Resumo:
Arundo donax L., common name giant cane or giant reed, is a plant that grows spontaneously in different kinds of environments and that it is widespread in temperate and hot areas all over the world. Plant adaptability to different kinds of environment, soils and growing conditions, in combination with the high biomass production and the low input required for its cultivation, give to A. donax many advantages when compared to other energy crops. A. donax can be used in the production of biofuels/bioenergy not only by biological fermentation, i.e. biogas and bio-ethanol, but also, by direct biomass combustion. Both its industrial uses and the extraction of chemical compounds are largely proved, so that A. donax can be proposed as the feedstock to develop a bio-refinery.

Nowadays, the use of this non-food plant in both biofuel/bioenergy and bio-based compound production is just beginning, with great possibilities for expanding its cultivation in the future. To this end, this speech highlights the potential of using A. donax for energy and bio-compound production, by collecting and critically discussing the data available on these first applications for the crop.

Resumo:
Catalysis is a key technology of our modern societies, since it allows for increased levels of selectivity and efficacy of chemical transformations. While significant progress can be made by rational design or engineered step-by-step improvements, many pressing challenges in the field require the discovery of new and formerly unexpected results. Arguably, the question "How to discover?" is at the heart of the scientific process.
In this talk, strategies and discoveries from the Glorius group will be discussed. Topics will involve the use of N-heterocyclic carbenes¹ in different fields of catalysis^2-3 and also photocatalysis.^4-5



References
1. Hopkinson, M. N.; Richter, C.; Schedler, M.; Glorius, F. Nature 2014, 510, 485.
2. Wiesenfeldt, M. P.; Nairoukh, Z.; Li, W.; Glorius, F. Science 2017, 357, 908.
3. Wang, G.; Rühling, A.; Amirjalayer, S.; Knor, M.; Ernst, J. B.; Richter, C.; Gao, H.-J. ; Timmer, A.; Gao, H.-Y.; Doltsinis, N. L.; Glorius, F.; Fuchs, H. Nat. Chem. 2017, 9, 152.
4. Hopkinson, M. N.; Gomez-Suarez, A.; Teders, M.; Sahoo, B.; Glorius, F. Angew. Chem. Int. Ed. 2016, 55, 4361.
5. Candish, L.; Teders, M.; Glorius, F. J. Am. Chem. Soc. 2017, 139, 7440.

Resumo:
A eletro-oxidação de moléculas orgânicas pequenas é uma área ativa de pesquisa em eletrocatálise, principalmente pelo seu papel na inter-conversão entre energias química e elétrica. Além da cinética lenta a baixas temperaturas e alguns aspectos mecanísticos ainda desconhecidos, esses sistemas também são conhecidos por apresentar cinética oscilatória e auto-organização espaço-temporal em intervalos de parâmetros consideravelmente amplos. Serão apresentados nessa palestra os últimos desenvolvimentos do Grupo de Eletrqouímica do IQSC/USP na eletro-oxidação oscilatória de moléculas orgânicas pequenas sobre platina e em superfícies à base de platina. Os resultados incluem experimentos em poli- e monocristais, modelagem e simulações numéricas, e são discutidos em conexão com a literatura atual. Também são apresentadas algumas perspectivas e orientações para futuras pesquisas.

Resumo:
Clouds of atoms, ions and excited chemical species are usually generated at high temperatures. Flames, electrothermal atomizers, plasmas and lasers are frequently used for providing thermal energy and consequent formation of these species. In this sense, I will discuss how tungsten coils and argon plasmas are used for generating atoms and ions in ground and excited states. These species are used for measurements based on atomic absorption, atomic and ionic emission, and also mass/charge ratios. Instruments, applications, and analytical performance will be discussed with emphasis on selectivity and chemical processes. Aspects related to costs of instrumentation and funding for research will also be commented.

Resumo:
Supramolecular assemblies made of multifunctional biomimetic polyelectrolytes are of great interest in biophysical, bioanalytical, and biomedical fields. Normally these structures are formed by electrostatic interactions, e.g. by layer-by-layer (LbL) films between chains of opposite charge, or by interaction with charged surfaces or molecules. Modification of polyelectrolyte chains with hydrophobic and/or reactive pendant groups can introduce new alternatives for the construction and properties of these supramolecular assemblies, e.g. size, shape, film thickness, mechanical stability, permeation, etc.

