Epoxide silylant agent ethylenediamine reaction product anchored on silica gel - thermodynamics of cation-nitrogen interaction at solid/liquid interface

The silylant agent 3-glycidoxypropyltrimethoxysilane has the epoxide ring opened by incorporating an ethylenediamine molecule under homogeneous conditions, to yield a new silylant agent, which is then anchored on silica gel. Based on nitrogen elemental analysis a large degree of immobilization gives 1.59 mmol g(-1), and consequently, a drastic decrease in surface area of the original silica from 420.8 +/- 3.4 to 70.6 +/- 0.5 m(2) g(-1) is observed for the immobilized surface. The basic centers attached on pendant groups have the capacity to extract cations from aqueous solution, whose adsorption process is adjusted to the Langmuir model. Similar profiles of adsorption were obtained on the isotherms with values 3.06, 2.91, 1.57 and 1.24 mmol g(-1) in the maximum of the curves for copper, cobalt, zinc and nickel, respectively. Thermodynamic data were obtained from calorimetric titration, indicating a spontaneity of these interactive reactions, caused by the favorable exothermic enthalpy due to the cation/basic center interaction in the solid/liquid interface and endothermic entropy originating from the increase in free water molecule content in the medium, which were displaced from the anchored surface, and the cation desolvation process, as the bond is formed. (C) 2003 Elsevier B.V. All rights reserved.3304169914214

The incorporation of propane-1,3-diamine into silylant epoxide group through hornogeneous and heterogeneous routes

The polar organic molecule propane-1,3-diamine reacted: (i) with a 3-glycidoxypropyltrimethoxysilane silylant agent, previously anchored on a silica surface in a heterogeneous route to yield the product SiHT or (ii) with the same agent before immobilizing it on the support, in a homogeneous method, to produce a SiHM surface. The epoxy group was opened yielding chelating pendant groups bonded to the inorganic surface. Both products were characterized through elemental analysis, infrared spectroscopy, surface area and thermogravimetry. The ligand concentrations were 0.80 (SiHT) and 1.53 mmol (SiHM), per gram of silica. The heterogeneous route is an easier procedure to produce immobilization. However the homogeneous route provided conditions to obtain a higher density of pendant groups on the surface, which are potentially useful for extracting cations from solutions in an effective way. (C) 2002 Elsevier Science Ltd. All rights reserved.2125-262647265

Interaction of divalent copper with two diaminealkyl hexagonal mesoporous silicas evaluated by adsorption and thermochemical data

Hexagonal mesoporous silicas chemically modified with ethylenediamine moieties were synthesized through the co-condensation of tetraethylorthosilicate (TEOS) with two different silylating agents: (i) N-[3-(trimethoxysilyl)propyl]ethylenediamine and (ii) the new agent prepared from the incorporation of the ethylenediamine molecule into the epoxide group of the precursor 3-glycidoxypropyltrimethoxysilane. From these silylating agents under neutral n-octylamine template methodology, the respective MNN and MGNN inorganic-organic hybrids were synthesized. Elemental analysis showed that the number of pendant groups in these hybrids were 1.69 and 1.62 mmol g(-1), with pore diameters and surface areas of 1.81 and 1.53 nm and 663 +/- 14 and 614 +/- 16 m(2) g(-1). Infrared spectroscopy, nuclear magnetic resonance for C-13 and Si-29 nuclei and X-ray diffraction patterns are in agreement with the success of the proposed synthetic methods, as confirmed for the formation of the mesoporous hybrids. Both mesoporous materials have been used for divalent copper adsorption from aqueous solution at 298 I K. The series of adsorption isotherms were adjusted to a modified Langmuir equation. The maximum number of moles adsorbed gave 1.4 +/- 0.1 and 1.4 +/- 0.2 mmol g(-1) for MNN and MGNN, respectively. The same interactions were calorimetrically followed and gave exothermic enthalpy, negative Gibbs free energy and positive entropy values. These favorable thermodynamic data indicate cation/nitrogen basic center interactions on the new mesoporous materials at the liquid/solid interface for both systems. (c) 2005 Elsevier B.V. All rights reserved.5901516

Attachment of 2-aminomethylpyridine molecule onto grafted silica gel surface and its ability in chelating cations

A route for incorporating the chelate molecule, AMP, onto silica gel was established. In the first stage a precursor silylant agent, 3-chloropropyltrimethoxysilane, is reacted with the support. The chelate molecule was then covalently bonded to the precursor surface to give 0.76 mmol of chelate per gram of silica. The immobilization reaction was confirmed through infrared spectroscopy and thermogravimetry. The anchored surface showed ability for adsorbing cations from water solution, presenting the maximum adsorption, calculated from the Langmuir equation, of: 0.84, 0.67, 0.40 and 0.22 mmol g(-1) for the divalent cations copper, cobalt, nickel and zinc, respectively. All cation/surface interactions showed favorable enthalpic and entropic values, reflected in a thermodynamic stability of the complex formed. (C) 2003 Elsevier Ltd. All rights reserved.23571972

Some features associated with organosilane groups grafted by the sol-gel process onto synthetic talc-like phyllosilicate

