A new route to molecular self-assembly using a simple acid-base hydrolytic approach on silica based surfaces, is reported in this thesis. Based on this methodology, a number of compounds containing terminal groups with acidic protons, such as alcohols, thiols, carboxylic acids, and terminal alkynes, can be easily deposited on silica surfaces. The quality of the thin films was monitored by contact angle goniometry, ellipsometry, XPS, FTIR-ATR and UV-Vis absorption spectroscopies. The deposition conditions were optimized to produce ordered and densely packed mono- and multilayers. Using the two-step process, self-assembled monolayers (SAMs) of a variety of long chain alcohols containing terminal alkyl, phenyl and acetylene groups on silica surfaces were successfully prepared. The newly formed monolayers were found to be relatively ordered and densely packed. They showed comparable stabilities to OTS/SiO 2 at ambient and high temperatures, and upon treatment with acids and bases. A layer-by-layer construction methodology, based on acid-base hydrolysis of aminosilanes and dihydroxy terminated molecules containing rigid-rod type and alkyldiacetylene backbones, led to multilayers with higher stability under various conditions compared to monolayers. The thin film assemblies were subjected to topochemical polymerization, and upon UV-Vis exposure, the formation of a blue film was observed. / Using the acid-base hydrolytic chemistry approach, silica surfaces functionalized with Sn-NEt2 groups can be easily modified using a number of terminal alkyne molecules with varied backbones. SAMs of a variety of rigid-rod alkynes on silica surfaces were successfully prepared. The pi-pi interactions in the molecules lead to ordered and densely packed thin film structures with a surface coverage of 2--7 molecules/100 A 2. The thin film assembly with diacetylene backbone was also subjected to topochemical polymerization, and upon UV-Vis exposure, the formation of a blue film was observed. Furthermore, a layer-by-layer construction methodology using aminostannanes and dialkyne terminated molecules containing alkyl or aromatic type backbone led to multilayered structures on silica surfaces without increasing disorder in the thin films with the increase in number of layers. The acetylene groups in the thin film assemblies were found to coordinate with cobalt carbonyl, corroborated by the observation of lambdamax at 277 nm.

A number of organometallic and biological systems have been investigated by infrared and Raman spectroscopy. The IR and Raman spectra of 17$ beta$-estradiol have been assigned. In pressure-tuning IR studies, hydrogen bonding of 17$ alpha$-ethinylestradiol through the 17$ alpha$-ethinyl group was detected, while in organometallic estradiol derivatives, the effect of substitution mainly affected the region near the point of substitution. In analogous pressure-tuning studies of $ alpha$- and $ beta$-(Cr(CO)$ sb3$) estradiol derivatives, differences between the two diastereomers were observed and the steric effect of the $ alpha$-diastereomer on hydrogen bonding was observed. In surface enhanced Raman scattering (SERS) work, two modes of binding for 17$ alpha$-ethinylestradiol were observed. In aqueous systems, the ethinyl group was deprotonated, permitting adsorption on the silver surface through $ eta sp1$-coordination, while in aqueous-CH$ sb2$Cl$ sb2$ mixtures, the 17$ alpha$-ethinyl group was bound to the silver surface via $ eta sp2$-coordination. The new technique of pressure-tuning FT-Raman spectroscopy was developed and applied in the study of Cr(CO)$ sb4$(bipy) and no breakdown in ring aromaticity was discovered. In the study of covalent and dative metal-metal bonded complexes (L)(L$ sp prime$)(OC)$ sb3$Os-M(CO)$ sb4$(L$ sp{ prime prime}$) (L = Me$ sb3$P, (MeO)$ sb3$P; L$ sp prime$ = CO, Cl, Br, I; M = Cr, W, Mo, Re; L$ sp{ prime prime}$ = CO, Cl, Br, I), the datively-bonded complexes exhibited slightly lower v(M-M) values. Permutation theory was used to illustrate that in complexes with M(CO)$ sb5$ receptor fragments, the depolarization ratios of certain carbonyl stretching modes may be indicative of dative or covalent metal-metal bonding.

