Modern society is entirely dependent on the products of the chemical industry. Common articles from furniture to clothes and from mobile phones to pharmaceuticals all require chemicals.  But traditional supply chains for chemicals are not sustainable.  The feedstocks are often based on limited resources, the manufacturing employs old chemistry that is dangerous and wasteful, the chemicals are often not environmentally compatible and the final articles can end up thrown away causing environmental pollution.  The bio-resources of Brazil represent a great opportunity for new supply chains starting with a renewable resource; with green chemistry methods to add value through benign extraction and downstream chemical conversions, we have the opportunity to build a new family of truly green and sustainable chemicals to feed our consumer goods companies.  In my talk I will consider examples of how this can work, and in a way that is economically feasible as well as environmentally sound and socially acceptable.  The examples will be based on a range of feedstocks including agricultural residues and food processing by-products and waste.

The research of our group has always been related with the study of natural products, in particular the Amaryllidaceae alkaloids, which are nearly exclusive to plants of the Amaryllidaceae family.  The first alkaloid isolated from this plant family was lycorine, obtained from Lycoris radiata in 1877 and since then, more than 400 alkaloids have been isolated, many of them with interesting biological and pharmacological properties.
In an early phase, our research was focused on the genus Narcissus, which is distributed in the Mediterranean area, and is an important source of lycorine and homolycorine type alkaloids. Unexpectedly, one of the species studied, N. confusus, was found to have a remarkably high content of galanthamine, an alkaloid that inhibits the enzyme acetylcholinesterase and is used for the palliative treatment of Alzheimer’s disease (Reminyl®).
We went on to study several Amaryllidaceae species used in the traditional medicine of South Africa, which, together with Latin America, is the main centre of diversification of this plant family. It is worth noting that the predominant alkaloids in the South African species are of the crinine type with the ethane bridge in beta, which are absent in the species of the genus Narcissus.
Currently we are focused on finding new sources of galanthamine since, although its synthesis has been successfully accomplished, pharmaceutical manufacture continues to rely on the extraction of the natural product from Leucojum aestivum. We are also searching for new natural products in Central and South American countries as potential lead compounds for therapeutic purposes. In this context, in recent studies we have shown that haemanthamine type alkaloids, with the ethane bridge in alpha, present a very selective apoptotic activity against tumour cells. Additionally, we are testing the new isolated compounds for antiprotozoal activities (against malaria, leishmania, Chagas’ disease and sleeping sickness).
Finally, we are developing docking studies of these compounds for predicting inhibitory activity against several key enzymes (acetylcholinesterase, GSK-3 etc.), thus avoiding the necessity to isolate a high number of inactive compounds.

The single chirality of biological molecules has fascinated scientists and laymen alike since Pasteur’s first painstaking separation of the enantiomorphic crystals of a tartrate salt over 150 years ago. In the past decade, a number of theoretical and experimental investigations have helped to delineate models for how one enantiomer might have come to dominate over the other from what presumably was a racemic prebiotic world.  Our work has highlighted mechanisms that include either chemical or physical processes, or a combination of both. While much of the scientific driving force for this work arises from an interest in understanding the origin of life, research focusing on mechanisms for the enantioenrichment of chiral molecules has the potential to impact a wide range of applications, most notably in the synthesis and formulation of pharmaceuticals.

There has been tremendous interest in recent years to study two-dimensional atomic layers which form building blocks of many bulk layered materials. This was initiated by the spectacular discovery of graphene. This talk will focus on the materials science of graphene and the emerging field of 2D atomic layers beyond graphene. Several aspects that include synthesis, characterization and device fabrication will be explored with the objective of achieving all 2D functional structures for future technologies. The concept of nanoscale engineering and the goal of creating new artificially stacked van der Waals solids will be discussed through a number of examples including graphene and other 2D layer compositions. The talk will explore the emerging landscape of 2D materials systems that include graphene, boron-nitrogen-carbon systems, and a large number of transition metal dichalcogenide compositions. Some of anticipated applications of these materials will also be discussed.

It is now 50 years since the first molecular dynamics simulation of liquids using realistic potentials were pioneered by Aneesur Rahman. In this talk we will discuss the developments of these methods that have resulted in the accurate modelling of interfaces and to the prediction of the surface tension of a simple liquid. Here the simulation can be used to test the in two-body and three-body intermolecular potentials that describe the gas-liquid interface.

