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1
Wang, Yang. "Novel amphiphilic dendrimers as nanovectors for siRNA delivery." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4017.
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Les dendrimères, font partie d'une famille particulière de polymères synthétiques, pouvant être utilisés comme nanovecteurs pour l'administration de médicaments grâce à leur structure polyvalente et leur action coopérative, ces fonctions étant confinées dans un volume de taille nanométrique. Notre groupe a récemment démontré que de petites unités dendritiques amphiphiles pouvaient s'auto-assembler en dendrimères supramoléculaires pouvant délivrer du siARN, avec une efficacité similaire à celle des dendrimères de grande génération construits de manière covalente. Dans cette thèse, ans le but de explorer des nouveaux dendrimères amphiphiles possédant des propriétés particulières d'auto-assemblage pour la délivrance de médicaments, j'ai synthétisé et caractérisé deux familles de dendrimères amphiphiles, à savoir des dendrimères bola-amphiphiliques de type PAMAM ainsi que des dendrimères amphiphiles biodégradables de type poly(aminoester). Leurs propriétés physico-chimiques et l'activité biologique pour la délivrance de siARN ont été étudiées. Nos résultats soulignent qu'elles constituent de nouveaux nanotransporteurs prometteurs pour la délivrance d'acide nucléique, voie dans laquelle nous poursuivons activement nos effortsDendrimers, a special family of synthetic polymers, emerge as appealing nanovectors for drug delivery thanks to their unique precisely-controlled achitecture along with multivalency and cooperativity confined within a nanosized volume. Our group has recently demonstrated that small amphiphilic dendrons could self-assemble into supramolecular dendrimers, which mimick the covalently constructed high generation dendrimers and effectively deliver siRNA therapeutics in vitro and in vivo. In order to further explore novel amphiphilic dendrimers with special self-assembly properties for nucleic acid delivery, in this Ph.D thesis, I have synthesized and characterized two families of amphiphilic dendrimers, namely bola-amphiphilic PAMAM dendrimer and biodegradable amphiphilic poly(aminoester) dendrimer. Their physico-chemical properties and biological activity for siRNA delivery have been investigated. Our results demonstrate that they may constitute, via supramolecular self-assembling, effective and promising nanocarriers for nuclide acid delivery, in which we are actively pursuing our effort
2
Deakin, Peter C. "Optoelectronic dendrimers." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510945.
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Frampton, Michael John. "Electroluminescent dendrimers." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270614.
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Huang, Adela Ya-Ting. "Advancing dendrimer synthesis : solid-phase and self-assembly approach." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0146.
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Les dendrimères sont très prometteurs du fait de leur structure unique et de leur multivalence. Cependant, leur synthèse souffre de problèmes de défauts de structure et de présence de produits secondaires très similaires. Des approches synthétiques alternatives sont donc fortement désirées. L'objectif de ma thèse consiste à explorer la synthèse sur support solide et l’approche d'autoassemblage pour la préparation de dendrimères.La première partie de ma thèse se concentre sur la synthèse de dendrimères en phase solide. Nous avons tout d'abord développé une méthode de synthèse pour les dendrimères poly(amidoamines) basée sur la chimie des peptides. Nous avons ensuite construit une petite bibliothèque de dendrimères de type triazine en faisant varier la taille et la terminaison des dendrimères pour créer une variété de dendrimères. Nous avons aussi tenté de synthétiser des dendrimères poly(aminoesters) bien que nous n'ayons pu les obtenir du fait du caractère labile de ces dendrimères.La deuxième partie de ma thèse vise à appliquer l’approche d'autoassemblage pour la construction de dendrimères supramoléculaires comme théranostiques combinant l'imagerie et la thérapie. Nous avons synthétisé un petit dendrimère amphiphile portant DOTA pour chélater le Gd (III). Ce dendrimère est capable de s'autoassembler en supramolécule et d’encapsuler l’agent anticancéreux doxorubicine, pour construire des agents théranostiques à base de dendrimères multivalents.L’ensemble de ma thèse se consacre au développement de stratégies en phase solide et de l'autoassemblage pour construire des dendrimères pour les applications dans les domaines biomédicaux et des matériauxDendrimers hold great promise for wide applications thanks to their unique structural architecture and multivalent cooperativity. However, dendrimer synthesis often suffers from structural defects caused by incomplete reactions and difficulties associated with purification. Consequently, alternative synthetic approaches to overcome the limitations of current dendrimer synthesis are in high demand.My first PhD project mainly focuses on establishing novel strategies and methodologies for solid-phase dendrimer synthesis with advantages of convenient complete synthesis and easy purification procedures. We first developed a new and concise solid-phase synthesis of PAMAM dendrimers based on the adoption of peptide synthesis chemistry. We then constructed a small library of triazine dendrimers varying in generations and surface groups with a view to rapidly synthesizing dendrimers with structural diversity. We also strived to synthesize poly(aminoester) dendrimers although we had difficult to get it thorough.My second PhD program aims to apply the self-assembly approach for constructing supramolecular dendrimer theranostics. A small DOTA-conjugated amphiphilic dendrimer with Gd(III)-chelation was synthesized and self-assembled into supramolecular nanomicelles to encapsulate the anticancer drug doxorubicin. The obtained system constitutes a multivalent nanotheranostic to combine imaging purpose with therapeutic utility.In summary, my PhD program mainly contributes to elaborating strategies for dendrimer synthesis using both solid-phase method and self-assembly approach in the view to realizing and broadening their applications in the arenas of biomedical and material sciences
5
Wang, Yang. "Novel amphiphilic dendrimers as nanovectors for siRNA delivery." Electronic Thesis or Diss., Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4017.
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Les dendrimères, font partie d'une famille particulière de polymères synthétiques, pouvant être utilisés comme nanovecteurs pour l'administration de médicaments grâce à leur structure polyvalente et leur action coopérative, ces fonctions étant confinées dans un volume de taille nanométrique. Notre groupe a récemment démontré que de petites unités dendritiques amphiphiles pouvaient s'auto-assembler en dendrimères supramoléculaires pouvant délivrer du siARN, avec une efficacité similaire à celle des dendrimères de grande génération construits de manière covalente. Dans cette thèse, ans le but de explorer des nouveaux dendrimères amphiphiles possédant des propriétés particulières d'auto-assemblage pour la délivrance de médicaments, j'ai synthétisé et caractérisé deux familles de dendrimères amphiphiles, à savoir des dendrimères bola-amphiphiliques de type PAMAM ainsi que des dendrimères amphiphiles biodégradables de type poly(aminoester). Leurs propriétés physico-chimiques et l'activité biologique pour la délivrance de siARN ont été étudiées. Nos résultats soulignent qu'elles constituent de nouveaux nanotransporteurs prometteurs pour la délivrance d'acide nucléique, voie dans laquelle nous poursuivons activement nos effortsDendrimers, a special family of synthetic polymers, emerge as appealing nanovectors for drug delivery thanks to their unique precisely-controlled achitecture along with multivalency and cooperativity confined within a nanosized volume. Our group has recently demonstrated that small amphiphilic dendrons could self-assemble into supramolecular dendrimers, which mimick the covalently constructed high generation dendrimers and effectively deliver siRNA therapeutics in vitro and in vivo. In order to further explore novel amphiphilic dendrimers with special self-assembly properties for nucleic acid delivery, in this Ph.D thesis, I have synthesized and characterized two families of amphiphilic dendrimers, namely bola-amphiphilic PAMAM dendrimer and biodegradable amphiphilic poly(aminoester) dendrimer. Their physico-chemical properties and biological activity for siRNA delivery have been investigated. Our results demonstrate that they may constitute, via supramolecular self-assembling, effective and promising nanocarriers for nuclide acid delivery, in which we are actively pursuing our effort
6
Huang, Adela Ya-Ting. "Advancing dendrimer synthesis : solid-phase and self-assembly approach." Electronic Thesis or Diss., Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0146.