The purpose of this study was to develop new routes to couple commercially and/or readily available starting materials into biologically relevant structures via one-pot transition metal catalyzed multicomponent coupling reactions. More specifically, we showed that a palladium catalyst could couple imines, acid chlorides and carbon monoxide to directly generate 1,3-oxazolium-5-oxides (Munchnones). / Chapter 2 of this thesis describes a new palladium catalyzed multicomponent synthesis of beta-lactams. This reaction was developed based upon previous work in this laboratory, which showed that imidazoline-carboxylates could be generated from coupling two imines, an acid chloride and CO. Mechanistic studies suggested that this product arose from a 1,3-dipolar cycloaddition of an imine-HCl molecule with Munchnone. Removal of this acid combined with adjusting reactant ratios, and the utilization of ligands generated 3-amido substituted beta-lactams in moderate to good yields. / Chapter 3 discusses studies that further explain the origin of the beta-lactam and imidazoline-carboxylate products obtained from catalysis. These studies demonstrate that imidazoline-carboxylates are generated either directly through a 1,3-dipolar cycloaddition reaction of imine-HCl with Munchnone, or indirectly from acid catalyzed rearrangement of an initially formed beta-lactam. In addition, the potential intermediates in the catalytic cycle, including the palladium bound carbonyl complex are completely characterized. / Chapter 4 describes the first example of a metal-catalyzed synthesis of Munchnones. Reaction optimization focused on modifying the catalyst structure to {Pd(Cl)[eta2-CH(R1)NR 2COR3]}2 (formed by pre-treating Pd 2(dba)3 CHCl3 with imine (R1C(H) = NR2) and acid chloride (R3COCl)), increasing CO pressures and employing bromide salts to stabilize the palladium catalyst. These modifications to the reaction enabled the development of a catalytic Munchnone synthesis from imines, acid chlorides, and CO. / Chapter 5 describes the development of a highly modular one-step palladium catalyzed synthesis of pyrroles. This reaction shows that pyrroles can be thought of as being a coupling product of an imine, acid chloride and an alkyne, formed via the in situ trapping of Munchnones with alkynes. In addition, further improvements to the Munchnone synthesis through the utilization of sterically bulky phosphine ligands (i.e. [P(o-Tol) 3]) will be discussed. As well as broadening the scope of accessible Munchnones, this ligand also increased the rate of product formation. / Chapter 6 describes some preliminary studies on the mechanism of Munchnone synthesis. Based upon kinetic data and catalyst resting state analyses, the rate determining step was suggested to possibly be N-acyliminium salt oxidative addition to Pd(0). In addition, crystal structures of {[P( o-Tol)3]Pd(eta2-CH(Tol)N(PMB)COPh)} and its dimeric precursor {Pd(eta2-CH(Tol)N(PMB)COPh)}2 were obtained.

The incorporation of phosphine or amine structural units into dendritic polymers offer significant potential in building macromolecular species with desired properties for heterogenizing homogeneous catalysis. To this end, synthetic methodologies based on the chemistry of acid-base hydrolysis of aminosilanes with molecules possessing hydroxyl end groups, and that of phosphorus halides/amides with alkynyl/alcohol monomers were explored as approaches to construct phosphorus(III)- and nitrogen-containing dendritic polymers. Attempted implementation of a three-step, divergent synthetic methodology led to the discovery of two new phosphorus(III)-based compounds, P[O(CH2) 2C≡CH]3 and P[O(CH2)2C≡CSn(CH 3)3]3. Efforts to execute a two-step, divergent synthetic route to nitrogen-containing dendrimers afforded first- and second-generation dendrimers, N4 and N10. Attempts to adapt this methodology to one-pot procedures for hyperbranched polyamines show promise. Finally, single-step and pseudo-single-step procedures for synthesizing hyperbranched polyphosphines were employed in the preparation of several phosphorus(III)-containing macromolecules. These materials were successfully functionalized with Rh(I) organometallic complexes.

