La conception et la synthèse de nanomatériaux à base d'éléments de transition tardifs est d’un intérêt considérable pour des applications potentielles respectueuses de l’environnement en nanomédecine, pour la reconnaissance moléculaire, dans le domaine des capteurs, et en catalyse. Onze différents types de nanoparticules de métaux de transition (TMNPs) stabilisées par des dendrimères ont été synthétisées et caractérisées. Ces nanomatériaux ont été employés en tant que catalyseurs dans des réactions ''click'' et de réduction du nitrophénol en aminophénol dans le but d’établir une relation entre leurs activités catalytiques et la localisation de la nanoparticule qui peut être totalement ou partiellement encapsulée par le dendrimère. Par ailleurs, un complexe moléculaire base de Schiff organométallique de Cu(II) et le métallopolymère correspondant résultant de son greffage sur une matrice PMMA ont été préparés et utilisés comme précatalyseurs efficaces de réactions de cycloaddition [3+2] d’azotures organiques avec des alcynes terminaux. De plus, le dérivé supporté a été recyclé au moins trois fois sans perte d’activité ni de cuivre. Une réaction sélective de N-alkylation d’amines par des alcools en utilisant Pd/C comme catalyseur recyclable a également été développée. / The design and synthesis of late transition-metal nanomaterials is of considerable interest towards applications in nanomedicine, molecular recognition, sensing and catalysis under environmentally friendly conditions. Eleven different kinds of dendrimer-stabilized TMNPs have been synthesized and characterized. They were employed as catalysts for “click” and 4-nitrophenol reduction reactions, to study the relationship between their catalytic activities and their ''inside vs. partly outside'' dendrimer localization. On the other hand, a new ferrocenyl-containing unsymmetrical CuII-Schiff-base complex, and its covalently poly(methyl) (methacrylate) (PMMA)-grafted counterpart were synthesized and employed as efficient precatalyst in the CuAAC “click reaction. The PMMA-supported catalyst has been reused at least three times without any lost of activity or copper leaching. A selective NAlkylation reaction of amines with alcohols using Pd/C as an efficient and reusable catalyst has also been developed.

