenzaldeído ainda foi o produto principal, sendo a conversão ao álcool p-metoxibenzílico observada em escala menor. Já com o substrato p-nitrobenzil metil éter, novamente o efeito provocado pelo substituinte na posição para no anel benzênico pôde ser percebida na distribuição final dos produtos, sendo que houve seletividade total para a formação de p-nitrobenzaldeído em detrimento ao álcool p-nitrobenzóico. Em relação aos dois últimos substratos da série proposta, metil p-metilbenzil éter e metil p-clorobenzil éter, de um modo geral, as reações realizadas com o p-clorobenzil metil éter não se mostraram tão seletivas quanto as do metil p-nitrobenzil éter, mostrando que o grupo cloro aumentou a reatividade do cloroéter em relação ao éter com o substituinte nitro- original. Mesmo assim, o p-clorobenzaldeído foi o produto principal, sendo a conversão ao álcool p-clorobenzílico observada em menor escala. Em relação às reações de oxidação do p-metilbenzil metil éter, observou-se que os resultados experimentais são semelhantes aos encontrados para o metil benzil éter. Esses resultados corroboram o principal mecanismo proposto para os sistemas modelo do citocromo P-450 que envolve abstração inicial do átomo de hidrogênio, o mecanismo por recombinação de oxigênio. / O-dealkylation oxidative reactions are among the several oxidations accomplished by the cytochrome P-450 enzymes. However, few studies on O-dealkylation catalyzed by such enzymes or chemical models based on synthetic metalloporphyrins have resulted in doubts concerning the mechanism of these reactions involving organic compounds. In this work, we studied the oxidative O-dealkylation by PhIO of benzyl methyl ether and some of its para-substituted derivatives (with the electron donor groups -OCH3 and -CH3 and the electronwithdrawing groups -NO2 and -Cl) catalyzed by the following Mn(III)P: [Mn(TPP)]Cl, [Mn{T(4-N-MePy)P}] (PF6)5, [Mn(TMP)]Cl, [Mn(TDCSPP)] Cl, and [Mn(TFPP)]Cl. Our aim was to verify the effect of these different catalysts on the conversion yields and product selectivity, as well as evaluate the effect of the several substituents on the ether on the O-dealkylation mechanism. We initially studied the catalytic oxidation of methyl benzyl ether. All the reactions catalyzed by the various MnPs were selective, and benzaldehyde was the product common to all oxidations. The best reaction condition was catalyst/oxidant/substrate molar ration = 1:50:1224. As for the reactions with the substituted substrates, the catalytic oxidation of p-methoxybenzyl methyl ether by PhIO was not as selective as the ones of methyl benzyl ether, clearly showing that the methoxy group affects the reactivity of the original aryl ether. Nevertheless, p-methoxybenzaldehyde was still the main product, being the conversion to p-methoxybenzylic alcohol observed in minor amount. With the substrate p-nitrobenzyl methyl ether, the effect of the electronwithdrawing substituent in the para- position of the aromatic ring could be observed in the final product distribution once again, and total selectivity toward the formation of p-nitrobenzaldehyde to the detriment of p-nitrobenzoic alcohol was observed. In relation to the two last substrates of the proposed series, the methyl p-methylbenzyl and methyl p-chlorobenzyl ethers, the reactions accomplished with p-chlorobenzyl methyl ether were not as selective as the ones carried out with methyl p-nitrobenzyl ether, showing that the chloro group increased the reactivity of the chloro-ether in relation to the ether with the original nitro- substituent. Even so, p-chlorobenzaldehyde was the main product, being the conversion to the p-chlorobenzylic alcohol observed in smaller amount. Concerning the oxidation reactions of p-methylbenzyl methyl ether, the experimental results were similar to those obtained in the case of methyl benzyl ether. These results corroborate the main mechanism proposed for the cytochrome P-450 model systems, which involves initial hydrogen atom abstraction, followed by oxygen rebound.

