Structure-conserving spontaneous transformations between nanoparticles

K R Krishnadas; Ananya Baksi; Atanu Ghosh; Ganapati Natarajan; Thalappil Pradeep

doi:10.1038/ncomms13447

Structure-conserving spontaneous transformations between nanoparticles

Nat Commun. 2016 Nov 10:7:13447. doi: 10.1038/ncomms13447.

Authors

K R Krishnadas¹, Ananya Baksi¹, Atanu Ghosh¹, Ganapati Natarajan¹, Thalappil Pradeep¹

Affiliation

¹ Department of Chemistry, DST Unit of Nanoscience (DST UNS) and Thematic Unit of Excellence (TUE), Indian Institute of Technology Madras, Chennai 600036, India.

Abstract

Ambient, structure- and topology-preserving chemical reactions between two archetypal nanoparticles, Ag₂₅(SR)₁₈ and Au₂₅(SR)₁₈, are presented. Despite their geometric robustness and electronic stability, reactions between them in solution produce alloys, Ag_mAu_n(SR)₁₈ (m+n=25), keeping their M₂₅(SR)₁₈ composition, structure and topology intact. We demonstrate that a mixture of Ag₂₅(SR)₁₈ and Au₂₅(SR)₁₈ can be transformed to any arbitrary alloy composition, Ag_mAu_n(SR)₁₈ (n=1-24), merely by controlling the reactant compositions. We capture one of the earliest events of the process, namely the formation of the dianionic adduct, (Ag₂₅Au₂₅(SR)₃₆)^2-, by electrospray ionization mass spectrometry. Molecular docking simulations and density functional theory (DFT) calculations also suggest that metal atom exchanges occur through the formation of an adduct between the two clusters. DFT calculations further confirm that metal atom exchanges are thermodynamically feasible. Such isomorphous transformations between nanoparticles imply that microscopic pieces of matter can be transformed completely to chemically different entities, preserving their structures, at least in the nanometric regime.