Crystal engineering has recently emerged as a method of choice for the design and the construction of functional materials. Solid-state synthesis, of the most commonly studied aspects of crystal engineering, has been shown to provide access to molecular targets that are hardly obtainable using principles of conventional (i.e. solution-based) organic synthesis. Reactions in the solid state are, however, not routinely used in organic synthetic chemistry. The scarce use of solid-state reactions can be attributed to the difficulty of predicting molecular arrangements in the solid state, as well as to the lack of methodologies to control crystal packing. Template-directed solid-state synthesis is a recently developed modus operandi that enables control over reactivity within multi-component crystals. The thesis is focused on the application of template-directed solid-state approach to [2+2] photocycloaddition reactions in the solid state, as well as on the understanding of intermolecular interactions in crystals. Synthetic templates have been utilized to construct cocrystals that enable a class of hitherto underdeveloped organic solid-state reactions, namely [2+2] cross-photoaddition reactions. In addition, products derived form templated solid state reactions, namely tetrapyridylcyclobutanes, have been utilized to generate exceptional materials, such as thixothropic hydrogels based on nano-dimensional metal-organic particles. The utility of crystal engineering has also been expanded to the nanoscience and the development of nanomaterials. A crystallization method for the preparation of nano-dimensional cocrystals has been developed. The method has been shown to enable single-crystal-to-single-crystal [2+2] photodimerizations of olefins. In addition, nano-dimensional cocrystals have been shown to exhibit distinctive mechanical properties upon single-crystal-to-single-crystal transformations. In addition to solid-state reactions and materials derived therefrom, we systematically studied hierarchies of supramolecular synthons in pharmaceutical cocrystals comprised of multi-functional molecules. Pharmaceutical cocrystals have been recently shown to exhibit physical properties superior to those of parent drugs. Our studies involved xanthine alkaloids as pharmaceutical agents and a series of hydroxylated benzoic acids as cocrystal formers. Synthon hierarchies have been established for three xanthine alkaloids. We also discovered pharmaceutical salts that formed where cocrystallization was expected to occur. Reasons contributing to such unexpected salt formation were investigated using X-ray crystallography and computational methods. The established synthon hierarchies are expected to contribute to a better understanding of self-assembly processes in cocrystals that is crucial for the development of state-of-art drugs, and the design of organic reactions in the solid state.

Carbon quantum dots (CQDs) are the latest generation of carbon nanomaterials in applications where fullerenes, carbon nanotubes, and graphene are abundantly used. With several attractive properties such as tunable optical property, edge-functionalization, and defect-rich chemical structure, CQDs have the potential to revolutionize optoelectronics, electro- and photocatalysis, and biomedical applications. Chemical modifications through the addition of heteroatoms, chemical reduction, and surface passivation are found to alter the band gap, spectral position, and emission pathways of CQDs. Despite extensive studies, fundamental understanding of structure-property relationship remains unclear due to the inhomogeneity in chemical structure and a complex emission mechanism for CQDs. This dissertation outlines a series of works that investigate the structure-property relationship of CQDs and its impact in a variety of applications. First, this relationship was explored by modifying specific chemical functionalities of CQDs and relating them to differences observed in optical, catalytic, and pharmacological performance. While a number of scientific articles reported that top-down or bottom-up synthesized CQDs yielded similar properties, the results herein present dissimilar chemical structures as well as photoluminescent and metal sensing properties. Second, the role of nitrogen heteroatoms in top-down synthesized CQD was studied. The effect of nitrogen atoms on spectral position and fluorescence quantum yield was considerably studied in past reports; however, thorough investigation to differentiate various nitrogen related chemical states was rarely reported. By finely tuning both the quantity of nitrogen doping and the distribution of nitrogen-related chemical states, we found that primary amine and pyridine induce a red-shift in emission while pyrrolic and graphitic nitrogen produced a blue-shift in emission. The investigation of nitrogen chemical states was extended to bottom-up synthesized CQDs with similar results. Finally, top-down, bottom-up, nitrogen-doped and chemically reduced CQDs were separately tested for their ability to act as photodynamic anti-cancer agents. This series of experiments uncovered the distribution of reactive oxygen species produced during light exposure which elucidated the photodynamic mechanisms of cancer cytotoxicity. The results presented in this dissertation provide key insight into engineering finely-tailored CQDs as the ideal nanomaterial for a broad range of applications.

