Vita F, Boccia A, Marrani AG, Zanoni R, Rossi F, Arduini A, Secchi A. Calix[4]arene-Functionalised Silver Nanoparticles as Hosts for Pyridinium-Loaded Gold Nanoparticles as Guests.
Chemistry 2015;
21:15428-38. [PMID:
26471448 DOI:
10.1002/chem.201501920]
[Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 07/06/2015] [Indexed: 12/26/2022]
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.
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