Sulfur ligand-stabilized palladium aggregates produced on the surface of benzoylthiourea-functionalized silica xerogels

Abstract

Twobenzoylthiourea-functionalized silica xerogels, 4.5Si0,*Si0,/,(CH2),NHC(S)NHC(0)Ph (XGbztu) and SiO,,,(CH,),NHC(S)NH-C(0)Ph (XGbztu*), prepared by the sol-gel process, are able to bind palladium by reaction with Pd(OAc),, giving the hybrid materials Pd/XGbztu and Pd/XGbztu*. The ligand CH,(CH,),NHC(S)NHC(O)Ph (Hbztu), a model of the surface-binding function, on reaction with Pd(OAc),, afforded the mononuclear complex [Pd(bztu),] and a sulfur-containing metal colloid. Diffuse reflectance FTlR (DRIFT) experiments have shown that Pd/XGbztu* is able to fix CO at room temperature, giving a three v(C0) frequency pattern, which changes with increasing temperature. Pd/XGbztu and Pd/XGbztu* are effective catalysts in the hydrogenation of phenylacetylene to give styrene or ethylbenzene, depending on the reaction time. Nanoscale palladium aggregates have been evidenced by transmission electron microscopy (TEM) investigations on the materials after the hydrogenation processes; energy-dispersive Xray (EDX) analysis has revealed a significant presence of sulfur in the vicinity of the particles. X-Ray photoelectron spectroscopy (XPS) data have shown that Pd2+ and Pdo are simultaneously present in Pd/XGbztu recovered after the catalytic cycle.

O uso de sílica gel organofuncionalizada como agente sequestrante para metais

“…Para a reação do cátion, na forma MX 2 com a superfície imobilizada em suspensão, Sup, em um determinado solvente, podemos escrever: O avanço dos aspectos sintéticos possibilitou a incorporação de uma variedade de moléculas no arcabouço da estrutura inorgânica polimérica da sílica, contendo diversos centros bási-cos em suas estruturas, no que resultou uma condição de uso destas superfícies como agentes quelantes . Nestas matrizes, as espécies químicas responsáveis pela adsorção de metais apresentam nitrogênio [76][77][78][79][80][81][82][83][84][85][86][87][88] , oxigênio [89][90][91][92][93][94][95][96][97][98][99] , ou enxofre [100][101][102][103][104][105][106][107][108][109][110][111][112][113][114] , como áto-mo doador.…”

Diamine Immobilization on Silica Gel through the Sol−Gel Process and Increase in the Organic Chain by Using Glutaraldehyde followed by Ethylenediamine

“…In this case, Si(OEt) 4 is normally used as a skeletal-forming agent for silica gel. , By selecting the silylant agent or by using a sequence of reactions, one can anchor molecules with a high capacity to adsorb metal cations on the surface. These materials exhibit wide applicability in diverse areas such as adsorption of metal cations from solvents , and seawater, use as a stationary phase in high-performance liquid chromatography, and catalysis of enzymatic reactions as well as metal-supported organic reactions …”

“…These materials exhibit wide applicability in diverse areas such as adsorption of metal cations from solvents 7,8 and seawater, 9 use as a stationary phase in high-performance liquid chromatography, 10 and catalysis of enzymatic reactions 11 as well as metal-supported organic reactions. 12 The adsorption capacity of a given anchored molecule is intimately related to the kind of anchored organic group 13 and the levels or values of several experimental factors. Recently, the adsorption capacity was studied by using fractional factorial designs to calculate the importance of some experimental factors and their interactions in adsorption capacity in order to distinguish different silicas.…”

Simultaneous Monitoring of the Adenosine Triphosphate Levels in the Cytoplasm and Nucleus of a Single Cell with a Single Nanowire-Based Fluorescent Biosensor

“…An intense peak corresponding to bulk Si (99 eV) and a moderated peak corresponding to silicon oxide (103 eV) were observed from the SiNWs. , For the SiNWs-FITC@SiO 2 -20, the peak from the bulk silicon disappeared and the peak from the silicon oxide still existed (Figure S7a). A new intense peak corresponding to the −NH–C­( S )–NH– (400.6 eV) appeared, indicating the formation of the FITC@SiO 2 layer on the SiNWs (Figure S7b). After the decoration of the carboxyl-terminal siloxane reagents and Rho-N 3 H 5 , intense peaks corresponding to −N­(C 2 H 5 ) 2 (399.5 eV) and −C­(O)–NH– (401.6 eV) were observed from the SiNWs-FITC@SiO 2 -20-Rho-100, , demonstrating the successful modification of the SiNWs-FITC@SiO 2 -20 by the Rho-N 3 H 5 .…”