The lubrication of surfaces coated with polymers is an important technological problem and one that is difficult to solve effectively using non-equilibrium molecular dynamics with atomistic models. The timescale of the simulation is such that shearing rates that can be achieved are many orders of magnitude higher than those observed in experiment. This problem can be addressed in part by switching to a mesoscale model, which still preserves the important elements such as the shape and charge of the adsorbed polymers but allows for a longer in-silico time step.

We conclude that the kinetic friction coefficient between charged brushes is higher than that of neutral brushes at low compressions and smaller at high compressions. We also show that it is possible to simulate ultra-low friction coefficients, comparable with experiments, using the smallest shear rate accessible in a mesoscale simulation. The unexpected behaviour of the shear deformation-induced structural heterogeneities in charged polymer brushes calls for further experiments to elucidate this local reorganization of the ions in adsorbed charged polymers.

A maior compreensão das bases moleculares das doenças associada à completa caracterização do genoma humano em 2001, tem permitido a identificação de um número crescente de alvos terapêuticos e novas vias de sinalização celular passíveis de serem exploradas no desenvolvimento de fármacos inovadores. Estes avanços permitiram mapear redes de interações entre diferentes alvos farmacológicos relacionados a gênese de uma determinada doença (network pharmacology) e compreender porque doenças multifatoriais, e.g. asma brônquica, artrite reumatoide, esquizofrenia, diabetes mellitus e o câncer, são muito pouco responsivas a terapia mono-alvo. Nestes casos, a baixa eficácia é facilmente explicada pelas interações polifarmacológicas entre algumas proteínas humanas, criando mecanismos de comunicação intracelulares robustos e cooperativos capazes de contornar perturbações induzidas pela ação de um simples fármaco na resposta produzida por um dos seus constituintes, que resultam em redução de sua eficácia e/ou aumento de sua toxicidade relativa. Por esta razão, a abordagem “uma doença-múltiplos alvos” que explora a ação de um ou mais fármacos em mais de uma biomacromolécula-alvo relacionada à gênese de um processo patológico de cunho multifatorial, vem ganhando crescente destaque na literatura internacional. Esta abordagem de terapia polifarmacológica consiste em combinar em um só fármaco as características estruturais necessárias para permitir seu reconhecimento molecular por mais de um diferente biorreceptor envolvido na gênese da doença alvo. Esta estratégia, explorada no passado para o desenvolvimento de ligantes de ação dupla, teve sua terminologia alterada para fármacos multialvos,de forma a contemplar substâncias bioativas que atuam em mais de dois alvos moleculares, de forma não promíscua.

Neste contexto, nosso grupo de pesquisas vem envidando esforços no desenvolvimento de fármacos multialvos racionalmente planejados com base na estrutura de ligantes seletivos ou dos receptores que se deseja modular, através da cuidadosa aplicação de algumas estratégias da Química Medicinal para a adequada combinação de grupos farmacofóricos necessários ao seu reconhecimento molecular pelos biorreceptores alvo com afinidade e eficácia adequados, como a hibridação molecular. Nesta apresentação, descreveremos a gênese estrutural e o perfil farmacológico de novos protótipos multialvos capazes atuar em doenças crônico-degenerativas de alta prevalência, como a hipertensão arterial pulmonar, a artrite reumatoide e o câncer, explorando o grupamento N-acilidrazona (NAH) como estrutura privilegiada.

