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Diplomsko delo sestoji iz trenutnih znanstvenih spoznanj o grafenu, njegovi sintezi, vrstični elektronski mikroskopiji in reakciji redukcije kisika ter eksperimentalnega dela, ki sem ga izvedla z grafenom na osnovi teh metod. Kemijsko naparevanje iz parne faze je eden izmed možnih načinov proizvodnje grafena, ki je cenovno ugoden, primeren pa je tudi za njegovo masovno proizvodnjo. Obsega uvajanje plina, ki služi kot vir ogljikovih atomov, na substrat, ki je navadno ena izmed prehodnih kovin. Na substratu se plin razgradi, ob ohlajanju pa začne na njem rasti grafen. V moji diplomski nalogi sem kot substrat uporabila polikristaliničen platinast disk, kot vir ogljikovih atomov pa je služil metan. Za čim bolj jasno sliko, koliko grafena je zraslo na disku, z vrstičnim elektronskim mikroskopom posnamemo slike platine pred in po rasti grafena. Glavni cilj diplomske naloge je bilo preverjanje katalitske aktivnosti grafena za reakcijo redukcije kisika, saj je ta pomembna v gorivnih celicah s protonsko prevodno membrano in v kovinsko-zračnih baterijah, ki bodo služile za zagotavljanje trajnostnega vira energije s čim manjšim ogljičnim odtisom, saj se zaradi emisij ogljikovega dioksida pri uporabi fosilnih goriv segreva globalno ozračje, kar pa želimo preprečiti, da bo naš planet še vedno naseljiv za prihodnje generacije. The thesis consists of current scientific knowledge of graphene, its synthesis, scanning electron microscopy and oxygen reduction reactions. In the end I conducted experimental research, which I carried out with graphene based on these methods. Chemical vapor deposition is one of the possible methods of graphene production, which is not too expensive and is also suitable for mass production. It involves introducing gas, which serves as a source of carbon atoms, on a substrate, which is usually one of the transition metals. On the substrate, the gas degrades and, when cooled, graphene grows on it. In my thesis, I used a polycrystalline platinum disc as a substrate and methane served as the source of carbon atoms. To see how much graphene has grown on the disk, we took some photos of platinum before and after the growth of graphene with a scanning electron microscope. The main objective of this thesis was to check the catalytic activity of graphene for oxygen reduction reaction, as it is important in fuel cells with a proton exchange membrane and in metal-air batteries, which will serve to provide a sustainable energy source with the least carbon footprint, as carbon dioxide emissions from fossil fuels heat the global atmosphere, which we want to prevent, so that our planet will still be habitable for generations to come

Water electrolysis powered by renewables is regarded as the feasible route for the production of hydrogen, obtained at the cathode side through electrochemical hydrogen evolution reaction (HER). Herein, we present a rational strategy to improve the overall HER catalytic performance of Pt, which is known as the best monometallic catalyst for this reaction, by supporting it on a conductive titanium oxynitride (TiON$_x$) dispersed over reduced graphene oxide nanoribbons. Characterization of the Pt/TiON$_x$ composite revealed the presence of small Pt particles with diameters between 2 and 3 nm, which are well dispersed over the TiON$_x$ support. The Pt/TiON$_x$ nanocomposite exhibited improved HER activity and stability with respect to the Pt/C benchmark in an acid electrolyte, which was ascribed to the strong metal−support interaction (SMSI) triggered between the TiON$_x$ support and grafted Pt nanoparticles. SMSI between TiON$_x$ and Pt was evidenced by X-ray photoelectron spectroscopy (XPS) through a shift of the binding energies of the characteristic Pt 4f photoelectron lines with respect to Pt/C. Density functional theory (DFT) calculations confirmed the strong interaction between Pt nanoparticles and the TiON$_x$ support. This strong interaction improves the stability of Pt nanoparticles and weakens the binding of chemisorbed H atoms thereon. Both of these effects may result in enhanced HER activity.

In this study, we investigate the hydrogenation reaction of levulinic acid to 4-hydroxypentanoic acid on ligand-modified Pt(111) using DFT. Modifying nanoparticle surfaces with ligands can have beneficial effects on the desired reaction such as improved selectivity or lower activation energies. The N3,N3-dimethyl-N2-(quinolin-2-yl)propane-1,2-diamine (AQ) ligand was selected to modify the surface, since it combines good surface adsorption properties with functional groups that can influence the reaction. The adsorption geometry of the AQ ligand was studied as well as the co-adsorption of a second AQ ligand for the possibility of self-assembly. We found that dissociated hydrogen from the Pt(111) surface can protonate the AQ ligand and discuss the role this plays on the mechanism of the hydrogenation reaction of levulinic acid (LA). By comparing the ligand-modified Pt(111) surface to the bare Pt(111) surface we show that the reaction changes from a step-wise to a concerted mechanism due to the influence of the ligand molecule. This demonstrates the effect that ligand-modified surfaces can have on catalyzing reactions and shows that desired reactions can be achieved by tuning the reaction environment. peerReviewed

In the past, platinum–copper catalysts have proven to be highly active for the oxygen reduction reaction (ORR), but transferring the high activities measured in thin-film rotating disk electrodes (TF-RDEs) to high-performing membrane electrode assemblies (MEAs) has proven difficult due to stability issues during operation. High initial performance can be achieved. However, fast performance decay on a timescale of 24 h is induced by repeated voltage load steps with H2/air supplied. This performance decay is accelerated if high relative humidity (>60% RH) is set for a prolonged time and low voltages are applied during polarization. The reasons and possible solutions for this issue have been investigated by means of electrochemical impedance spectroscopy and distribution of relaxation time analysis (EIS–DRT). The affected electrochemical sub-processes have been identified by comparing the PtCu electrocatalyst with commercial Pt/C benchmark materials in homemade catalyst-coated membranes (CCMs). The proton transport resistance (Rpt) increased by a factor of ~2 compared to the benchmark materials. These results provide important insight into the challenges encountered with the de-alloyed PtCu/KB electrocatalyst during cell break-in and operation. This provides a basis for improvements in the catalysts’ design and break-in procedures for the highly attractive PtCu/KB catalyst system.

L’étude porte sur quelques exemples significatifs du paradigme médical dans les discours antérotiques latins du xve siècle italien : exprimant la nécessité de remédier à la passion d’amour, Piccolomini, Ficin, Platina, y recourent pour étayer leurs argumentations diverses, témoignant d’une actualisation de l’héritage antique – et médiéval – et de la richesse du débat contemporain. La poésie, quant à elle, ouvre parfois des voies inattendues, où le remède procède d’une sublimation par l’écriture.