In this talk, are presented recent studies from our lab regarding the preparation and characterization of supramolecular structures prepared with DNA-bioinspired polyelectrolytes containing vinylbenzylthymine (VBT) and vinylbenzyltriethylammonium chloride (VBA) or sodium vinylphenylsulfonate (VPS) monomers, to form polyelectrolytes of general structure {[(VBT)(VBA)_m]^m+}_n or {[(VBT)(VPS)_m]^m-}_n with m = 1, 2, 4 and 8 and n = 20-40.

The DNA-bioinspired polyelectrolytes were used for the preparation of hydrogels containing nanoclays and redox enzymes for the preparation of bioelectrodes and their application in chemical sensing in food matrices; hollow microcapsules with mechanical stability and solute permeability modulated by photo-crosslinking of polyelectrolyte chains by dimerization of thymine pendant groups; stabilization of silver nanoparticles, and interaction with the xanthene dye Eosin Yellow to form supramolecular aggregates with optimal photosensitizing properties.

In summary, the DNA-bioinspired polyelectrolytes {[(VBT)(VBA)_m]^m+}_n are {[(VBT)(VPS)_m]^m-}_n are versatile molecules behaving as a "Swiss Army knife" for the preparation of supramolecular assemblies with application in biosensing, drug delivery, nanoparticle stabilization and photosensibilization.

Resumo:
Gels are a part of broad class of materials, commonly referred to as 'soft matter.' By definition, gels are comprised of a relatively small concentration of a small molecule or polymer that forms a 3-dimensional network that immobilizes macroscopically a liquid component via capillary forces and surface tension. Results from studies of some structurally simple molecular and polymeric gelators developed at Georgetown and the properties of their organo- and hydro-gels in a variety of liquids will be presented. Different modes by which sol/solution phases can be transformed into their corresponding gels will be described as well. Dynamic and structural aspects of the gels at different distance and time scales will be discussed. Results from oscillatory and extensional rheology will be employed to assess some of the dynamic properties, including their thixotropy and ability to be self-healing and self-standing. Analyses of X-ray diffraction, neutron scattering, and optical microscopy experiments will be used to describe the self-assembled fibrillar networks of the molecular gels and the crosslinked networks of the polymeric gels.

Several examples of the realized and potential application of the gels for oil spill recovery and conservation of objects of cultural heritage will be presented as well. They will include: (1) the use of a small well that has been developed to determine the influence of wave action on the viscoelastic properties of gel layers on water; (2) how surfaces of paintings, frescos, and sculptures can be treated to remove different types of unwanted coatings; and (3) how halogenated pollutants in water supplies can be removed by iron zero nanoparticles embedded in gel layers. In each case, the methods used to analyze the systems before and after treatment will be discussed.

Resumo:
Recently, the growing population has led to the increase of world food production and the intense use of pesticides in agriculture. This current outlook is still aggravated because organophousphorus (OP) compounds, which are potent EPSP synthase inhibitors, are the most widely used pesticides. Accordingly, their persistent overuse worldwide has caused accumulation of their compounds in food, fertile land or wasterwater runoff. Thus, it is also important to mention that the action of OP compounds, as toxic compounds and acetylcholinesterase (AChE) inhibitors, is well known. In fact, those compounds are able to stop the hydrolysis of the neurotransmitter acetylcholine and can lead to an irreversible inhibition of the AChE enzyme (aging), thus causing the cholinergic syndrome. In this line, the high frequency of contamination by pesticides suggests the need for more active and selective agrochemicals. As such, molecular modeling studies using molecular dynamics simulations and DFT techniques were performed to understand the interaction and the action mechanism of OP compounds with the wild type enzyme and Gly96Ala mutant EPSP synthase. In addition, we investigated the reaction mechanism of the natural substrate. It is also important to keep in mind that organotin compounds are also the active components of some fungicides, which are potential inhibitors of the F1F0-ATP synthase. Studies about the reaction mechanism can indicate a pathway to understand how these compounds work in biological systems. In this line, molecular modeling studies, quantum calculations and experiments were performed in order to understand the molecular behavior of those compounds in solution and in the enzyme active site. Our findings indicate some key points for the design of new and more selective agrochemicals. The insightful microscopic explanations for the biological and physical-chemical properties can demonstrate the power of joint experimental-computational approaches to environmental problems.

Resumo:
O monitoramento de parâmetros químicos e físico-químicos em matrizes ambientais é fundamental para controle de qualidade e classificação. A utilização de sistemas de ICP-MS representa praticidade e excelentes parâmetros de desempenho para o atendimento de normas ambientais. Nesta apresentação, mostraremos os recentes resultados obtidos com o sistema de ICP-MS 7800 Agilent em parceria com a Universidade Federal de São Carlos, onde diferentes amostras de água foram analisadas usando recursos de hardware diferenciais.