There has been an increase in the incorporation of silver nanomaterials into consumer products due to their antimicrobial properties. Therefore there is potential for silver nanoparticles (Ag-NPs) to leach out into the environment during different life-cycle stages of these nanomaterial-containing products. Concern about the toxicity of Ag-NPs has led to investigations into their toxic effects on a variety of organisms mainly using acute and sub-chronic, single-generation exposures. The focus of this project was to understand the effects of long-term continuous multigenerational exposure to AgNO3 and Ag-NPs in both pristine and environmentally transformed forms, on the model organism, Caenorhabditis elegans, a soil nematode. A previous multigenerational C. elegans study, showed increased sensitivity in terms of reproductive toxicity, in response to AgNO3 and Ag-NPs, but not sulfidized Ag-NPs (sAg-NPs), with increasing generations of exposure. The reproductive toxicity persisted in subsequently unexposed generations even after rescue from the exposure. We hypothesized that genomic mutations and/or epigenetic changes were possible mechanisms by which the reproductive toxicity was inherited. We investigated the potential for induction of germline mutations in C. elegans after exposures for ten generations to AgNO3, Ag-NPs, and sAg-NPs using whole genome DNA sequencing. Epigenetic changes at histone methylation markers, (H3K4me2 and H3K9me3), and DNA methylation at adenosine (N6-methyl-2’-deoxyadenosine) were investigated after multigenerational exposure as well as after rescue from the exposure using enzyme-linked immunosorbent assays (ELISA) and liquid chromatography with tandem mass spectrometry (LC-MS/MS), respectively. Expression levels of the genes of methyltransferases and demethylases, associated with the histone methylation markers and DNA methylation, were also examined. Our results for germline mutations reveal no significant differences between the nematodes exposed to AgNO3 or pristine Ag-NPs when compared to controls. The significant increase in the number of transversion was observed only for sAg-NPs. However, a trend toward an increase in the total number of mutations was observed in all Ag treatments with some of those mutations having a predicted moderate or high impact. This potentially contributed towards reproductive as well as growth toxicity shown previously after ten generations of exposure in every treatment.. These results did not entirely support the multigenerational reproductive toxicity observed previously. Epigenetic responses at histone methylation markers revealed opposite patterns between pristine and transformed Ag-NPs with Ag-NPs causing a significant increase while exposure to sAg-NPs resulted in significant decrease in methylation at H3K4me2 mark. The increase in H3K4me2 levels was also inherited by subsequent unexposed generations rescued from Ag-NP exposure. Only sAg-NPs caused a significant decrease in methylation at H3K9me3 mark. Changes in mRNA levels for histone methyltransferases and demethylase corresponded with the histone methylation levels affected by Ag-NPs and sAg-NPs. For DNA methylation, a significant increase was observed only for AgNO3, which was not inherited after the rescue. In conclusion, while germline mutations with a high or moderate impact may affect reproduction, our results do not support this as a mechanism for the heritable increase in C. elegans sensitivity to reproductive toxicity from AgNO3 and pristine Ag-NPs. The epigenetic changes, however, do show partial correlation with the observed reproductive toxicity. The reproductive multigenerational effects of AgNO3 can be attributed to changes in DNA methylation whereas that of Ag-NPs can be attributed to changes in histone methylation. Further studies, focused on the investigation of changes in histone and DNA methylation levels at specific loci using chromatin immunoprecipitation sequencing (ChIP-Seq) and methylated DNA immunoprecipitation sequencing (MeDIP-Seq), respectively, are warranted for a better understanding of the impact of such changes.