Full textAbstract:
Les dendrimères sont très prometteurs du fait de leur structure unique et de leur multivalence. Cependant, leur synthèse souffre de problèmes de défauts de structure et de présence de produits secondaires très similaires. Des approches synthétiques alternatives sont donc fortement désirées. L'objectif de ma thèse consiste à explorer la synthèse sur support solide et l’approche d'autoassemblage pour la préparation de dendrimères.La première partie de ma thèse se concentre sur la synthèse de dendrimères en phase solide. Nous avons tout d'abord développé une méthode de synthèse pour les dendrimères poly(amidoamines) basée sur la chimie des peptides. Nous avons ensuite construit une petite bibliothèque de dendrimères de type triazine en faisant varier la taille et la terminaison des dendrimères pour créer une variété de dendrimères. Nous avons aussi tenté de synthétiser des dendrimères poly(aminoesters) bien que nous n'ayons pu les obtenir du fait du caractère labile de ces dendrimères.La deuxième partie de ma thèse vise à appliquer l’approche d'autoassemblage pour la construction de dendrimères supramoléculaires comme théranostiques combinant l'imagerie et la thérapie. Nous avons synthétisé un petit dendrimère amphiphile portant DOTA pour chélater le Gd (III). Ce dendrimère est capable de s'autoassembler en supramolécule et d’encapsuler l’agent anticancéreux doxorubicine, pour construire des agents théranostiques à base de dendrimères multivalents.L’ensemble de ma thèse se consacre au développement de stratégies en phase solide et de l'autoassemblage pour construire des dendrimères pour les applications dans les domaines biomédicaux et des matériauxDendrimers hold great promise for wide applications thanks to their unique structural architecture and multivalent cooperativity. However, dendrimer synthesis often suffers from structural defects caused by incomplete reactions and difficulties associated with purification. Consequently, alternative synthetic approaches to overcome the limitations of current dendrimer synthesis are in high demand.My first PhD project mainly focuses on establishing novel strategies and methodologies for solid-phase dendrimer synthesis with advantages of convenient complete synthesis and easy purification procedures. We first developed a new and concise solid-phase synthesis of PAMAM dendrimers based on the adoption of peptide synthesis chemistry. We then constructed a small library of triazine dendrimers varying in generations and surface groups with a view to rapidly synthesizing dendrimers with structural diversity. We also strived to synthesize poly(aminoester) dendrimers although we had difficult to get it thorough.My second PhD program aims to apply the self-assembly approach for constructing supramolecular dendrimer theranostics. A small DOTA-conjugated amphiphilic dendrimer with Gd(III)-chelation was synthesized and self-assembled into supramolecular nanomicelles to encapsulate the anticancer drug doxorubicin. The obtained system constitutes a multivalent nanotheranostic to combine imaging purpose with therapeutic utility.In summary, my PhD program mainly contributes to elaborating strategies for dendrimer synthesis using both solid-phase method and self-assembly approach in the view to realizing and broadening their applications in the arenas of biomedical and material sciences
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Liang, Liyuan. "Inorganic Aspects of “Click” Chemistry in Polymers and Dendrimers : synthesis, Nanoparticle Stabilization and Catalysis." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14277/document.
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La thèse concerne les aspects inorganiques de la réaction des alcynes terminaux avec les azotures, la principale des réactions dites ”click”. La catalyse de cette réaction par des dendrimères centrés sur le cuivre (I) nous a permis de mettre en évidence des effets dendritiques originaux. Les assemblages dendritiques et polymériques fonctionnels réalisés à l’aide cette réaction “click”, en particulier avec des carboranes, nous ont conduits à la stabilisation de nanoparticules d’or et de palladium à partirde cations coordonnés aux triazoles “click”. La catalyse très efficace dans aqueux milieu et dans les conditions ambiantes de formation de liaison carbone-carbone a été réalisée à l’aide de très faibles quantités de ces nanoparticulesde palladium stabiliséesThe thesis concerns aspects of inorganic reaction between organic azides and terminal alkynes, the main “click” reactions. Catalysis of this reaction by copper (I)-centered dendrimers allowed us to highlight the dendritic effects originals. The dendritic and polymeric functional assemblies produced using the "click" reaction, especially with carboranes, led us to the stabilization of gold nanoparticles and palladium from cation-coordinated "click" triazole. The highly efficient catalysis in aqueous medium under ambient conditions of formation of carbon-carbon was carried out using very small amounts of stabilized palladium nanoparticles
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Wang, Qi. "Synthesis of multi-functional dendrimers for targeted delivery of nucleic acids." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4068/document.
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Nous avons démontré que structurellement flexibles poly(amidoamine) (PAMAM) dendrimères sont efficaces système de livraison de siRNA in vitro et in vivo récemment. Nous voulons mener une enquête plus approfondie sur la livraison de siRNA ciblés en utilisant des dendrimères conjugués avec des ligands spécifiques ou d'anticorps, qui peuvent reconnaître les récepteurs correspondants ou des protéines exprimées à la surface des cellules. De cette façon, le siRNA peuvent être livrés spécifiquement aux cellules d'intérêt, conduisant à une délivrance ciblée, ce qui peut améliorer l'efficacité livraison et de réduire la toxicité en évitant les interactions non spécifiques et à des doses plus faibles. À cette fin, nous avons développé des dendrimères portant une chaîne PEG long et un dendron individu polyvalent. La chaîne PEG est de libérer l'encombrement stérique entre dendrimère et ligand / anticorps, tandis que le dendron multivalent fournit une plate-forme d'une conjugaison contrôlable de ligands. Par ailleurs, nous avons également conçu et synthétisé une autre dendrimères PEGylées portant un groupe thiol libre pour la préparation des anticorps / dendrimère conjuguésWe have demonstrated that structurally flexible poly(amido)amine (PAMAM) dendrimers are efficient siRNA delivery system in vitro and in vivo recently. We would like to undertake further investigation on targeted siRNA delivery using dendrimers conjugated with specific ligands or antibodies, which can recognize the corresponding receptors or proteins expressed on the cell surface. In this way, siRNA can be delivered specifically to the cells of interest, leading to targeted delivery, which can further improve the delivery efficiency and reduce the toxicity by avoiding non-specific interactions and at lower doses. To this end, we have developed dendrimers bearing a long PEG chain and an individual multivalent dendron. The PEG chain is to release the steric congestion between dendrimer and ligand/antibody, whereas the multivalent dendron provides a platform of a controllable conjugation for ligands. Besides, we also designed and synthesized another PEGylated dendrimers bearing a free thiol group for the preparation of antibody/dendrimer conjugates
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Appelhans, Dietmar, and Brigitte Voit. "Dendrimere als vielseitige, nano-skalige Objekte für biomimetische, biomedizinische und katalytische Fragestellungen." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1188377327860-73166.
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With their three-dimensional macromolecular structure and shape, and with their tuneable properties in both the inner and outer spheres, dendrimers are ideal model compounds in the nanometre range between 1 and 10 nm. The possibility to combine different properties within one macromolecule destines them for use in various high-end research fields such as medicine, pharmacy, biology, supramolecular chemistry, nanotechnology and material sciences. On the basis of their high end-group density and a compact, highly branched molecular structure, dendrimers are successfully investigated as carrier systems for active substances and metal ions (e.g. contrast agents for the visualisation of blood vessels), as templates for metal nanoparticles, as artificial enzymes with defined functions, and as materials for catalysisDendrimere sind aufgrund ihrer dreidimensionalen Makromolekülstruktur und -form und ihrer steuerbaren Eigenschaften sowohl an der Oberfläche als auch im Molekülinneren ideale Modellverbindungen im Nanometerbereich – sie sind zwischen 1 und 10 nm groß –, die vorzugsweise in der Medizin, Pharmazie, Biologie, Supramolekularen Chemie, Nanotechnologie und den Materialwissenschaften eingesetzt werden. Aufgrund ihrer hohen Endgruppendichte und der kompakten, stark verzweigten Molekülform werden Dendrimere unter anderem als Trägermaterialien und Transportsysteme für Wirkstoffe und Metallionen, zum Beispiel als Kontrastmittel zur Visualisierung von Organen und Blutgefäßen, als Template für metallische Nanopartikel, zur Erzeugung künstlicher Enzymfunktionen und in der Katalyse erfolgreich untersucht
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Dirksen, Anouk. "Photoinduced processes in dendrimers." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2003. http://dare.uva.nl/document/87283.
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Cumpstey, Neil. "Highly branched phosphorescent dendrimers." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433310.
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Coleshill, Anita. "Synthesis of polyester dendrimers." Thesis, University of Warwick, 1998. http://wrap.warwick.ac.uk/55728/.
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Dendrimers are a fairly new class of macromolecule. They have many potential uses including use in surface coatings and as host molecules. There are two main methods available for constructing dendrimers, the convergent approach and the divergent approach. In this thesis dendrimers were synthesised using the divergent approach. In chapter one our original aim was to synthesise dendrimers based on bicine, but there were complications involved in synthesis and storage of the monomer. However, it was possible to make a iminium salt using bicine as the starting material, which was reacted with various nucleophiles. With 2,2-bishydroxymethylpropionic acid it was possible to produce a generation one protected dendrimer, but deprotection could not be achieved. In the third chapter the syntheses of dendrimers based on 4,4-bis(4- hydroxyphenyl)valeric acid are described. Dendrimers were successfully synthesised up to and including generation two. These were made using various esterification methods. Chapter four describes the synthesis of functionalised dendrimers. Generation one deprotected dendrimers were reacted with a variety of reagents to produce pent-4-enoyl, urethane and lineoyl functionalised dendrimers. Chapter five describes the analysis of dendrimers using MALDI-MS. For every dendrimer synthesis molecular weights were obtained well within the boundaries of experimental error. It was also shown how preparation time and laser power can affect the spectra obtained.
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Drew, Philip Morton. "Computer simulation of dendrimers." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418245.
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Ortiz-Hernández, Wilfredo. "Energy transfer in dendrimers." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0009300.
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Jung, Jiyoung. "Preparation of flat dendrimers and polycyclic aromatic hydrocarbons connected via 1,3,5-triethynylbenzene core." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9768/.