Resumo:
Tetrapyrrole macrocycles encompass a venerable set of enzymatic cofactors (heme, vitamin B₁₂, F₄₃₀) and photosynthetic pigments (chlorophylls, bacteriochlorophylls) of great interest across numerous disciplines including biology, chemistry, medicine, energy and materials sciences. Our interests – originating in a desire to better understand photosynthetic processes – have prompted a lifelong focus on development of synthetic methodology for preparing tetrapyrrole macrocycles. We now have in hand straightforward methods for the preparation of porphyrins and various hydroporphyrins including the chlorins and bacteriochlorins (analogues of chlorophylls and bacteriochlorophylls) and some simple analogues of corrins (similar to vitamin B₁₂). Yet much remains to be done in methodology to achieve high efficiency and broad scope. In this regard, we have recently begun investigating the biosynthesis of novel hydroporphyrins known as tolyporphins, which are found in a novel cyanobacterial strain (that may be similar to strains classified as Brasilonema). Our objective is to gain control of the enzymes and ultimately develop methods of chemoenzymatic syntheses of diverse hydroporphyrins. In the meantime, we are exploiting syntheses of tetrapyrrole macrocycles to explore fundamental photophysical issues including the origin of panchromaticity in novel dyads composed of a chromophore–tetrapyrrole joined via an ethynyl linkage. Other ongoing studies concern the development of a palette of tetrapyrroles suitable for use as fluorescent labels in clinical diagnostics. A longstanding interest concerns the esoteric (and unresolved) issue of how tetrapyrroles might have originated under prebiotic conditions. In short, the studies in synthesis and application have yielded more questions than answers concerning the fascinating family of tetrapyrrole macrocycles.

Resumo:
Organisms interact with each with other in Nature, and organic compounds play an important role in mediating such complex cross-talk. Microorganisms are ubiquitous in all environments and are frequently associated with other organisms (hosts), such as plants, invertebrates, vertebrates, etc. Indeed, the metabolic capabilities of microorganisms enable hosts to access chemical diversity unavailable from their genomes. Therefore, studies of microbial symbionts allow understanding the molecular basis of interspecies interactions and evolution, and also lead to chemical innovation.

Our research group has been focusing on microbial symbionts of plants and social insects in natural products research. We have been studying endophytes –symbiotic microorganisms living inside plant tissues causing no symptoms of disease – and microbial symbionts of social insects – such as leaf-cutter ants, myrmecophytes, and stingless bees. The main goals are to decipher the role of small molecules in symbiotic interspecies interactions, and to take advantage of this knowledge to rationally guide the discovery of useful biologically active compounds. Modern analytical methods combined with biological experiments and genome sequencing are applied to achieve these goals.

In this presentation, I will discuss recent results on the understanding of chemical signaling between endophytic communities of medicinal plants. Microbial chemical signaling in insect systems will also be presented to highlight the intricate symbiosis in leaf-cutter ants and stingless bees. Finally, examples will be addressed to illustrate the successful strategy of using the chemical ecology-driven approach for the discovery of biologically active natural products.

Resumo:
A multiplicidade de exigências da sociedade atual faz do ser humano um ser multidimensional ao qual a educação precisa responder. As diferentes produções culturais humanas configuram-se, assim, como uma possibilidade para fomentar a ampliação das dimensões educativas. Nesse sentido, a presente conferência tem por finalidade estabelecer elos entre o conhecimento químico e artístico no contexto educacional e, mais especificamente, da educação química. Pautado em bases teóricas da psicologia e da semiótica social, as artes serão focadas como via de ampliar as experiências e as formas de pensar o mundo sob o viés científico, na medida em que possibilitam suscitar o desenvolvimento de diferentes dimensões humanas (cognitivas, estéticas, éticas, lúdicas, afetivas). Ao tocar o sujeito em diferente aspectos, ciência e arte favorecem o engajamento; condição psicológica essencial para a aprendizagem; abrindo, portanto, caminhos para o desenvolvimento social e cognitivo. A exploração das dimensões afetivo-cognitivas permite que a ciência química seja contemplada estética e criticamente, o que tornaria seu ensino mais prazeroso, rigoroso e eficaz. Para tanto, a apresentação será divididade em três partes de igual importância. Na primeira parte, a partir de exemplos concretos, buscar-se-á mostrar o papel da arte em ampliar as reações cognitivas dos sujeitos a partir da dimensão estética. Na segunda parte estabelecer-se-ão as conexões e a fundamenteção teórica entre ciência (química) e arte calcadas em referenciais advindos da psicologia e semiótica. Na última parte serão apresentadas pesquisas empíricas concatenando química, arte e educação: seriam os resultados soluções ou precitações?