Single Atom Catalysts (SACs) have shown that the miniaturization of the active site implies new phenomena like dynamic charge transfer between isolated metal atoms and the oxide. To obtain direct proof of this character is challenging, as many experimental techniques provide averaged properties or have limitations with poorly conductive materials, leaving kinetic measurements from catalytic testing as the only reliable reference. Here we present an integrated Density Functional Theory-Microkinetic model including ground and metastable states to address the reactivity of Pt1/CeO2 for CO oxidation. Our results agree with experimentally available kinetic data in the literature and show that CO oxidation activity of Pt1/CeO2 is tunable via the electronic properties of the support. Particularly, samples with higher n-doping via oxygen depletion should be better in CO oxidation, as they help maintain the active state Pt0 of the catalyst. This provides an alternative strategy for tuning the performance of low-temperature oxidations in single-atom catalysts via charge transfer control. peerReviewed

V okviru diplomske naloge sem pregledala znanstveno literaturo za postopke sintez kovinskih kompleksov 6-metoksikinolina z zlatom(I/III) oziroma platino(II). Enake sintezne postopke sem po preizkušenih reakcijah s 6-metoksikinolinom preizkusila še z molekulo dihidrokinidina. Pri tem sem v reakcijah spreminjala reakcijske pogoje in sinteze preizkušala z uporabo različnih topil. Večino reakcij sem opravljala v temi zaradi občutljivosti na svetlobo zlatovih in platinskih soli. Cilj diplomske naloge je bil pripraviti kompleks 6-metoksikinolina ali dihidrokinidina z zlatom oziroma platino brez nečistoč. Sintetizirane produkte sem okarakterizirala z NMR, masno spektrometrijo in rentgensko strukturno analizo. As part of my diploma thesis, I reviewed the scientific literature for the synthesis procedures of metal complexes of 6-methoxyquinoline with gold(I/III) and platinum(II). After the tested reactions with 6-methoxyquinoline, I tried the same synthesis procedures with the dihydroquinidine molecule. While doing that, I changed the reaction conditions in the reactions and tested the syntheses using different solvents. Most of the reactions were preformed in the dark, due to the light sensitivity of gold and platinum salts. The goal of my thesis was to prepare a complex of 6-methoxyquinoline or dihydroquinidine with gold or platinum without impurities. I characterized the synthesized products by NMR, mass spectrometry and X-ray structural analysis.

Herein, we report the synthesis and characterization of two Pt(II) coordination compounds, the new platinum(II)[N,N′-bis(salicylidene)-3,4-diaminobenzophenone)] ([Pt(sal-3,4-ben)]) and the already well-known platinum(II)[N,N′-bis(salicylidene)-o-phenylenediamine] ([Pt(salophen)]), along with their application as guests in a poly [9,9-dioctylfluorenyl-2,7-diyl] (PFO) conjugated polymer in all-solution processed single-layer white organic light-emitting diodes. Completely different performances were achieved: 2.2% and 15.3% of external quantum efficiencies; 2.8 cd A−1 and 12.1 cd A−1 of current efficiencies; and 3103 cd m−2 and 6224 cd m−2 of luminance for the [Pt(salophen)] and [Pt(sal-3,4-ben)] complexes, respectively. The Commission Internationale de l’Eclairage (CIE 1931) chromaticity color coordinates are (0.33, 0.33) for both 0.1% mol/mol Pt(II):PFO composites at between approximately 3.2 and 8 V. The optoelectronic properties of doped and neat PFO films have been investigated, using steady-state and time-resolved photoluminescence. Theoretical calculations at the level of relativistic density functional theory explained these results, based on the presence of the Pt(II) central ion’s phosphorescence emission, considering spin-orbit coupling relationships. The overall results are explained, taking into account the active layer morphological properties, along with the device’s electric balance and the emitter’s efficiencies, according to deep-trap space-charge models. Considering the very simple structure of the device and the ease of synthesis of such compounds, the developed framework can offer a good trade-off for solution-deposited white organic light-emitting diodes (WOLEDs), with further applications in the field of lighting and signage.

Carbon materials with developed porosity are usually used as supports for platinum catalysts. Physico-chemical characteristics of the support influence the properties of platinum deposited and its catalytic activity. In our studies, we deposited platinum on carbon fibrous like materials obtained from platanus seeds - achenes. The precursor was chemically activated with different reagents: NaOH, pyrogallol, and H2O2, before the carbonization process. Platinum was deposited on all substrates to study the influence of the substrate properties on the activity of the catalyst. Carbon materials were characterized by nitrogen adsorption/desorption isotherms measurements, X-ray diffraction, and scanning electron microscopy. It was noticed that the adsorption characteristics of carbon support affected the structure of platinum deposits and thus their activity.

Carbon-based nanofibers decorated with metallic nanoparticles (NPs) as hierarchically structured electrodes offer significant opportunities for use in low-temperature fuel cells, electrolyzers, flow and air batteries, and electrochemical sensors. We present a facile and scalable method for preparing nanostructured electrodes composed of Pt NPs on graphitized carbon nanofibers. Electrospinning directly addresses the issues related to large-scale production of Pt-based fuel cell electrocatalysts. Through precursors containing polyacrylonitrile and Pt salt electrospinning along with an annealing protocol, we obtain approximately 180 nm thick graphitized nanofibers decorated with approximately 5 nm Pt NPs. By in situ annealing scanning transmission electron microscopy, we qualitatively resolve and quantitatively analyze the unique dynamics of Pt NP formation and movement. Interestingly, by very efficient thermal-induced segregation of all Pt from the inside to the surface of the nanofibers, we increase overall Pt utilization as electrocatalysis is a surface phenomenon. The obtained nanomaterials are also investigated by spatially resolved Raman spectroscopy, highlighting the higher structural order in nanofibers upon doping with Pt precursors. The rationalization of the observed phenomena of segregation and ordering mechanisms in complex carbon-based nanostructured systems is critically important for the effective utilization of all metal-containing catalysts, such as electrochemical oxygen reduction reactions, among many other applications.

Submitted by Rodolfo Fini (rodolfo_fini@hotmail.com) on 2022-05-02T08:54:15Z No. of bitstreams: 1 Tese De Doutorado - Versão Final_Folha de aprovação.pdf: 6191667 bytes, checksum: db078d3297d6ed8caba99873dd0c42ae (MD5) Approved for entry into archive by Ana Carolina Gonçalves Bet null (abet@iq.unesp.br) on 2022-05-03T10:57:39Z (GMT) No. of bitstreams: 1 fini_r_dr_araiq_int.pdf: 6191667 bytes, checksum: db078d3297d6ed8caba99873dd0c42ae (MD5) Made available in DSpace on 2022-05-03T10:57:39Z (GMT). No. of bitstreams: 1 fini_r_dr_araiq_int.pdf: 6191667 bytes, checksum: db078d3297d6ed8caba99873dd0c42ae (MD5) Previous issue date: 2022-03-31 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Nesta tese de doutorado, propusemo-nos a sintetizar nanopartículas de platina (Pt) por rota de redução clássica, utilizando borohidreto de sódio e ácido ascórbico, pela roda solvotermal, utilizando o 1-propanol, e pela rota de deslocamento galvânico, utilizando o cobre como agente redutor. Além disso, propusemo-nos a elucidar o mecanismo de formação e crescimento de duas abordagens sintéticas: a redução da platina via deslocamento galvânico e via redução com ácido ascórbico. Para entender as características estruturais das nanopartículas, nós as caracterizamos com técnicas de difração de raios X (DRX), espectroscopia de absorção de raios X (XAS), microscopia eletrônica de varredura (SEM), microscopia eletrônica de transmissão (TEM), microscopia eletrônica de transmissão por varredura (STEM) e espalhamento de raios X à baixo ângulo (SAXS). Para investigar os mecanismos de formação e crescimento de nanopartículas de platina nós monitoramos a síntese in situ com técnicas de SAXS e espectroscopia na região do UV-vis. Os resultados obtidos apontam para as diferenças na morfologia e distribuição de tamanho das nanopartículas. A avaliação do mecanismo de formação e crescimento das nanopartículas reduzidas com ácido ascórbico indicaram um tipo de crescimento não clássico, onde o processo agregativo foi dominante. Nossa avaliação do impacto da variação da concentração do agente estabilizante na cinética de formação e crescimento indicaram que estes possuem papel fundamental no controle do processo de nucleação agregativa, que por sua vez tem influência na distribuição de tamanho das partículas e no raio médio. In this work, we aimed to synthesize platinum (Pt) nanoparticles by classical reduction route, using sodium borohydride and ascorbic acid, by solvothermal route, using 1- propanol, and by galvanic displacement route, using copper as reducer agent. Furthermore, we aimed to elucidate the growth mechanism for two synthetic approaches: platinum reduction via galvanic displacement and via ascorbic acid reduction. To understand the structural characteristics of the nanoparticles, we have used the following techniques: X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and small angle X-ray scattering (SAXS). To investigate the growth mechanisms of platinum nanoparticles we monitored the synthesis in situ with SAXS and UV-vis spectroscopy techniques. The results obtained point to the differences in the morphology and size distribution of the nanoparticles. The evaluation of the formation and growth mechanism of the nanoparticles reduced with ascorbic acid indicated a non-classical type of growth, where the aggregation process was dominant. Our evaluation of the impact of the stabilizing agent concentration variation in the formation and growth kinetics indicated that the surfactant plays a fundamental role in controlling the aggregative nucleation process, which in turn influences the particle size distribution and the mean radius. CNPq: 141041/2017-0