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Flat dendrimers, consisting of a hexavalent aromatic core and rigid ethynyl units locked in place by ether connections were developed based upon the divergent synthetic method. Alternating functional groups were adopted on each site of the hexa-substituted benzene, in order to avoid undesired cyclization pathways. The flat structures of conjugated dendrimers would allow investigation on the discotic liquid crystal properties. In addition, these ethylnyl dendrimers are expected to show directed energy and electron transfer with a highly conjugated system, and thus are effective in the preparation of photoreactive materials such as electronic sensors or light harvesting materials. Conjugated polycyclic aromatic hydrocarbons, consisting of naphthalene, anthracene, pyrene, and phenanthrene groups connected via 1,3,5-triethynylbenzene cores, were synthesized. These molecules exhibited luminescence properties and the π-complexation with a mercury trifunctional lewis acid are expected to enhance the phosphorescence in the presence of the heavy metal due to the spin-orbit coupling. Besides, owing to the presence of heavy metal atom in the Au (I) complexes linked by s-bonded triethynyltriphenylene luminophore, the phosphorescence occurs from a metal-centered emission. The conjugated organic luminophores have been developed to produce excellent quantum efficiencies, brightness, and long lifetimes.
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Berezhnaia, Veronika. "Synthesis and characterization of helicenes, dendrimers and molecular asterisks." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0341.
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Projet de thèse consiste de plusieurs parties:-synthèse de nanographène chirale, caractérisation de ses propriétés photo-physiques (publication en JACS acceptée);-synthèse des astérisques moléculaires, qui combinent les propriétés luminescences du noyau benzène persulfuré et des solubilité aqueuse et biocompatibilité des dendrons avec des branches de PEG; une application de ces dendrons pour couvrir les nanoparticules de silice ;-synthèse des astérisques moléculaires avec noyau de benzène persulfuré et branches des heterocycles, pour explorer leurs auto-assemblage et propriétés chelatantes vers métauxThe synthesis of molecular asterisks as "smart sensors" with a persulfurated benzene core and various ligands was explored. Asterisks with heteroaromatic ligands were synthesized for exploring their metal ions complexing ability. PEG dendrons were tested for increasing the water solubility of the asterisks, and to verify if PEG asterisks could encapsulate some hydrophobic molecules. The PEG dendrons were synthesized for making smart asterisks sensors, and for another purpose: the coating of silica nanoparticles to prevent their fast degradation in water. Unfortunately, this protection from degradation was ineffective, but we could make PEG asterisks to encapsulate molecules (Nile Red) toward new drug nanocarriers.The synthesis of chiral nanographenes embedding [5]- or [7]helicenes is reported. Usually [5]helicenes are configurationally labile, while higher helicene homologs are stable. We synthesized a stable chiral nanographene with six embedded [5]helicene units (a [5]helicene trimer). We found a strong distortion of benzene rings, especially in the triphenylene core. The enantiomers were separated and the chiroptical properties were measured.The synthesis of [7]helicene trimer was also performed with a great enantio- and diastereoselectivity. When a Ni(0)- mediated cyclotrimerization is achieved with an enantiopure [7]helicene substrate, only one enantiomer of the trimer is obtained, while keeping intact the configuration of the substrate. On a racemic substrate, three diastereomers were obtained. One of them demonstrated the highest values of a benzene ring distortion reported to date (mean puckering angle and twisting angle)
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Qiu, Jieru. "Dendrons phosphorés fluorescents amphiphiles : synthèse, caractérisation, applications en oncologie." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30274.
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Les nanotechnologies ont le grand potentiel de révolutionner des technologies classiques variées, dû au développement de nombreux nanodispositifs et ont été intensément étudiées durant la dernière décade. Parmi les nanoparticules utilisées, les dendrimères et dendrons appartiennent à ce "nano-monde" en vertu de leur taille nanométrique, qui peut être modifiée à volonté, ainsi que par exemple leur multivalence et leurs charges. A l'intérieur de l'espace dendrimère, les dendrimères phosphorés apparaissent comme étant parmi les systèmes dendritiques les plus utiles, grâce à l'extraordinaire réactivité et adaptabilité de la chimie du phosphore. Dans ce mémoire nous décrivons la synthèse de plusieurs familles de dendrons phosphorés fluorescent amphiphiles potentiellement intéressants dans les domaines des nanomatériaux et de la nanomédecine. L'hexachlorocyclotriphosphazene utilisé comme cœur a été substitué par cinq groupements hydroxybenzaldehyde et un monomère tel que le pyrene ou un dérivé maleimide comme entité fluorescente ou l'azabisdimethylphosphonate comme groupement non fluorescent. Ces dendrons ont été préparés jusqu'à la génération 2 selon une voie divergente. La dernière étape a consisté en un greffage d'aminopyrrolidine ou aminopipéridine, suivi par protonation par HCl des groupements amines cycliques terminaux conduisant à la formation de dendrons phosphorés amphiphiles. La caractérisation physico-chimique a été réalisée par tout un ensemble de techniques : RMN, UV, CMC, diffusion dynamique de la lumière, potentiel zéta, microscopie électronique à transmission, fluorescence, dichroïsme circulaire, thermogravimétrie. L'étape suivante a consisté en l'étude des propriétés biologiques. Leur cytotoxicité a été déterminée en utilisant des tests MTT et Alamar Blue, effectués sur onze lignées cancéreuses ou saines (HL-60, HCT-116, A549, MCF7, PC3, U87, K562, K562R, MCR5, MDA-MB231 and HT-29). Des tests d'hémolyse ont été effectués pour tester l'effet des dendrons sur la membrane des cellules. Leur habilité à s'associer à du matériel génétique tels que les petits ARN interférents (siRNA siBCL-xL) a été mise en évidence par des expériences notamment d'électrophorèse sur gel. L'internalisation de ces associations (dendriplexes) dans les cellules tumorales a été suivie par cytométrie en flux. Dans le but de moduler les propriétés anticancéreuses des dendrons fluorescents amphiphiles, des quantum dots de carbone (CQDs) ont été associés avec les dendrons pyrene en présence d'un agent cytotoxique comme la doxorubicine encapsulée dans les micelles formées par les dendron pyrene et les CQDs. [...]Nanotechnologies have the high potential to revolutionize various other classical technologies in many fields, due to the development of numerous nanodevice types, and have been intensively studied over the last decade. Among these nanoparticles, dendrimers and dendrons pertain to the "nano-world" by virtue of their size. Their nanometric sizes can be tailored as well, for instance, their multivalency and charges. Within the dendrimer space, phosphorus dendrimers and dendrons appear to be among the most useful dendritic systems due to the extraordinary reactivity and versatility of the phosphorus chemistry. In this thesis, we designed several families of original amphiphilic fluorescent phosphorus dendrons with interesting potential in the fields of nanomaterials and nanomedicine. Hexachlorocyclotriphosphazene used as a core was linked with five 4-hydroxybenzaldehyde and one monomer (pyrene and maleimide derivatives as fluorescent monomers and azabisdimethylphosphonate derivatives as non-fluorescent monomer). The dendrons were prepared up to generation 2 by a divergent method. The last step is the grafting of amino pyrrolidine or amino piperidine following by protonation with HCl to get the expected cationic amphiphilic fluorescent phosphorus dendrons. Their physical characterization were evaluated through numerous technics: NMR, UV, critical micelle concentration (CMC), dynamic light scattering (DLS), zeta potential, transmission electron microscopy (TEM), fluorescent spectra, circular dichroism and thermogravimetry. In a next step, the biological properties of the dendrons have been examined. The cytotoxicity of dendrons was determined using MTT test and Alamar Blue assay performed on eleven cells lines including both cancer cells and healthy cells (HL-60, HCT-116, A549, MCF7, PC3, U87, K562, K562R, MCR5, MDA-MB231 and HT-29 cells line). Hemolysis assays were used to test the effect of dendrons on the cell membrane. Their ability to bind genetic material was studied by gel electrophoresis using fluorescein-labeled small interference RNA siBCL-xL. Flow cytometry method was used to study the internalization of dendriplexes into tumor cells. In order to modulate the anticancer properties of the fluorescent dendrons, carbon quantum dots (CQDs) were chosen to conjugate with the pyrene dendrons in the presence of a cytotoxic agent like doxorubicin (DOX), physically loaded into 'micelles'. [...]
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Preston, Adam J. "Structural and functional relationships in dendrimers Part 1: synthesis and study of liquid crystalline dendrimers as additives to dental composites. Part 2: effect of selective metal coordination on dendrimer structure /." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1104355003.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xxvi, 533 p.; also includes graphics (some col.) Includes bibliographical references (p. 259-292).
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Javor, Sacha. "Peptide dendrimers as enzyme mimics /." [S.l.] : [s.n.], 2008. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000277027.
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Hemingway, Leon Robert. "Dendrimers for light emitting diodes." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325840.
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Muhanna, Muhanna Kamal. "Approaches to functionalised pamam dendrimers." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286768.
