title: Single-Walled Carbon Nanotube-Polyamidoamine Dendrimer Hybrids for Heterogeneous Catalysis.
abstract: We report the synthesis and catalytic properties of single-walled carbon nanotube-polyamidoamine dendrimers hybrids (SWCNT-PAMAM), prepared via a convergent strategy. The direct reaction of cystamine-based PAMAM dendrimers (generations 2.5 and 3.0) with pristine SWCNTs in refluxing toluene, followed by immobilization and reduction of [PdCl4](2-), led to the formation of highly dispersed small palladium nanoparticles homogeneously confined throughout the nanotube length. One of these functional materials proved to be an efficient catalyst in Suzuki and Heck reactions, able to promote the above processes down to 0.002 mol % showing a turnover number (TON) of 48 000 and a turnover frequency (TOF) of 566 000 h(-1). In addition, the hybrid material could be recovered and recycled for up to 6 times. No leaching of the metal has been detected during the Suzuki coupling. Additional experiments carried out on the spent catalyst permitted to suggest that a "release and catch" mechanism is operative in both reactions, although during Heck reaction small catalytically active soluble Pd species are also present.
authors.affiliation: Dipartimento Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF) Università degli Studi di Palermo , Viale delle Scienze, Ed. 17, 90128 Palermo, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Giacalone
authors.affiliation: Dipartimento Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF) Università degli Studi di Palermo , Viale delle Scienze, Ed. 17, 90128 Palermo, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Campisciano
authors.affiliation: Dipartimento Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF) Università degli Studi di Palermo , Viale delle Scienze, Ed. 17, 90128 Palermo, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Calabrese
authors.affiliation: Istituto per lo Studio dei Materiali Nanostrutturati ISMN-CNR , Via Ugo La Malfa 153, 90146 Palermo, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: La Parola
authors.affiliation: Centre of Excellence for Nanostructured Materials (CENMAT), INSTM, Unit of Trieste, Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste , Via L. Giorgieri 1, 34127 Trieste, Italy.
authors.forename: Zois
authors.initials: Z
authors.lastname: Syrgiannis
authors.affiliation: Centre of Excellence for Nanostructured Materials (CENMAT), INSTM, Unit of Trieste, Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste , Via L. Giorgieri 1, 34127 Trieste, Italy.|CIC BiomaGUNE , Parque Tecnológico de San Sebastián, Paseo Miramón, 182, 20009 San Sebastián, Guipúzcoa, Spain.|Basque Foundation for Science, Ikerbasque , Bilbao 48013, Spain.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Prato
authors.affiliation: Dipartimento Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF) Università degli Studi di Palermo , Viale delle Scienze, Ed. 17, 90128 Palermo, Italy.
authors.forename: Michelangelo
authors.initials: M
authors.lastname: Gruttadauria
keywords: C−C cross coupling; PAMAM dendrimers; TEM; carbon nanotubes; heterogeneous catalysis; palladium nanoparticles