Purpose: The study of asymmetric and symmetric fission of 180,182,183Hg and 178Pt nuclei as a function of their excitation energy and isospin. Methods: Mass-energy distributions of fission fragments of 180Hg, 178Pt (two protons less than 180Hg), and 182Hg (two neutrons more than 180Hg) formed in the 36Ar+144Sm,142Nd, and 40Ca+142Nd reactions were measured at energies near and above the Coulomb barrier. Fission of 183Hg obtained in the reaction of 40Ca with 143Nd was also investigated to see if one extra neutron could lead to dramatic changes in the fission process due to the shape-staggering effect in radii, known in 183Hg. The measurements were performed with the double-arm time-of-flight spectrometer CORSET. Results: The observed peculiarities in the fission fragment mass-energy distributions for all studied nuclei may be explained by the presence of a symmetric fission mode and three asymmetric fission modes, manifested by the different total kinetic energies and fragment mass splits. The yield of symmetric mode grows with increasing excitation energy of compound nucleus. Conclusions: The investigated properties of asymmetric fission of 180,182,183Hg and 178Pt nuclei point out the existence of well-deformed proton shell at Z≈36 and a less deformed proton shell at Z ≈ 46. peerReviewed

The extremely neutron-deficient isotope 179Au has been studied by a combination of in-beam γ-ray and isomeric-decay spectroscopy. For in-beam spectroscopy, the recoil-isomer tagging technique was employed, using the known 3/2−, T1/2=328 ns isomer. A new rotational band, associated with the unfavored signature band of the 1h9/2⊕2f7/2 proton-intruder configuration, was revealed. A previously unknown, high-spin isomeric state with an excitation energy of 1743(17) keV and T1/2=2.16(8)µs was discovered. Five decay paths were identified, some of them feeding previously unknown non-yrast excited states, associated with the 1i13/2 proton-intruder configuration. Calculations based on the particle-plus-triaxial-rotor model were performed to interpret the data. On the basis of these calculations, the new 1h9/2⊕2f7/2 rotational band is interpreted as due to triaxial deformation of the underlying configuration with β2≈0.26 and γ≈27∘. Observed non-yrast states of the positive-parity 1i13/2 intruder configuration are interpreted as due to triaxial deformation with β2≈0.26 and γ≈20∘. peerReviewed

Orientador: Pablo Sebastian Fernandez Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química Resumo: Alternativas à atual dependência por combustíveis fósseis são constantemente visadas, pois representam a única maneira de minimizar os impactos causados pelo aquecimento global. O gás hidrogênio de alta pureza é unanimemente considerado como a mais importante fonte de energia renovável para o futuro próximo, e pode ser obtido de forma sustentável a partir da eletrólise da água. Dos vários problemas que cerceiam o assunto, a substituição da reação anódica (evolução de oxigênio) pela oxidação de biomassa, como a oxidação de glicerol, não só reduziria o custo energético para operar esses dispositivos, mas também possibilitaria a geração de produtos de maior valor agregado a partir da conversão da biomassa. O glicerol é obtido em abundância como coproduto de síntese durante a produção de biodiesel, um combustível renovável de amplo uso no setor de transporte, e o próprio glicerol também pode ser utilizado como fonte de energia a partir da sua oxidação direta, com a possibilidade de gerar hidrogênio verde, além da sua conversão em outras moléculas de maior interesse econômico. Nesse contexto, o presente trabalho tem por objetivo desenvolver catalisadores a partir de platina para a oxidação eletroquímica do glicerol em meio alcalino, e posteriormente transferir o conhecimento adquirido para dispositivos eletroquímicos. A partir de uma investigação eletroquímica inicial, os eletrodos de platina foram modificados por nove elementos distintos do bloco "p", e foi observado que três deles aumentaram a atividade do eletrodo, com respeito ao eletrodo de platina não modificado: chumbo, bismuto e tálio. A adição desses elementos resultou em maiores correntes anódicas durante um período de tempo mais longo. Usando FTIR in situ, nós mostramos que a presença desses adátomos reduziu a quebra de ligações C-C durante a oxidação, e preveniram a adsorção de CO no eletrodo, um intermediário responsável por envenenar o catalisador. Os produtos de oxidação solúveis foram identificados através de cromatografia líquida, e apesar de não haver mudanças na seletividade com a modificação, houve um aumento significativo no rendimento da reação. Por último, conseguimos transferir o conhecimento acumulado para uma célula a combustível microfluídica, onde modificamos o anodo, nanopartículas de Pt/C suportadas em papel carbono, com bismuto. Foi observado um aumento significativo na voltagem de circuito aberto e potência extraída do dispositivo, e uma mistura de glicolato e formato foi identificada a partir do eletrólito de exaustão do dispositivo, confirmando a possibilidade de cogeração de energia com produtos de alto valor agregado Abstract: Alternatives to the current dependency on fossil fuels are constantly sought after, as it is the only way to minimize the current impact of global warming effect. High-purity hydrogen gas is unanimously considered an important renewable energy source in the foreseeable future, and it can be sustainably synthesized from water electrolysis. Of the many issues surrounding water electrolysis, substituting the anode reaction (oxygen evolution) for biomass oxidation, like the glycerol oxidation, not only would decrease the energy cost needed to operate these devices, but would also enable the generation of value-added products from the biomass conversion. Glycerol is readily obtained as a byproduct from the biodiesel synthesis, another renewable fuel source widely used in the transportation sector, and glycerol itself can also be used as an energy source by its direct oxidation, with the added possibility of generating green hydrogen, in addition to its conversion into other value-added molecules. In this context, this work aims to develop platinum-based catalysts for the electrochemical oxidation of glycerol in alkaline media, and later apply the acquired knowledge to electrochemical devices. In an initial electrochemical investigation, we modified the electrodes with nine different elements from the p-block and identified three elements that improved the electrode activity when compared to the clean platinum electrode: lead, bismuth, and thallium. The addition of these elements resulted in higher anodic currents for a longer period. Using in situ FTIR, we showed that the presence of adatoms reduced the cleavage of C-C bonds during the oxidation, and prevented the adsorption of CO, a poisonous intermediate. Soluble oxidation products were identified using liquid chromatography, and while the selectivity of the reaction did not change, there was a significant increase in the reaction yield. Lastly, we were able to transfer the resulting knowledge to a glycerol-based microfluidic fuel cell, where we modified the anode, Pt/C nanoparticles supported on carbon paper, with bismuth. We saw a significant increase in the open circuit voltage and power extracted from the device after modification, and a mixture of glycolate and formate was generated in the exhaust electrolyte, confirming the possibility of the cogeneration of energy with value-added chemicals Doutorado Físico-Química Doutor em Ciências FAPESP 2019/00305-2 CNPQ 142478/2018-0 CAPES 001

