Hydrogen-bonded structure and mechanical chiral response of a silver nanoparticle superlattice.
Self-assembled nanoparticle superlattices-materials made of inorganic cores capped by organic ligands, of varied structures, and held together by diverse binding motifs-exhibit size-dependent properties as well as tunable collective behaviour arising from couplings between their nanoscale constituents. Here, we report the single-crystal X-ray structure of a superlattice made in the high-yield synthesis of Na(4)Ag(44)(p-MBA)(30) nanoparticles, and find with large-scale quantum-mechanical simulations that its atomically precise structure and cohesion derive from hydrogen bonds between bundledp-MBA ligands. We also find that the superlattice's mechanical response to hydrostatic compression is characterized by a molecular-solid-like bulk modulus B(0) = 16.7 GPa, exhibiting anomalous pressure softening and a compression-induced transition to a soft-solid phase. Such a transition involves ligand flexure, which causes gear-like correlated chiral rotation of the nanoparticles. The interplay of compositional diversity, spatial packing efficiency, hydrogen-bond connectivity, and cooperative response in this system exemplifies the melding of the seemingly contrasting paradigms of emergent behaviour 'small is different' and 'more is different'.
School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA.
Bokwon
B
Yoon
School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA.
W D
WD
Luedtke
School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA.
Robert N
RN
Barnett
School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA.
Jianping
J
Gao
Department of Chemistry and School of Solar and Advanced Renewable Energy, University of Toledo, Toledo, Ohio 43606, USA.
Anil
A
Desireddy
Department of Chemistry and School of Solar and Advanced Renewable Energy, University of Toledo, Toledo, Ohio 43606, USA.
Brian E
BE
Conn
Department of Chemistry and School of Solar and Advanced Renewable Energy, University of Toledo, Toledo, Ohio 43606, USA.
Terry
T
Bigioni
School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA.
Uzi
U
Landman