Mango industry processing disposes 40-60% of this fruit as residues, such as peels and kernels. The exploration of bioproducts from these industrial rejects can reduce environmental impact besides of producing high value-added materials. In this scenario, carboxymethyl starch nanoparticles were produced from mango (Mangifera indica L.) kernel starch. These nanoparticles were then decorated with thermoresponsive chains of the amino terminated poly(N-isopropylacrylamide) (PNIPAM-NH2), with the intention of evaluating their applicability in the biomedical area. Elemental analysis, Fourier transform infrared (FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopy confirmed successful grafting of PNIPAM-NH2 onto the carboxymethyl starch backbone. Scanning electron microscopy (SEM) images and dynamic light scattering (DLS) data showed sizes of 100 and 112 nm in the dry state and of 744 and 598 nm in the hydrated state, when the grafting degree (GD) was of 6 and 14.3%, respectively. The degree of swelling was of 41,100 and 15,100% for GD of 6 and 14.3% respectively, suggesting that the nanogels are suitable for drug incorporation. The toxicity of the nanogels to human adipose-derived stem cells (ADSCs) and red blood cells (RBCs) was evaluated by lactate dehydrogenase (LDH), alamarBlue and hemolysis assays. Both nanogels were non-cytotoxic and non-hemolytic, suggesting the suitability of these biomaterials for cell-and blood-contacting applications.

Recent studies on tungsten oxide preparation are mainly motivated by its applications in smart windows, energy harvesting and, recently, in cancer therapy. Peroxotungstic acid (PTA) is an important precursor to obtain tungsten oxide in an environmentally-friendly way, through the colloidal synthesis in aqueous media. Despite giving chemically pure products, PTA originates oxides with various morphologies depending on the experimental conditions, a subject open to discussion. PTA, in the presence of sodium dodecyl sulfate (SDS) as architecture-directing agent, was investigated in ethanol/water medium by small angle X-ray scattering (SAXS), fluorescence, surface tension and conductivity measurements; the morphology of tungsten oxide obtained from the precursor systems was also characterized by scanning electron microscopy (SEM). PTA/SDS/ethanol/water systems show a two-level organization in which small micelles are aggregated as fractal structures. There is an inverse correlation between gyration radius of the fractal structures of the PTA/SDS systems and particle size of the tungsten oxide films. The interaction of PTA with SDS is observed by reducing the Gibbs energy of micellization; also, it is evidenced that the supressive effect of PTA on pyrene emission is overrided in presence of SDS.

Poli(acrilamida-co-dihexilacrilamida) (PAHM-0) e poli(acrilamida-co-acrilato de sódio-co-dihexilacrilamida) (PAHM-21) foram estudadas por espalhamento de raios-X a baixos ângulos (SAXS), espalhamento de luz (LS) e reologia. Os resultados de SAXS ressaltaram o caráter polieletrolítico da PAHM-21, com uma conformação altamente estendida em solução aquosa devido às repulsões entre as cargas, enquanto a PAHM-0 tem uma conformação em novelo aleatório. As medidas de LS indicaram que a PAHM-0 forma aglomerados intermoleculares em solução, na presença e na ausência de sal, mesmo com um conteúdo hidrofóbico menor que o descrito na literatura para poliacrilamidas associativas. Contudo, os resultados reológicos mostraram que, apesar de haver associação hidrofóbica, não há um aumento da viscosidade. Os resultados de LS da PAHM-21 sugerem que esse polímero forma, predominantemente, associações intramoleculares na presença de sais. Além disso, as medidas viscosimétricas mostram que a sua viscosidade diminui com a blindagem das cargas pela adição de sais.

Poly(acrylamide-co-dihexylacrylamide) (PAHM-0) and poly(acrylamide-co-sodium acrylate-co-dihexylacrylamide) (PAHM-21) were studied through small-angle X-ray scattering (SAXS), light scattering (LS) and rheology. SAXS results highlighted the polyelectrolyte character of PAHM-21, with highly extended conformation in aqueous solution owing to charge repulsion, while the PAHM-0 has a coil conformation. LS measurements indicated that PAHM-0 makes intermolecular clusters in solution, in presence and absence of salt, even with a lower hydrophobic content than that described in the literature to the associative polyacrylamides. However, the rheological results showed that there is not an enhancement of the viscosity although hydrophobic association takes place. LS results for PAHM-21 suggest that this polymer makes intramolecular associations mainly in the presence of salts. Furthermore, the viscosity measurements show that its viscosity decreases due to screening of the charges by the addition of salts.

Uma poliacrilamida hidrofobicamente modificada e dois dos seus derivados parcialmente hidrolisados, contendo grupos hidrofóbicos e carboxila, foram preparados por polimerização micelar e pós-hidrólise. A massa molar, o segundo coeficiente do virial e o raio de giração foram determinados por espalhamento de luz estático (SLS). O espalhamento de luz dinâmico (DLS) e o espalhamento de raios-X a baixos ângulos (SAXS) foram utilizados respectivamente para determinar a formação de agregados e o tipo de empacotamento das cadeias em regime semi-diluído. O comportamento das soluções, em regime diluído e semi-diluído foi estudado por viscosimetria e reologia. A poliacrilamida modificada hidrofobicamente apresentou tendência à formação de agregados devido aos grupos hidrofóbicos, mas essa agregação não foi suficiente para aumentar a viscosidade aparente. Embora os derivados parcialmente hidrolisados não apresentassem a mesma tendência para agregação, eles apresentaram um comportamento anisotrópico devido à introdução de densidade de carga sobre a cadeia polimérica, a qual levou a uma conformação mais alongada da macromolécula e maior viscosidade.

