The work described herein deals with the synthesis and characterization of lead chalcogenide thin films and nanocrystals. The first part of thesis describes the properties of semiconductors followed by an analysis on the chemical vapour deposition and nanoparticulate formation. In the next part of thesis, single-source precursors of type thioselenophosphinato, selenoureato, dithiocarbamato and dithiocarbanato complexes of lead have been synthesised and characterised. As-synthesised compounds have been utilised for the fabrication of lead sulfide and lead selenide thin films by aerosol-assisted chemical vapour deposition as well as nanocrystals by colloidal injection method. Lead sulfide thin films were also deposited by liquid-liquid interface from lead dithiocarbanato at room temperature. The as grown thin films of lead sulfide and lead selenide have been characterised by XRD, SEM and energy dispersive x-ray (EDX) analysis. In the second part of the thesis, preparation of lead sulfide and lead selenide nanocrystals in olive oil at low growth temperatures (50-60°C) is described and have shown that by controlling experimental conditions, well-defined particles with tunable emission in mid and far-infrared region can be synthesised. Furthermore, compositionally-tuned PbSxSe1-x nanocrystals has also been prepared by adding controlled amount of sulur and selenium ingredients into lead oxide. Homogenous distribution of sulfur and selenium within alloyed nanocrystals is confirmed by transmission electron microscope studies. Moreover, attempts have been made to prepare quaternary (PbTe/Se/S) nanocrystals of lead chalcogenides and depth (1.9-5.8 nm) profile analysis by x-ray photoelectron spectroscopy confirmed the formation of core/shell/shell type structure i.e. PbTe/S/Se.

Depuis les années quatre-vingt, la construction d’édifices supramoléculaires à base de complexes de coordination suscite un intérêt considérable dans la recherche de nouveaux nanomatériaux fonctionnels. L’utilisation de complexes métalliques permet non seulement l’obtention d’une multitude de supramolécules de géométrie et de dimensionnalité très variées, mais également l’introduction de processus remarquables au sein des entités nanométriques, comme par exemple le transfert d’énergie lumineuse, le transport d’électrons et la séparation photo-induite de charges. La recherche menée au cours de cette thèse s’est plus particulièrement focalisée sur l’étude de deux types d’édifices supramoléculaires polymétalliques de dimensions différentes, l’un tridimensionnel, construit au départ d’ions ruthénium (II), l’autre unidimensionnel, obtenu à partir d’ions cuivre (II) ou cuivre (I).<p><p>Plus précisément, la première partie de ce travail a été consacrée à la synthèse d’un complexe hexanucléaire symétrique de Ru(II), à base de ligands pontants PHEHAT et TPAC, afin de développer de nouvelles antennes collectrices d’énergie lumineuse. Dans ce cadre, nos travaux se sont principalement concentrés sur la synthèse ainsi que sur l’étude électrochimique et photophysique de deux nouveaux composés précurseurs trinucléaires, le cis-{[(phen)2Ru(PHEHAT)]2Ru(CH3CN)2}6+ et le {[(phen)2Ru(PHEHAT)]2Ru(TPAC)}6+, pouvant également servir de bloc de construction pour l’élaboration d’entités de tailles encore plus importantes. Une analyse par spectrométrie de masse du produit obtenu par chélation de l’entité bis-CH3CN sur le composé trinucléaire à base de TPAC ne nous a pas permis de prouver la présence de l’entité hexanucléaire. La nature du composé identifié semble toutefois confirmer la formation de l’espèce souhaitée à un moment ou un autre. <p><p>La seconde partie de notre travail a consisté à tester le TPAC ainsi que deux ligands dérivés du dipyrrométhène (m-DipyH et m-dpDipyH) comme agents pontants pour la construction de nouveaux complexes polynucléaires cuivrés unidimensionnels. D’une part, nous nous sommes penchés sur la synthèse des sous-unités monométalliques [Cu(II)(Dipy)2]0, [Cu(II)(dpDipy)2]0 et [Cu(I)(dpDipy)2]-. L’ensemble des études réalisées sur les deux composés mononucléaires de Cu(II) a permis la mise en évidence de propriétés extrêmement différentes de celles des complexes de Cu(II) polypyridiniques, tant du point de vue structural, qu’électrochimique et photophysique. Par ailleurs, les analyses consacrées à la caractérisation du [Cu(I)(dpDipy)2]- ont révélé de manière surprenante un comportement instable pour cette entité, à l’inverse des complexes de Cu(I) à base de phénanthrolines « encombrées ». Le recours à des calculs théoriques