Ce travail de thèse a pour objet le développement d'une nouvelle voie de synthèse de nanomatériaux métalliques à base d'éléments légers : bore et phosphore. L'intérêt porté à ces composés s'explique par les propriétés variées qu'ils présentent, tels que la supraconductivité, la thermoélectricité ou le stockage d'énergie. Dans le cadre de ce travail, les domaines de la catalyse et de l'électrocatalyse sont explorés. Les borures de différents métaux de transition, en particulier le nickel, le palladium et un composite nickel-cobalt, ont tout d'abord été étudiés. Pour cela une synthèse a été mise au point, reposant sur la réactivité de nanoparticules métalliques avec un précurseur de bore en milieu sels fondus inorganiques. Elle a notamment permis d'obtenir des nanoparticules de borures de nickel avec un bon contrôle de composition, structure, morphologie et taille. Les propriétés de ces nanomatériaux ont par la suite été étudiées en catalyse dans la réaction d'hydrodésoxygénation, et en électrocatalyse dans les réactions de génération d'hydrogène ou d'oxygène à partir de l'eau. Enfin la réactivité du phosphore rouge en milieu sels fondus a été abordée, ouvrant ainsi une nouvelle voie vers l'élaboration de phosphures de métaux de transition. / This PhD work deals with a novel synthesis of metal boride and metal phosphide nanomaterials. Nanostructures of these solids are subject to an increasing interest due to their exciting properties for various applications fields such as superconductivity, high temperature thermoelectricity, energy conversion and storage. In this work, the catalytic and electrocatalytic properties of these nanomaterials are explored. First of all, borides of various transition metals, such as nickel, palladium or a nickel-cobalt composite are studied. To do so, a new liquid-phase synthesis was developed, based on the reactivity of already formed metal nanoparticles with a boron precursor in inorganic molten salts. This new synthesis allowed a precise control over the nanoparticle morphology, size, composition and crystalline structure. By accessing such nanoscale objects, we were able to investigate their properties and performances, especially in the fields of catalysis with the hydrodeoxygenation reaction and electrocatalysis for the hydrogen evolution reaction and oxygen evolution reaction. Finally, the reactivity of red phosphorus in molten salts was addressed, thus paving the way to the extension of this synthetic pathway to metal phosphides.

Mesoporous thin films are promising architectures for positive electrodes in Li-ion battery applications. A particular challenge in this field has been successful templating of vanadium-based oxides, materials known for their ability to host lithium, since their thermal instability and complex vanadium chemistry hinder templating through traditional soft-chemistry approaches. To address these technical problems we here develop the soft-templating of vanadium and niobium mixed oxides based on Evaporation Induced Micelles Packing using thermally stable polystyrene-b-polyethyleneoxide structuring agents. In-situ thermal monitoring via ellipsometry allows successful navigation of the thermal stability landscape. TEM and AFM analyses reveal homogeneous wormlike mesoporous structures whose pore and inorganic wall sizes can be tuned from 15 to 100 nm by changing the hydrophobic/hydrophilic surfactant chain lengths. Ellipsometric porosimetry shows that 100 nm thick films with a 15 nm pore size displays 30% electrolyte accessible porosity. The interconnected tridimensional mesoporous network has been highlighted by electronic tomography. Thicker films up to 1.3 µm are prepared by a multidipping process. The superiority of such nanoarchitectures compared to non porous materials in terms of electrochemical properties such as capacity are revealed using cyclic voltammetry.