Referências selecionadas: Duarte, C. D.; Barreiro, E. J.;  Fraga, C. A. M. (2007) Mini Rev. Med. Chem. 7, 1108-1119; Kümmerle, A. E.; Schmitt, M.; Cardozo, S. V. S.; Lugnier, C.; Villa, P.; Lopes, A. B.; Romeiro, N. C.; Justiniano, H.; Martins, M. A.; Fraga, C. A. M.; Bourguignon, J.-J.; Barreiro, E. J. (2012) J. Med. Chem., 55, 7525-7545; Alencar, A. K. N.; Pereira, S. L.; Montagnoli, T. L.; Maia, R. C.; Kümmerle, A. E. ; Landgraf, S. S. ; Caruso-Neves, C. ; Ferraz, E. B. ; Tesch, R. ; Nascimento, J. H. M.; Santanna, C. M. R.; Fraga, C. A. M.; Barreiro, E. J.; Sudo, R. T. ; Zapata-Sudo, G. (2013) Brit. J. Pharmacol., 169, 753-762; Barreiro, E. J.; Kummerle, A.E.; Fraga, C. A. M. (2011) Chem. Rev. 111, 5215-5246; Alencar, A. K. N.; Pereira, S. L.; DaSilva, F. E.; Mendes, L. V.P.; Cunha, V. M. N.; Lima, L. M.; Montagnoli, T. L.; Caruso-Neves, C.; Ferraz, E. B.; Tesch, R.; Nascimento, J. H. M.; Sant’Anna, C. M. R.; Fraga, Carlos A. M.; Barreiro, E. J.; Sudo, R. T.; Zapata-Sudo, G. (2014) Int. J. Cardiol., 173, 154-162.
SUPORTE FINANCEIRO: FAPERJ, CNPq, INCT-INOFAR

Commonly used heterogeneous catalysts often involve supported metallic nanoparticles, oxides and sulfides being among the most popular types of supports. The final activity of a supported catalyst is the result of delicate interplay between particles size, nature of the support and metal-support interface leading to a very rich but also complex chemistry. To optimize the performance of supported catalysts it is necessary to discern the contribution of each of these effects to the final catalytic activity and selectivity. This is, however, not a simple task requiring the use of model systems either from experiment and theory. Two examples will be used to illustrate how a combined use of computational modeling and experiment on model systems under controlled conditions allows us to gain detailed understanding of the chemistry behind a reaction taking place on a supported catalyst. The firs example involves the water gas shift (WGS) reaction catalyzed by Pt/CeO2 whereas the second one correspond to recent work regarding CO2 hydrogenation to methanol catalyzed by a new class of catalysts consisting of Cu or Au nanoparticles supported on TiC. In the case of the WGS, we will show that small Pt nanoparticles are the most active and that the activity involves the reduction of Ce4+ sites of the underlying ceria support to Ce3+. This strong metal-support interaction is precisely the key for the high catalytic activity of this system.1 In the case of the Cu/TiC and Au/TiC catalysts we will show that the polarization of the electronic density induced by the underlying carbide is the reason for their high catalytic activity. The experiments show that the major product over these model catalysts is CO which is produced by the reverse water-gas shift reaction (RWGS, CO2 + H2 → CO + H2O) whereas the secondary product is methanol (CO2 + 3H2 → CH3OH + H2O). Density functional theory based calculations on suitable models show that these systems strongly activate CO2 and point to HOCO as a key intermediate for the generation of CO through the RWGS, with the production of methanol probably involving the hydrogenation of a HCOO intermediate or the CO generated by the RWGS.2

[1]  A. Bruix, J. A. Rodriguez, P. J. Ramírez, S. D. Senanayake, J. Evans, J. B. Park, D. Stacchiola, P. Liu, J. Hrbek and F. Illas, J. Am. Chem. Soc. 2012 ,134,  8968
[2]  J. A. Rodriguez, J. Evans, L. Feria, A. B. Vidal, P. Liu, K. Nakamura, F. Illas, J. Catal. 2013, 307, 162

Conjugated polyelectrolytes (CPE) feature π-conjugated backbones that are functionalized with polar, ionic side chains. These polymers have very strong optical absorptivity due to the conjugated electronic system, and the HOMO-LUMO gap can be controlled by tuning the electronic nature of the monomer units. CPEs are polymer amphiphiles, and consequently they self-assemble in solution into colloidal aggregates, and they can be deposited onto surfaces to afford nanostructured films by using the layer-by-layer method. Due to the π-conjugated backbone, CPEs exhibit photonic properties, exhibiting strong absorption in the visible region and strong fluorescence. Fundamental studies of the self-assembly of CPEs in solution and at interfaces, along with their application as biosensors and in hybrid solar cells will be discussed.

Leading References:

1) Jiang, H. et al. "Conjugated Polyelectrolytes: Synthesis, Photophysics and Applications", Angew. Chem. Int. Ed. Engl. 2009, 48, 2300.

