Search

Abstract: An interpenetrating polymer network based on poly(glycidyl methacrylate), diethylenetriamine, poly(4-vinylpyridine) and 1,4-dibromobutane has been investigated as sensitive material to build a sensor for the detection of ethanol in hydrocarbons. Preliminary tests have been carried out by impedance spectroscopy in ethanol/cyclohexane mixtures. The sensor showed a measurement range between 5% and 100%, good reversibility and fast response time. [Copyright &y& Elsevier]

A new and effective palladium catalyst supported on a magnesium organosilicate for application in the Heck reaction is presented. A group of compounds comprising 22 examples were synthesized in moderate to high yields (up to 99%) within a short time. The palladium supported on magnesium organosilicate catalyst was characterized as an amorphous solid by SEM, containing around 33% of palladium inside the solid, and even with this low quantity of palladium, the catalyst was very efficient in the Heck reaction. Besides, based on the Scherrer equation, the crystallite size of the synthesized palladium nanoparticles was ultrasmall (around 1.3 nm). This strategy is a simple and efficient route for the formation of C–C bonds via the Heck cross-coupling reaction. [ABSTRACT FROM AUTHOR]

The synthesis of isatin-derived N , S -acetals using cobalt as a recyclable heterogeneous catalyst in batch and continuous flow is reported for the first time. The present protocol produced high yields, which can be observed from the reaction between ketimines and thiols. Such reactions can also be applied to a gram-scale. In addition, the catalyst is recyclable, economically-viable, and nontoxic as well as easy to prepare. The remarkable features of this new methodology are high conversion and cleaner reaction profiles. [ABSTRACT FROM AUTHOR]

Abstract In this work, a pecan nutshell was used as a precursor to prepare activated hydrochar (HPN-ATV) with a high specific area. HPN-ATV was engineered as an adsorbent for the removal of methylene blue (MB) from aqueous environments. The obtained materials were characterized using textural, morphological, and chemical analysis techniques. HPN-ATV showed a BET specific area of 2342 m2 g−1 and an average pore diameter of 2.24 nm. Boehm titration and FTIR spectral analysis indicated the presence of acidic and basic functional groups on the surface of HPN-ATV, which rendered the removal of cationic molecules more favorable. The kinetic experimental data better correlated with the pseudo-second-order kinetic and Elovich equations, and the Langmuir model showed a better fit for the data of MB adsorption. The adjusting parameters indicated a monolayer with an adsorption capacity of 1190.62 mg g−1, which is higher than that of the other adsorbents reported in literature. In addition, the thermodynamic data suggested a spontaneous adsorption process with endothermic characteristics. Highlights • Hydrobiochar with a specific area of 2342 m2 g−1 was obtained from Pecan nutshell. • The results indicated a monolayer with an adsorption capacity of 1190.62 mg g−1 • Methylene blue was absorbed predominantly via chemisorption. • The adsorption process is spontaneous with endothermic characteristics. [ABSTRACT FROM AUTHOR]

Abstract This work reports the synthesis of hybrid hydrogels based on alginate and π-bonds coupled silica (SiO 2) microspheres (~250 nm) with high performance for water absorption. For formation of the hybrid hydrogel, the alginate was covalently gelled in the presence of SiO 2 vinylated with vinyltrimethoxysilane using crosslinking chemistry. These hydrogels can absorb until 889.76 ± (12.65) g of water per 1 g of dry polymer without their tridimensional shape being unmade. The chemical nature of the polymer and the surface charges of the microspheres play a major role in creating the highly hydrophilic structure and determining the superabsorption properties. The porosity of the matrix also contributes to increase the effectiveness of the absorption, owing to an interconnected pore network that allows absorbed water to be distributed throughout the polymer matrix. In the buffer solutions, the hydrogels showed lower capacity for absorption, which was attributed to ions from weak acids and their respective salts changing charge distribution between the polymer network and the surrounding liquid layer. The applicability of the hydrogel for removal of methylene blue (MB) was investigated. The removal of MB increases with an increase in the amount of modified alginate and monomers, but reduces with a decrease in the amount of vinylated SiO 2. The experimental data were better correlated with pseudo-second order model and the Langmuir model was better fit for the equilibrium data, indicating that MB was absorbed predominantly via chemisorption owing to electrostatic interactions of the dye molecule with a single absorption site. Highlights • Ultra-absorbent hybrid hydrogels based on alginate and vinyl silica were developed. • These hydrogels can absorb until 889.76 ± (12.65) g of water per 1 g of dry polymer. • In the buffer solutions, the hydrogels showed lower capacity for absorption. • The experimental data were better correlated with pseudo-second order model. • Methylene blue was absorbed predominantly via chemisorption. [ABSTRACT FROM AUTHOR]