nous a permis de proposer une hypothèse pouvant expliquer cette différence de comportement. D’autre part, bien que des incertitudes subsistent toujours quant à la possibilité de former des entités polynucléaires à base de Cu(II) et de TPAC, les résultats obtenus par spectrométrie de masse ont clairement prouvé l’obtention d’espèces de Cu(II) de très haute nucléarité au départ du m-DipyH. Les ligands pontants dérivés du dipyrrométhène se révèlent donc être de très bons candidats pour l’élaboration d’entités unidimensionnelles de Cu(II). Celles-ci pourraient susciter un grand intérêt dans le cadre d’une application impliquant l’utilisation de la lumière, en raison des propriétés d’absorption et de luminescence intéressantes détectées pour les sous-unités monométalliques de Cu(II). <p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Organic semiconductors have witnessed a prolific boom for their potential in the manufacturing of lightweight, flexible, and even biocompatible electronics. One of the fields of research that has yet to benefit from organic semiconductors is high temperature electronics. The lightweight nature and robust processability is attractive for applications such as aerospace engineering, which require high temperature stability, but little has been reported on taking such a leap because charge transport is temperature dependent and commonly unstable at elevated temperatures in organics. Historically, mechanistic studies have been bound to low temperature regimes where structural disorders are minimal in most materials. Discussed here is a blending approach to render semiconducting polymer thin films thermally stable in unprecedented operation temperature ranges for organic materials. We found that by utilizing highly rigid host materials, semiconducting polymer domains could be confined, thus improving their molecular and microstructural ordering, and a thermally stable charge transport could be realized up to 220°C. With this blending approach, all-plastic high temperature electronics that are extremely stable could also be demonstrated. In efforts to establish a universal route towards forming thermally stable semiconducting blends, we found that the molecular weight of conjugated polymer plays a crucial role on the miscibility of the blends. Finally, we found that the choice of the host matrix ought to consider the charge trapping nature of the insulator.<br>

<p dir="ltr">Nanoparticles have seen immense development in the past several decades due to their intriguing physicochemical properties. The modern chemist is interested not only in methods of synthesizing nanoparticles with tunable properties but also in the chemistry that nanoparticles can drive. While several methods exist to synthesize nanoparticles, it is often advantageous to put nanoparticles on a variety of conductive substrates for multiple applications (such as energy storage and conversion). Despite enjoying over 200 years of development, the electrodeposition of nanoparticles suffers from a lack of control over nanoparticle size and morphology. Understanding that structure-function studies are imperative to understand the chemistry of nanoparticles, new methods are necessary to electrodeposit a variety of nanoparticles with control over macro-morphology but also microstructure. When a nanodroplet full of a metal salt precursor is incident on the electrode biased sufficiently negative to drive electroplating, nanoparticles form at a shocking rate (on the order of microseconds to milliseconds). We start with the general nuts-and-bolts of the experiment (nanodroplet formation and methods for electrodeposition). The deposition of new nanomaterials often requires one to develop new methods of measurement, and we detail new measurement tools for quantifying nanoparticle porosity and nanopore tortuosity within single nanodroplets. Owing to the small size of the nanodroplets and fast mass transfer, the use of nanodroplets also allows the electrodeposition of high entropy alloy nanoparticles at room temperature. Electrodeposition in aqueous nanodroplets can also be combined with stochastic electrochemistry for a variety of interesting studies. We detail the quantification of the growth kinetics of single nanoparticles in single aqueous nanodroplets. Nanodroplets can also be used as tiny reactors to trap only a few molecules, and the reactivity of those molecules can be electrochemically probed and evaluated with time. Overall, this burgeoning synthetic tool is providing unexpected avenues of tunability of metal nanoparticles on conductive substrates. Moreover, there is little understanding of how ion transfer can affect the fundamental of nanoparticle synthesis with nanodroplet-mediated electrodeposition. This thesis details different experiments performed to study the role of ion transfer during the nucleation and growth of nanoparticles.</p>

