title: Polymer-coated palladium nanoparticle catalysts for Suzuki coupling reactions.
abstract: A set of seven different palladium nanoparticle (PdNP) systems stabilized by small amounts (1.0mg/mL) of structurally related macromolecular capping agents were comparatively tested as catalyst in p-nitrophenol (Nip) reduction and Suzuki cross-coupling reactions. The observed rate constants (kobs) for Nip reduction were in the range of 0.052-3.120×10(-2)s(-1), and the variation reflected the effects of polymer chain conformation, ionic strength and palladium-polymer complex coordination. Macromolecules featuring pendant pyridyl moieties or inverse temperature-dependent solubility were found to be unsuitable capping agents for PdNPs catalysts, despite being active. The catalytic activity in Suzuki cross-coupling reactions followed the same behavior; the most active particles in the Nip reaction also mediated the cross-coupling reaction providing the expected products in quantitative yields under relatively mild conditions after only 4h at 50°C. Experiments involving the successive addition of reactants and catalyst recovery/re-use indicated that the recycling potential was comparable to those of the standards used in this field.
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil.
authors.forename: Tanize
authors.initials: T
authors.lastname: Bortolotto
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil.
authors.forename: Sara Elisa
authors.initials: SE
authors.lastname: Facchinetto
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil.
authors.forename: Suelen Gauna
authors.initials: SG
authors.lastname: Trindade
authors.affiliation: Instituto de Química, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, RS, Brazil.
authors.forename: Andreia
authors.initials: A
authors.lastname: Ossig
authors.affiliation: Instituto de Química, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, RS, Brazil.
authors.forename: Cesar Liberato
authors.initials: CL
authors.lastname: Petzhold
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil.
authors.forename: Josimar
authors.initials: J
authors.lastname: Vargas
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil.
authors.forename: Oscar Endrigo Dorneles
authors.initials: OE
authors.lastname: Rodrigues
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil.
authors.forename: Cristiano
authors.initials: C
authors.lastname: Giacomelli
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil. Electronic address: vschmidt@ufsm.br.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Schmidt
keywords: Capping agents; Palladium nanoparticles; Polymers; Suzuki−Miyaura reaction; p-Nitrophenol reduction