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Submitted by MARIA BEATRIZ ALVES AFONSO null (mbaafonso@hotmail.com) on 2017-06-12T21:05:33Z No. of bitstreams: 1 Dissertação_ Maria Beatriz Alves Afonso.pdf: 2111821 bytes, checksum: 42668991264b1d02752d3be1fc9cc953 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-06-13T17:19:35Z (GMT) No. of bitstreams: 1 afonso_mba_me_sjrp.pdf: 2111821 bytes, checksum: 42668991264b1d02752d3be1fc9cc953 (MD5) / Made available in DSpace on 2017-06-13T17:19:35Z (GMT). No. of bitstreams: 1 afonso_mba_me_sjrp.pdf: 2111821 bytes, checksum: 42668991264b1d02752d3be1fc9cc953 (MD5) Previous issue date: 2017-05-12 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A investigação de sistemas catalíticos duais capazes de mediar as reações de polimerização por abertura de anel via metátese (ROMP) e de polimerização radicalar por transferência de átomo (ATRP) simultaneamente é de grande interesse e importância na obtenção de novos materiais com potencial de aplicação. Neste estudo, novos complexos de rutênio(II) coordenados a diferentes bases de Schiff derivadas de cicloalquilaminas (ciclopentil 1a, cicloexil 1b, cicloheptil 1c e ciclooctil 1d) foram sintetizados: [RuCl(CyPen-Salen)(PPh3)2] 2a, [RuCl(CyHex-Salen)(PPh3)2] 2b, [RuCl(CyHep-Salen)(PPh3)2] 2c e [RuCl(CyOct-Salen)(PPh3)2] 2d. As bases de Schiff e seus respectivos complexos de rutênio foram caracterizados por FTIR, UV-Vis, RMN e voltametria cíclica. Os complexos planejados foram avaliados como precursores catalíticos em reações de ROMP de norborneno (NBE) e em reações de ATRP de metacrilato de metila (MMA). As sínteses de polinorborneno (poliNBE) via ROMP com os complexos 2a-d como pré-catalisadores foram avaliadas sob diferentes condições de reação ([HCl]/[Ru], [EDA]/[Ru], [NBE]/[Ru] e temperatura). Os melhores rendimentos de poliNBE foram obtidos a 50 °C com razão molar [NBE]/[HCl]/[Ru] = 5000/25/1 na presença de 5 µL de EDA por 60 minutos. A polimerização de MMA via ATRP foi conduzida usando os complexos 2a-d na presença de etil-α-bromoisobutirato (EBiB) como iniciador. Os testes catalíticos foram avaliados em função do tempo de reação usando a razão molar [MMA]/[EBiB]/[Ru] = 1000/2/1. Todos os experimentos via ATRP foram conduzidos à 85 °C. A correlação linear do ln([MMA]0/[MMA]) em função do tempo na ATRP de MMA mediada pelos complexos 2a-d indica que a concentração de radicais permanece constante durante a polimerização. As massas moleculares aumentaram linearmente com a conversão com a diminuição dos valores de IPD, no entanto, as massas moleculares experimentais foram maiores do que as massas moleculares teóricas. / The investigation of dual catalytic systems able to mediate simultaneously ring-opening metathesis polymerization (ROMP) and atom-transfer radical polymerization (ATRP) reactions is of great interest and importance in obtaining new materials with potential for application. In the study, ruthenium(II) complexes of Schiff base derived from cycloalkylamines (cycloalkyl = cyclopentyl 1a, cyclohexyl 1b, cycloheptyl 1c and cyclooctyl) 1d were synthesized: [RuCl(CyPen-Salen)(PPh3)2] 2a, [RuCl(CyHex-Salen)(PPh3)2] 2b, [RuCl(CyHep-Salen)(PPh3)2] 2c and [RuCl(CyOct-Salen)(PPh3)2] 2d. The Schiff bases 1a-d and their respective RuII complexes 2a-d were characterized by FTIR, UV-Vis, NMR, and cyclic voltammetry. The complexes 2a-d were evaluated as catalytic precursors for ROMP of norbornene (NBE) and for ATRP of methyl methacrylate (MMA). The syntheses of polynorbornene (polyNBE) via ROMP with complexes 2a-d as pre-catalysts were evaluated under different reaction conditions ([HCl]/[Ru], [EDA]/[Ru], [NBE]/[Ru], and temperature). The highest yields of polyNBE were obtained with [NBE]/[HCl]/[Ru] = 5000/25/1 molar ratio in the presence of 5 µL of EDA for 60 minutes at 50 °C. MMA polymerization via ATRP was conducted using the complexes 2a-d in the presence of ethyl-α-bromoisobutyrate (EBiB) as initiator. The catalytic tests were evaluated as a function of the reaction time using the initial molar ratio of [MMA]/[EBiB]/[Ru] = 1000/2/1 at 85 °C. The linear correlation of ln([MMA]0/[MMA]) and time clearly indicates that the concentration of radicals remains constant during the polymerization and that the ATRP of MMA mediated by 2a-d proceeds in a controlled manner. Molecular weights increased linearly with conversion, however, the experimental molecular weights were higher than the theoretical ones.

Esta tese apresenta a obtenção de sílica xerogel a partir de carvão de cascas de arroz e a modificação da sua superfície com um ligante orgânico tipo base de Schiff. O objetivo da utilização deste resíduo agroindustrial é a obtenção de um adsorvente capaz de atuar no tratamento de águas contaminadas contendo íons cádmio II, em uma concepção de valorização de resíduos. A sílica contida na biomassa foi obtida na forma de silicato de sódio através de extração química com solução de hidróxido de sódio, seguida de hidrólise e condensação do monômero através do processo solgel. A modificação da superfície da sílica com o ligante salen foi realizada utilizando o 1,2-dicloroetano como espaçador bifuncional. A sílica xerogel modificada foi avaliada através de análises de isotermas de adsorção e dessorção de nitrogênio (BET/BJH), difração de raios-X (DRX), análise química elementar (CHN), espectroscopia de infravermelho com transformada de Fourier (FTIR), microscopia eletrônica de varredura (MEV) e termogravimetria (TG/DTG). A análise elementar indicou que 0,341 mmol/g de 1,2-dicloroetano e 0,095 mmol/g de salen foi ancorado na superfície da sílica, que apresentou estabilidade térmica até 209°C e área de superfície específica de 106,4 m²/g. Foi realizado um estudo sobre a capacidade de adsorção de íons cádmio (II) pela sílica modificada e não modificada. Os resultados indicam a superior capacidade de adsorção de cádmio pela sílica modificada, em soluções com baixa concentração do íon. / This thesis presents the obtainment of silica xerogel by rice husk charcoal and its surface modification using an organic ligand type Schiff-base. The purpose of this agro-industrial residue utilization is the production of an adsorbent capable to remove heavy metals present in contaminated waters. The silica contained in the biomass was obtained by alkaline extraction in sodium silicate with hydrolysis through sol-gel process, and modified with salen, using 1,2-dichloroethane as bi-functional spacer. The modified xerogel silica was evaluated through analysis of nitrogen adsorption/desorption isotherms (BET/BJH), X-ray diffraction (XRD), chemical elementary analysis (CHN), Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM) and thermogravimetric analysis (TG/DTG). The elementary analysis pointed that 0,341mmol/g of the 1,2-dichloroethane and 0,095mmol/g of the salen was anchored to the silica surface, that presented thermal stability until 209°C and specific surface area of 106,4 m²/g. An evaluation about the ion cadmium II adsorption capacity of the silica modified and unmodified was performed. The results pointed to the superior cadmium adsorption capacity for the modified silica if low ion concentration solutions.