International audience; Conducting polymers have been used as support for catalysts towards distinct electrocatalytic reactions. The overall activity of the modified interfaces critically depends on both the processes on the catalyst surface and of the charge compensation within the polymer matrix. Therefore, understand the coupling between surface and volumetric processes in such systems is of utmost importance. In this contribution we report on the experimental investigation of the interplay between surface and volumetric processes during the electrooxidation of formic acid (and also formaldehyde) on platinum modified polyaniline electrodes. The study was performed through in situ nanogravimetry, with the Electrochemical Quartz Crystal Nanobalance (EQCN). We have explored the dynamics of charge and mass changes along several experimental conditions, including the self-organized potential oscillations. The systematic study included the analysis of several configurations: gold electrodes covered with a PANI film and dispersed platinum (Au/PANI/Pt); platinum electrodes covered with PANI (Pt/PANI); and bare platinum electrodes. The methodology introduced includes the detailed analysis of the charge compensation process and of the time-derivative of the mass variations. Typical results for the electro-oxidation of formic acid on PANI supported platinum indicate that the electrocatalysis itself is reflected in the current profile, whereas the charge compensation rules the gravimetric response. This general observation also holds for the oscillatory electro-oxidation of formic acid. The physicochemical description of the support/catalyst systems described here opens interesting perspectives for the investigation of parent systems.

Made available in DSpace on 2022-04-28T19:48:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-02-01 There is a growing demand in the development of environmentally friendly technologies, based on the use of more biocompatible solvents for the recovery of natural bioactive compounds. In this work, the red yeast Phaffia rhodozyma biomass was used as a source of carotenoids to develop an integrative and efficient platform that promotes the recovery of astaxanthin and β-carotene using bio-based solvents (BioSs). The extraction aptitude of pure BioSs was evaluated and compared with the conventional organic method. At this point, the influence of the BioSs molecular structures involved in the extraction procedures were also investigated. Overall, envisaging the industrial application of the process, an integrative platform was proposed for the recovery of astaxanthin/β-carotene from P. rhodozyma biomass and the recycle of the BioSs. The life cycle assessment of the proposed technology using EtOH was evaluated, validating the sustainability of BioSs in the process with environmental impact reduction of 3–12%. Department of Pharmaceutical-Biochemical Technology School of Pharmaceutical Sciences University of São Paulo Department of Engineering of Bioprocesses and Biotechnology School of Pharmaceutical Sciences São Paulo State University (UNESP), Araraquara 14800-903 Department of Chemical Engineering Faculty of Industrial Technology Institut Teknologi Bandung, Jalan Ganesha No. 10 CESAM − Centre for Environmental and Marine Studies Department of Environment and Planning University of Aveiro Department of Bioresource Engineering Faculty of Agricultural and Environmental Sciences McGill University Department of Engineering of Bioprocesses and Biotechnology School of Pharmaceutical Sciences São Paulo State University (UNESP), Araraquara 14800-903

Submitted by Rosendo Parra Milian (rosendo.p.milian@unesp.br) on 2021-11-12T15:14:11Z No. of bitstreams: 1 Tese_DOUTORADO_Rosendo.pdf: 5479997 bytes, checksum: 795e9e327ca56b53def3dbd9d2145c1d (MD5) Approved for entry into archive by Ana Carolina Gonçalves Bet null (abet@iq.unesp.br) on 2021-11-16T11:00:09Z (GMT) No. of bitstreams: 1 milian_rp_dr_araiq_int.pdf: 5377596 bytes, checksum: 589fe50144ecff6dd7073eb0d2161611 (MD5) Made available in DSpace on 2021-11-16T11:00:09Z (GMT). No. of bitstreams: 1 milian_rp_dr_araiq_int.pdf: 5377596 bytes, checksum: 589fe50144ecff6dd7073eb0d2161611 (MD5) Previous issue date: 2021-10-27 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) O estudo da oxidação eletroquímica de etanol foi realizado em catalisadores baseados em nanopartículas de Pt e Pd suportadas em misturas de carbono e óxidos metálicos (MOx = Co3O4, Fe3O4, Sb2O3, In2O3 e Bi2O3). As nanopartículas de Pt e Pd foram sintetizadas pelo método de poliol modificado e de transferência de fases, respectivamente. Os materiais foram caracterizados por difração de raios X (DRX), microscopia eletrônica de transmissão (TEM), espectroscopia de absorção de raios X (XAS), e técnicas eletroquímicas (voltamentria cíclica, cronoamperometria). Os resultados da caracterização revelaram que o parâmetro de rede e a distância Pt-Pt nos catalisadores Pt/C-MOx são semelhantes aos de Pt/C, e que as nanopartículas de Pt tem tamanho médio de 2,8 nm e estão bem distribuídas nos suportes. As propriedades eletrônicas estudadas por XAS em meio ácido e alcalino revelaram que os suportes e a presença de etanol na solução modificam os estados eletrônicos da banda 5d da Pt. O desempenho eletrocatalítico para a reação de oxidação de etanol avaliado em solução ácida e alcalina mostrou que os catalisadores Pt/C-M3O4 (M=Co, Fe) apresentaram maior atividade em ambos os meios e o catalisador Pt/C-In2O3 somente em meio ácido, em relação ao catalisador Pt/C. Os resultados obtidos para os catalisadores Pd/C-MOx e Pd/C indicam que os materiais não apresentaram variação no parâmetro de rede do Pd, que as partículas de Pd tem tamanho médio de 2,6 nm, com distribuição homogênea no suporte. Os suportes híbridos afetam os estados eletrônicos da banda 4d do Pd. A atividade catalítica para oxidar etanol foi menor que a atividade do Pd/C. Embora tenham sido observadas variações de atividade catalítica para a oxidação de etanol e mudanças nas propriedades eletrônicas que dependem do óxido incorporado no suporte, não se encontrou uma correlação entre a atividade e os estados eletrônicos da banda d do metal catalisador. Pode se afirmar com base nos resultados que os diferentes suportes afetam a atividade catalítica da Pt e do Pd para oxidar etanol, envolvendo provavelmente efeitos eletrônicos e geométricos e a capacidade do óxido de fornecer espécies oxigenadas procedentes de hidroxilas adsorvidas na sua superfície. The study of the electrochemical oxidation of ethanol was carried out on catalysts containing Pt and Pd nanoparticles supported on mixtures of carbon and metal oxides (MOx = Co3O4, Fe3O4, Sb2O3, In2O3 and Bi2O3). Pt and Pd nanoparticles were synthesized by a modified polyol and by a phase-transfer method, respectively. The materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS) and by electrochemical techniques (cyclic voltammetry, chronoamperometry). The characterization results revealed that the lattice parameter and the Pt-Pt distance in Pt/C-MOx catalysts are similar to those of Pt/C, and that Pt nanoparticles have average size of 2.8 nm and are well distributed on the supports. The electronic properties studied by XAS in acid and alkaline media revealed that the supports and the presence of ethanol in the solution modify the electronic states of the Pt 5d band. The electrocatalytic performance towards ethanol oxidation evaluated in acid and alkaline solution showed that Pt/C-M3O4 (M=Co, Fe) catalysts exhibited higher activities in both media and the Pt/C-In2O3 only in acid, as compared to the Pt/C catalyst. The results obtained for Pd/C-MOx and Pd/C catalysts indicate that these materials do not show variations in the Pd lattice parameter and that Pd particles have mean size of 2.6 nm and are homogeneously distributed on the supports. The hybrid supports affect the electronic states of the Pd 4d band. The catalytic activity for ethanol oxidation was lower than the activity of Pd/C. Even though variations in catalytic activity for ethanol oxidation and changes in the electronic properties, which depend on the oxide incorporated to the support, were observed, a correlation between activity and the electronic states of the d band of the catalytic metal was not found. It is possible to say, based on the results, that the different supports affect the catalytic activity of Pt and Pd for the oxidation of ethanol, probably involving electronic and geometric effects and the capacity of the oxide to provide oxygenated species from hydroxyls adsorbed on their surface. 143270/2017-6