Os retardantes de chama bromados são substâncias utilizadas em bens de consumo para aumentar sua resistência ao fogo e/ou altas temperaturas. Para este fim os Éteres Difenílicos Polibromados (PBDEs do inglês polybrominated diphenyl ether) representam a classe mais utilizada tendo em vista sua eficiência no controle da propagação da chama e baixo custo. Estes compostos são considerados persistentes, bioacumuláveis, podem ser transportados para longas distâncias e apresentam toxicidade podendo causar desregulação endócrina, entretanto os mecanismos de toxicidade ainda não foram bem estabelecidos. Desta forma, o presente projeto utilizou linhagens celulares de Hepatoblastoma Humano (HepG2), HeLa, Hepatócitos e linfócitos humanos a fim de elucidar seus mecanismos de toxicidade. Os resultados significativos demonstram a capacidade destes compostos em induzir dano primário no DNA (0,5 ?mol/L para o BDE-153 e 5 ?mol/L para o BDE-100) monitorado pelo teste do cometa, que não foi reparado após 24 horas de exposição. No entanto, não se observou um aumento de micronúcleos em HepG2 e linfócitos após exposição aos congêneres (0,1 - 25 ?mol/L) nem mesmo mutagenicidade no ensaio de Salmonella typhimurium. Contudo, os compostos apresentam capacidade de diminuir a redução do brometo de 3-(4,5 dimetiltiazol-2il)-2,5 difenil tetrazólio (MTT), proliferação e interferem no ciclo celular nos cultivos celulares avaliados. Estes efeitos de citotoxicidade estão relacionados com a disfunção mitocondrial, uma vez que ambos PBDEs geram dissipação do potencial de membrana mitocondrial, formação e acúmulo de espécies reativas, culminando em morte celular apoptótica, demonstrada pela manutenção da fosfatidil serina na face externa da membrana celular, pela condensação e fragmentação nuclear, presença de fatores pró-apoptóticos no citosol da célula, tais como citocromo C e AIF além da ativação de caspases 3 e 9. Estes dados corroboram com o fato de não ter liberação de lactato desidrogenase intracelular, excluindo a morte celular por necrose. E por fim, foi possível observar que a exposição aos compostos ativa o processo autofágico, a princípio como um mecanismo de citoproteção observado pela conversão de LC3I em LC3II e acúmulo de p62 (marcadores autofágicos) além de marcações imunicitoquímicas para LC3II e co-localização de lisossomos no padrão pontuado, indicanto acúmulos da proteína LC3 e lisossomos, formando os autofagossomos. Em conjunto nossos resultados apresentam a capacidade de induzir instabilidade genômica e citotoxicidade desta classe de compostos, reforçando a idéia de que os PBDEs representam risco à população exposta / The brominated flame retardants are substances used in consumer goods to increase its fire resistance and/or high temperatures. Due to, the polybrominated diphenyl ethers (Polybrominated diphenyl ether) are the most commonly used class in view of its efficiency in controlling the spread of flame and low cost. These compounds are considered persistent, bioaccumulative, can be transported over long distances and have toxicity. However the toxic mechanisms of action have not been well established. Thus, this project held cytotoxic, genotoxic and mutagenic assays in HepG2, HeLa, hepatocytes and human lymphocytes cells in order to elucidate the mechanisms of toxicity. The results demonstrate the ability of these compounds to induce primary DNA damage (0.5 ?M for BDE-153 and 5 ?M for BDE-100) monitored by the comet assay, it was not repaired after 24 hours of exposure. However, there was not observed nether increase in micronuclei in HepG2 cells and lymphocytes after exposure to the congeners (0.1 - 25 ?M) even in the Salmonella typhimurium mutagenicity assay. However, the compounds show the ability to reduce MTT reduction, proliferation, and interfere with cell cycle evaluated in cell cultures. These cytotoxic effects are related to mitochondrial dysfunction, since both PBDE generate dissipation of the mitochondrial membrane potential, accumulation of reactive oxygen species, resulting in apoptotic cell death, demonstrated by the maintenance of serine phosphatidyl on the external surface of the cell membrane, by condensation and nuclear fragmentation, the presence of pro-apoptotic factors in the cytosol of the cell, such as cytochrome c and AIF plus activating caspase 3 and 9. These data corroborate the fact of not having to intracellular lactate dehydrogenase release, excluding death cell necrosis. Finally, it was observed that exposure to the active compounds the autophagic process, at first as a cytoprotective mechanism observed by LC3I conversion in LC3II and accumulation of p62 (autophagic markers) plus imunicitoquímicas markings for LC3II and co-location lysosomes in dotted pattern, indicanto accumulations of LC3 protein and lysosomes, forming autophagosomes. Together our results show the ability to induce genomic instability and cytotoxicity of this class of compounds, reinforcing the idea that PBDEs pose a risk to the exposed population

Polybrominated diphenyl ethers belong to group of brominated flame retardants. Important property of these substances is their ability to reduce flammability or to prevent ignition of many products of daily use, such us televisions, carpets, mattresses and many others. Polybrominated diphenyl ethers however are characterized by high persistence and lipophility, leading to their accumulation in the environment. In recent years, concerns about the effects of organic halogen compounds on human health, suggesting their inclusion in the list of persistent organic pollutants in 2009. These contaminants are capable of long-range transport and accumulation in the environment. Therefore, the presence of polybrominated diphenyl ethers is systematically observed in the abiotic and biotic components of the environment worldwide. Their presence has been demonstrated in areas that are clearly very distant from sources of contamination. This thesis is focused on the use of gas chromatography to assess the level of contamination of selected components of the environment, especially of soil. For these purposes was used method of gas chromatography with electron capture detection mass spectrometry.