<p dir="ltr">DNA sequence design requires the ability to identify possible tertiary structural defects, secondary structure disruptions, and self-complimentary stretches that will disallow your complimentary strands to come together to form the desired duplex design. However, there is a need for those self-complimentary stretches, especially when designed with the intent for this to homo-oligomerize into the desired building block. With the programmability of nucleic acid hybridization, there is an expanding field wherein this specific, self-complimentary design feature can give new possibility of fine-tuning DNA self-assembly (Chapter 1) or overcome a previously thought limit of DNA ligation (Chapter 2).</p><p dir="ltr">The first chapter will closely look at the branched kissing loop interaction. This interaction was studied as a homo-polymerizable DNA building block that is topologically closed. As such, this paranemic motif has increased stability due to the Watson-Crick base pairing being “protected” by a 3-base adenine branch which close the loop of the sticky-end, meaning no free ends in the binding region. With this, herein we report that the intended higher-level structure could influence the lower-level building block formation. In DNA nanotechnology, this could mean the final higher-level structure would allow for fine-tuning as this would dictate the building blocks that fill in the defected parts of the higher-level structure.</p><p dir="ltr">The second chapter looks at the more finite than broad picture. Whilst the first chapter focusses on the impact the microscale has on the nanoscale through a homo-polymerizable design, the second chapter focusses on the ability to break barriers with homo-polymerizable design. In this chapter, we prove that with our splint strand design, when improved with a hairpin loop on the terminal ends, we can ligate DNA strands enzymatically as short as 16 nucleotides with an efficiency of 97% at high concentrations (100 uM). These hairpins allow for a stable, robust splint strand as they are a self-complimentary region which will maintain its shape throughout the process of joining together the 5’ and 3’ ends of the target strand.</p><p dir="ltr">Overall, this dissertation hopes to prove that homo-polymerizable DNA sequence designs are helping expand upon the DNA nanotechnology toolbox by introducing new possibilities for nanoscale design, as well as push past previously held boundaries through necessary added stability afforded by the self-complimentary strands.</p>

La spintronique moléculaire et la photocatalyse sont deux domaines en constante évolution. Le premier s’attache à exploiter la possibilité de coupler deux phénomènes physiques, à savoir le transport d’un flux de porteurs de charges et le spin de l’électron, tandis que le second se concentre sur l’exaltation des propriétés chimiques de transfert d’électrons d’une espèce donnée grâce au phénomène physique d’irradiation lumineuse. Depuis quelques années, les nanotubes de carbone ont suscité un grand intérêt à la fois en tant que composant pour la spintronique moléculaire, en raison de leur grande cohérence de spin, et en tant que support idéal pour la catalyse moléculaire, grâce à leurs exceptionnelles propriétés électroniques de surface. Au cours de ce travail de thèse, nous nous sommes attachés à concevoir des complexes inorganiques possédant des propriétés physiques, (magnétiques ou optiques) et des propriétés chimiques (permettant leur assemblage non-covalent sur des nanotubes de carbone monoparoi) de manière à former des adduits complexes inorganiques-nanotubes aux propriétés exploitables en spintronique moléculaire et en photocatalyse. Les propriétés des complexes synthétisés ont été extensivement caractérisées (Chapitre 2), et les plus prometteurs de ces composés ont été assemblés avec succès sur les nanotubes de carbone (Chapitre 3), comme en attestent les mesures spectroscopiques réalisées. Enfin, les deux domaines d’applications concernés par nos travaux faisant intervenir des phénomènes de transport électronique, des études spécifiques sur des dispositifs électriques de type transistor à effet de champ dont le canal de conduction est constitué