Orientador: Gilson Herbert Magalhães Dias Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica Mestrado

Recently, an electro-kinetic model based on a specified reaction scheme for the electro-oxidation of formic acid on platinum was reported. The model evaluated three reaction pathways towards the production of CO2: the dehydrogenation and the dehydration of formic acid, and the third and most active pathway includes fast oxidation of the formate ion. Numerical integrations showed that the model is well-suited to describe the experimental results in voltammetric and oscillatory regimes. In the present paper, we provide detailed stability phase diagrams characterizing the dynamical evolution of this system under galvanostatic and potentiostatic regimes. We find the triple-pathway electro-oxidation of formic acid on platinum to have rather intertwined stability phases and, surprisingly, a total absence of chaotic oscillations. To the best of our knowledge, this is the first study in this direction using a realistic electrochemical model.

Four new MPtAl2 (M=Ca, Sr, Ba, Eu) compounds, adopting the orthorhombic MgCuAl2 -type structure, have been synthesized from the elements using tantalum ampoules. All compounds are obtained as platelet-shaped crystallites and exhibit an increasing moisture sensitivity with increasing size of the formal M cation. Structural investigations indicate a pronounced elongation of the crystallographic b-axis, which results in a significant distortion of the [PtAl2 ]δ- polyanion. Within the polyanion, layer-like arrangements can be found with bonding Pt-Al interactions within the slab; the increase of the b-axis can be attributed to increasing Al-Al distances and therefore decreasing interactions between the slabs, caused by the differently-sized formal M cations. While the alkaline earth (M=Ca, Sr) representatives exhibit Pauli paramagnetism, BaPtAl2 shows diamagnetic behavior, finally EuPtAl2 is ferromagnetic with TC =54.0(5) K. The effective magnetic moment indicates that the Eu atoms are in a divalent oxidation state, which is confirmed by 151 Eu Mossbauer spectroscopic investigations. Measurements below the Curie-temperature show a full magnetic hyperfine field splitting with Bhf =21.7(1) T. 27 Al and 195 Pt magic-angle spinning NMR spectroscopy corroborates the presence of single crystallographic sites for the Pt and Al atoms. The large 27 Al nuclear electric quadrupolar coupling constants confirm unusually strong electric field gradients, in agreement with the structural distortions and the respective theoretical calculations. X-ray photoelectron spectroscopy has been utilized to investigate the charge transfer within the polyanion. The Pt 4f binding energy decreases with decreasing electronegativity / ionization energy of the alkaline earth elements, suggesting an increasing electron density at the Pt atoms. Theoretical investigations underline the platinide character of the investigated compounds by Bader charge calculations. The analysis of the integrated crystal orbital Hamilton population (ICOHP) values, electron localization function (ELF) and isosurface analyses lead to a consistent structural picture, indicating stable layer-like arrangements of the [PtAl2 ]δ- polyanion.

Orientador : Gilson Herbert Magalhães Dias Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica Doutorado

Submitted by Patricia dos Santos de Carvalho (patriciadecarvalho.42@gmail.com) on 2021-06-22T00:23:11Z No. of bitstreams: 1 Dissertação Final - Patricia dos Santos de Carvalho.pdf: 1921168 bytes, checksum: 0b4602b5247a119602c9d486a1535384 (MD5) Approved for entry into archive by Jacqueline de Almeida null (jacquie@franca.unesp.br) on 2021-06-22T14:46:56Z (GMT) No. of bitstreams: 1 Carvalho, P.S._me_franca.pdf: 1921168 bytes, checksum: 0b4602b5247a119602c9d486a1535384 (MD5) Made available in DSpace on 2021-06-22T14:46:56Z (GMT). No. of bitstreams: 1 Carvalho, P.S._me_franca.pdf: 1921168 bytes, checksum: 0b4602b5247a119602c9d486a1535384 (MD5) Previous issue date: 2021-06-11 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) A platina foi um metal amplamente empregado e manuseado pelos povos La Tolita-Tumaco, indígenas da América na confecção de máscaras e apetrechos. Devido a rigidez deste metal estes povos desenvolveram técnicas como a laminação em relevo, a soldadura e o ensamblado [técnica de união e ajustamento]. Após o contato dos europeus com a platina através do espanhol Antonio de Ulloa em 1735 e publicação do anúncio oficial deste contato em 1748 houve um impulso no interesse da Europa por este metal e diversos cientistas se sobre ele, estudando suas formas e manejo com o objetivo de conseguir desenvolver um método para sua purificação e aproveitamento. Muitas técnicas foram desenvolvidas e quase todas convergem para um ponto em comum: o uso de métodos criados pelos indígenas americanos. Como a ciência europeia incorporou este metal, aproveitou as técnicas indígenas de manuseio da platina e traduziu seus usos para uma sociedade de antigo regime é o que este projeto de pesquisa pretende compreender, tendo em vista o forte interesse das reformas bourbônicas por novos metais, sobretudo aqueles encontrados junto ao ouro e que contribuíam para sua falsificação, como é o caso da platina. Para alcançar os objetivos propostos foram pesquisadas fontes de duas naturezas, escritas e da cultura material, tais como algumas imagens de máscaras e ornamentos dos povos La Tolita-Tumaco confeccionados em ouro e platina, bem como as obras Relación histórica del viage a la América Meridional... [1748], de Antonio de Ulloa; da obra Introdución a la Historia Natural y a la Geografia Física de Espanha [1775], de Guillermo Bowles, a carta Several papers concerning a new semi-metal, called platina [1750] de William Brownring, além de fontes bibliográficas que trataram dos estudos realizados por Pierre-François Chabaneau e Joseph Louis Proust. A análise dos dados levantados neste grupo de fontes mostrou o viés etnográfico americano na mineralogia da época e revisou padrões difusionistas na narrativa da história da ciência. Platinum was a consecrated metal and handled by the La Tolita-Tumaco peoples, indigenous to America in the manufacture of masks and paraphernalia. Due to the rigidity of this metal, these people developed techniques such as embossing lamination, welding and assembly [joining and adjustment technique]. After the Europeans' contact with platinum through the Spanish Antonio de Ulloa in 1735 and the publication of the official announcement of this contact in 1748, Europe returned to the new metal and several scholars studied before a platinum to study it with the aim of achieving develop a method for the purification and handling of the metal. Many techniques have been developed and almost all converge on a common point: the use of methods created by the Native Americans. As European science incorporated this metal, it took advantage of the use of indigenous platinum handling technicians and translated its uses into an old regime society, as this research project understands, in view of the strong interest of Bourbon reforms in new metals, especially those found with gold and that contributed to its counterfeiting, as is the case with platinum. To achieve the proposed objectives, sources of two natures, written and of material culture, were researched, such as some images of masks and ornaments of the La TolitaTumaco peoples made in gold and platinum, as well as the works Relación histórico del viage a la América Meridional ... [1748], by Antonio de Ulloa; from Guillermo Bowles' Introduction to Natural History and Physical Geography of Spain [1775], by Guillermo Bowles, the letter Several articles on a new semimetal, called platinum [1750] by William Brownring, in addition to bibliographic sources that dealt with studies carried out by Pierre -François Chabaneau and Joseph Louis Proust, since the original works are not available online. From the group analysis of sources we can conclude about the American ethnographic weight in the development of mineralogy in the 18th century. 2019/03707-4

