title: Calix[4]arene-Functionalised Silver Nanoparticles as Hosts for Pyridinium-Loaded Gold Nanoparticles as Guests.
abstract: A series of lipophilic gold nanoparticles (AuNPs) circa 5 nm in diameter and having a mixed organic layer consisting of 1-dodecanethiol and 1-(11-mercaptoundecyl) pyridinium bromide was synthesised by reacting tetraoctylammonium bromide stabilised AuNPs in toluene with different mixtures of the two thiolate ligands. A bidentate ω-alkylthiolate calix[4]arene derivative was instead used as a functional protecting layer on AgNPs of approximately 3 nm. The functionalised nanoparticles were characterised by transmission electron microscopy (TEM), and by UV/Vis and X-ray photoelectron spectroscopy (XPS). Recognition of the pyridinium moieties loaded on the AuNPs by the calix[4]arene units immobilised on the AgNPs was demonstrated in solution of weakly polar solvents by UV/Vis titrations and DLS measurements. The extent of Au-AgNPs aggregation, shown through the low-energy shift of their surface plasmon bands (SPB), was strongly dependent on the loading of the pyridinium moieties present in the organic layer of the AuNPs. Extensive aggregation between dodecanethiol-capped AuNPs and the Ag calix[4]arene-functionalised NPs was also promoted by the action of a simple N-octyl pyridinium difunctional supramolecular linker. This linker can interdigitate through its long fatty tail in the organic layer of the dodecanethiol-capped AuNPs, and simultaneously interact through its pyridinium moiety with the calix[4]arene units at the surface of the modified AgNPs.
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Parma, Parco Area delle Scienze 17A, 43124 Parma (Italy), Fax: (+39) 0521-905472.|Istituto dei Materiali per l'Elettronica ed il Magnetismo (IMEM-CNR), Parco Area delle Scienze 37A, 43124 Parma (Italy).
authors.forename: Francesco
authors.initials: F
authors.lastname: Vita
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", Piazzale Aldo Moro 5, 00185 Roma (Italy).
authors.forename: Alice
authors.initials: A
authors.lastname: Boccia
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", Piazzale Aldo Moro 5, 00185 Roma (Italy).
authors.forename: Andrea G
authors.initials: AG
authors.lastname: Marrani
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", Piazzale Aldo Moro 5, 00185 Roma (Italy). robertino.zanoni@uniroma1.it.
authors.forename: Robertino
authors.initials: R
authors.lastname: Zanoni
authors.affiliation: Istituto dei Materiali per l'Elettronica ed il Magnetismo (IMEM-CNR), Parco Area delle Scienze 37A, 43124 Parma (Italy).
authors.forename: Francesca
authors.initials: F
authors.lastname: Rossi
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Parma, Parco Area delle Scienze 17A, 43124 Parma (Italy), Fax: (+39) 0521-905472.
authors.forename: Arturo
authors.initials: A
authors.lastname: Arduini
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Parma, Parco Area delle Scienze 17A, 43124 Parma (Italy), Fax: (+39) 0521-905472. andrea.secchi@unipr.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Secchi
keywords: calixarenes; gold; nanoparticles; silver; supramolecular chemistry