de nanotubes de carbone ont été réalisées (Chapitre 4). Celles-ci mettent à chaque fois en évidence l’existence d’une communication électronique entre les complexes inorganique et les nanotubes de carbone sur lesquels ils sont assemblés au sein des dispositifs. Bien qu’au final un couplage entre les propriétés magnétiques des complexes synthétisés et les propriétés de transport des nanotubes n’ait pas pu être mis en évidence, de nombreux phénomènes inattendus et extrêmement intéressants tels que des effets ambipolaires, des transferts de charge ou des ruptures de liaisons ont été observés. Par contre, un fort couplage opto-électronique a pu être obtenu entre un complexe et le flux de porteurs de charge des dispositifs, ce qui s’avère être de très bon augure pour des futures applications en photocatalyse. / Molecular spintronic and photocatalysis are two fields in constant evolution. While the first deals with the coupling of two physical properties, the flux of charge carriers and the spin of the electron, the second is focusing on the enhancement of the electron transfer of chemical species under light irradiation. Recently, there has been an increasing interest in carbon nanotubes as new components for molecular spintronics, since they possess high spin coherence, and as ideal materials for molecular catalysis, for their tremendous electronic surface properties. Our work consisted in conceiving inorganic complexes with both physical (magnetic or optic) and chemical (ability of realizing non covalent assembly on single-walled carbon nanotubes) properties, in order to create new nanotube-complex nanohybrids which could be exploited for molecular spintronics or photocatalysis applications. The properties of the synthesized complexes were extensively characterized (Chapter 2), and the most promising molecules were successfully assembled onto carbon nanotubes, as is proven by the spectroscopic measurement which were performed (Chapter 3). Finally, since both domains of applications we considered involve electronic transportation, specific studies were realized on field effect transistor devices with carbon nanotubes as the conduction channel (Chapter 4). They evidence strong electronic communications between the inorganic complexes and the carbon nanotubes onto which they are assembled in the devices. Even if in the end no coupling was observed between the magnetic properties of the inorganic complexes and the transport ones of the carbon nanotubes, numerous unexpected and very interesting phenomena such as ambipolar behavior, charge transfer effect or bond cleavage were evidenced. As for the optoelectronic coupling which was investigated for photocatalytic applications, a first step was made as the transport of the carbon nanotube field effect transistor devices onto which a complex was assembled shows a strong dependence with the applied light irradiation.

<p>Noble metal nanostructures display collective oscillation of the surface conduction electrons upon light irradiation as a form of localized surface plasmon resonance (LSPR) properties. Size, shape and the refractive index of surrounding environment are the key features that controls the LSPR properties. Surface passivating ligands have the ability to modify the charge density of nanostructures to allow resonant wavelength to match that of the incident light, a phenomenon called “plasmoelectric effect,”. According to the drude model Red and blue shifts of LSPR peak of nanostructures are observed in the event of reducing and increasing charge density, respectively. However, herein we report unusual LSPR properties of gold triangular nanoprisms (Au TNPs) upon functionalization with para-substituted thiophenols (X-Ph-SH, X = -NH₂, -OCH₃, -CH₃, -H, -Cl, -CF₃, and -NO₂). Accordingly, we hypothesized that an appropriate energy level alignment between the Au Fermi energy and the HOMO or LUMO of ligands allows delocalization of surface plasmon excitation at the hybrid inorganic-organic interface, and thus provides a thermodynamically driven plasmoelectric effect. We further validated our hypothesis by calculating the HOMO and LUMO levels and also work function changes of Au TNPs upon functionalization with para substituted thiol. We further utilized our unique finding to design ultrasensitive plasmonic substrate for biosensing of cancer microRNA in bladder cancer and owe to unpresidential sensitivity of the developed Au TNPs based LSPR sensor, for the first time we have been utilized to analysis the tumor suppressor microRNA for more accurate