Metal nanaoclusters of gold, silver and palladium having dimensions in between atoms and large nanoparticles demonstrate excellent optical and catalytic activity. In this study, the synthesis of fluorescent palladium nanoclusters (PdNC) at ambient conditions is reported by using modified Brust–Schiffrin method (BSM) with alkyl thiosulfate ligand precursors. The phase transfer of PdCl42- by tetra-N-octylammonium bromide (TOAB) from water to dichlormethane (DCM) was followed by the addition of sodium 2-phenylethylthiosulfate dissolved in aqueous methanol of varying ratios. The addition of pure methanol to the DCM solution containing alkylthiosulfate-Pd2+ complexes led to a change of color of the solution from dark red wine to light orange and ended up with precipitation of yellowish particles. The yellowish dispersion in pure ethanol was reduced to PdNC and found to turn into light brown after the addition of various amounts and concentration of sodium borohydride (NaBH4). PdNCs exhibit green emission under UV-lamp at 365 nm, and it was further confirmed by photoluminescence spectroscopy. Transmission electron microscope (TEM) images indicated that the size of the clusters is in a range of 3-6 nm with spherical morphology and an average diameter of 5 nm. Nuclear magnetic resonance (NMR) spectroscopy was also applied to characterize alkanethiolate-protected PdNC. The catalytic activity of PdNC is investigated using various model reactions including hydrogenation and C-C coupling reaction.

Facile synthesis of alkanethiolate-capped fluorescent palladium nanocluster as a catalyst

ACS Spring Meeting 2021

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