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Leire, Eva Emma Maria. "Multifunctional dendrimers for antibacterial applications." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/36191/.
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In this thesis gallic acid-triethylene glycol (GATG) dendrimers were synthesised and efficiently functionalized with hydroxyl groups, phenylboronic acids and primary amines. The interactions of the dendrimers with bacteria and the potential for development of new antimicrobials were evaluated in this study. Specifically, the ability of the dendrimers to induce bacterial clustering and interfere with small molecule autoinducer-2 (AI-2) in the Quorum Sensing (QS) pathway of the marine bacteria V. harveyi was studied with the use of Coulter Counter aggregation assays and detection of QS–controlled luminescence. Novel alkynylated ligands with diol-, tetraol-, glucose- and mannose- moieties were synthesised and successfully functionalized to GATG dendrimers of generation G1 and G3 through catalyst-free azide-alkyne cycloaddition (AAC). The results of luminescence experiments reveled that the dendrimers functionalized with hydroxyl groups decreased AI-2 induced luminescence of V. harveyi MM32 at the at early time points (4 h) while a dose-dependent increase of luminescence and increased bacterial growth was observed at later time points. GATG dendrimers of generation G1 and G3 were decorated with 9 and 81 phenylboronic acid in the periphery. These dendrimers had an inhibitory effect on growth and luminescence as observed by luminescence, aggregation and colony forming unit-counting assays. Although the mechanism is not yet fully understood, these promising results should be further explored. Cationic GATG dendrimers of generation G1, G2 and G3 with 9, 27 and 81 primary amines in the periphery induced formation of clusters in V. harveyi in a generation dependent manner, an improved ability to induce cluster formation when compared with poly(N-[2- (dimethylamino)propyl]methacrylamide), a cationic linear polymer previously shown to cluster bacteria. Viability of the bacteria within the formed clusters and the evaluation of the QS controlled luminescence suggests that the GATG dendrimers may be activating microbial responses by maintaining a high concentration of QS signals inside the clusters while increasing permeability of the microbial outer membrane. Thus, a generation-dependent effect in bacterial luminescence production and membrane permeability was induced by the cationic dendrimers. The inhibition of growth and increased membrane permeability in combination with cell clustering may be promising antibacterial features of these dendrimers. These results highlight the potential of the GATG dendritic platform to develop new antimicrobials aimed to target microbial viability and/or virulence (e.g. adhesion) and encourage further investigations on the importance of polymeric architecture and multivalency in the antimicrobial field.
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Chen, Chao. "Amphiphilic dendrimers for siRNA delivery." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4738.
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Le défi majeur de la thérapie génique à base de siARN est sa délivrance sûre et efficace. Récemment, notre groupe a mis au point des dendrimères amphiphiles comme vecteurs robustes et efficaces de délivrance non-virale de siARN, qui combinent les avantages de délivrance des vecteurs lipidiques et polymèriques. J’ai effectué au cours de ma thèse de doctorat une analyse de la relation structure/activité (SAR) d'une série de dendrimères comportant des queues hydrophobes de différentes longueurs. Nos résultats démontrent qu’un équilibre optimal entre la longueur de la chaîne alkyle hydrophobe et la partie hydrophile dendritique joue un rôle crucial sur leur capacité d’auto-assemblage, ainsi que sur leur activité de transport des siRNA. En outre, en combinant bola-amphiphiles et nos dendrimères amphiphiles, nous avons développé un nouveau dendrimère bola-amphiphile dont nous avons étudié les propriétés d’auto-assemblage et l'efficacité de transport du siARN correspondant. Ce dendrimère bola-amphiphile particulier a été en mesure de réagir à des espèces réactives de l'oxygène pour la délivrance spécifique, ouvrant ainsi de nouvelles perspectives pour la conception de vecteurs stimuli-déclencheurs pour siARN ciblés. Enfin, nous avons étudié l’«effet d'éponge à protons» des vecteurs dendritiques amphiphiles à l'aide de la technique du film Langmuir en monocouche. Nos résultats ont prouvé le gonflement des vecteurs dendritiques amphiphiles par protonation, offrant ainsi des données expérimentales permettant de soutenir sans ambiguïté l’hypothèse de l'«effet d'éponge à protons»A key challenge in RNAi-based gene therapy is the safe and effective siRNA delivery. Recently, our group has established amphiphilic dendrimers as robust and effective nonviral delivery vectors for siRNA, which combine the beneficial delivery features of both lipid and dendritic polymer vectors while overcoming their shortcomings.With the desire to understand the underlying mechanism of amphiphilic dendrimers for efficient delivery, I performed a structure/activity relationship (SAR) analysis of a series of dendrimers featuring hydrophobic tails of different lengths during my PhD thesis. We systematically investigated these dendrimers for their self-assembling characters and their capacities for both binding and delivery of siRNA. Our results demonstrate that an optimal balance between the hydrophobic alkyl chain length and the hydrophilic dendritic portion plays a crucial role in the self-assembly and the delivery activity towards siRNA.Furthermore, we developed a novel bola-amphiphilic dendrimer by combining bola-amphiphiles and our amphiphilic dendrimers and studied their self-assembly properties and the corresponding siRNA delivery efficiency. This peculiar bola-amphiphilic vector was able to respond to reactive oxygen species for specific delivery, opening a new perspective for the design of stimuli-trigged vectors for targeted siRNA delivery.Finally, I studied the “proton sponge effect” of the amphiphilic dendrimer vectors using the Langmuir monolayer film technique. Our results gave direct evidence of swelling of the amphiphilic dendrimers upon protonation, offering unambiguous experimental data to support the “proton sponge effect”
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Chen, Chao. "Amphiphilic dendrimers for siRNA delivery." Electronic Thesis or Diss., Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4738.
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Le défi majeur de la thérapie génique à base de siARN est sa délivrance sûre et efficace. Récemment, notre groupe a mis au point des dendrimères amphiphiles comme vecteurs robustes et efficaces de délivrance non-virale de siARN, qui combinent les avantages de délivrance des vecteurs lipidiques et polymèriques. J’ai effectué au cours de ma thèse de doctorat une analyse de la relation structure/activité (SAR) d'une série de dendrimères comportant des queues hydrophobes de différentes longueurs. Nos résultats démontrent qu’un équilibre optimal entre la longueur de la chaîne alkyle hydrophobe et la partie hydrophile dendritique joue un rôle crucial sur leur capacité d’auto-assemblage, ainsi que sur leur activité de transport des siRNA. En outre, en combinant bola-amphiphiles et nos dendrimères amphiphiles, nous avons développé un nouveau dendrimère bola-amphiphile dont nous avons étudié les propriétés d’auto-assemblage et l'efficacité de transport du siARN correspondant. Ce dendrimère bola-amphiphile particulier a été en mesure de réagir à des espèces réactives de l'oxygène pour la délivrance spécifique, ouvrant ainsi de nouvelles perspectives pour la conception de vecteurs stimuli-déclencheurs pour siARN ciblés. Enfin, nous avons étudié l’«effet d'éponge à protons» des vecteurs dendritiques amphiphiles à l'aide de la technique du film Langmuir en monocouche. Nos résultats ont prouvé le gonflement des vecteurs dendritiques amphiphiles par protonation, offrant ainsi des données expérimentales permettant de soutenir sans ambiguïté l’hypothèse de l'«effet d'éponge à protons»A key challenge in RNAi-based gene therapy is the safe and effective siRNA delivery. Recently, our group has established amphiphilic dendrimers as robust and effective nonviral delivery vectors for siRNA, which combine the beneficial delivery features of both lipid and dendritic polymer vectors while overcoming their shortcomings.With the desire to understand the underlying mechanism of amphiphilic dendrimers for efficient delivery, I performed a structure/activity relationship (SAR) analysis of a series of dendrimers featuring hydrophobic tails of different lengths during my PhD thesis. We systematically investigated these dendrimers for their self-assembling characters and their capacities for both binding and delivery of siRNA. Our results demonstrate that an optimal balance between the hydrophobic alkyl chain length and the hydrophilic dendritic portion plays a crucial role in the self-assembly and the delivery activity towards siRNA.Furthermore, we developed a novel bola-amphiphilic dendrimer by combining bola-amphiphiles and our amphiphilic dendrimers and studied their self-assembly properties and the corresponding siRNA delivery efficiency. This peculiar bola-amphiphilic vector was able to respond to reactive oxygen species for specific delivery, opening a new perspective for the design of stimuli-trigged vectors for targeted siRNA delivery.Finally, I studied the “proton sponge effect” of the amphiphilic dendrimer vectors using the Langmuir monolayer film technique. Our results gave direct evidence of swelling of the amphiphilic dendrimers upon protonation, offering unambiguous experimental data to support the “proton sponge effect”
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PRINCIVAL, Iza Mirela Rodini Garcia. "Síntese de Derivado de Furano ligados em Dendrímero bis-MPA e sua atividade anticâncer." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/17327.