diagnosis of BC. Additionally, we have been advancing our sensing platform to mitigate the false positive and negative responses of the sensing platform using surface enhanced fluorescence technique. This noninvasive, highly sensitive, highly specific, also does not have false positives technique provide strong key to detect cancer at very early stage, hence increase the cancer survival rate. Moreover, the electromagnetic field enhancement of Surface-Enhanced Raman Scattering (SERS) and other related surface-enhanced spectroscopic processes resulted from the LSPR property. This dissertation describes the design and development of entirely new SERS nanosensors using flexible SERS substrate based on unique LSPR property of Au TNPs and developed sensors shows excellent SERS activity (enhancement factor = ~6.0 x 106) and limit of detection (as low as 56 parts-per-quadrillions) with high selectivity by chemometric analyses among three commonly used explosives (TNT, RDX, and PETN). Further we achieved the programable self-assembly of Au TNPs using molecular tailoring to form a 3D supper lattice array based on the substrate effect. Here we achieved the highest reported sensitivity for potent drug analysis, including opioids and synthetic cannabinoids from human plasma obtained from the emergency room. This exquisite sensitivity is mainly due to the two reasons, including molecular resonance of the adsorbate molecules and the plasmonic coupling among the nanoparticles. Altogether we are highly optimistic that our research will not only increase the patient survival rate through early detection of cancer but also help to battle the “war against drugs” that together is expected to enhance the quality of human life. </p> <p> </p>

<div>Surface level molecules act as an interface that mediates between the surface and the environment. In this way, interfacial molecules are responsible for conferring characteristics of relevance to many modern material science problems, such as electrical conductivity and wettability. For many applications, such as organic photovoltaics and nanoelectronics, macroscopic placement of chemical patterns at the sub-10 nm must be achieved to advance next generation device applications.</div><div><br></div><div>In the work presented here, we show that sub-10 nm orthogonal features can be prepared by translating the building principles of the lipid bilayer into striped phase lipids on 2D materials (e.g. highly ordered pyrolytic graphite (HOPG), MoS2). Macroscopic patterning of these nanoscopic elements is achieved via Langmuir Schafer deposition of polymerizable diyne amphiphiles. On the Langmuir trough, amphiphiles at the air water interface are ordered into features that can be observed on the macroscale using Brewster angle microscopy. Upon contact of the 2D material with the air-water interface the macroscopic pattern on the trough is transferred to the 2D material creating a macroscopic pattern consisting of sub-10 nm orthogonal chemistries. We also show here how hierarchical ordering can be accomplished via noncovalent microcontact printing of amphiphiles onto 2D materials. Microcontact printing allows a greater measure of control over the placement and clustering of interfacial molecules.</div><div><br></div><div>The alkyl chain/surface enthalpy has a great deal of influence over the ordering of amphiphiles at the sub-nm scale. Here, we examine this influence by depositing diyne amphiphiles onto MoS2 which has a weaker alkyl adsorption enthalpy compared to HOPG. We found that dual-chain amphiphiles deposited on MoS2 adopt a geometry that maximized the molecule-molecule interaction compared to the geometry adopted on HOPG.</div><div><br></div><div>Finally, we show how the hierarchical pattern of diyne amphiphiles can be transferred off of the 2D material onto an amorphous material. This is done by reacting the amorphous material with the conjugated backbone of the diyne moiety through a hydrosilylation reaction to exfoliate the film from the 2D crystalline material. The resulting polymer ‘skin’ has many applications were controlling interfacial properties of an amorphous material is important.</div>

