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Luminescent ruthenium diimine complexes have been covalently bound to the surface of a silica polyamine composite (SPC) using peptide coupling agents. The loading of the complexes using this route is quite low (∼0.01-0.04 mmol/g) leaving sufficient surface amines to coordinate added metal ions. When the composite particles containing the Ru complexes are exposed to solutions of Cu2+, Ni2+ or Zn2+, luminescence is quenched with efficiencies that follow concentration dependence and the relative binding affinities of the ions. When heavy metal ions such as mercury or lead are adsorbed onto the same surface, luminescence is enhanced by a factor of ∼3.5. When the complexes are exposed to these metals in solution, no quenching or enhancement is observed. Both phenomena were shown to be the result of adsorption of the cations onto the polyamine surface by using the Stern-Volmer relationship. The mechanism of both quenching and enhancement is discussed and the options for further development of this novel metal sensing technique are presented. [ABSTRACT FROM AUTHOR]

A series of Pd-Ag mixed-metal nanocatalysts were prepared by reduction of Pd-Ag salts in the presence of poly(propylene imine) dendrimers, which were covalently bound to the surface of a silica polyamine composite, BP-1 (polyallylamine covalently bound to a silanized amorphous silica gel). Three different Pd-to-Ag ratios were evaluated (50:50, catalyst 1; 40:60, catalyst 2; 60:40, catalyst 3) with the goal of determining how the amount of Ag effects selectivity, rate and conversion in the selective , such as phenylacetylene and 1- or 4-octyne, to the corresponding alkenes. Conditions for the are reported where there is improved selectivity without a serious reduction in rate when compared with the analogous Pd-only catalysts. Catalyst 2 worked best for phenylacetylene and catalyst 3 worked best for the octynes. The catalysts could be reused seven times without loss of activity. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT The structure and properties of silica polyamine composites (SPC) made from microparticles of amorphous silica gel (300-600 microns) and silica nanoparticles (10-20 nm) modified with aminopropyltrimethoxysilane (APTMS), poly(allylamine) (PAA) or poly(ethyleneimine) (PEI) have been studied. The APTMS nano-hybrids showed batch capacities for copper equal to or better than the corresponding polymer-based micro-hybrids. Loading of the PEI on the nanoparticles was independent of molecular weight of the polymer. Dynamic light scattering measurements showed that the SiO2 nanoparticles and the composites made from them aggregate in water and the degree of aggregation is dependent on the surface modification. All of the amine-modified materials were catalysts for the Knoevenagel reaction but interestingly, the microparticles modified with APTMS were better catalysts than the corresponding nanoparticles or the polyamine modified composites. Solid-state 19Si NMR has been used to elucidate the surface structure of the various composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42271. [ABSTRACT FROM AUTHOR]

Novel catalysts consisting of ruthenium nanoparticles encapsulated in cross-linked matrices based on the poly(propylene imine) dendrimers of the 1st and 3rd generations have been synthesized with a narrow particle size distribution (3.8 and 1.0 nm, respectively). The resulting materials showed high activity for the hydrogenation of phenols in aqueous media (specific catalytic activity reached turnover frequencies of 2975 h−1 with respect to hydrogen uptake). It has been shown that the use of water as a solvent leads to a 1.5 to 50-fold increase in the reaction rate depending upon the nature of the substrate. It has been established that unlike the traditional heterogeneous catalysts based on ruthenium, during the hydrogenation of dihydroxybenzenes, the hydrogenation rate decreases in the order: resorcinol>hydroquinone≫catechol. The maximum specific activity for resorcinol was a turnover frequency of 243150 h−1 with respect to hydrogen uptake. The catalyst based on the dendrimer of the 3rd generation containing finer particles has significantly inferior activity to the catalyst based on the dendrimer of the 1st generation by virtue of steric factors, as well as the need for prereduction of the ruthenium oxide contained on the surface. These catalysts showed resistance to metal leaching and may be reused several times without loss of activity. [ABSTRACT FROM AUTHOR]

A series of oxine ligands, 5-X, 8&bond;OH&bond;C9H6N (X = H, Cl, SO3H) have been covalently bound to a silica gel polyamine composite made from a silanized amorphous silica xerogel and poly(allylamine) (BP-1) by the Mannich reaction. The resulting modified composites WP-4(X = H), CB-1(X = Cl), and SB-1(X = SO3H) were characterized by elemental analysis, FTIR, and solid state CPMAS-13C-NMR. Using the analytical data before and after the ligand modification, the ligand loading could be estimated and in combination with metal ion capacities a metal to ligand ratio could be obtained. The composites WP-4 and CB-1 both showed ratios of approximately 1 : 1 while the sulfonate modified composite, SB-1, showed a metal to ligand ratio of 1 : 2. This is tentatively interpreted in terms of a zwitterionic oxine as the dominant species at pH = 2 where the sulfonic acid group is ionized, the quinoline nitrogen is protonated and where two sulfonate groups on adjacent oxines bind a trivalent or divalent ion. All the modified composites show a clear selectivity for trivalent over divalent ions and a good selectivity for gallium over aluminum. The substituent groups on the oxine ligand have only a minor influence on these selectivity trends but SB-1 shows slightly better capture kinetics. The selectivity for gallium over aluminum is applied to the separation of gallium from aluminum, ferrous, and zinc in an acid ore leach of solid tailings obtained from a zinc mine using WP-4. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]