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FACEPE
Descrevemos aqui, um estudo citotóxico comparativo utilizando uma biblioteca de compostos contendo a função furano, e o dendrímero Bis-MPA. Dos compostos furânicos testados, os que apresentaram melhor resultado citotóxico frente às células tumorais foram sintetizados em grande escala (5 g). Assim, estes compostos, puderam ser submetidos à estudos de incorporação física (por interações químicas) ou ligação química (via ligação covalente) ao dendrímero. No intuito de estudar os efeitos citotóxicos que ambos os sistemas poderiam apresentar, os testes foram realizados empregando as seguintes linhagens celulares HEP-2, HT-29, MCF-7, NCI-H292 e HL-60, correspondentes ao câncer de Carcinoma de laringe, Carcinoma de Cólon, Adenocarcinoma de Mama e Leucemia promielocítica aguda. Cada teste foi realizado em quadruplicata, utilizando os compostos com alto grau de pureza (>99%), e de um mesmo lote do material, para todos os testes de toxicidade. Os testes de citotoxicidade r com o dendrímero bis-MPA, foram realizados utilizando o composto comercial, porém com checagem de pureza via RMN antes de realizar os testes e as reações químicas. Todos os testes biológicos após serem realizados, foram analisados utilizando o método colorimétrico MTT. Em suma, este estudo levou ao preparo de compostos em escala de gramas, com alto grau de pureza, necessário para estudar a possibilidade de desenvolver novos ligantes bifuncionais, na tentativa de se construir dendrímeros polifuncionalizados, contendo moléculas que apresentaram atividade citotóxica em sua estrutura química. Esse estudo vem sendo explorado pelo grupo na tentativa de expandir essa linha de raciocínio, e tentar corroborar com estudos da literatura no que diz respeito ao mecanismo de ação, e como esses se comportam frente a células tumorais, em testes in vitro. Dentre os compostos que apresentaram boas respostas aos ensaios biológicos, dois deles merecem destaque por mostrarem-se substâncias extremamente eficazes em testes de inibição total das células. Estes compostos têm em comum um anel furano ligado diretamente a uma enona ou a um ácido acrílico (compostos 32 e 35 respectivamente).
Here we describe a comparative cytotoxic study by using a library of compounds containing a furan moiety and the dendrimer Bis-MPA. Among furan tested compounds against tumor cancer cells, those that have shown better results were synthesized in a large scale reaction (5 g). Thus, these compounds, which have shown high biological activity, underwent physical incorporation studies (for chemical interactions) or chemically linked (via covalent bond) with the dendrimer. In order to study the cytotoxic effects that could exhibit by both systems, tests were conducted using the following tumor cancer cells: HEp-2, HT-29, MCF-7 e HL60. Each test was performed in quadruplicate using the compounds in their high purity (>99%) and used as a single batch of material for all toxicity tests. The dendrimer Bis-MPA cytotoxic tests were conducted subjecting the commercial reagent although with a pre checked in its purity by NMR before do the tests and chemical reactions. All biological tests after have been done were analyzed using the MTT colorimetric method. In summary, this study has led to preparation of compounds in multi gram scale in a high purity, necessary to realize the possibility of developing new bifunctional links, in an attempt to build polifuncionalized dendrimers containing active cytotoxic active molecules in their chemical structure. This study is being explored by the group in an attempt to expand this line of reasoning, and try to corroborate with literature data regarding the mechanism of action, and their behavior against the tumor cancer cells in an in vitro tests. Among the compounds that showed good activity to biological assays, two of them are noteworthy due to their extremely effective activity in total inhibition tests of cells. These compounds have in common a furan ring attached to an enone or an acrylic acid (compounds 32 and 35 respectively).
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Wang, Qi. "Synthesis of multi-functional dendrimers for targeted delivery of nucleic acids." Electronic Thesis or Diss., Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4068.
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Nous avons démontré que structurellement flexibles poly(amidoamine) (PAMAM) dendrimères sont efficaces système de livraison de siRNA in vitro et in vivo récemment. Nous voulons mener une enquête plus approfondie sur la livraison de siRNA ciblés en utilisant des dendrimères conjugués avec des ligands spécifiques ou d'anticorps, qui peuvent reconnaître les récepteurs correspondants ou des protéines exprimées à la surface des cellules. De cette façon, le siRNA peuvent être livrés spécifiquement aux cellules d'intérêt, conduisant à une délivrance ciblée, ce qui peut améliorer l'efficacité livraison et de réduire la toxicité en évitant les interactions non spécifiques et à des doses plus faibles. À cette fin, nous avons développé des dendrimères portant une chaîne PEG long et un dendron individu polyvalent. La chaîne PEG est de libérer l'encombrement stérique entre dendrimère et ligand / anticorps, tandis que le dendron multivalent fournit une plate-forme d'une conjugaison contrôlable de ligands. Par ailleurs, nous avons également conçu et synthétisé une autre dendrimères PEGylées portant un groupe thiol libre pour la préparation des anticorps / dendrimère conjuguésWe have demonstrated that structurally flexible poly(amido)amine (PAMAM) dendrimers are efficient siRNA delivery system in vitro and in vivo recently. We would like to undertake further investigation on targeted siRNA delivery using dendrimers conjugated with specific ligands or antibodies, which can recognize the corresponding receptors or proteins expressed on the cell surface. In this way, siRNA can be delivered specifically to the cells of interest, leading to targeted delivery, which can further improve the delivery efficiency and reduce the toxicity by avoiding non-specific interactions and at lower doses. To this end, we have developed dendrimers bearing a long PEG chain and an individual multivalent dendron. The PEG chain is to release the steric congestion between dendrimer and ligand/antibody, whereas the multivalent dendron provides a platform of a controllable conjugation for ligands. Besides, we also designed and synthesized another PEGylated dendrimers bearing a free thiol group for the preparation of antibody/dendrimer conjugates
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Kevwitch, Robert M. "Strategies for degradable dendrimers: Fragmenting o-nitrobenzyl ether dendrimers and disassembling oligomers of model dendritic systems." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280481.
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Two dendrimer cores that contain o-nitrobenzyl photolabile moieties have been synthesized from piperonal. Methylated core analogs undergo clean photocleavage as indicated by the evolution of isosbestic points in the UV spectra during photolysis and the observation of degradation products by ¹H NMR. These dendrimer cores serve as precursors to dendrimer-based photodegradable materials. Second generation benzyl aryl ether dendrimers have been synthesized and undergo clean photocleavage as indicated by the evolution of isosbestic points in the UV spectra during photolysis and the observation of degradation products by ¹H NMR. Two oligomeric models of disassembling dendrimers have been synthesized from vanillin and o-vanillin. The first system tests the para cleavage vector while the latter test cleavage through the ortho vector of dendrimer disassembly. These systems are used to test potential trigger groups prior to dendrimer synthesis due to their ease of synthesis. Each system shows clean cleavage when triggered by an allyloxy or o-nitrobenzyloxy trigger group as indicated by the evolution of isosbestic points in the UV spectra during disassembly and the observation of disassembly products by ¹H NMR. Dendrimers with a 2,4-branching motif have been synthesized. These dendritic systems have been triggered with and allyloxy group and undergo disassembly via both the ortho and para cleavage vectors simultaneously. Cleavage was noted by the evolution of an isosbestic point in the UV spectra during disassembly.
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Menot, Bérengère. "Dendrimères dérivés du glycérol : Synthèses et Applications." Thesis, Reims, 2015. http://www.theses.fr/2015REIMS044.
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Depuis plusieurs années, notre équipe de recherche s'intéresse au développement de nouvelles familles de dendrimères utilisant des dérivés bio sourcés (pentoses, glycérol ou dérivés correspondants) dont la valorisation est un sujet de recherche d'intérêt de notre région. Ainsi, certains glyco- ou glycérodendrimères dérivés de PPIs (polypropylène imines) ont déjà été obtenus et valorisés dans plusieurs domaines. Cette thèse présente la synthèse et la caractérisation de nouveaux dendrimères dérivés du glycérol. Leur efficacité dans des processus catalytiques et d'encapsulation de molécules d'intérêt a également été démontrée.Dans un premier temps, deux nouvelles familles de dendrimères directement constitués de glycérol en tant que brique élémentaire ont été synthétisées : l'une via des réactions de « click chemistry » pour obtenir des glycéroclickdendrimères, et l'autre via des réactions successives d'allylation et d'oxydation pour obtenir des glycéroladendrimères.Dans un second temps, la fonctionnalisation de dendrimères PAMAMs par du carbonate de glycérol a été effectuée par synthèse « classique » ou assistée par micro-ondes. L'efficacité de ces glycérodendrimères ainsi obtenus (en comparaison avec des glycérodendrimères dérivés de PPIs) a été évaluée : tout d'abord, pour la stabilisation de nanoparticules de platine utilisées en catalyse d'hydrogénation de cétones α,β-insaturées en milieu aqueux, puis, pour l'encapsulation de molécules organiques d'intérêt. Pour finir, une première approche de dynamique moléculaire a été réalisée afin de déterminer les propriétés structurales de deux glycérodendrimères issus de la réaction de couplage entre le carbonate de glycérol et un PAMAM ou un PPISince a few years, our team is interested in developing dendrimers using different biosourced derivatives (pentoses, glycerol or derivatives) whose valuation is a prime research topic within our region. Some glyco- or glycerodendrimers derivate from PPIs (polypropylenimines) were already obtained and valued in several domains. This thesis presents the synthesis and the characterization of new glycerol-based dendrimers. Their efficiency in catalytic processes or for the encapsulation of molecules of interest was also demonstrated. First, two new families of dendrimers directly constituted of glycerol as building block, were synthesized: one via click chemistry reactions to obtain glyceroclickdendrimers, and the other, via successive reactions of allylation and oxidation to obtain glyceroladendrimers. Secondly, the functionalization of PAMAM's dendrimers with glycerol carbonate was carried out either by “classical” or microwave assisted synthesis. The efficiency of these glycerodendrimers (in comparison with PPI-based glycerodendrimers) was evaluated: firstly, for the stabilization of platinum nanoparticles used for the catalysis of hydrogenation of α,β-unsaturated ketones in aqueous media, and then, for the encapsulation of organic molecules of interest. Finally, a first molecular dynamics approach was realized to determine the structural properties of two glycerodendrimers from the coupling reaction between the glycerol carbonate and PAMAM or PPI
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Bos�ko, Jaroslaw Tomasz, and jbosko@unimelb edu au. "Molecular simulation of dendrimers under shear." Swinburne University of Technology. Centre for Molecular Simulation, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20050804.141034.