Here we report a new highly microporous zirconium phosphonate material synthesized under solvothemal conditions. The specific Brunauer‐Emmett‐Teller (BET) surface area of the "unconventional metal−organic framework" (UMOF) is measured to be ∼900 m2/g, after following an appropriate activation protocol. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) shows that the material bears a free −OH functionality on the phosphonate linker that may interact with CO2. CO2 adsorption isotherms were collected and a measured heat of adsorption of 31 kJ/mol was obtained. In addition, adsorption isotherms of CO2, N2, and CH4 at 298 K combined with Ideal Adsorbed Solution Theory (IAST) show that the material can be expected to display high selectivities for uptake of CO2 versus N2 or CH4. [ABSTRACT FROM AUTHOR]

This work reports the preparation, the characterization and the prednisolone release profile of biocompatible hydrogel nanocomposites containing mesoporous silica (SBA) and alginate as a biomaterial for enhanced drug delivery with reduced burst effect and improved mechanical properties. Such systems, which were prepared using specific SBA/alginate-crosslinking chemistry, exhibited interconnecting pore hybrid network owing to both mesoporous silica and hydrogel characteristics. Activated SBA was shown to be a determinant factor in inhibiting initial burst by nearly 90% and the drug was released with minimal burst kinetics. The nanoparticles reduced the movements of polymer chains, affecting macromolecular relaxation, and the distribution of mesoporous silica within the hydrogel made drug release into surrounding liquid less favorable. The proposed systems are biocompatible with human immortalized RWPE-1 prostatic epithelial cells. This report offers an approach of up-to-date interest for the development of advanced biomaterials for further physiological and pathological applications. [ABSTRACT FROM AUTHOR]

Abstract: A simple, efficient and green methodology for the C−S cross‐coupling reaction using Pd(L‐Pro)2 as a heterogeneous catalyst was developed involving aryl iodides, thiols, green‐solvent and a low catalytic loading of palladium prolinate. In addition, the catalyst turned out to be recyclable and the products were obtained in good to excellent yields. [ABSTRACT FROM AUTHOR]

An efficient method has been developed for the preparation of a-aminophosphonates by using zinc di(L-prolinate) as a catalyst under mild reaction conditions. The method has the advantages of high yields, short reaction times, and easy workup conditions. [ABSTRACT FROM AUTHOR]

An abstract of the article "Biosynthesis of some Mannich bases" by Bruna S. D. R. Aranha, Nelson L. C. Domingues, and Andrelson W. Rinaldi is presented.

Composite films based on Poly(vinylidene fluoride) (PVDF) polymer filled with Nickel oxide (NiO) nanosheets were prepared via the solution casting method. The effect of NiO filler introduction on the structure and morphology of the composite films were analyzed by X-ray diffraction, Fourier transformed infrared spectroscopy and Scanning Electron Microscopy. The results showed that the crystallinity, β-phase content and morphology are directly related to the NiO filler concentration into the polymer matrix owing to a heterogeneous nucleation. Electrical measurements revealed dielectric constants up to 45 at 1 kHz and an increasing in conductivity more than two orders of magnitude, with a percolation threshold of about 4.0% v/v of NiO filler content. [ABSTRACT FROM AUTHOR]

• Sustainable zeolite A was synthetized and functionalized with silver nanoparticles. • Silver nanoparticles were obtained by a sodium citrate route reduction approach. • Zeolite A functionalized with silver nanoparticles showed attenuated Ag+ release. • Our bactericidal screening was successful, showing antimicrobial activity. This paper reports the synthesis of a microporous sustainable Zeolite A material using an agroindustry solid waste (SZA) and its functionalization with silver nanoparticles. Silver nanoparticles with ca. 9.0 nm of diameter onto SZA where were obtained using a sodium citrate reduction route. The release transport properties of Ag+ ions from SZA were investigated. We found that silver ions released from the SZA is controlled by the pseudo-Fickian diffusion mechanism. Furthermore, its demonstrate that the Colony-Forming Units (CFU) of (L. monocytogenes; P. auriginosa; S. aureus; S. typhinimurium; E. coli and S. epidermidis) decreases significantly after exposure to the SZA loaded with silver nanoparticles. The antimicrobial activity of this SZA loaded with silver nanoparticles relies on the exposure time with microorganism and concentration of these materials. [ABSTRACT FROM AUTHOR]