Dissertation submitted in partial fulfillment of a Philosophiae Doctor degree in Chemistry, The oxygen reduction reaction (ORR) is of central importance in the development of more efficient and durable fuel cells and computer simulations can be used to help explain and predict properties of ORR catalysts. In this thesis, various simulation methods are used, their accuracy tested, and some new tools developed for simulations of different types of ORR catalysts. The first part of the thesis presents a ReaxFF reactive force field study of the oxidation of platinum nanoparticles, the catalyst currently used in most fuel cells. The simulations make use of a grand-canonical Monte Carlo simulation approach to study the mechanism of oxidative nanoparticle degradation. Electrochemical oxidation phase diagrams are constructed and they show that stable surface oxides can form under fuel cell operating conditions. Furthermore, clusters of Pt6O8 stoichiometry are identified as the primary oxidation product and this provides a detailed, atomic scale mechanism for the degradation of platinum nanoparticle ORR catalysts. In the second part of the thesis, metal-free ORR catalysts are studied, namely nitrogen-doped graphene (NG). There, electron density functional theory calculations are used to estimate the thermodynamics of possible reaction paths and provide an estimate of the overpotential. Various density functional approximations are tested against high level diffusion Monte Carlo calculations on the binding and migration of an *O adatom on graphene, an important intermediate in the ORR. It is found that generalized-gradient approximation (GGA) functionals have low accuracy while some hybrid functionals and a self-interaction corrected GGA functional give good agreement with the reference calculation. A hybrid functional is then used to calculate the free energy of ORR intermediates to estimate the overpotential for various catalyst structures and compositions. While overpotentials are initially found to be unfavorable, the presence of water molecules at the catalyst surface is estimated to reduce the calculated overpotentials significantly. This shows that proper inclusion of the aqueous electrolyte is important. From this conclusion, a significant challenge arises as inclusion of many solvent molecules makes the simulated system too large for electronic structure calculations. In the third part of the thesis, a new methodology is developed to make it possible to include the aqueous electrolyte in simulations by using a hybrid simulation approach where part of the system — the catalyst as well as the reacting species and nearby water molecules — are included in the electronic structure calculation, while the rest of the aqueous electrolyte is described using a potential energy function. The separation between the two regions is made to lie through the aqueous phase in order to make it easier to describe the interaction between atoms on opposite sides of the boundary. Therein, the challenge is to enforce the boundary in such a way that atoms and molecules do not wander from one region to another. A new method referred to as scattering-adapted flexible inner region ensemble separator (SAFIRES) is developed for this purpose. It represents an improvement on a previous algorithm called FIRES. With SAFIRES, the boundary between the two regions is flexible and adjusts automatically but particles cannot move between the regions. It is demonstrated that using SAFIRES, the energy, atomic forces, and probability distribution for the location of atoms are reproduced accurately compared to results of simulations where where no boundary is present. The SAFIRES algorithm dynamically changes the time step in the iterative algorithm for time evolution to identify and enforce elastic collisions of atoms with the boundary separating the two regions. A new propagator is introduced to simulate the time evolution of the system with or without a connection to a heat bath. Tests are carried out by simulating a Lennard-Jones liquid, a Lennard-Jones liquid/solid interface, and water described using a potential energy function. With the SAFIRES method, along with the recently developed, self-consistent polarizable hybrid simulation methodology, the stage is set for proper inclusion of the aqueous phase at the electrode surface in future electrochemistry simulations., Supported by a PhD fellowship from the University of Iceland research fund

Pt/CeO2/C electrocatalysts in different compositions were prepared and their structural characteristics and activities for ethanol oxidation in alkaline media were evaluated. In the presence of CeO2, an increase in the platinum particle size was observed. XANES measurements indicated that the Pt d-band vacancies increased with increasing CeO2 amounts. For the first time, the decrease in electro activity was described to an electronic effect for high CeO2 contents. The dependence of the activity for ethanol oxidation on CeO2 content went to a maximum, due to the counteracting bifunctional and electronic effects of the metal oxide.