Resumo:
The solar fuel production through artificial photosynthesis is attracting a great deal of attention due to its potential application for sustainable solar energy harvesting, storage and utilization. The popularization of such technology relies heavily on the development of suitable photo-electrodes that are efficient, thermally and chemically stable in aqueous environment, inexpensive and capable of harvesting the visible sunlight. However, the underlying physicochemical properties that govern these processes are not yet fully resolved, hindering the rational design of suitable photo-electrodes. In this talk, such properties will be discussed in the light of complementary computational materials science methods. First, the band-edge alignments, relevant to favor the charge transfer reactions, are analyzed from quasi-particle theory using GW-approximation based on density functional theory (DFT). Second, the optical properties will be discussed by meanings of time-dependent DFT.

Special attention is given to graphitic-C₃N₄ and polymeric organic photo-catalysts. The effect of Schottky barriers, and interface engineering, on the catalytic performance will be discussed within the context of 2D electrocatalysts, e.g. MoS₂. Here, the thermodynamics of the hydrogen evolution reactions are assessed via self-consistent reaction field methods in combination with DFT. Finally, first-principles theory to calculate the X-ray photoelectron spectroscopy (XPS) properties and the near edge X-ray absorption fine structure (NEXAFS) are employed with the aim of fingerprinting possible reaction pathways in aqueous environment.

Resumo:
Nowadays, our ability to develop chemical based procedures permits us to produce an enormous variety of well-defined nanomaterials with highly controlled composition, size, shape and surface features. The rich field of nanochemistry, based in the reproducible production of nanobuilding blocks (NBB) with tunable properties, is one of the pillars of current nanotechnology. The combination of NBB synthesis with self-assembly processes led to a significant advance in the production of more complex hybrid inorganic-organic materials with hierarchical structures and localized functions. Our ability to produce highly precise complex architectures with well-defined localized functions that can interact with each other opens the path to create intelligent matter that can change their physical or chemical properties in response to the environment. Programmable nanosystems can be envisaged, in which confinement effects, responsivity, or collaborative functionality can be imparted into the structure through the control of positional chemistry of different chemical building blocks.

In this presentation, we will illustrate the richness of this emergent field by focusing in mesoporous materials (MM). Mesoporous architectures can be produced through the self-assembly of inorganic nanobuilding blocks in the presence of supramolecular templates. MM can then be decorated by small molecular species, biomolecules, polymers or nanospecies. An amazing variety of chemical behaviors can be programmed into these structures, from tunable catalysis to light guiding or responsiveness to external stimuli. In addition to synthetic and characterization tools, theoretical models and simulations are essential to understand the complexity of the synthesis paths and the final properties. This in-depth knowledge is key to evolve from materials synthesis to ultimate nanosystems design. We will present examples of tunable catalysts, enzyme cascade hosts, intelligent bioscaffolds, remotely activated nanoparticles, chemical-to-optical transducers or perm-selective membranes. A potentially infinite variety of nanosystems with externally controllable behavior is at our disposal, opening the path to design intelligent matter.

Resumo:

The interface between supramolecular chemistry and transition metal catalysis has received surprisingly little attention in contrast to the individual disciplines. It provides, however, novel and elegant strategies that lead to new tools for the search of effective catalysts, and as such this has been an important research theme in our laboratories. In this presentation I will focus on supramolecular strategies to control activity and selectivity in transition metal catalysis, which is especially important for reactions that are impossible to control using traditional catalyst development. For substrates with functional groups we use substrate orientation effects to control selectivity, whereas for non-functionalized substrates we create cages around the active transition metal. What these strategies have in common is the contribution of the second coordination sphere to the catalytic properties, which is quite different from the traditional ligand effects. More recently, we also explored the use of large nanospheres that allows to perform catalysis at high local concentrations, leading to rate acceleration for several different reactions. These nanospheres can also be used for electrochemical events and as such for water oxidation and proton reduction catalysis. The lecture will focus on our most recent results.