Abstract: This Letter introduces a new, cheap and green protocol for the thio-Michael reaction. Here we applied three free enzymes such as lipase from pancreas porcine, chymosin and papain and an immobilized one: the Liposyme®. The reactions were executed at room temperature and resulted in the thio-Michael adduct in good or excellent yields. The protocol describes the use of EtOH as solvent and a less percentage of enzymes, which is in concordance with the green chemistry topics, so we can mention that chymosin and papain were used as biocatalyst in an organic reaction for the first time in this Letter. [Copyright &y& Elsevier]

Recently, methodologies that are in accordance with green chemistry principles have been garnering increasing attention. One of the most applied methods in this field is heterogeneous catalysis. In this context, many catalysts have been developed, and there is one remarkable class that has emerged: hybrid materials. Such heterogeneous catalysts are developed from organic and inorganic portions, especially from amino acids and metal salts, which are commonly found in the literature. Herein, we introduce Zn[Pro] 2 and Zn[Gly] 2 as heterogeneous catalysts in thio-Michael reactions via the implementation of two methods: via (1) a magnetic stirrer and (2) via an ultrasound device; the latter method resulted in minimally increased reaction yields in all cases. [ABSTRACT FROM AUTHOR]

Hybrid materials have seized attention from scientific community mainly as heterogenic catalysts in organic reactions on a large scale succeeding in some organic compounds with high yields. One of the most important classes of hybrid materials used for this purpose involves the complexation of Zn and aminoacids. Herein, we introduced Zn[Pro]2 and Zn[Gly]2 in the synthesis of several β-enaminones via solvent free protocol and using an ultrasound device. [ABSTRACT FROM AUTHOR]

• Organic–inorganic hybrid hydrogel using alginate and UIO-66 AA was synthetized. • UIO 66 MOFs with different crystal sizes (600, 1500, and 2500 nm) were prepared. • The properties of the materials depend on the size and amount of UIO-66 crystals. • The hybrid materials showed reduced burst release and mechanical robustness. • Cytotoxicity screening indicated a promising biocompatible architecture. Herein, we report the preparation of an organic–inorganic hybrid hydrogel architecture using vinyl alginate and UiO-66 MOFs (metal-organic frameworks) modified with acrylic acid (AA) UiO-66AA. UiO-66 MOFs with different crystal sizes (600, 1500, and 2500 nm) were synthesized and the effect on the mechanical and transport properties of the resulting materials, such as water absorption capacity and drug release, were evaluated. HydroMOF showed higher water absorption capacity than the pure hydrogel and enhanced mechanical properties, which depend on crystal size and the amount of UiO-66AA MOF used. The initial release rate of drug (burst release) from hydroMOFs was lower when small-sized crystals or a small amount of large-sized crystals were used; thus these are essential in changing half-life values of release rates. Finally, the cytotoxicity screening successfully showed that hydroMOFs are promising biocompatible compounds proven to have the advantages of minimized burst release and mechanical robustness. [ABSTRACT FROM AUTHOR]

• Chondroitin sulfate hydrogel with superabsorption of methylene blue was obtained. • All mechanical parameter values of the hybrid hydrogel significantly increased. • The hybrid exhibited outstanding absorption capacity of water up to 4000 times. • The hybrid showed absorption capacity of methylene blue up to 3982.30. This paper describes the synthesis of hybrid hydrogels based on chondroitin sulfate (CS) and mesoporous silica (MCM-41). The combination of the CS network and surface-modified MCM-41 yields resilient hybrids with a high water absorption power and excellent capacity for the removal of methylene blue (MB). In this system, two types of solute transport mechanisms exist: absorption and adsorption. The effect of MCM-41 on the physical-chemical properties of the hydrogels was assessed over a wide pH scale, and the absorption kinetics and isotherms of MB were studied by theoretical models. The mechanical properties of the hydrogels, such as the modulus of elasticity, yield strength, modulus of resilience, and fracture toughness, were significantly improved. This hydrogel exhibited high performance for water absorption (4000 % beyond its initial weight) and removal of MB (3982 ± 123.6 mg g−1), while the pure hydrogel removed 2912 ± 163.8 mg g−1. [ABSTRACT FROM AUTHOR]