<p> Ring cleaving dioxygenases, such as o-aminophenol dioxygenase (APDO) and extradiol catechol dioxygenases (CatD), play an important role in human metabolism and the degradation of aromatic pollutants, yet questions still remain concerning the enzymatic mechanisms. One area of the catalytic cycle that remains controversial is the geometric and electronic structure of the intermediate formed after O₂ binding to the Fe(II) centers. Synthetic model systems can be useful for studying enzyme active sites, as they are easier to modify and characterize than the enzymes themselves. However, synthetic models of APDOs have been relatively rare thus far. </p><p> We prepared several monoiron(II) complexes that faithfully model the enzyme-substrate intermediates of <i>o</i>-aminophenol dioxygenases (APDO) and catechol dioxygenases. The complexes use either the ^Ph2Tp (^Ph2Tp = hydrotris(3,5-diphenylpyrazol-1-yl)borate) or ^Ph2TIP (^Ph2TIP = tris(4,5-diphenyl-1-methylimidazole)phosphine) supporting ligands and one of three bidentate, redox-active ligands: 4-<i> tert</i>-butylcatecholate, 4,6-di-<i>tert</i>-butyl-2-aminophenolate, or 4-<i>tert</i>-butyl-1,2-phenylenediamine. These complexes have been extensively characterized with crystallographic, spectroscopic, and electrochemical techniques, in conjunction with computational methods (e.g, density functional theory). Each complex is reactive towards O₂, and the geometric and electronic structures of the resulting species were examined with various methods to determine whether the oxidation is iron-based, ligand-based, or a combination of both. </p><p> Treatment of the ^Ph2Tp ^Ph2TIP monoiron(II) aminophenolate complex with a phenoxyl radical results in formation of a complex containing an iron(II) center coordinated to an iminobenzosemiquinonate radical, that to the best of our knowledge has no synthetic precedence. Further oxidation leads to a complex best described as a ferric center bound to the iminiobenzosemiquinate radical. The electronic structures of these complexes were determined with the aid of spectroscopic and computational methods. </p><p> Several monoiron(II) complexes were also prepared to model the active-site structure of &beta;-diketone dioxygenase (Dke1). For this purpose, we employed the ^Ph2Tp supporting ligand and acac^X substrate ligands, where acac^X represents the anion of dialkyl malonate. Upon exposure to O₂ in toluene it was found that the complexes exhibited reactivity similar to Dke1, although at a much slower rate than the native enzyme.</p>

Processes for chemical conversions often either involve one of two divergent catalyst types. Heterogeneous catalysts (bulk material) represent a simple system, which can easily be removed from the reaction mixture after use. Homogeneous catalysts (soluble species) on the other hand, are often much more difficult to separate, but generally provide excellent improved catalytic performance in part because of their equal homogeneous distribution within the reaction media. Moreover, they allow for more tuneability through the use of various ligands. The emerging use of nanoparticle catalysts effectively bridges the gap between homogeneous and heterogeneous catalysis. Often, the smaller the particles become, the more they offer catalytic properties similar to homogeneous catalyst systems. Unfortunately, the reduction in size also makes separation increasingly difficult—again, similar to homogeneous systems. To address the issue of separation, the field of magnetic nanoparticle catalysis emerged. By simple application of an external magnet, magnetic nanoparticle catalysts can be recovered and easily reused. Most examples of magnetic nanoparticle catalysis employ the particle only as a vehicle for magnetic recovery, rather than the catalyst itself. Complex strategies of this kind include coating with a polymer or silica, to which a metal-binding ligand can be anchored. By such a system, one could envision anchoring of nearly any pseudo-homogeneous metal, enabling a broad catalytic scope. The focus of this work is instead on the use of simple magnetic nanoparticles where the particles themselves act not only as the means for magnetic recovery, but also as catalysts. This thesis covers three general types of simple magnetic nanoparticle catalysts. First, this work demonstrated that reduced