Figure 1. An example of template assembly of a caged catalyst, substrate pre-organization at the metal complex for selective hydroformylation and a nano-cage for catalyst/substrate pre-organization

1) For reviews see: 1) Reek et al "New directions in supramolecular catalysis," Nature Chemistry, 2010, 2, 615. 2) Reek et al, "Transition metal catalysis in confined spaces" Chem. Soc. Rev, 2015, 44, 433 – 448 3) Reek et al , "Supramolecular control of selectivity in transition-metal catalysis through substrate preorganization" Chem. Sci, 2014, 5, 2135

2) Substrate preorganization: Reek et al. Angew. Chem. Int. Ed., 2013, 52, 3878; Nature Protocols, 2014, 9, 1183 J. Am. Chem. Soc. 2013 135, 10817; Angew. Chem. Int. Ed., 2017 in press

3) Nanospheres: J.N.H. Reek et al., Nature Chemistry, 2016 8, 225-230; Angew. Chem., Int. Ed., 2014, 52, 13380–13384.

Resumo:
O Laboratório de Química Orgânica Sintética (LQOS), no instituto de Química da Unicamp firmou, em março de 2013, um acordo de cooperação inédito na América Latina, com a Drugs for Neglected Diseases initiative (DNDi, www.dndi.org/) e com a Medicines for Malaria Venture (MMV, www.mmv.org/), com o objetivo de desenvolver novos medicamentos e tratamentos para doenças parasitárias tropicais negligenciadas como malária, Doença de Chagas e leishmaniose visceral. O projeto envolve otimização de compostos líderes visando o desenvolvimento de candidatos clínicos para tratamento de doenças parasitárias tropicais em colaboração com a DNDi e com a MMV. Este modelo de projeto, inédito no Brasil, permitirá avançar na cadeia de descoberta de medicamentos para o tratamento de doenças tropicais parasitárias no País e envolve colaborações entre o LQOS no IQ-UNICAMP, a DNDi, a MMV, O IFSC-USP São Carlos, através do Centre for Research and Innovation in Biodiversity and New Drugs-CIBFAR e várias instituições acadêmicas, institutos de pesquisas e grandes farmacêuticas mundiais. O objetivo da parceria com a DNDi é entregar um composto de alta qualidade, otimizado e pronto para desenvolvimento clínico, para o tratamento da Doença de Chagas e da leishmaniose visceral (LV). O candidato clínico almejado deverá combinar a eficácia anti-protozoários com um perfil de segurança aceitável e propriedades farmacocinéticas e físico-químicas compatíveis com a administração oral. O objetivo da parceria com a MMV é fornecer um candidato clínico para o tratamento da malária, com potencial de ser desenvolvido, em combinação, com o objetivo de criar cura radical em dose única e profilaxia e/ou um medicamento com quimioproteção em dose única. Um candidato clínico de um modo geral precisa ter potência contra parasitas relevantes, baixa propensão para gerar resistência, eficácia oral em modelos de roedores, bom perfil de segurança e baixo custo final. A DNDi e a MMV estão fornecendo ao projeto moléculas de alta qualidade, alinhadas com um perfil de produto alvo (TPP) de interesse. A equipe vai investigar as relações estrutura-atividade nestas séries, entregar candidatos clínicos e elucidar novos mecanismos de ação.


Title: Lead optimization programs to discover new drugs for the treatment of parasitic tropical neglected diseases in collaboration with MMV and DNDi

Abstract:
In March 2013 we initiated a collaboration with DNDi (Drugs for Neglected Diseases initiative, www.dndi.org), a nonprofit organization, designated LOLA (Lead Optimization Latin America). LOLA´s mission is to discover and develop new drugs for the treatment of parasitic tropical diseases with an emphasis on Chagas disease and visceral leishmaniasis. At the same time, we initiated a collaboration with MMV (Medicines for Malaria Venture, www.mmv.org), also a nonprofit organization, designated Brazil Heterocycles. A key element of these projects is to exploit published active compounds, including those from the MMV Open Access Malaria Box, as starting points to discover a compound that could ultimately be used for the prevention and treatment of malaria. The approach of the MMV/DNDi/UNICAMP/USP consortium is to use drug discovery leads from both the MMV and DNDi as starting points to deliver clinical candidates meeting the target product profiles (TPPs) for malaria, Chagas disease and visceral leishmaniasis (VL). A clinical candidate broadly speaking needs to have potency against relevant parasites, a low propensity to generate resistance, have oral efficacy in rodent models, good developability, a good safety profile, low cost of goods, and good solid state properties. This collaboration with both DNDi and MMV is unprecedented in Brazil and will help to advance drug discovery of poverty-related diseases endemic to the country. This project involves collaborations with the University of Sao Paulo at Sao Carlos, Centre for Research and Innovation in Biodiversity and New Drugs-CIBFAR (IFSC-USP, Brazil), and several academic institutions and pharma companies abroad.