Orientador: Edson Tomaz Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química Resumo: Compostos orgânicos voláteis, ou COV, são uma importante classe de poluentes do ar comumente encontrados na atmosfera ao nível do solo, nos centros urbanos e industriais. O tratamento de COV provenientes de fontes industriais através da fotocatálise heterogênea é uma técnica eficiente para a degradação de baixas concentrações de uma grande gama de compostos orgânicos diferentes (hidrocarbonetos, aromáticos, alcóois, cetonas, etc) operando em condições ambientes. Um dos problemas que ainda impede sua aplicação industrial é a desativação do catalisador e por isso muitos grupos de pesquisa têm se dedicado ao estudo desta técnica na tentativa de melhorá-la e solucionar estes entraves. A atividade fotocatalítica do TiO2 pode ser melhorada pela adição de metais na sua superfície. Neste trabalho, preparou-se catalisadores de TiO2 por impregnação de Pt (1% m/m). A platina foi reduzida com NaBH4, fazendo-se posteriormente caracterização por DRX, XPS, UV ¿Vis, BET, Quimissorção de H2 e MEV/EDS para a validação do método de síntese. Todas as técnicas confirmaram que o método de redução com NaBH4 não modifica estruturalmente o TiO2, mantendo a sua cristalinidade e a razão de anatase/rutilo. A técnica de XPS indicou a presença de metal em estado de oxidação reduzido. Para o estudo da influência da impregnação de Pt no óxido titânio, foram realizados experimentos de fotocatálise em um reator recoberto com TiO2puro, e em um reator recoberto com TiO2/Pt variando-se a concentração de entrada (de 50 à 500 ppmv) ou o tempo de residência (de 10 à 50 s) para os COV n-octano, iso-octano, n-hexano e ciclohexano. Utilizou-se reatores tubulares com volume interno de 1160 ml com os catalisadores, dióxido de titânio puro ou modificado, imobilizados na parede interna dos reatores. A fonte de radiação UV foi uma lâmpada do tipo germicida de 100W de potência, caracterizada por comprimentos de onda de 254 nm (banda de emissão UV-C). As concentrações na entrada e na saída do reator foram analisadas através de um monitor contínuo de hidrocarbonetos do tipo FID. A adição de platina ao TiO2 gera uma melhoria na eficiência fotocatalítica nas reações de oxidação de COV; a conversão dos COV utilizando o catalisador impregnado com platina atingiu 99 % de conversão, enquanto que TiO2 puro atingiu, no máximo 93% Abstract: Volatile organic compounds, or VOC, are an important class of air pollutants commonly found in the atmosphere at ground level in urban and industrial centers. The treatment of VOC from industrial sources by oxidative photodegradation is presented as a good alternative. These systems are promising as pollution control technology, since they can decompose low concentrations of VOC efficiently and in ambient conditions. The recombination of electrons and holes formed on the surface of TiO2 is a factor that limits the photocatalytic efficiency. For this reason, many efforts have been made to maximize the separation of charges, in order to improve the photocatalytic efficiency. A proposed alternative is to add noble metals to TiO2 structure. This work aims to study the degradation of volatile organic compounds by heterogeneous photocatalytic oxidation using ultraviolet light, bare TiO2 and TiO2 impregnated with 1% w/w platinum as catalysts. TiO2 catalysts were prepared by impregnating Pt on TiO2 structure by reduction method with NaBH4. The photocatalysts were characterized using analytical techniques like XRD, XPS, UV-Vis Diffuse Reflectance, BET, H2 Chemisorption and SEM/EDS to validate the method of synthesis. All analysis confirmed that the reduction method with NaBH4 do not structurally modify TiO2, keeping its crystallinity and the ratio of anatase/rutile. XPS indicates the presence of metal in reduced oxidation state. To study the influence of the impregnation of platinum on titania, after synthesis and characterization, the study of gas-solid heterogeneous photocatalytic oxidation of some VOC was carried out at room temperature with annular plug flow reactors (1160 ml), one coated with pure TiO2 and another coated with TiO2/Pt, the catalysts were immobilized on reactor¿s internal walls. The photocatalystic tests were performed for n-octane , iso-octane, n-hexane and ciclohexane varying the inlet concentration (from 50 to 500 ppm) or residence time (from 10 to 50 s). The light source was an UV lamp (100 W, wavelengths with a maximum intensity at 254 nm. Reactants and products concentrations were analyzed using a continuous monitoring with a total hydrocarbon analyzer with flame ionization detector (FID). The addition of platinum to TiO2 improves photocatalytic efficiency of oxidation of VOC; conversion of the VOC using impregnated catalyst reached 99%, whereas pure TiO2 was at most 93%. No título do trabalho, a fórmula TiO2 deve vir com o "2" em subscrito, pois trata-se da fómula química da substância Mestrado Processos em Tecnologia Química Mestra em Engenharia Química

This paper presents a numerical method for simultaneous optimization of blank shape and forming tool geometry in three-dimensional sheet metal forming operations. The proposed iterative procedure enables the manufacturing of sheet metal products with geometry fitting within specific tolerances (surface and edge deviations less than 0.5 or 1.0 mm, respectively) that prescribe the maximum allowable deviation between the simulated and desired geometry. Moreover, the edge geometry of the product is affected by the shape of the blank and by an additional trimming phase after the forming process. The influences of sheet metal thinning, edge geometry, and springback after forming and trimming are considered throughout the blank and tool optimization process. It is demonstrated that the procedure effectively optimizes the tool and blank shape within seven iterations without unexpected convergence oscillations. Finally, the procedure thus developed is experimentally validated on an automobile product with elaborated design and geometry which prone to large springback amounts owning to complex-phase advanced high strength steel material selection.

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior FAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas Gerais Metalofármacos vêm sendo desenvolvidos com o intuito de minimizar os efeitos colaterais e/ou sobrepujar a resistência intrínseca ou adquirida aos medicamentos antitumorais disponíveis na clínica médica. Neste sentido, buscam-se também novos agentes farmacológicos capazes de curar ou de pelo menos aumentar a sobrevida de pacientes com tumores classificados como incuráveis até então. Considerando a necessidade de produção racional de novos agentes antitumorais, este trabalho descreve a síntese e caracterização estrutural de novos complexos de Pt(II) e Pd(II) do tipo [M(L1)2(L2)2] (L1 = derivados de 5-alquil-1,3,4-oxadiazol-2-tiona (5-alquil-odztH) e L2 = trifenilfosfina) e do tipo [M(L1)2L2] (L1 = derivados de 5-alquil-odztH ou 5-amino-1,3,4-tiadiazol-2-tiol (5amino-tdztH) e L2 = 1,10-fenantrolina). Os complexos de platina e paládio foram caracterizados por análise elementar, medidas de condutividade, espectrometria de massas em alta resolução com ionização por electrospray (HRESIMS), espectroscopia de infravermelho (FT-IR) e RMN multinuclear. Três complexos do tipo [Pt(L1)2(PPh3)2] e um complexo do tipo [Pt(L1)2fen] tiveram suas estruturas cristalinas determinadas por difração de raios-X por monocristais. Em todos os complexos, o íon metálico coordenou-se aos dois ligantes L1 via átomo de enxofre, no qual duas moléculas de trifenilfosfina ou uma de fenantrolina completam sua esfera de coordenação. Os valores de condutividade molar de soluções 1,0 × 10−3 mol L−1 confirmam que os complexos são não eletrólitos. A atividade citotóxica dos complexos [Pt(heptil-odzt)2fen] e [Pt(nonil-odzt)2fen] foi avaliada em duas linhagens de células tumorais (MCF 7 e MDA-MB-231), sendo o complexo [Pt(5 nonil odzt)2fen] mais ativo em ambas, uma vez que os seus valores de IC50 foram menores. Estudos de interação com o ADN para ambos os complexos revelaram valores de Kb na ordem de 104 M−1, não sendo observado nenhuma variação nas bandas positivas e negativas nos espectros de dicroísmo circular (DC). Por sua vez, nos espectros de fluorescência do sistema Hoechst ADN observou-se uma redução na intensidade de fluorescência, indicando que estes complexos interagem com o ADN por meio do sulco menor. Estas observações estão de acordo com o esperado para os compostos com propriedades lipofílicas, pois é observado que há uma melhora significativa tanto na atividade citotóxica quanto na interação com o ADN, do complexo cujo ligante apresenta uma cadeia alifática maior. Metal-based drugs have been developed in order to minimize side effects and/or to overcome intrinsic or acquired resistance to antitumor drugs available in medical clinics. In this sense, we are also looking for new pharmacological agents capable of curing or at least prolonging the survival of patients with tumors classified as incurable until then. Considering the need for rational production of new antitumor agents, this work describes the synthesis and structural characterization of new complexes of Pt (II) and Pd (II) of the type [M(L1)2(L2)2] (L1 = derived from 5-alkyl-1,3,4-oxadiazole-2-thione (5-alkyl-odztH) and L2 = triphenylphosphine) and of the type [M(L1)2L2] (L1 = derived from 5-alkyl-odztH or 5-amino-1,3,4- thiadiazole-2-thiol (5amino-tdztH) and L2 = 1,10- phenanthroline). The platinum and palladium complexes were characterized by elemental analysis, conductivity measurements, high-resolution electrospray ionization mass spectrometry (HRESIMS), infrared spectroscopy (FT-IR) and multinuclear NMR spectroscopy. Three complexes of the type [Pt(L1)2(PPh3)2] and one complex of the type [Pt(L1)2fen] had their crystalline structures determined by single-crystal X-ray diffraction. In all the complexes, the metal ion was coordinated with the two L1 ligands via a sulfur atom, in which two triphenylphosphine molecules or one phenanthroline molecule completes its coordination sphere. The molar conductivity values of 1.0 × 10−3 mol L−1 solutions confirm that the complexes are non-electrolytes. The cytotoxic activity of the [Pt(heptyl-odzt)2fen] and [Pt(nonyl-odzt)2fen] complexes was evaluated in two tumor-cell lines (MCF 7 and MDA MB 231), with the complex [Pt(5 nonil odztH)2fen] being more active in both, since their IC50 values were lower. DNA interaction studies for both complexes reveled Kb values on the order of 104 M−1, with no variation observed in positive or negative bands of circular dichroism (CD) spectra. In turn, in the fluorescence spectra of the Hoechst-DNA system, an observed reduction in fluorescence intensity indicated that these complexes interact with DNA through the minor groove. These observations are in line with what is expected for compounds with lipophilic properties, as it is observed that there is a significant improvement both in cytotoxic activity and in the interaction with DNA, of the complex whose ligand has a larger aliphatic chain. Tese (Doutorado)