iron nanoparticles with a shell of iron oxide can efficiently catalyze the hydrogenation of unsaturated hydrocarbons. This scheme can also be adapted to a flow system by growing the nanoparticles in the presence of amphiphillic polymers. Second, in order to address the limited catalytic offering of iron, the scope of reactions can be expanded by decorating these same iron/iron oxide nanoparticles with a more catalytically active metal. Copper- and ruthenium- decorated nanoparticles have been synthesized and used for the azide-alkyne click reaction and transfer hydrogenation, respectively. Third, work presented in this thesis shows that other metals can also be incorporated directly into the magnetic nanoparticle lattice. For example, CuFe2O4 nanoparticles have been used to catalyze the Biginilli condensation and cross-dehydrogenative coupling reactions. By the use of these three general types of bare particles, we have expanded the scope of simple magnetic nanoparticle catalyzed reactions. / Les procédés chimiques impliquent souvent des catalyseurs de l'un des deux types suivants. Les catalyseurs hétérogènes (matériaux) constituent un système simple, qui peut généralement être aisément retiré du mélange réactionnel après usage. D'autre part, les catalyseurs homogènes (espèces solubles) sont souvent beaucoup plus difficiles à séparer ; en revanche, ils offrent en general une excellente performance catalytique étant donnée leur répartition homogène dans le milieu réactionnel. De plus, ces derniers peuvent être facilement modifiés par l'usage de divers ligands pour ainsi améliorer leur performance. L'utilisation croissante de nanoparticules en catalyse offre une alternative entre la catalyse homogène et hétérogène. De façon générale, plus leur taille est petite, plus les particules possèdent des propriétés catalytiques similaires à celles des systèmes homogènes. Malheureusement, la réduction de leur taille rend d'autant plus difficile leur séparation, comme dans le cas des systèmes homogènes. Pour résourdre ce problème de séparation, le domaine de la catalyse à base de nanoparticules magnétiques a vu le jour. Grâce à l'utilisation d'un aimant externe, les catalyseurs de nanoparticules magnétiques peuvent être récupérés et réutilisés facilement. Dans la plupart des exemples de catalyse faisant usage de nanoparticules magnétiques, les particules sont uniquement utilisées comme ancre pour la récupération magnétique, et non comme catalyseurs. Les stratégies complexes de ce type comprennent l'enrobage des nanoparticules avec un polymère ou bien avec de la silice, auquel un ligand de coordination peut être ancré. Par un tel système, on peut envisager l'ancrage de presque n'importe quel métal pseudo-homogène, ce qui permet un large éventail catalytique. L'objectif de ce travail est plutôt axé sur l'utilisation de nanoparticules magnétiques simples où les particules agissent non seulement comme moyen de récupération magnétique, mais également en tant que catalyseurs. Cette thèse porte sur trois types généraux de catalyseurs simples de nanoparticules magnétiques. Tout d'abord, il est démontré que des nanoparticules de fer réduit, dotés d'une coquille d'oxyde de fer, peuvent catalyser efficacement l'hydrogénation d'hydrocarbures insaturés. Cette réaction peut également être adaptée à un système "in flow", en préparant les nanoparticules en présence de polymères amphiphiles. Deuxièmement, considérant le potentiel catalytique limité du fer, la portée de ces réactions peut être étendue par la décoration de ces mêmes nanoparticules de fer / oxyde de fer à l'aide d'un second métal possédant un potentiel catalytique plus élevé. Des nanoparticules décorées de cuivre et de ruthénium ont été synthétisées et utilisées pour effectuer des réactions de couplage azoture-alcyne (click) et d'hydrogénation de transfert, respectivement. Troisièmement, il est démontré que d'autres métaux peuvent également directement être incorporés dans un réseau de nanoparticules magnétiques. Par exemple, des nanoparticules de CuFe2O4 peuvent être utilisées pour catalyser des réactions de condensation de Biginilli ainsi que des réactions de couplage inter-déshydrogénation. Par l'utilisation de ces trois types généraux de particules nues, nous avons élargi la portée des réactions catalysées par des nanoparticules magnétiques simples.

