18/02/2019 @ 11:00 AM – 12:00 PM Asia/Singapore Timezone
Physics Conference Room (S11-02-07)

Speaker: Prof. Hannu Häkkinen
Affiliation: University of Jyväskylä, Finland
Host: Prof. Feng Yuan Ping and Associate Professor Zhang Chun
Location: Click HERE for directions

Abstract Details: The last decade has seen a remarkable development in the science of ligand-stabilized noble metal nanoclusters, when synthesis, purification and characterization methods have been refined to produce reproducibly an array of atomically precise compounds with metal cores ranging from sub-nanometer to three nanometers. (1,2) Recipes exist now for synthesis of ambient-stable gold- and silver-based clusters, which can also be doped by other coinage metals and protected by various organic ligands that control the solubility and interactions of the clusters with the environment. Variation of size and shape of the metal core gives control over the physical properties, for instance, the band gap can be tuned from semiconducting to metallic regime. These rather stable building blocks can be expected to find diverse applications. One of the important challenges for the coming years is to learn to control macroscopic assemblies of these well-defined building blocks to produce materials with desired or sometimes surprising novel properties. This talk reviews some recent attempts where well-defined, thiolate-stabilized gold nanoclusters have been used to assemble hybrid inorganic-organic materials or where directed or spontaneous assemblies have been discovered. Specifically, these examples are discussed: (i) Site-specific binding of Au102(p-MBA)44 clusters to enterovirus capsid by covalent or weak (hydrophobic) interactions (3,4); (ii) dimers, trimers, tetramers of Au102(p-MBA)44 and Au~250(p-MBA)~90 clusters linked by molecular (dithiolate) bridges (5); and (iii) Au102(p-MBA)44 clusters self-assembled to colloidal plate nanocrystals or light-weight micrometer-scale materials composed of empty 3D capsids of clusters producing <10% volume filling ratio in the material.(6)

1. T. Tsukuda and H. Häkkinen (eds.), Protected Metal Clusters: From Fundamentals to Applications, Elsevier, 2015.
2. H. Yang, Y. Wang, X. Chen, X. Zhao, L. Gu, H. Huang, J. Yan, C. Xu, G. Li, J. Wu, A. Edwards, B. Dittrich, Z. Tang, D. Wang, L. Lehtovaara, H. Häkkinen, and N. Zheng Plasmonic twinned silver nanoparticles with molecular precision, Nature Comm. 7, 12809 (2016).
3. V. Marjomäki, T. Lahtinen, M. Martikainen, J. Koivisto, S. Malola, K. Salorinne, M. Pettersson and H. Häkkinen, Site-specific targeting of enterovirus capsid by functionalized monodisperse gold nanoclusters, Proc. Natl. Acad. Sci. USA 111, 1277 (2014).
4. M. Martikainen, K. Salorinne, T. Lahtinen, S. Malola, P. Permi, H. Häkkinen and V. Marjomäki, Hydrophobic pocket targeting probe for enteroviruses, Nanoscale 7, 17457 (2015).
5. T. Lahtinen, E. Hulkko, K. Sokolowska, T-R. Tero, V. Saarnio, J. Lindgren, M. Pettersson, H. Häkkinen and L. Lehtovaara, Covalently linked multimers of gold nanoclusters Au102(p-MBA)44 and Au~250(p-MBA)n, Nanoscale 8, 18665 (2016).
6. Nonappa, T. Lahtinen, J.S. Haataja, T.R. Tero, H. Häkkinen, and O.Ikkala, Template-free supracolloidal self-assembly of atomically precise gold nanoclusters: From 2D colloidal crystals to spherical capsids, Angew. Chemie Int. Ed. (2016), doi: 10.1002/anie.201609036

About the Speaker: Hannu Häkkinen is Professor in Computational Nanoscience at the University of Jyväskylä, Finland. His interests cover methods of electronic structure calculations of nanoparticles, nanostructures and solids. His group investigates electronic, optical, magnetic, chemical and catalytic properties of bare, supported, and ligand-protected metal nanoparticles, electrical conductivity of molecule-metal interfaces in nanostructures, and structural and chemical properties of metal nanoparticle / bionanoparticle (virus) hybrids. He has published over 220 peer-reviewed publications and was listed as "Highly Cited Researcher" by Clarivate Analytics in 2018, in the field of cross-disciplinary science. He is currently a research professor supported by the Academy of Finland 2016-2020 and a visiting professor in Xiamen University in China.