No description available.

New synthetic routes were designed and applied for novel bisperfluoroalkylated benzene derivatives: 2,5-bis(perfluorooctyl)benzene-1,4-dicarbaldehyde, its dimethylacetal and 2,5- bis(trifluoromethyl)benzene-1,4-diamine. Methods for purification of those derivatives were developed and used to obtain pure crystalline compounds. Crystals of the mentioned diamine and diacetal were obtained in quality suitable for RTG analysis while crystals of dialdehyde were of sufficient quality. New synthesis and purification protocol was designed for 2,5-bis(trifluoromethyl)benzene- 1,4-dialdehyde yielding sufficiently pure product, although isolated amounts are rather small ( yields about 20%) . 2,5-diiodobenzene-1,4-diamine was synthetised. It should be possible to prepare 2,5- bis(perfluorooktyl)benzene-1,4-diamine from this compound either by direct or indirect approach. Nevertheless, the syntheses were yet unsuccessful. A series of eight Schiff bases derived from 3,5-bistrifluoromethylated benzeneamine, benzylamine and benzaldehyde, and three reference bases based on thiophene-2-carbadehyde, benzaldehyde and phenylacetaldehyde was prepared. Kinetics of those species' formation in CDCl3 (all reactions run without catalyst) and THF (necessity of catalysis and susceptibility of equilibria to water) were studied. The...

yes / The first use of a dinuclear UIII/UIII complex in the activation of small molecules is reported. The octadentate Schiff-base pyrrole, anthracene-hinged ‘Pacman’ ligand LA combines two strongly reducing UIII centres and three borohydride ligands in [M(THF)4][{U(BH4)}2(m-BH4)(LA)(THF)2] 1-M, (M ¼ Li, Na, K). The two borohydride ligands bound to uranium outside the macrocyclic cleft are readily substituted by aryloxide ligands, resulting in a single, weakly-bound, encapsulated endo group 1 metal borohydride bridging the two UIII centres in [{U(OAr)}2(m-MBH4)(LA)(THF)2] 2-M (OAr ¼ OC6H2tBu3-2,4,6, M ¼ Na, K). X-ray crystallographic analysis shows that, for 2-K, in addition to the endo-BH4 ligand the potassium countercation is also incorporated into the cleft through h5-interactions with the pyrrolides instead of extraneous donor solvent. As such, 2-K has a significantly higher solubility in non-polar solvents and a wider U–U separation compared to the ‘ate’ complex 1. The cooperative reducing capability of the two UIII centres now enforced by the large and relatively flexible macrocycle is compared for the two complexes, recognising that the borohydrides can provide additional reducing capability, and that the aryloxide-capped 2-K is constrained to reactions within the cleft. The reaction between 1-Na and S8 affords an insoluble, presumably polymeric paramagnetic complex with bridging uranium sulfides, while that with CS2 results in oxidation of each UIII to the notably high UV oxidation state, forming the unusual trithiocarbonate (CS3)2 as a ligand in [{U(CS3)}2(m-k2:k2-CS3)(LA)] (4). The reaction between 2-K and S8 results in quantitative substitution of the endo-KBH4 by a bridging persulfido (S2)2 group and oxidation of each UIII to UIV, yielding [{U(OAr)}2(m-k2:k2-S2)(LA)] (5). The reaction of 2-K with CS2 affords a thermally unstable adduct which is tentatively assigned as containing a carbon disulfido (CS2)2 ligand bridging the two U centres (6a), but only the mono-bridged sulfido (S)2 complex [{U(OAr)}2(m-S (LA)] (6) is isolated. The persulfido complex (5) can also be synthesised from the mono-bridged sulfido complex (6) by the addition of another equivalent of sulfur. / EPSRC, European COST network