Two new lamellar inorganic-organic magnesium silicates have been successfully synthesized by using sol-gel based processes Under mild temperature conditions. The talc-organosilicates derived using two silylating agents as the silicon source, (i) 3-chloropropyltrimethoxysilane, and (ii) from file attachment of 5-amino-1,3,4-thiadiazole-2-thiol molecule to this precursor agent, yielded PhMg-Cl and PhMg-Tz phyllosilicates. These organoclays were characterized through elemental analyses, infrared spectroscopy, X-ray diffractometry, surface area, thermogravimetry, and carbon and silicon solid state nuclear magnetic resonance spectroscopy. The results confirmed the presence of organic moieties covalently bonded to the inorganic silicon sheet network of the 2:1 class of phyllosilicates, with a density of organic molecules of 6.6 +/- 0.1 and 2.7 +/- 0.2 mmol g(-1) anchored oil the inorganic layer and with interlayer distances of 1158 and 1628 pm, respectively. The nuclear magnetic resonances results in the solid state are in agreement with the sequence of carbons distributed in the pendant chains of the original silylating agents and the silicon bonded to oxygen atoms or carbon atoms of the inorganic sheet, as expected for the organically functionalized phyllosilicates. The enhanced potential of the new compound PhMg-Tz as a multi property material was explored in adsorbing cations from aqueous solution. The basic sulfur and nitrogen centers attached to the pendant chains inside the lamellar cavity call coordinate mercury, by presenting all isotherm saturated at 0.19 mmol g(-1) of this heavy metal. The functionality of this organoclay-like material expresses its potential for heavy cation removal from all ecosystem. (c) 2005 Published by Elsevier Inc.29719510

Immobilization of 5-amino-1,3,4-thiadiazole-thiol onto silica gel surface by heterogeneous and homogeneous routes

The compound 5-amino-1,3,4-thiadiazole-thiol (ATT) was anchored onto silica gel surfaces by homogeneous and heterogeneous routes. Both silica modification methodologies resulted in similar products, named SiCTT and SiATT, respectively. These materials were characterized by infrared and Raman spectroscopies, superficial area and elemental analysis as well as C-13 and Si-29 NMR spectroscopy. Elemental analysis proved that the material SiCTT presented a higher ATT immobilization than SiATT, with values of 0.73 and 0.65 mmol g(-1), respectively. NMR, Raman and infrared spectroscopy corroborate to confirm the immobilization of ATT on both surfaces. Raman spectroscopy showed that the reaction of the ATT with silylant agent or pre-modified silica occurred by the thiol group, resulting in a surface with two sulfur groups and one free amine group able to complex soft and hard acids. (C) 2003 Elsevier B.V. All rights reserved.3331616

Toll-Like Receptor 6 Ser249Pro Polymorphism Is Associated With Lower Left Ventricular Wall Thickness and Inflammatory Response in Hypertensive Women

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)BACKGROUND Experimental data demonstrated that inactivation of toll-like receptor (TLR) pathway components attenuated left ventricular (LV) remodeling induced by pressure overload.This study investigated the impact of TLR6 Ser249Pro polymorphism on LV structure in hypertensive subjects. METHODS A sample of 443 patients (266 women and 177 men) was evaluated by clinical history, physical examination, analysis of inflammatory and metabolic parameters, echocardiography, and genotyping of the TLR6 variant. Moreover, the relationship between genotypes and in vitro responsiveness of peripheral blood monocytic cells to TLR agonists was also assessed. RESULTS Homozygous women for the TLR6 2495er allele had lower LV posterior wall thickness (9.4 +/- 0.4 vs. 10.5 +/- 0.1 mm; P=0.02), interventricular septum thickness (9.7 +/- 0.3 vs. 10.7 +/- 0.1 mm; P = 0.03), and LV relative wall thickness (0.39 +/- 0.02 vs. 0.44 +/- 0.01; P = 0.02) than women with other genotypes. These results were confirmed by stepwise regression analyses adjusted by potential confounders. Conversely, homozygous men for the 2495er variant showed no differences in LV structure in comparison to males carrying the 249Pro allele. In addition, monocytes from hypertensive women homozygous for the 2495er allele showed a lower release of tumor necrosis factor-a and interleukin-6 in response to zymosan (TLR6 agonist), but not to lipopolysaccharide (TLR4 agonist). CONCLUSION These data suggest that hypertensive women homozygous for the TLR6 249Ser polymorphism might exhibit lower LV wall thickness and reduced TLR6-mediated inflammatory response than females carrying the major allele.236649654Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [05/56986-5, 08/10069-0]CNPq [304329/06-1, 474206/07-6

The functional Toll-like receptor 4 Asp299Gly polymorphism is associated with lower left ventricular mass in hypertensive women

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Background: This study investigated the impact of a putative functional TLR4 polymorphism (Asp299Gly) on left ventricular (LV) structure in hypertensive subjects. Methods: A sample of 443 patients (266 women and 177 men) was evaluated by clinical history, physical examination, anthropometry, analysis of inflammatory and metabolic parameters, echocardiography and TLR4 Asp299Gly genotyping. In addition, the relationship between the polymorphism and in vitro lipopolysaccharide responsiveness of peripheral blood monocytic cells was also assessed. Results: Women carrying the 299Gly allele presented lower posterior wall thickness (p = 0.01), interventricular septum thickness (p = 0.04). LV mass (p = 0.01) and LV mass index (p = 0.03), as well as a reduced prevalence of LV hypertrophy (p = 0.002), in comparison to women with the wild-type genotype. These results were confirmed by stepwise and logistic regression analyses adjusted for potential confounders. Conversely, the 299Gly allele did not influence LV structure in men. Furthermore, in vitro assays revealed that monocytes of either men or women heterozygous for the 299Gly allele presented a lower lipopolysaccharide-induced production of interleukin-6, compared to non-carriers. Conclusions: The functional TLR4 Asp299Gly polymorphism is associated with lower LV mass in hypertensive women. These findings suggest that interactions among gender, LV remodeling and TLR4 gene variants may occur in hypertensive subjects. (C) 2010 Elsevier B.V. All rights reserved.41141921744748Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [05/56986-5]CNPq [304329/06-1, 474206/07-6