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In this work flow properties of dendrimers are studied with the aid of molecular simulations. For the first time the results of the nonequilibrium molecular dynamics simulations of the dendrimers in the melt are reported. Molecules are modelled at the coarse-grained level using the bead-spring model. The objective of this research is to analyse the influence of the molecular topology in the macroscopic flow behaviour of the melts. Systems of dendrimers of generations 1 to 4 undergoing planar shear are compared to the melts composed of linear chain polymers. The internal structure and shape of dendrimers is extensively analysed. The response of the molecules to the shearing in the form of stretching and alignment is studied. The correlation between the onset of shear thinning and the onset of deformation of molecules is observed. The changes in the fractal dimensionality of dendrimers due to shearing are also analysed. Dendrimers, due to their highly branched structure and compact globular conformations in the melt, are found to behave differently when sheared, compared to traditional linear polymers. Unlike linear polymers, they do not undergo transition form the Rouse to the reptation regimes. This effect is explained in terms of the suppressed entanglement between molecules. Moreover, dendrimers when compared to linear chain systems exhibit lower Newtonian viscosity, onset of the shear thinning at higher strain rates, and less pronounced shear thinning in the non-Newtonian regime. They can be used as rheology modifiers, as it is shown in the preliminary results obtained from the simulations of the dendrimers-linear polymer blends. In agreement with other theoretical and experimental studies, dendrimers in the melt are found to have compact space-filling structure with terminal groups distributed throughout the interior of the molecule. Suggestions for the further study of dendrimers via molecular simulations are made.
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Nijhuis, Christian Albertus. "Redox-active dendrimers at molecular printboards." Enschede : University of Twente [Host], 2006. http://doc.utwente.nl/57611.
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Groot, Debby de. "Dendrimers as homogeneous transition metal catalysts." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2001. http://dare.uva.nl/document/58731.
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Suek, Nicholas William. "Molecular dynamics simulations of amphiphilic dendrimers." [Ames, Iowa : Iowa State University], 2008.
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Peori, M. Brad (Michael Brad). "New synthetic routes to organometallic dendrimers." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33819.
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The incorporation of organometallic motifs into dendrimers offers significant potential in building macromolecular species with desired properties for heterogenizing homogeneous catalysis. To this end, poly-phosphorus monomers O=P[O(CH 2)3PPh2]3, P[O(CH2) nPPh2]3, PhP[O(CH2)nPPh 2]2 (where n = 3, 10) were prepared, and their complexation chemistry with [mup-Cl)(1,5-C8H12)Rh]2 was examined. It led a new route to contruct multimetallic compounds, in which the evolving structure is controlled by the phosphorus units yielding either typical spherical or non-spherical macromolecules. Selected polymetallic complexes formed using these poly-phosphorus ligands were found to be active catalysts for olefin hydrogenation. A novel divergent synthetic route to starburst dendritic structures was also developed by preparing monomers such as Si[O(CH2 )nPPh2]4, MeSi[O(CH2) nPPh2]3 (where n = 3, 10, 16), and Me2Si[O(CH 2)nPPh2]2 (where n = 3, 10). They were then linked with transition metals to produce starburst organometallic dendrimers Si[O(CH 2)nPPh2Ni(CO)2PPh3] 4, MeSi[O(CH2)nPPh2Ni(CO)2PPh 3]3 (where n = 3, 10, 16), Me2Si[O(CH2) nPPh2Ni(CO)2PPh3]2 (where n = 3, 10) and Si[O(CH2)nPPh2RhCl(1,5-COD)] 4, MeSi[O(CH2)nPPh2RhCl(1,5-COD)] 3 (where n = 3, 10, 16) Me2Si[O(CH2)nPPh 2RhCl(1,5-COD]2 (where n = 3, 10).
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Barata, Teresa Silva. "Structural studies on glycosylated polyamidoamine dendrimers." Thesis, University of London, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535500.
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King, Amy Sarah Helen. "Synthetic studies toward novel crystalline dendrimers." Thesis, University of East Anglia, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327493.
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Urdang, Zachary D. "Towards Quinone Methids Releasing Disassembling Dendrimers." Thesis, The University of Arizona, 2010. http://hdl.handle.net/10150/146912.
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Chen, Jiaxuan. "Amphiphilic dendrimers for nucleic acid delivery." Electronic Thesis or Diss., Aix-Marseille, 2021. http://theses.univ-amu.fr.lama.univ-amu.fr/210310_CHEN_287zgujq865yybu380ckoiv981e_TH%20(1).pdf.
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La thérapie génique utilisant les acides nucléiques représente un des progrès les plus récents de la révolution biotechnologique en médecine en pouvant traiter presque toutes les maladies à sa racine. Cependant, les acides nucléiques sont sensibles à la dégradation enzymatique et leurs charges négatives sont un obstacle majeur pour l'absorption cellulaire. Dans ce contexte, les dendrimères amphiphiles émergent comme des vecteurs non viraux attrayants pour le transport d'acide nucléique car ils sont capables de bénéficier des avantages des vecteurs lipidiques et polymères. Dans ma thèse de doctorat, j'ai pu concevoir, synthétiser et caractériser une série de dendrimères amphiphiles pour la délivrance d'acide nucléique. Ces dendrimères amphiphiles portent soit des chaînes alkyle hydrophobes avec une insaturation variable, soit une chaîne bola-lipide avec un groupe thioacétal sensible aux espèces réactives de l'oxygène (ROS), soit des dendrons PAMAM hydrophiles avec différentes générations et terminaisons cationiques, y compris les fonctionnalités amine tertiaire, arginine et guanidine. J'ai ainsi pu établir des synthèses fiables et reproductibles de ces dendrimères. Des études préliminaires sur ces dendrimères ont révélé qu’avec des terminaisons arginine et guanidine ils montraient une meilleure efficacité pour le transport d'acide nucléique. En outre, les dendrimères bola-amphiphiles de différentes générations avaient des performances différentes pour la délivrance d'ADN et d'ARNsi. En conclusion, ces dendrimères amphiphiles sont des vecteurs non-viraux prometteurs pour la thérapie géniqueGene therapy via nucleic acid therapeutics represents the most recent advance made during the biotechnology revolution in medicine. While allowing the treatment of almost any disease with known gene sequence at its root, nucleic acid therapeutics are vulnerable to enzymatic degradation and their negative charge also presents a major obstacle for cellular uptake. Amphiphilic dendrimers are emerging as appealing non-viral vectors for nucleic acid delivery thanks to their ability to offer delivery advantages of both lipid and polymer vectors. In my PhD thesis, I designed, synthesized and characterized a series of amphiphilic dendrimers for nucleic acid delivery. These amphiphilic dendrimers bear either hydrophobic alkyl chains with varying levels of unsaturation or bola-lipid core with thioacetal group responsive to the reactive oxygen species (ROS), alongside hydrophilic PAMAM dendrons the generation number and cationic terminals (tertiary amine, arginine and guanidine functionalities) of which vary between amphiphilic dendrimers. I established a robust and reproducible synthesis for these dendrimers. Preliminary studies on the use of these dendrimers for nucleic acid delivery revealed that those with arginine and guanidine terminals showed better delivery efficiency compared to those bearing primary amine terminals. Also, performance of bola-amphiphilic dendrimers in DNA and siRNA delivery was generation-dependent. Collectively, the results provide both a proof-of-principle of the use of amphiphilic dendrimers as vectors for nucleic acid delivery, and a means to understanding the structure-activity relationship involved
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Gobouri, Adil Abdullah H. "Synthesis and characterization of novel BINOL-based symmetrical and asymmetrical axially chiral dendrimers." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/synthesis-and-characterization-of-novel-binolbased-symmetrical-and-asymmetrical-axially-chiral-dendrimers(27e9cb60-7ef9-4178-9ed1-44fcfd216a65).html.