In recent years considerable attention is paid to problems of brominated flame retardants (BFR's – Brominated Flame retardants), which are a diverse group of organic compounds. Even in the recent past have been the most often represented group particularly polybrominated diphenyl ethers (PBDEs), which have found wide use in many industrial sectors. The reason of aplication of these substances is the ability to slow down the combustion process and reduce the risk of ignition by the excessive heating of material. On the other hand, serious concerns about the use of PBDEs was added. The most serious trouble is particular their possible to release from consumer products during their normal use, toxicity and high persistence in parts of environment. Some of these contaminants are more characterized by a high degree of accumulation in biological systems. In this work by several sub-studies the issue of assessment the level of pollution of the aquatic ecosystem of selected localities of the Czech Republic just PBDEs was addressed. One of objectives was monitored the situation of breeding ponds near the village Záhlinice in Central Moravia. Here was assessed level of contamination in fish and birds as two consecutive segments of food chain. The obtained results largely confirmed the assumption that with increasing trophic level of organisms leads to bioaccumulation and thus also higher findings. For comparison, the capture of fish and birds in other localities of the CR was also implemented. In Bartošovice and Hustopeče nad Becvou levels at the buzzard and heron were detected as comparable. The cormorants of the order higher levels of PBDEs were found. Further were also evaluated levels of PBDEs detected in individuals of bioindicator kind of chub caught in two locations on the river Svratka in spring and autumn. Findings of PBDE in muscle, skin and intestines were compared. The obtained results show that between tissues and sites wasn’t significant variability respectively and the findings of controlled substances are practically comparable. With aim to determine the dependence of the concentration of PBDEs in organisms on the length of the river was conducted monitoring of Vír and Brno water reservoirs. In both locations was main monitored kind of bream, which was completed by the other species. The results of the analysis indicate a higher total concentration at the lower part of river Svratka. Differences were also the distribution of individual congeners in both sampling locations. For monitoring of terrestrial system contamination levels of PBDEs has been selected several types of plant bioindicators. These are mainly pine needles (Scots pine, Eastern white pine, Silver fir, Blue spruce) collected from different localities of the Czech Republic. Other matrices were chosen roughages (Common wheat, Naked barley, Alfalfa wheat, Red clover) and oilseeds (Rapeseed) from the Novy Jicin, where Agriculture plant school of the University of Veterinary and Pharmaceutical Sciences Brno. Detected values of PBDE concentrations were very low, generally ranged at the detection limits of the analytical method.

Les composés oxygénés de faible poids moléculaire présentent un fort intérêt en chimie des parfums. Un grand nombre d’odorants contiennent un ou plusieurs cycles au sein de leur structure. Ce travail de thèse est dédié au développement de nouvelles carbocyclisations intramoléculaires de dérivés d’éthers d’énol catalysées par des (super)acides de Lewis. L’étude s’intéresse à la réactivité bivalente des alcools (bis)allyliques portant une fonction alkoxy. Dans ce contexte, la réactivité de la fonction éther d’énol en présence d’un alcool allylique a été développée en présence d’acides de Lewis et de Brønsted comme catalyseurs. En l’occurrence, une chimiodivergence contrôlée par le substrat a été démontrée pour des précurseurs dérivés de différents types d’éthers d’énol. Ainsi, des cyclopenténones ont été formées par électrocyclisation catalysée par le triflate de bismuth(III). Ou alors, des cétones insaturées α-oxygénées ou soufrées ont été obtenues par activation préferentielle de l’éther d’énol en présence de l’acide ptoluènesulfonique. Une étude mécanistique a été effectuée mettant en avant la différence entre la catalyse par acides de Lewis et de Brønsted ainsi que l’influence de l’acidité du catalyseur. Il a été possible de contrôler la chimiodivergence par le catalyseur dans le cas des dérivés du phenyl vinyl sulfure. Deux produits différents ont été obtenus à partir d’un seul substrat de départ en utilisant des systèmes catalytiques robustes et peu onéreux. La plupart des nouveaux composés présentent des notes olfactives intéressantes. En outre, l’électrocyclisation catalysée par le triflate de bismuth a été appliquée à la synthèse de la rotundone, un odorant naturel à la note typique du poivre. / Oxygenated low molecular weight compounds are of particular interest in fragrance chemistry. A large number of odorants present one or more rings within their structure. This work is dedicated to the development of novel intramolecular carbocyclizations of enol ether derivatives catalyzed by Lewis (super)acids. The study turns around the dual reactivity of alkoxy-substituted bis(allylic) alcohols. In this context, the behavior of the enol ether function in the presence of an allylic alcohol has been elaborated under Lewis and Brønsted acid-catalysis. Hereby, a pronounced substrate-controlled chemodivergence as demonstrated for precursors derived from different types of enol ethers. Either, cyclopentenones were formed by electrocyclization under bismuthIII triflate catalysis, or a skeletal rearrangement after preferential activation of the enol ether in the presence of p-toluenesulfonic led to α-oxygenated or αsulfenylated unsaturated ketones. Mechanistic studies have been performed and the difference between Lewis and Brønsted acid-catalysis as well as the influence of the catalyst acidity have been highlighted. The chemodivergence could be tuned by the nature of the catalyst in the case of phenyl vinyl sulfide derivatives. Two different products were obtained from a single and easily accessible starting material using robust, air- and water-compatible catalytic systems. Most of the new compounds presented interesting olfactory notes. The developed bismuthIII triflate-catalyzed electrocyclization was further applied to the total synthesis of the natural pepper odorant rotundone.