Submitted by Thamires Mariano (thamires.mariano@unesp.br) on 2021-03-02T13:42:06Z No. of bitstreams: 1 Dissertação Thamires UNESP - Versão corrigida.pdf: 2651746 bytes, checksum: 0b04771632736695a4837f92414bc7a3 (MD5) Approved for entry into archive by Ana Carolina Gonçalves Bet null (abet@iq.unesp.br) on 2021-03-02T15:00:54Z (GMT) No. of bitstreams: 1 mariano_t_me_araiq_int.pdf: 2651746 bytes, checksum: 0b04771632736695a4837f92414bc7a3 (MD5) Made available in DSpace on 2021-03-02T15:00:54Z (GMT). No. of bitstreams: 1 mariano_t_me_araiq_int.pdf: 2651746 bytes, checksum: 0b04771632736695a4837f92414bc7a3 (MD5) Previous issue date: 2021-02-24 O trabalho visa aperfeiçoar métodos de síntese de baixo custo para preparar catalisadores à base de grafeno modificados com metais de transição para serem utilizados como eletrocatalisadores de algumas reações de interesse ambiental como a redução de oxigênio, de nitrogênio e eletro-oxidação de álcoois. A proposta de pesquisa é de cunho fundamental e está relacionada ao desenvolvimento de materiais simples e baratos com importância tecnológica e ambiental. Propôs-se sintetizar os catalisadores e avaliar sistematicamente a influência da rota de síntese nas propriedades caracterizadas. O grafeno foi preparado a partir do óxido de grafeno obtido pelo método adaptado de Marcano e colaboradores, para ser posteriormente modificado com platina pelo método do poliol com etilenoglicol. Os catalisadores foram caracterizados por difração de raios X (DRX), microscopias eletrônicas de varredura (MEV-FEG) e transmissão (MET), análise térmica (TG-DTA), espectroscopia Raman e espectroscopia de energia dispersiva de raios X (EDX). A caracterização eletroquímica geral foi realizada por voltametria cíclica (CV) em meio ácido e por cronoamperometria em meio ácido contendo metanol. Os métodos empregados produziram grafeno de alta qualidade e mostraram-se vantajosos pois a formação das partículas de platina e a redução do grafeno puderam ser realizadas em uma mesma etapa. Os resultados demonstram que foi possível obter partículas muito pequenas (1,5 nm), com alto grau de monodispersão e com excelente distribuição sobre o suporte de grafeno por meio de um método simples e barato. Espera-se que os resultados do projeto permitam estabelecer correlações entre propriedades e atividade catalítica de reações de interesse, contribuindo assim para o desenvolvimento de catalisadores mais eficientes para serem aplicados a sistemas de interesse ambiental. This work aims to improve low-cost synthesis methods to prepare graphene-based catalysts modified with transition metals to be used as electrocatalysts for some reactions of environmental interest such as the oxygen and nitrogen reductions, and electro-oxidation of alcohols. This is a fundamental research related to the development of simple and inexpensive materials with technological and environmental importance. It was proposed to synthesize the catalysts and systematically evaluate the influence of the synthesis on the characterized properties. Graphene was prepared from graphene oxide obtained by the adapted method of Marcano and coworkers, to be later modified with platinum by the polyol method with ethylene glycol. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission (TEM), thermal analysis (TG-DTA), Raman spectroscopy and energy-dispersive X-ray spectroscopy (EDX). The general electrochemical characterization was performed by cyclic voltammetry (CV) in an acidic medium and by chronoamperometry (CA) in methanol acidic solution. The methods employed produced high-quality graphene and proved to be advantageous since the formation of platinum particles and the reduction of graphene could be carried out in the same step. The results demonstrate that it was possible to obtain very small particles (1.5 nm), with a high monodispersion degree and with excellent distribution on the graphene support by means of a simple and inexpensive method. It is expected that the results of the project will make it possible to establish correlations between properties and catalytic activity of reactions of interest, and therefore contribute to the development of more efficient catalysts to be applied to systems of environmental significance.

Two isostructural trans-[MI2(CNXyl)2]·I2 (M = Pd or Pt; CNXyl = 2,6-dimethylphenyl isocyanide) metallopolymeric cocrystals containing uncommon bifurcated iodine···(metal–iodide) contact were obtained. In addition to classical halogen bonding, single-crystal X-ray diffraction analysis revealed a rare type of metal-involved stabilizing contact in both cocrystals. The nature of the noncovalent contact was studied computationally (via DFT, electrostatic surface potential, electron localization function, quantum theory of atoms in molecules, and noncovalent interactions plot methods). Studies confirmed that the I···I halogen bond is the strongest noncovalent interaction in the systems, followed by weaker I···M interaction. The electrophilic and nucleophilic nature of atoms participating in I···M interaction was studied with ED/ESP minima analysis. In trans-[PtI2(CNXyl)2]·I2 cocrystal, Pt atoms act as weak nucleophiles in I···Pt interaction. In the case of trans-[PdI2(CNXyl)2]·I2 cocrystal, electrophilic/nucleophilic roles of Pd and I are not clear, and thus the quasimetallophilic nature of the I···Pd interaction was suggested. peerReviewed

Coordination compounds of platinum(II) participate in various noncovalent axial interactions involving metal center. Weakly bound axial ligands can be electrophilic or nucleophilic; however, interactions with nucleophiles are compromised by electron density clashing. Consequently, simultaneous axial interaction of platinum(II) with two nucleophilic ligands is almost unprecedented. Herein, we report structural and computational study of a platinum(II) complex possessing such intramolecular noncovalent I⋅⋅⋅Pt⋅⋅⋅I interactions. Structural analysis indicates that the two iodine atoms approach the platinum(II) center in a “side‐on” fashion and act as nucleophilic ligands. According to computational studies, the interactions are dispersive, weak and anti‐cooperative in the ground electronic state, but strengthen substantially and become partially covalent and cooperative in the lowest excited state. Strengthening of I⋅⋅⋅Pt⋅⋅⋅I contacts in the excited state is also predicted for the sole previously reported complex with analogous axial interactions., From weak to strong: axial noncovalent interactions of platinum(II) center with two nucleophilic iodines are very weak, anti‐cooperative, and dispersive in nature in the ground electronic state. Depopulation of the anti‐bonding σ*(I⋅⋅⋅Pt⋅⋅⋅I) orbital in the excited electronic state results in substantial strengthening of the interactions, which become partially covalent and cooperative.