title: Functionalization of monodisperse iron oxide NPs and their properties as magnetically recoverable catalysts.
abstract: Here we report the functionalization of monodisperse iron oxide nanoparticles (NPs) with commercially available functional acids containing multiple double bonds such as linolenic (LLA) and linoleic (LEA) acids or pyridine moieties such as 6-methylpyridine-2-carboxylic acid, isonicotinic acid, 3-hydroxypicolinic acid, and 6-(1-piperidinyl)pyridine-3-carboxlic acid (PPCA). Both double bonds and pyridine groups can be reacted with noble metal compounds to form catalytically active species in the exterior of magnetic NPs, thus making them promising magnetically recoverable catalysts. We determined that both LLA and LEA stabilize magnetic iron oxide NPs, allowing the formation of π-complexes with bis(acetonitrile)dichloropalladium(II) in the NP shells. In both cases, this leads to the formation of NP aggregates because of interparticle complexation. In the case of pyridine-containing ligands, only PPCA with two N-containing rings is able to provide NP stabilization and functionalization whereas other pyridine-containing acids did now allow sufficient steric stabilization. The interaction of PPCA-based particles with Pd acetate also leads to aggregation because of interparticle interactions, but the aggregates that are formed are much smaller. Nevertheless, the catalytic properties in the selective hydrogenation of dimethylethynylcarbinol (DMEC) to dimethylvinylcarbinol were the best for the catalyst based on LLA, demonstrating that the NP aggregates in all cases are penetrable for DMEC. Easy magnetic separation of this catalyst from the reaction solution makes it promising as a magnetically recoverable catalyst.
authors.affiliation: Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States.
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Gage
authors.forename: Barry D
authors.initials: BD
authors.lastname: Stein
authors.forename: Linda Zh
authors.initials: LZh
authors.lastname: Nikoshvili
authors.forename: Valentina G
authors.initials: VG
authors.lastname: Matveeva
authors.forename: Mikhail G
authors.initials: MG
authors.lastname: Sulman
authors.forename: Esther M
authors.initials: EM
authors.lastname: Sulman
authors.forename: David Gene
authors.initials: DG
authors.lastname: Morgan
authors.forename: Ekaterina Yu
authors.initials: EY
authors.lastname: Yuzik-Klimova
authors.forename: Waleed E
authors.initials: WE
authors.lastname: Mahmoud
authors.forename: Lyudmila M
authors.initials: LM
authors.lastname: Bronstein
mesh_terms: D002384:Catalysis; D005290:Ferric Compounds / Q000737:chemistry*; D019787:Linoleic Acid / Q000737:chemistry; D008280:Magnetics; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D017962:alpha-Linolenic Acid
chemical_list: D005290:Ferric Compounds; D017962:alpha-Linolenic Acid; C000499:ferric oxide; D019787:Linoleic Acid