<p> Three new [Fe-N0]¹⁰ complexes coordinated with nitrogen chelating ligands have been synthesized and characterized. The new synthesized complexes are dinitrosyl(2-2'-biquinoline )iron(O), dinitrosyl(2,2' -bipyridine 4,4' -dimethyl)iron(O), and dinitrosy 1(2,2'-bipyridine 4,4' -diphenyl)iron(O). Each complex is synthesized utilizing a common starting material, dinitrosyldicarbonyliron(O), (Fe(N0)₂(C0)₂). Reaction conditions are in an inert atmosphere at ambient temperature and pressure.</p><p> The characterizations of these molecules are done with ultraviolet visible spectroscopy, infrared spectroscopy, and single crystal X-ray diffraction. Ultraviolet visible spectroscopy display metal ligand charge transfers between 250-550 nm. Peaks below this are due to intraligand transitions from the chelating ligands. Infrared spectroscopy data reveal that NO stretching frequencies shift to lower wavenumbers when compared to Fe(N0)₂(C0)₂ due to its better &sigma;-donating abilities of the nitrogen chelating ligands. Single crystal X-ray diffraction data show that all complexes are pseudo tetrahedral in an attracto conformation.</p>

<p> The main goal of this research project is to synthesize aluminosilicate glass materials that are doped with praseodymium. To be useful for optical studies, these glass materials must be optically transparent, strong enough to be handled and polished, and free of cracks. An advantage of the sol-gel process is that we have control over the amount of doping. However, a disadvantage of the sol-gel process is that cracking often occurs during the drying step. </p>

The development of new methods of generating alpha-amino acid derivatives via multi-component reactions remains an important challenge. The primary goal of this study is to develop new transition metal-mediated routes to synthesize these alpha-amino acid derivatives using combinations of simple reagents, such as imines, carbon monoxide, acid chlorides and organotin reagents. The proposed approach requires the sequential insertion of imine and carbon monoxide into late transition-metal sigma-bonds, as well as the further reactivity of the products. / In chapter 2, the ability of the nickel complex L2Ni(CH 3)N(R)=C(H)R'+X- (L2 = chelating nitrogen ligands, X- = non-coordinating counteranion) to mediate the insertion of imines is examined. Although L2Ni(CH3)N(R)=C(H)R' +X- does not undergo direct imine insertion into the Ni-CH3 bond, the addition of CO leads to the generation of the novel nickel complex (L2)Ni[n2-CH(R')NRCOCH 3]+X- via the insertion of imine into the nickel-acyl bond of L2Ni(COCH3)N(R)=C(H)R' +X-. This demonstrates as proof of concept, that these nickel complexes can mediate the sequential insertion of CO and imine into nickel-methyl bonds, in direct analogy to well known CO/olefin insertions. Further reactivity studies have demonstrated that the amide bound nickel chelates generated via the sequential insertion of CO and imines are generally inert towards subsequent migratory insertion with CO, imine and olefins (Chapter 3). These complexes are also inert towards auxiliary ligand exchange or amide de-chelation, with both mono- and bidenate nitrogen and phosphine ligands. / Studies involving the use of imines and alkenes as interchangeable insertion substrates, (Chapter 4) resulted in the first example of a metal mediated cyclocarbonylation incorporating imine as a formal insertion substrate. Based on these studies, one-pot sequential insertion cascade of CO, olefin, a second unit of CO, and imine was developed for the synthesis of 5 and 6 membered lactams. In addition, the competitive insertion propensity of imines and alpha-olefins was examined, and clear steric and electronic effects were identified. / The isoelectronic palladium-bound amide complexes, generated via the oxidative addition of N-acyl iminium salts (R(H)C=N(R')COR") to Pd2(dba) 3·CHCl3 can undergo a Stille-tye coupling with organotin reagents to generate alpha-substituted amide derivatives (Chapter 5). This reactivity was extended into a convenient and general one-pot synthesis of alpha-substituted amides and N-protected amines by a palladium-catalyzed three-component coupling of imines, acid chlorides or chloroformates, and organotin reagents. Mechanistically, this process provides an oxidative addition/reductive elimination-based alternative to nucleophilic approaches to C-C bond formation with imines, in which the imines are activated towards addition to palladium by RCOCl.