• A domestic microwave (DMW) was for synthesis of crystalline porous materials. • A simple, fast and low-cost synthesis of MOFs was developed. • The approach allowed the control of the solvent losses and temperature. • DMW uses timed and pulsed power as the control method of the heating process. • The produced MOFs showed excellent chemical properties. This work shows a facile modification of a modified domestic microwave oven that allows for the control of solvent losses and the monitoring of temperature during the synthesis of metal-organic frameworks (MOFs) MIL 100 under hydrofluoric acid-free conditions, HKUST-1 with unique properties, and MIL 88B. In order to obtain the best efficiency irradiation, a thermal mapping image from the domestic microwave DMW was obtained. The results showed that the chemical properties of the produced MOFs were excellent: the observed yield calculation and the BET surface area of the MIL-100 active crystals were 97% and 1300 m2g−1, respectively, and 90% and 1365 m2g−1, respectively for HKUST-1 with unique properties. A simple and low-cost alternative to a commercial microwave oven was developed, making it safer and its parameters controllable during the synthesis of MOFs. [ABSTRACT FROM AUTHOR]

An abstract of the article "Synthesis of some derivatives of compounds β-aminoketonic through Mannich reaction by using biocatalysts" by Ana Claudia S. Lima, Paula Vanessa S. Rizzo, Mariana P. Darbem, Cristiane R. Winck, Andrelson W. Rinaldi and colleagues is presented.

This paper reports the synthesis of a superabsorbent hybrid based on Arabic gum (AG) and a cross-linkable inorganic material for water dye absorption with enhanced mechanical properties. The inorganic material (MOF-UIO-66) was modified with acrylic acid (AA) using solvent-assisted ligand incorporation for further chemical hydrogelation with AG. This approach leads to a stable structure whose constituent phases are covalently bonded to each other. The mechanical properties and swelling degree were evaluated, and the effects of the pH, time, concentration, and reuse were investigated using absorption measures. The superabsorbent hydrogel (HAGMA, without MOF-UIO-66) absorbed 1014 g of water per 1 g of dry polymer, while the superabsorbent hybrid (AGMOF@AA) swelled hundreds times beyond its dry weight and maintained its three-dimensional shape. The elastic modulus of AGMOF@AA increased by 535% compared with that of HAGMA. The hybrid absorbs five times more energy until the fracture than the hydrogel. In the absorption process, AGMOF@AA showed a high amount of absorbed MB (768.03 mg g−1). Both samples exhibited pH-dependent absorption, and the Langmuir isotherm model correlated well with the experimental data. HAGMA and AGMOF@AA exhibited excellent regeneration capacity and were successfully used over five absorption-desorption cycles. • MOF-UIO-66/Arabic gum hybrid with enhanced mechanical properties was prepared. • The elastic modulus of hybrid increased by 535%, compared with pure material. • The hybrid absorbs five times more energy until the fracture. • In the absorption, the hybrid showed a high amount of absorbed blue methylene. • The proposed materials showed excellent regeneration capacity. [ABSTRACT FROM AUTHOR]

An abstract of the article "Sinthetic study of some beta-aminoketones using thiazolidine as catalyst" by Andrelson W. Rinaldi, Ana Claudia da S. Lima, Paula Vanessa de S. Rizzo, Érica Cristina da Silva, and Nelson Luis de Campos Domingues is presented.

An abstract of the article "Synthesis and characterization of nickel complexes derived from Schiff-Bases" by Mirian Y. Matsumoto, Keila B. Dias, Vicente L. Kupfer, Elias B. O. Filho, Larisse G. Salazar, Adalberto V. Mezacasa, Persiely P. Rosa and Andrelson W. Rinaldi is presented.

An abstract of the article "Synthesis and characterization of the polyaniline dopant Schiff base" by Persiely P. Rosa, Mirian Y. Matsumoto, Keila B. Dias, Vicente L. Kupfer, Nelson L. C. Domingues, and Andrelson W. Rinaldi is presented.

An abstract of the article "Application of bis-(L) zinc prolinate (II) on the synthesis reactions of some 1,4-dyhidropyridines" by Cristiane R. Winck, Ana Claúdia S. Lima, Paula Vanessa S. Rizzo, Andrelson W. Rinaldi, and Nelson Luís de Campos Domingues is presented.

An abstract of the article "Systematic study of the employment of enzymatic catalysts on the formation of carbon-heteroatoms" by Paula Vanessa S. Rizzo, Ana Claudia S. Lima, Érica Cristina da Silva, Cristiane R. Winck, Mariana P. Darbem, Andrelson W. Rinaldi and colleaues is presented.

The article presents chemical equation for the article "Zn[Aminoacid]2 Hybrid Materials Applied as Heterogeneous Catalysts in the Synthesis of beta-Enaminones" by M. Darbem and others, published in the periodical "Tetrahedron Letters" in 2014.