2) Sambur, J.; et al. “Interfacial Morphology and Photoelectrochemistry of Conjugated Polyelectrolytes Adsorbed on Single Crystal TiO2”, Langmuir 2011, 27, 11906-11916.

3) Zhu, X. Z.; et al. “Photosensitization of Single-Crystal ZnO by a Conjugated Polyelectrolyte Designed to Avoid Aggregation”, J. Phys. Chem. Lett. 2013, 4, 3216-3220.

4) Fang, Z.; et al. “Low-Bandgap Donor-Acceptor Conjugated Polymer Sensitizers for Dye-Sensitized Solar Cells” J. Am. Chem. Soc. 2011, 133, 3063-3069.

The marine environment is a complex system, not only because of the challenges posed by the nature of the waters, but especially due to the interactions of physical, chemical and biological processes that control the cycles of the elements. Together with analytical chemists, oceanographers have been making advancements in knowledge of the distribution patterns of trace elements and processes that determine their biogeochemical cycles and influences on planetary changes. Such happens due to the development of highly sensitive detection methods and the use of clean sampling and handling techniques, together with international programs working toward expanding the frontiers of marine biogeochemistry, including climate change, ocean acidification and alterations in the carbon cycle. It is expected that the oceanographic data produced from now on will allow understanding of biogeochemical cycles, and especially the assessment of changes in trace elements and contaminants in the oceans due to anthropogenic influences, as well as its effects on ecosystems and climate. The environmental changes arising from human activity since the 18th century have made the biogeochemistry of the surface of the Earth even more complex. Anthropogenic activities have altered both terrestrial and marine ecosystems, and the legacy of these impacts in the oceans include plastics, substances such as hormones, antibiotics, legal and illegal drugs and ocean acidification. This knowledge brings with it greater responsibility: helping to envisage viable adaptation and mitigation solutions to the problems identified. The greatest challenge is currently to create a framework project to develop education, science and technology applied to oceanography. Advances in knowledge, and the increasing availability of analytical resources offer favorable conditions for chemistry and oceanography to grow together in order to preserve the oceans and to promote the development of society.

Reference: Vanessa Hatje; Monica Ferreira da Costa; Letícia Cotrim da Cunha. OCEANOGRAFIA E QUÍMICA: UNINDO CONHECIMENTOS EM PROL DOS OCEANOS E DA SOCIEDADE. Quim. Nova, Vol. 36, No. 10, 1497-1508, 2013.

Biomass is an important renewable source of carbon for the sustainable production of fuels, chemicals, and materials. We will present results from our recent work on liquid-phase catalytic processing of lignocellulosic biomass, with an emphasis on the synthesis of new catalytic materials and the elucidation of solvent effects for these processes. We will show aqueous-phase processing can be carried out over bimetallic catalysts (e.g, RhRe, RhMo, PtMo) to achieve selective production of -diols from biomass-derived reactants. We will show that the active sites on these bimetallic catalysts are bi-functional in nature, where the more reducible metal (Rh, Pt) catalyzes hydrogenation/dehydrogenation processes, and the more oxophilic metal (Re, Mo) provides sites that facilitate acid-catalyzed reactions. We will then present strategies for the catalytic conversion of the C5 and C6 sugars present in hemi-cellulose and cellulose, respectively, to produce gamma-valerolactone (GVL). We will present a processing approach that uses GVL as a solvent to convert simultaneously the C5 and C6 sugars in biomass, thereby simplifying separation steps, because GVL is one of the reaction products. We will demonstrate that we can produce soluble carbohydrates from corn stover, hardwood and softwood at high yields (80-90%) in a solvent consisting of biomass-derived GVL, water, and dilute acid (0.005 M). We will show that these carbohydrates can be recovered and concentrated (up to 130 g/L) in an aqueous phase by extraction of GVL using CO2. We will then present results from reaction kinetics studies to quantify the effects of polar aprotic organic solvents on reaction rates and selectivities of acid-catalyzed reactions of relevance for biomass conversion (e.g., xylose dehydration to furfural). We will suggest that the aprotic organic solvent affects the stabilization of the acidic proton relative to protonated transition states, leading to accelerated reaction rates for these acid-catalyzed biomass conversion reactions.