Photophysical, electronic, and compositional properties of single-walled carbon nanotubes (SWCNTs) and bulk nanotube samples were investigated together with graphene oxide photoluminescence. First, we studied the effect of external electric fields on SWCNT photoluminescence. Fields of up to 10 7 V/m caused dramatic, reversible decreases in emission intensity. Quenching efficiency was proportional to the projection of the field on the SWCNT axis, and showed inverse correlation with optical band gap. The magnitude of the effect was experimentally related to exciton binding energy, as consistent with a proposed field-induced exciton dissociation model. Further, the electronic composition of various SWCNT samples was studied. A new method was developed to measure the fraction of semiconducting nanotubes in as- grown or processed samples. SWCNT number densities were compared in images from near-IR photoluminescence (semiconducting species) and AFM (all species) to compute the semiconducting fraction. The results provide important information about SWCNT sample compositions that can guide controlled growth methods and help calibrate bulk characterization techniques. The nature of absorption backgrounds in SWCNT samples was also studied. A number of extrinsic perturbations such as extensive ultrasonication, sidewall functionalization, amorphous carbon impurities, and SWCNT aggregation were applied and their background contributions quantified. Spectral congestion backgrounds from overlapping absorption bands were assessed with spectral modeling. Unlike semiconducting nanotubes, metallic SWCNTs gave broad intrinsic absorption backgrounds. The shape of the metallic background component and its absorptivity coefficient were determined. These results can be used to minimize and evaluate SWCNT absorption backgrounds. Length dependence of SWCNT optical properties was investigated. Samples were dispersed by ultrasonication or shear processing, and then length-fractionated by gel electrophoresis or controlled ultrasonication shortening. Fractions from both methods showed no significant absorbance variations with SWCNT length. The photoluminescence intensity increased linearly with length, and the relative quantum yield gradually increased, approaching a limiting value. Finally, a strong pH dependence of graphene oxide photoluminescence was observed. Sharp and structured excitation/emission features resembling the spectra of molecular fluorophores were obtained in basic conditions. Based on the observed pH-dependence and quantum calculations, these spectral features were assigned to quasi-molecular fluorophores formed by the electronic coupling of oxygen-containing addends with nearby graphene carbon atoms.

In this study, several synthesis routes were adopted to prepare nanometer sized metal-phosphonate particles to expand their use in the delivery of phosphonate mineral scale inhibitors into formation porous media for oilfield scale control. An aqueous solution of calcium chloride or zinc chloride was mixed with a basic phosphonate solution to form nanometer sized particles. The physical and chemical properties of the fabricated nanomaterials and their solutions have been carefully evaluated. The obtained nanomaterial suspensions were stable for a certain period of time at 70°C in saline solutions. The nanomaterials demonstrated a good migration performance through formation porous media. Transportability was affected by both the flow velocity and the surface chemistry of the nanomaterials as well as the formation medium. The transport of these nanomaterials can be enhanced, when the formation materials were pre-flushed by surfactant solutions. The potential application of the synthesized nanomaterials for scale treatment in oilfields has been investigated by a series of laboratory squeeze simulation tests. The synthesized nanomaterials were injected into formation medium and retained on the medium surfaces. After a shut-in period, the inhibitor nanomaterials slowly released phosphonates into the produced fluid to prevent scale formation. It has been observed that the prepared nanomaterials are able to return phosphonates in a similar return profile as that of the conventional acidic pills. Moreover, the crystalline phase Ca-DTPMP nanomaterials, developed from their amorphous precursors, demonstrate a long term phosphonate return behavior with a stable phosphonate return concentration for an extended period of time. The long term flow back performance of metal-phosphonate nanomaterials can be interpreted by their solubility product in brine solutions.

Polyanionic compounds have been heavily investigated as possible electrode materials in lithium- and sodium-ion batteries. Chief among these is lithium iron phosphate (LiFePO4) which adopts the olivine structure and has a potential of 3.5 V vs. Li/Li+. Many aspects of ion transport, solid-solution behaviour and their relation to particle size in olivine systems are not entirely understood. Morphology, unit cell parameters, purity and electrochemical performance of prepared LiFePO4 powders were greatly affected by the synthetic conditions. Partially delithiated olivines were heated and studied by Mössbauer spectroscopy and solid-solution behaviour by electron delocalization was observed. The onset of this phenomenon was around 470-500 K in bulk material but in nanocrystalline powders, the onset of a solid solution was observed around 420 K. The isostructural manganese member of this family (LiMnPO4) was also prepared hydrothermally. Owing to the thermal instability of MnPO4, partially delithiated LiMnPO4 did not display any solid-solution behaviour. Phosphates based on the tavorite (LiFePO4OH) structure include LiVPO4F and LiFePO4(OH)1-xFx which may be prepared hydrothermally or by solid state routes. LiVPO4F is a high capacity (2 electrons/transition metal) electrode material and the structures of the fully reduced Li2VPO4F and fully oxidized VPO4F were ascertained. Owing to structural nuances, the potential of the iron tavorites are much lower than that of the olivines. The structure of Li2FePO4F was determined by a combined X-ray and neutron diffraction analysis. The electrochemical properties of very few phosphates based on sodium are known. A novel fluorophosphate, Na2FePO4F, was prepared by both solid state and hydrothermal methods. This material exhibited two two-phase plateau regions on cycling in a half cell versus sodium but displayed solid-solution behaviour when cycled versus lithium, where the average potential was 3.3 V. On successive cycling versus Li a decrease in the sodium content of the active material was observed, which implied an ion-exchange reaction occurred between the material and the lithium electrolyte. Studies of polyanionic materials as positive electrode materials in alkali metal-ion batteries show that some of these materials, namely those which contain iron, hold the most promise in replacing battery technologies currently available.

