title: Preparation of Partially Poisoned Alkanethiolate-Capped Platinum Nanoparticles for Hydrogenation of Activated Terminal Alkynes.
abstract: Stable and isolable alkanethiolate-stabilized Pt nanoparticles (PtNP) were synthesized using the two-phase thiosulfate method with sodium S-alkylthiosulfate as ligand precursor. The mechanistic formation of octanethiolate-capped PtNP (Pt-SC8) from both sodium S-octylthiosulfate and 1-octanethiol ligands was investigated by using1H NMR and UV-vis spectroscopies, which revealed the formation of different Pt complexes as the reaction intermediates. The synthesis using S-octylthiosulfate ligand precursor produced Pt-SC8in higher yields than that using 1-octanethiol ligand. The obtained nanoparticles were characterized by1H NMR, UV-vis spectroscopy, infrared spectroscopy (IR), thermogravimetric analysis, and transmission electron microscopy (TEM). The results obtained from1H NMR, IR, and UV-vis spectroscopy were consistent with the formation of stable and pure alkanethiolate-capped PtNP. TEM images of PtNP confirmed their small average core size (∼1.5 nm) and high monodispersity. The partially poisoned PtNP with thiolate monolayer ligands were further investigated for the hydrogenation of various alkynes to understand the organic ligands-induced geometric and electronic surface properties of colloidal Pt nanoparticle catalysts. The high catalytic activity of activated terminal alkynes, but the significantly low activity of internal alkynes and unactivated terminal alkynes, were observed under the mild reaction conditions (room temperature and atmospheric pressure). These results indicated that the presence of alkanethiolate ligands could decrease the coordination activity of PtNP surface especially for the bulkier and unactivated substrates.
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Long Beach , 1250 Bellflower Boulevard, Long Beach, California 90840, United States.
authors.forename: Khin Aye
authors.initials: KA
authors.lastname: San
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Long Beach , 1250 Bellflower Boulevard, Long Beach, California 90840, United States.
authors.forename: Vivian
authors.initials: V
authors.lastname: Chen
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Long Beach , 1250 Bellflower Boulevard, Long Beach, California 90840, United States.
authors.forename: Young-Seok
authors.identifier: http://orcid.org/0000-0003-4765-6130
authors.initials: YS
authors.lastname: Shon
keywords: alkylthiosulfate; catalysis; colloidal; nanoparticles; platinum; unsupported