There are numerous advantages of replacing traditional non-biodegradable synthetic plastics with bio-based plastics. Starch is globally available, cheap, renewable, and biodegradable. However, starch has a poor product performance and is relatively difficult to process, as conventional melt processing techniques cannot be used. By introducing thermoplastic properties to starch, the mechanical properties and processability can be enhanced. The aim of the project was to modify starch and give it thermoplastic properties. The implementation of this included various experiments, where aromatic, cyclic and aliphatic side groups were added to the biopolymer. The effect of the different side groups provided valuable insight into how the material properties changed. Subsequently, the thermoplastic properties of the modified starch were analyzed by different analytical methods, including Fourier-transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). In conclusion, the TGA showed lower thermal stability in the functionalized starch compared to native starch. Some indications of thermoplastic behavior were observed from the DSC. Trade-off between functionality and thermostability needs to be overlooked when aiming to increase thermoplastic behavior and future work should explore TEMPO oxidation, to obtain better results from the TGA. / Det finns många fördelar med att ersätta traditionella, icke-biologiskt nedbrytbara syntetiska plaster med biobaserade plaster. Stärkelse är globalt tillgängligt, billigt, förnybart och nedbrytbart. I nuläget har stärkelse dock en bristande produktprestanda och är relativt svår att bearbeta eftersom konventionella smält bearbetningstekniker inte kan användas. Genom att ge stärkelse termoplastiska egenskaper kan man förbättra de mekaniska egenskaperna och bearbetbarheten. Syftet med projektet var därför att modifiera stärkelse och introducera termoplastiska egenskaper. Genomförandet av detta innefattade flera olika experiment där aromatiska, cykliska och alifatiska sidogrupper tillsattes till stärkelsen. Effekten av de olika sidogrupperna gav värdefull insikt i hur materialegenskaperna förändrades. Därefter analyserades de termoplastiska egenskaperna hos den modifierade stärkelsen med olika analytiska metoder, inklusive Fourier-transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA) och Differential Scanning Calorimetry (DSC). Slutsatsen var att TGA visade en lägre termisk stabilitet hos den funktionaliserade stärkelsen jämfört med i den naturliga stärkelsen samt att vissa indikationer på termoplastiskt beteende observerades med hjälp av DSC analysen. En avvägning mellan funktionalitet och termisk stabilitet bör tas i beaktande i strävandet efter att öka termoplastiskt beteende. Framtida arbete inom ämnet rekommenderas att utforska TEMPO-oxidation för att uppnå bättre resultat från TGA.

No description available.

MnO2 continues to gain traction in the research and development of advanced supercapacitor materials due to its arsenal of advantages, such as high capacitance, low cost, natural abundance, and environmental benignity. However, its low conductivity has hindered its adoption into real-life applications. Compositing MnO2 with conductive additives has proved to be a promising route for the improvement of its power-energy characteristics. Four novel colloidal techniques were developed for the synthesis of MnO2-CNT composites with enhanced performance at high active mass loading. One strategy utilized a Schiff-based linkage of dispersants such as 3,4-Dihydroxybenzaldehyde (DHB) and Toluidine Blue O (TDB) to effectively mix and disperse MnO2 and CNT. Secondly, a co-dispersion technique was also investigated using Gallocyanine to improve dispersion and mixing of MnO2 and MWCNT. Third, a novel liquid-liquid extraction technique opened new avenues in agglomerate-free processing of individual components, which allowed enhanced electrode performance. Lastly, a morphology-modification strategy was also undertaken by synthesizing MnO2 nanorods with the use of advanced organic dispersants to control the aspect ratio and composite nanorods with MWCNT. The second major material investigated was polypyrrole (PPy), a polymer material with high conductivity, ease of synthesis, low-cost, and non-toxicity. However, its low cyclic stability was prevented it from being applied for real-world applications. Certain anionic and aromatic dopants have shown to improve the conductivity and cyclic stability. Therefore, one of the investigations in this work attempted to improve the performance of PPy-CNT composites by use of a novel anionic dopant, Sunset Yellow (SY). For all investigations electrodes with high mass loadings were produced to achieve high areal capacitance, thus ensuring the practicality of the techniques / Thesis / Master of Applied Science (MASc) / Supercapacitors (SCs) and batteries are both electrochemical energy storage devices. While batteries excel at storing energy in high volumes, supercapacitors excel in charging (and discharging) at extremely high rates. It is desirable to obtain the best of both worlds in a single device; high energy volume and fast charging speeds. Although such a feat is not out of the realm of theoretical possibility, current projections forecast supercapacitors to compliment battery technologies instead of replacing them. Nonetheless, constant progression in the field of SCs is needed to sustain and proliferate their adoption into emerging markets. Therefore, the aim of this research was to assist in the endeavours to improve current SC technologies from a materials science standpoint.