Synthesis and detailed characterization of dendrimers that evolve symmetrically from a linear bifunctional core (2-butyne-1,4-diol) with 3,5-dihydroxybenzyl alcohol based dendron wedges, are reported. The divergent, layer-by-layer build-up of the dumbbell shaped dendrimers, is based on simple acid-base hydrolytic chemistry of bis(dimethylamino)dimethylsilane with OH terminated molecules. Evaluation of some of the structure-property relationships in these dendrimers was carried out to obtain a better understanding of their potential applications. The self-assembly of these dendrimers in THF and water is significantly influenced by their generation number, the backbone structure and the solvent. Generations 1-3 dendrimers form aggregates at a higher critical aggregation concentration (cac) compared to generation 4 in THF. This behavior is related to the open structure in the lower generations with a linear core becoming important in their self-assembly, while in generation 4, more globular architecture with more prominent hydrogen bonding sites, facilitates self-assembly at lower concentrations. In water and in generations 1 and 2 dendrimers, the inability of more polar solvent to interact with their backbones, leads to aggregates that are formed by minimizing the repulsive forces. In generations 3 and 4, the major interaction of the solvent with the dendrimer is at the periphery which has a higher concentration of polar OH groups, and it does not interfere significantly with their ability to self-associate. Using these dendrimers as templates, a simple methodology in which silver nanoparticles are synthesized in one pot reaction, has been developed. The dendrimer structure provides reactive peripheral hydroxyl groups as well / Ce master présente la synthèse et la caractérisation détaillée de dendrimères symétriques constitués d'un noyau bifonctionnel linéaire (2-butyne-1,4-diol) et de dendrons formés à partir de l'alcool 3,5-dihydroxybenzylique. La construction divergente, couche-par-couche de ces dendrimères en forme d'haltères est basée sur une simple hydrolyse acido-basique entre l'aminosilane Me2Si(NMe2)2 et les molecules possédant des groupements hydroxyles terminaux. Certaines propriétés physiques de ces dendrimères ont été explorées afin de mieux comprendre leurs applications potentielles. Notamment, nous avons démontré que l'auto- assemblage de ces dendrimères en agrégats dépend du nombre de génération, de leur structure et du solvant. En effet, les dendrimères de générations 1 à 3 forment des agrégats à une concentration critique d'agrégation plus élevée que celle des dendrimères de génération 4 dans le THF. Ce phénomène est dû à la structure plutôt ouverte des dendrimères de basse génération qui possèdent un noyau linéaire devenant prédominant dans le phénomène d'auto-assemblage. Par contre, les dendrimères de génération 4 adoptent une architecture plus globulaire qui favorisent les liaisons hydrogène et facilitent leur auto assemblage à basses concentrations. Dans l'eau, les dendrimères générations 1 et 2 forment des agrégats en minimisant leurs forces répulsives, ce solvant plus polaire ne pouvant que très peu interagir avec les noyaux aromatiques constituant les dendrons. Dans le cas des dendrimères de générations 3 et 4, le solvant interagit principalement avec les groupes hydroxyles terminaux présents à plus haute concentration, et ceci n'influence pas de manière sig