<p>Extracellular matrix (ECM) creates high-resolution chemical patterns, by assembling simple molecules with nm-scale features (e.g., carbohydrates, nucleotides, amino acids) into complex structures up to micrometers and extending to even larger scales across tissues (e.g., glycans, DNA, proteins), capable of carrying out the diverse and complex cellular functions. Mimicking the complexity of such biological systems requires precise control over the chemical patterning on substrates that exhibit physiochemical properties similar to biological systems (such as hydrogels). Although hydrogels provide tunable physiochemical properties suitable for biological applications; it is a porous material where pore sizes can range from 30 nm to greater than 1000 nm. Due to this structural heterogeneity, chemical patterning below the length scale of this heterogeneity is very challenging.</p> <p>Here, we demonstrate a new assembly system for generating a nanostructured presentation of carbohydrates on the hydrogel surface. This approach is based on the striped phases assembly of functional alkanes where 1-nm resolution functional patterns are readily assembled on substrates such as highly ordered pyrolytic graphite (HOPG). In this assembly, molecules are stabilized by noncovalent interactions, including alkyl-pi interactions underlying the HOPG, van der Waals interaction between the adjacent alkyl chains, and hydrogen bonding between polar head groups. Topochemical polymerization converts internal diynes into conjugated polydiacetylenes (PDAs). PDAs can also be utilized to covalently attach the striped pattern to polyacrylamide hydrogels through free radical chemistry.</p> <p>Here, we synthesize new amphiphiles with carbohydrate headgroups (N-acetyl-D-glucosamine (GlcNAc), and D-glucuronic acid (GlcA)), assembled into striped phases on HOPG and covalently transfer to polyacrylamide hydrogels. GlcNAc binds to wheat germ agglutinin (WGA), a lectin that binds specifically in a multivalent fashion (dissociation constant KD in nm range) to GlcNAc. We show that GlcNAc striped phases generate highly selective interactions with wheat germ agglutinin (WGA) but do not induce specific binding with concanavalin A (another lectin molecule that does not target GlcNAc). We further demonstrate that WGA binding affinity can be modulated by shifting the position of diacetylenes that bring the polymer backbone closer to the GlcNAc, increasing the effecting local concentration of carbohydrates.</p> <p>We investigated the possibility of using sPDA for secondary functionalization with complex biological molecules (such as biotin and cRGD) to mimic the ECM composition closely. The unusual reactivity of the sPDA backbones during the covalent transfer of the striped phase monolayer to hydrogels illustrates the potential of sPDA reactivity azides. In this work, we show that the addition of substituted azide molecules to sPDA-functionalized hydrogels produces a decrease in the fluorescence of the sPDA monolayer. Since these reactions are occurring on porous hydrogel surfaces characterization using techniques such as IR or NMR is difficult. We carried out further solution-phase reactions using a soluble PDA where PDA UV-vis absorption spectra red-shift after the reaction between the PDA backbone and azide. These experiments support the hypothesis of sPDA and azide click reaction.</p>

<p dir="ltr">Directed hydrogenation, in which product geometric selectivity is dictated by the binding of an ancillary directing group on the substrate to the catalyst, is typically achieved by homogeneous Rh and Ir complexes. No heterogeneous catalyst has been able to achieve equivalently high directivity due to a lack of control over substrate binding orientation at the catalyst surface. In this work, we demonstrate through structure-activity studies that careful control of surface ensemble geometry in bimetallic nanoparticle catalysts can confer hydroxyl-directed selectivity in heterogeneous double bond hydrogenation. We postulate that the oxophilic alloy component binds hydroxyl groups to pre-orient the molecule on the surface, while proximal noble metal atoms impart facially selective addition of hydride to the olefin. We found that controlling the degree of surface alloying between oxophilic and noble metal component as well as alloy component identity is critical to maximizing reaction selectivity and starting material conversion. Our optimized catalysts exhibit good functional group tolerance on a variety of cyclohexenol and cyclopentenol scaffolds, with Pd-Cu and Pt-Ni systems being developed for the diastereoselective hydrogenation of tri- and more challenging tetra-substituted olefins, respectively. The applicability of this method is then demonstrated in a four-step synthesis of a fine fragrance compound, (1<i>R</i>,2<i>S</i>)-(+)-<i>cis</i>-methyldihydrojasmonate (Paradisone®), with high yield and enantiopurity.</p>