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Synthesis of optically active dendrimers based on 1,1'-bi-2-naphthol enantiomers and their derivatives as core units is growing rapidly due to the unique behavior and properties of the new compounds and their various valuable applications in several fields such as asymmetric catalysts, enantioselective fluorescent sensors and in chiral molecular recognition. To the best of our knowledge, the synthesis of binaphthyl-based symmetrical and asymmetrical axially chiral dendrimers via 1,3-cycloaddition reactions ["Click" chemistry] using Fréchet-type dendrons and their azido-analogues has not been studied yet. The principal aim of this project was the synthesis and characterization of a novel series of binaphthyl-based symmetrical and asymmetrical axially chiral dendrimers via "Click" and etherification reactions, and then determination of the specific and molar rotation of the new dendrimers to investigate the influence of linkage nature between the dendritic wedges and the core units on the optical properties in presence of the triazole ring by comparing of the properties of the new dendrimers with the dendrimers reported in literature, in addition to study the influences of different chemical groups near the dendritic wedges on the optical properties of the novel synthesized dendrimers. In conclusion, several families of novel BINOL-based symmetrical and asymmetrical axially chiral dendrimers have been synthesized by the reaction of well-known BINOL derivatives as core units with Fréchet-type dendrons and their azido-analogues via "Click" and etherfication reactions for the first time. All new dendrimers were obtained in very good yields which confirm the effectiveness of "Click" reaction in this type of synthesis. The new dendrimers were fully characterized by 1H, 13C and HMQC NMR spectroscopy, mass spectrometry, IR spectroscopy and UV-Vis spectrometry. All new dendrimers show moderate optical activity. Changes in the specific and molar rotation are characterized by a general decrease in the specific rotation and a general increase in the molar rotation with the increase in the dendritic wedges generation in each series of the synthesized dendrimers. By our current knowledge, the increase in the specific rotation as generation increases of (S)-358, (S)-359 and (S)-360 observed in this research is the first such observation. The presence of the triazole ring in the linkage between the core unit and the dendritic wedges plays an important role in reducing of the steric repulsion between the two naphthyl units and in reducing of the effect of the dendritic wedges generation on the torsional angle by making the wedges far away from the attachment point of the two naphthyl units.
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Rapakousiou, Amalia. "Ingéniérie des nanomatériaux redox métallocèniques." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0437/document.
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Les dendrimères et polymères contenant des métaux de transition comme le fer, lecobalt et le rhodium peuvent servir à la fabrication des nanomatériaux utiles à lacatalyse, la reconnaissance moléculaire et l’électronique moléculaire. Pour leurconstruction, des liaisons ioniques, de la chimie click : CuAAC et hydroamination, lapolymérisation ROMP et la polymérisation radicalaire ont été utilisés et ont permis laformation de nouveaux types de polyélectrolytes metallocéniques. La synthèse denouvelles nanoparticules d’or, d’argent et de palladium à partir de cesmétallopolymères et métallodendrimères ont été mises au point, conduisant à desréseaux à architecture spécifique bien définie. Ces assemblages supramoléculaireset ingénierie moléculaire ouvrent la voie vers l’application de la chimieorganométallique dans la conception de nouveaux nanomatériaux nanoparticulairesstructurés à l’aide des propriétés rédox des métallomacromoléculesDendrimers and polymers containing transition metals such as iron, cobalt andrhodium can serve in the fabrication of useful nanomaterials for catalysis, molecularrecognition and molecular electronics. For their construction, ionic bonds, clickchemistry: CuAAC and hydroamination, ROMP and radical polymerization were usedand allowed the formation of new types of metallocenyl polyélectrolytes. Thesynthesis of new gold, silver and palladium nanoparticles from these metallopolymersand metallodendrimers has been developed, leading to specific and well-definedarchitectures. These supramolecular assemblies and molecular engineering opensthe way towards the application of organometallic chemistry in the design of newstructured nanoparticle-containing nanomaterials using the redox properties ofmetallomacromolecules
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Johansson, Emma M. V. "Combinatorial discovery of glycopeptide dendrimers targeting lectins /." [S.l.] : [s.n.], 2009. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Bhattacharya, Papri. "A Novel Series of Viologen-Containing Dendrimers." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_theses/134.
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This dissertation investigates the synthesis, characterization and electrochemical properties of viologen-containing dendrimers. Additionally, the self-assembled system of resorcinarenes was investigated with paramagnetic guests using EPR and 1H NMR techniques. Chapter one is a brief introduction to the dendrimers and describes its evolution, structural features, synthetic methods and emerging applications to various fields of research such as catalysis, material science, drug delivery and medicine. Chapter two describes the synthesis, characterization and electrochemical properties of a new series of dendrimers. These dendrimers have a viologen unit at the core surrounded by Newkome and Fr¨¦chet dendrons. The potentials of two consecutive one-electron reductions of the viologen core were determined by cyclic voltammetry. The electrochemistry of viologen unit showed a distinct and obvious trend. Newkome and Frechet dendrons having different functional groups as repeating units has opposite effect on the half-wave potentials. The overall effect of these two dendrons is reflected by the corresponding reduction potentials. The redox site encapsulation by the Frechet and Newkome dendrons is indicated by the attenuation in heterogeneous electron transfer rate constants. Chapter three describes the probing of self-assembled capsule of resorcinarenes with 4-amino tempo and 4-trimethyl-ammonium tempo derivative. EPR spectroscopy and 1H NMR spectroscopy were used to investigate the nature of complexations involved in these systems. We observed a subsequent change in their spectroscopic parameters. Careful investigation of rotational correlation times and NMR line-widths at half height revealed that 4-trimethyl-ammonium tempo has stronger binding affinity with these capsules compared to 4-amino tempo due to favorable cation -pi interactions.
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Nyström, Andreas. "Dendrimers and dendronized polymers : synthesis and characterization." Doctoral thesis, KTH, Fiber- och polymerteknik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3970.
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The goal of this work was to synthesize complex macromolecular architectures such as dendrimers and dendronized polymers, and evaluate the effect from the dendrons on the optical and material properties. The work presented in this doctoral thesis, Dendrimers and Dendronized Polymers - Synthesis and Characterization, is divided into one minor and one major part. The first part deals with the synthesis and characterization of two sets of dendritic porphyrins based on 2,2-bis(methylol)propionic acid (bis-MPA). The second part deals with the synthesis and characterization of dendronized poly(hydroxyl ethyl methacylate), dendronized poly(norbornene), and dendronized triblock copolymers, were the pendant dendrons are based on bis-MPA. Both free-base and zinc containing dendritic porphyrins was synthesized up to the fifth generation by employing iterative ester coupling utilizing the acetonide protected anhydride of bis-MPA as generic building block. First and second generation dendron bearing methacrylates based on 2-hydroxyethyl methacrylate were also synthesized by utilizing the acetonide protected anhydride of bis-MPA, and subsequently polymerized by atom transfer radical polymerization. By adopting a divergent “graft-to” approach starting from the first generation dendronized poly(hydroxyl ethyl methacrylate), well-defined dendronized polymers with acetonide, hydroxyl, acetate and hexadecyl surface functionality were obtained. By utilizing the same divergent iterative esterfication, first to fourth generation dendron functionalized norbornenes were synthesized. These monomers were polymerized by ring-opening metathesis polymerization, utilizing either Grubbs´ first or second generation catalyst. Acrylate functional first to fourth generation monomers were synthesized by the copper(I) catalyzed “click” coupling of azido functional dendrons and propargyl acrylate. The monomers were polymerized to dendronized triblock copolymers by reversible addition-fragmentation chain transfer polymerization, utilizing a difunctional poly(methyl methacrylate) as macro chain transfer agent. The bulk properties of the dendronized poly(hydroxyl ethyl methacrylate) and poly(norbornene) were investigated by dynamic rheological measurements and differential scanning calorimetry. It was found that all the acetonide functional bis-MPA based dendronized polymers had glass transitions temperatures in a similar range. The rheological behaviour showed that for the dendronized polymers having the same backbone length the complex viscosity as a function of functionality was independent of the surface functionality of the polymer. The generation number of the polymer had a profound influence on the complex viscosity, changing form a Newtonian behaviour to a shear thinning behaviour when the generation of the dendrons was increased from two to four. The dendronized poly(norbornene) had increasingly shorter backbone lengths for each generational increase, and for the materials set with comparably lower degree of polymerization, the G’ part of the complex modulus was mostly affected by attaching larger dendrons. In the case of the sample set of higher degree of polymerization, the second, third, and fourth generation samples had similar slopes of the G’ and G” curves, indicating a similar relaxation behaviour.QC 20100914
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Villavicencio, Ovette. "STUDIES OF MULTI-PHOTOCHROMIC LIQUID CRYSTALLINE DENDRIMERS." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1245%5F1%5Fm.pdf&type=application/pdf.