Thesis (DTech (Environmental Health))--Cape Peninsula University of Technology, 2011. / This study was aimed to provide baseline information about the environmental levels of selected PBDEs (BDE 28, 47, 100, 99, 154, 153, 183 & 209) and BB 153 in different matrices, including wastewater treatment plants' effluent, sludge, landfill leachate, river water and bottom sediment samples from different locations within the City of Cape Town. The monitoring of these contaminants was carried out bi-monthly over an extended period of 12 months beginning from April 2010 to March 2011. In this study, a total of 63, 168, 312, 93 and 108 samples for leachate, wastewater treatment plant (WWTP) sludge, effluent, river water and bottom sediment, respectively were collected from three landfill sites, four WWTPs and two rivers within the City of Cape Town. The aqueous matrices were extracted using a liquid-liquid extraction technique. The extraction of both sediment and sludge samples were performed using mechanical shaking and soxhlet extraction techniques, respectively. Extract obtained were further purified using multi-layer silica gel column chromatographic technique. The routine analysis of these target compounds was carried out using a gas chromatograph equipped with an electron capture detector (GC-µECD). However, the structural elucidation of these compounds was performed with a gas chromatography-time of flight-mass spectrometry (GC-TOF-MS) instrument.

The research presented in this thesis focused on pseudorotaxanes and supramolecular polymers based on a new recognition motif, the dibenzo-24-crown-8/paraquat recognition motif. Main kinds of pseudorotaxanes and rotaxanes and various protocols used for the study of them were discussed first. By preparation and characterization of a series of pesudorotaxanes based on DB24C8 and paraquat derivatives, it was found that these complexes were stabilized by N+...O interactions, C-H...O hydrogen bonding, and face-to-face p-stacking interactions. Because methyl protons of paraquat are involved in hydrogen bonding to the host, the substitution of any methyl hydrogen on paraquat causes apparent association constant of the pseudorotaxane to decrease. The concentration dependence of apparent association constants, Ka,exp, of fast exchange host-guest systems was studied for the first time by using complexes based on viologens and crown ethers as examples. While the bis(hexafluorophosphate) salts of paraquat derivatives are predominantly ion paired in acetone (and other low dielectric constant solvents presumably) the complex based on dibenzo-24-crown-8 and paraquat is not ion paired in solution, resulting in concentration dependence of Ka,exp. However, four complexes of two different bis(m-phenylene)-32-crown-10 (BMP32C10) derivatives and bis(p-phenylene)-34-crown-10 (BPP3C10) with viologens are ion paired in solution, as shown by the fact that Ka,exp is not concentration dependent for these systems involving hosts with freer access to bound guests. X-ray crystal structures support these soluton-based assessments in that there is clearly ion pairing of the cationic guest and its PF6- counterions in the solid states of the latter four examples, but not in the former. The complexes based on the new dibenzo-24-crown-8/paraquat recognition motif are thus different from the complexes based on two old recognition motifs: the BPP34C10/BMP32C10-paraquat and DB24C8-ammonium motives. In order to compare these recognition motives further, the selectivity between two hosts, DB24C8 and BPP34C10, and two guests, dimethyl paraquat and dibenzyl ammnonium salt, was discussed. By individual and competitive complexation studies, it was demonstrated that DB24C8 is a better host than BPP34C10 for paraquat, and that paraquat is a better guest than dibenzyl ammonium salt for DB24C8. Finally the DB24C8-paraquat recognition motif was successfully applied in the preparation the first star-shaped supramolecular polymer based on a tetraparaquat guest and a DB24C8 functionalized polystyrene oligomer. A model system based on this guest and DB24C8 was also studied for comparison. It was found that the complexation in these two systems is cooperative, as are most biological complexations of multitopic species. Due to the ready availability of DB24C8 and paraquat derivatives, the new recognition motif should prove to be very valuable for self-assembly of other more sophisticated supramolecular systems. / Master of Science