Ligand effects in catalysis by atomically precise gold nanoclusters.
basic_science · Level V
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- Record sourced from PubMed, PMID 28989966.
- Also identified by DOI 10.1126/sciadv.1701823 and PMC identifier 5630233.
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Abstract
Atomically precise gold nanoclusters are ideal model catalysts with well-defined compositions and tunable structures. Determination of the ligand effect on catalysis requires the use of gold nanoclusters with protecting ligands as the only variable. Two isostructural Au<sub>38</sub> nanoclusters, [Au<sub>38</sub>(L)<sub>20</sub>(Ph<sub>3</sub>P)<sub>4</sub>]<sup>2+</sup> (L = alkynyl or thiolate), have been synthesized by a direct reduction method, and they have an unprecedented face-centered cubic (fcc)-type Au<sub>34</sub> kernel surrounded by 4 AuL<sub>2</sub> staple motifs, 4 Ph<sub>3</sub>P, and 12 bridging L ligands. The Au<sub>34</sub> kernel can be derived from the fusion of two fcc-type Au<sub>20</sub> via sharing a Au<sub>6</sub> face. Catalytic performance was studied with these two nanoclusters supported on TiO<sub>2</sub> (1/TiO<sub>2</sub> and 2/TiO<sub>2</sub>) as catalysts. The alkynyl-protected Au<sub>38</sub> are very active (>97%) in the semihydrogenation of alkynes (including terminal and internal ones) to alkenes, whereas the thiolated Au<sub>38</sub> showed a very low conversion (<2%). This fact suggests that the protecting ligands play an important role in H<sub>2</sub> activation. This work presents a clear demonstration that catalytic performance of gold nanoclusters can be modulated by the controlled construction of ligand spheres.