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Nyström, Andreas. "Dendrimers and dendronized polymers : synthesis and characterization /." Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3970.
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Gardiner, Jonathan P. D. "Delivery of antibacterial triclosan by PAMAM dendrimers." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505414.
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Dental plaque can build up to levels which predispose the oral cavity to dental caries or periodontal disease. Therefore many dental products contain antimicrobial compounds to help control plaque formation. Triclosan (TeN) has been used as an antimicrobial in oral care for over 30 years. It has a broad spectrum of antimicrobial activity with high activity against Gram-negative bacteria (those associated with oral disease states). Strategies to increase the delivery efficiency of antibacterials using formulation aids such as polyamidoamine (P AMAM) dendrimers are of interest. P AMAM dendrimers can potentially act as a mucoadhesive delivery system due to electrostatic interactions between the cationic dendrimer and an ionic mulch in oral buccal mucus. Solubilisation studies demonstrated an increase in the level of triclosan solubilised with increasing dendrimer concentration over the range 1mM-5mM. However, solubilisation studies over the pH range 5-12 showed that the dendrimer was unable to enhance triclosan solubility at lower pH values. The solubilising effect observed was attributed to the ionization of triclosan (pKa 7.9) resulting from dendrimer induced pH changes. T\ IH NMR telaxation studies on a solution of 3 mM G3 PAMAM dendrimer and triclosan in pH 12 aqueous solution showed a reduction in T\ for proton resonances corresponding to triclosan, compared to triclosan without dendrimer. However, no significant chemical shift or line broadening effects were observed inferring the interaction between dendrimer and triclosan is relatively weak.
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Stoddart, Alison. "Synthesis, characterisation and properties of novel dendrimers." Thesis, Durham University, 2002. http://etheses.dur.ac.uk/4153/.
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A new family of aliphatic, polyurethane dendritic macromolecules has been designed, synthesised and characterised. The convergent route to dendrimers and the reactions of the selective coupling agent, carbonyl diimidazole (GDI) were employed. The method was successful in the preparation of first, second and third generation dendrimers and dendrons of the first to fourth generations. The structure of the termini of these branched macromolecules was varied to consist of r-butyl, benzhydryl, cyclohexyl or 4-heptyl groups. The dendrons were also coupled to a trifunctional aromatic core unit to create another series of dendrimers with an innermost layer of ester functions. The compounds prepared were soluble in most common organic solvents and insoluble in water. The physical state of the materials ranged from sticky oils to hard, amorphous solids depending on the nature of the end groups and the molecular weight of the macromolecules. The synthesis of the second generation dendrimer with (-butyl end groups was adapted to make a series of six codendrimers with differing arrangements of concentric layers of urethane and carbonate functions as well as the polycarbonate analogue. These second-generation dendrimers varied in their physical state from oils of low viscosity to hard amorphous solids depending on the proportion of carbonate and urethane functions in the molecule. The hydrogen bonding interactions in solution of some of the dendritic compounds were investigated by (^1)H NMR and infrared spectroscopy. From the analysis it was concluded that the hydrogen bonding was intramolecular rather than intermolecular in nature and that the degree of hydrogen bonding was dependent on the generation and the terminal groups of the structures. In addition, the degree of hydrogen bonding of the urethane functions was observed to be dependent on the location of the urethane layers in the second generation poly(urethane-carbonate) codendrimers. The thermal properties of the dendrimers were investigated and the materials observed to have a single glass transition. The glass transition temperatures of the dendritic families with different termini were found to be dependent on the composition of the end group and the molecular weight of the molecule. The glass transition temperatures of the codendrimers were dependent on the proportion of urethane and carbonate links in the structure and also the relative location of the layers. In a preliminary study, it was shown that blends of two different dendrimers were characterised by only one glass transition.
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Halim, Mounir. "Light-emission from conjugated dendrimers and polymers." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4297/.
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This thesis reports the photophysical and electroluminescence studies undertaken on two types of material: polymeric and dendritic. The dendritic architecture is a recent concept adopted to develop new materials for light-emitting diodes. The dendritic structure offers a combination of properties of both polymers and small organic molecules whilst having their own interesting characteristic of optimising processibility, charge transport, and optical properties independently. The dendritic structure consists of functional surface groups, conjugated dendrons and a conjugated core. Initial optical (absorption and photoluminescence) studies revealed that the dendrimer emission originates from the core and is independent of excitation wavelength. This was investigated further in distyrylbenzene based dendrimers where the effect of dendrimer generation number on photoluminescence and electroluminescence properties was studied. All dendrimers emit blue electroluminescence with, in some cases, reasonable electroluminescence quantum efficiency in the range of 0.09 % and brightness up to 150 Cd m(^-2). Having established that the furmel effect, where excitation is successfully transferred to the dendrimer core in both PL and EL, different chromophores were incorporated in the dendrimer structure. Colour control was thus demonstrated in EL devices of the different dendrimers, showing the possibility of using a large number of chromophores in a processible form for EL applications. Conjugated polymers were also studied to investigate the nature of the emitting species (poly(p-pyridine)) and the effect of side- chains (poly(p-phenylenevinylene)). In poly(p-pyridine) the emission was found to be strongly dependent on pyridyl ring rotation affecting the emission and its quantum yield while the side-chains in the poly(p-phenylenevinylene) derivatives were found to affect polymer properties such as degree of conversion of non-conjugated to conjugated polymer. The PL quantum yield system was set-up and proved useful in assessing synthesis of new materials.
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Simpson, Stephen Charles. "Computer simulations of Fréchet dendrimers in solutions." Doctoral thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/6363.
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Includes bibliographical references (leaves 187-210).The structure and dynamics of dendrimers in solution are studied through nanosecond atomistic Molecular Dynamics (MD) simulations of explicitly solvated Fréchet dendrimers, generations G1 to G5. The properties of these dendrimers are investigated in four solvent invironments: vacuum and water (representatives of poor solvents), and tetrahydrofuran (THF) and chloroform (representatives of good solvents). To establish the quality of the solvent on the conformation of the dendrimer, additional nanosecond MD simulations fo the dendrimers are performed, from both inititally folded and unfolded conformations.
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Takeda, Shigeo. "Functionalization of Glucan Dendrimers and Bio-applications." Kyoto University, 2020. http://hdl.handle.net/2433/253505.
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Yamaguchi, Nori. "Supramolecular Assemblies: Dendrimers, Linear Arrays, and Polypseudorotaxanes." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/28741.
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The chemistry of the non-covalent bond has developed rapidly over the last few decades. In particular, the successful construction of nanoscale assemblies by non-covalent forces has been described more frequently in the recent literature. This significant progress is largely due to transferring of concepts found in the biological systems (e.g., the tobacco mosaic virus and the DNA double helix) to the area of synthetic chemistry. As an example, the architecture of the double helix, perhaps the most well-known biological self-assembling structure, remarkably demonstrates the ability of biological systems to construct large supramolecules by multiple aggregations of relatively simple building blocks by means of hydrogen bonding. Scientists have begun to employ such synthetic strategy adopted in Nature to construct nanoscale systems.
The use of pseudorotaxane assemblies formed between the suitably sized crown ethers and dipyridinium salts (paraquats) or dibenzylammonium ions is a viable synthetic strategy to construct non-covalent systems because of their selectivity and strong hydrogen bonding ability. We describe the syntheses and characterization of non-covalent assemblies of different sizes and shapes via the pseudorotaxane approach.
A series of dendritic pseudorotaxanes were efficiently prepared from self-assembling complimentary building blocks, namely a triply charged ammonium ion and the 1st, 2nd, and 3rd generations of benzyl ether dendrons bearing dibenzo-24-crown-8 moiety. The wholly complexed self-assembling dendrimers were evidenced by 1H NMR spectroscopy and mass spectrometry.
Linear supramolecular pseudorotaxane polymers were formed with reversible chain extension in solution by self-assembly of two complimentary homoditopic molecules with secondary ammonium ion and dibenzo-24-crown-8 moieties. The fraction of the cyclic dimer and the size of the linear suprastructures were determined in solution by 1H NMR spectroscopy as a function of concentration. Viscosity measurements corroborated the presence of aggregates of large hydrodynamic volume at high concentrations. The solid state samples of the supramolecular polymers, prepared by freeze-drying, were analyzed by DSC and optical microscopy and shown to be distinct from the starting materials and the cyclic dimer. Fibers and films were formed from high concentration solutions, corroborating the polymeric nature of the aggregates. Similarly, polymolecular arrays were formed in solution from a heteroditopic self-complimentary molecule, comprising bis-m-phenylene-32-crown-10 and a paraquat unit.
Side-chain polypseudorotaxanes were prepared from spontaneous association of polymethacrylates bearing dibenzo-24-crown-8 and secondary ammonium ions. The complexation behavior in solution was investigated using 1H NMR spectroscopy. The solid state samples of side-chain polypseudorotaxanes, prepared by freeze-drying, showed noticeable changes in thermal behavior and morphology from the individual components.Ph. D.