M4Au12Ag32(p-MBA)30 (M = Na, Cs) bimetallic monolayer-protected clusters: synthesis and structure

Brian E Conn; Badri Bhattarai; Aydar Atnagulov; Bokwon Yoon; Uzi Landman; Terry P Bigioni

doi:10.1107/S2056989018008393

M₄Au₁₂Ag₃₂(p-MBA)₃₀ (M = Na, Cs) bimetallic monolayer-protected clusters: synthesis and structure

Acta Crystallogr E Crystallogr Commun. 2018 Jun 19;74(Pt 7):987-993. doi: 10.1107/S2056989018008393. eCollection 2018 Jul 1.

Authors

Brian E Conn¹, Badri Bhattarai¹, Aydar Atnagulov¹, Bokwon Yoon², Uzi Landman², Terry P Bigioni¹

Affiliations

¹ Department of Chemistry, University of Toledo, Toledo, Ohio 43606, USA.
² School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 0430, USA.

Abstract

Crystals of M₄Au₁₂Ag₃₂(p-MBA)₃₀ bimetallic monolayer-protected clusters (MPCs), where p-MBA is p-mercapto-benzoic acid and M⁺ is a counter-cation (M = Na, Cs) have been grown and their structure determined. The mol-ecular structure of triacontakis[(4-carboxylatophenyl)sulfanido]dodecagolddotriacontasilver, Au₁₂Ag₃₂(C₇H₅O₂S)₃₀ or C₂₁₀H₁₅₀Ag₃₂Au₁₂O₆₀S₃₀, exhib-its point group symmetry at 100 K. The overall diameter of the MPC is approximately 28 Å, while the diameter of the Au₁₂Ag₂₀ metallic core is 9 Å. The structure displays ligand bundling and inter-molecular hydrogen bonding, which gives rise to a framework structure with 52% solvent-filled void space. The positions of the M⁺ cations and the DMF solvent mol-ecules within the void space of the crystal could not be determined. Three out of the five crystallographically independent ligands in the asymmetric unit cell are disordered over two sets of sites. Comparisons are made to the all-silver M₄Ag₄₄(p-MBA)₃₀ MPCs and to expectations based on density functional theory.

Keywords: Bader analysis; bimetallic nanoparticle; crystal structure; gold nanoparticle; monolayer-protected cluster; silver nanoparticle.

Grants and funding

This work was funded by National Science Foundation, Directorate for Engineering grant CBET-0955148. University of Toledo grant to B. E. Conn. Air Force Office of Scientific Research grant FA9550-14-1-0005 to B. Yoon and U. Landman.