In this thesis two issues in nanotechnology have been addressed. The first is the comprehensive characterization of engineered nanomaterials prior to their examination in toxicology and environmental studies. The second is the development of a method to produce nanostructure arrays over large areas and for low cost. A major challenge when assessing nanomaterial’s risks is the robust characterization of their physicochemical properties, particularly in commercial products. Such data allows the critical features for biological outcomes to be determined. This work focused on the inorganic oxides that were studied in powdered and dispersed forms as well as directly in consumer sunscreen products. The most important finding was that the commercial sunscreens that listed titania or zinc oxide as ingredients contained nanoscale materials. Cell free photochemical tests revealed that ZnO particles without any surface coating were more active at generating ROS than surface coated TiO2 nanoparticles. These studies make clear the importance of exposure studies that examine the native form of nanomaterials directly in commercial products. The second part of this thesis presents the development of a new method to fabricate gold nanoring and nanocrescent arrays over large areas; such materials have unique optical properties consonant with those described as metamaterials. A new shaped nanosphere lithography approach was used to manipulate the form of silica nanospheres packed onto a surface; the resulting array of mushroom structures provided a mask that after gold evaporation and etching left either golden rings or crescents over the surface. The structures had tunable features, with outer diameters ranging from 200 to 350 nm for rings and crescent gap angles of ten to more than a hundred degrees. The use of a double mask method ensured the uniform coverage of these structured over 1 cm2 areas. Experimental and theoretical investigations of the optical properties of the arrays revealed the optical resonances in the infrared region. Finally, in the course of developing the nanorings, etch conditions were developed to deposit large area arrays of polystyrene nanodoughnuts with diameters from 128 to 242 nm. These non-conductive structures provide an ideal template for further attachment of magnetic of optically emissive nanoparticles.

Multi-scale ordering of the components is of utmost importance for the preparation of any functional system. This is particularly interesting for the assembly of plamonic nanoparticles which show drastic differences in their optical properties compared to the individual counterparts, giving rise to the unique opportunity to perform enhanced spectroscopies, sensing, and transporting optical information below the diffraction limitation of light. The control over ordering of nanoscale materials is therefore of paramount importance. Template based bottom up approaches such as using nematic liquid crystals promise a long range, reversible ordering of nanomaterials. It also promises active control over plasmonic properties of metal nanoparticles due to the electric field induced reorientation of liquid crystals, resulting in a change of the local refractive index. This thesis discusses the possibility of ordering anisotropic metal nanoparticles and performing active modulaton of the plasmonics response using a nematic liquid crystals. While long polymer chains can be solvated and aligned in liquid crystal solvents, anisotropic metal nanoparticles could not be dissolved in the nematic liquid crystal phase because of their poor solubility. Here, I show that appropriate surface functionalization can increase the otherwise low solubility of plasmonic nanoparticles in a nematic liquid crystal matrix. I also show that it is possible to reversibly modulate the polarized scattering of individual gold nanorods through an electric field induced phase transition of the liquid crystal. In this thesis, I also studied the motion of a molecular machine, commonly known as nanocars, over different solid surface. I show that individual nanocars, which consist of four carborane wheels attached to an aromatic backbone chassis, can move up to several micrometers over a glass surface at ambient temperature. Their movement is consistent with the rolling of the carborane wheels and can be controlled by tuning the interaction between the surface and the wheels.