A hydrophobically-modified polyacrylamide and two partially hydrolyzed derivatives containing hydrophobic and carboxylic groups were prepared by micellar polymerization and post-hydrolysis. The molecular weight, second virial coefficient and radius of gyration were determined by static light scattering (SLS). Dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) were employed to determine the aggregate formation and type of chain packing in the semidilute regime, respectively. The behavior of solutions in dilute and semidilute regimes was also studied by viscometry and rheology. The hydrophobically-modified polyacrylamide showed a tendency to form aggregates due to the hydrophobic groups, but not enough to increase apparent viscosity. The partially hydrolyzed derivatives did not show the same aggregate-forming tendency. Rather, they exhibited anisotropic behavior, due to the charge density introduced into the polymer chain, which led to a more elongated macromolecular conformation and higher viscosity.

Neste artigo estamos apresentando a síntese do composto [Cd8Cl2(µ4-Se)(SePh)12(PCy3)2]·2.5CH3OH pela reação de Cd(SePh)2 com CdCl2 e triciclohexilfosfina em metanol em um reator de aço inoxidável sob condições solvotérmicas a 130 ºC. Esse composto corresponde ao último resultado de uma série sistemática de reações e visando ao crescimento de clusters moleculares a partir de Cd(SePh)2 como reagente de partida. A importância desta síntese não está baseada somente nas propriedades do produto preparado, mas também no seu possível uso, por exemplo, no desenvolvimento de novas metodologias via estratégias "bottom up" para a obtenção de clusters a partir de uma mesma classe de reagentes - M(ER)2 (M = metal, E = calcogênio, R = alquil ou aril). O composto apresentado neste artigo foi caracterizado por difração de raios X em monocristal, análise elementar, análise termogravimétrica e espectroscopia no UV-Vis. Estes últimos resultados foram correlacionados com dados calculados por DFT, teoria do funcional de densidade.

In this article we present the synthesis of the compound [Cd8Cl2Se(SePh)12(PCy3)2]·2.5CH3OH by the reaction of Cd(SePh)2 with CdCl2 and PCy3 in methanol in a stainless steel sealed reactor under solvothermal conditions at 130 ºC. This compound represents the latest result of our systematic work on the growth of molecular clusters from Cd(SePh)2 as starting material. Their importance is based not only on the properties of the new compounds, but also by their possible use, for example, in the development of new methods via a ''bottom up" strategy to obtain different clusters from single components like M(ER)2 (M = metal, E = chalcogen, R = alkyl or aryl). The title compound was characterized by single crystal X-ray diffractometry, elemental analysis, thermogravimetrical analysis and the UV-Vis spectroscopy. These results were correlated with data calculated by DFT, density functional theory.

Três novos compostos foram preparados a partir de Hg(EPh)2 (E = Se, Te; Ph = fenila) em solventes orgânicos. Dois destes compostos são clusters moleculares, [Hg2Cl2(SePh)2(PCy3)2], (1), e [Hg2Br2(SePh)2(PCy3)2], (2), obtidos pela reação de Hg(SePh)2 com HgX2 (X = Cl, Br) e tricicloexilfosfina, PCy3, em dimetilformamida. A reação de Hg(TePh)2 e HgBr2 em tetrahidrofurano usando trifenilfosfina ou 2,2’-bipiridina como co-ligantes produz o cluster polimérico [{Hg5Br3(TePh)7}n], (3), cuja dissolução em dimetilsulfóxido leva à formação do cluster [Hg3Br3(TePh)3]·2dmso. Neste trabalho avalia-se a influência de diferentes ligantes, solventes coordenantes e estequiometrias de reações na formação dos produtos. Todos os compostos foram caracterizados por análise elementar, análise termogravimétrica e tiveram suas estruturas cristalinas determinadas por difratometria de raios X em monocristais.

Three new cluster compounds were synthesized from Hg(EPh)2 (E = Se, Te; Ph = phenyl) in organic solvents. Two of these compounds, [Hg2Cl2(SePh)2(PCy3)2], (1), and [Hg2Br2(SePh)2(PCy3)2], (2), were prepared by reaction of Hg(SePh)2, HgX2 (X = Cl, Br) and tricyclohexylphosphine, PCy3, in dimethylformamide. The reaction of Hg(TePh)2 with HgBr2 in tetrahydrofuran using triphenylphosphine or 2,2’-bipyridine as co-ligands gave the polymeric cluster [{Hg5Br3(TePh)7}n] (3), whose dissolution in dimethylsulfoxide yielded the cluster [Hg3Br3(TePh)3]·2dmso. The influence of different ligands, coordinating solvents and reaction stoichiometries on the formation of the title compounds is also discussed. All complexes were characterized by elemental analysis, thermogravimetric analysis and single crystal X-ray diffractometry.