Presentation Title: From chemical bonds to intelligent molecular tools
Prof. Harald Fuchs presented this talk in the webinar on Materials Science, Engineering and Technology organized by Vebleo
Author: Harald Fuchs1, Armido2 Studer2, Frank Glorius2, Nikos Doltsinis3, M. Rohlfing3, Hongying Gao1, Saaed Armirjalayer1, Harry Mönig1, Anne Bakker1, Lacheng Liu1, Q.Chen1, G. Wang1, Alexander Timmer1
Affiliation:
1Center for Nanotechnology, Heisenbergstraße 11, 48149 Münster Germany
2Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany
3Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
Biography
Prof. Harald Fuchs is a Professor of Experimental Physics at the University of Münster, Germany. After completion his PhD project in Material Science at the University of Saarbrücken with Prof. H. Gleiter, he spent a post-doctoral year with IBM Research Laboratory Zurich in the group of G. Binnig & H. Rohrer from 1984 –1985.
From 1985-1993 Prof. Harald Fuchs was heading the ‚Ultrathin Organic Films’ research project at BASF AG, Germany, before he became in 1993 a Full Professor and Director of the Physical Institute of the University of Münster.
Prof. Harald Fuchs is the founder of the Center for Nanotechnology (CeNTech) in Münster and its scientific director since 1993. His research focuses on nanoscale science and nanotechnology, ranging from scanning probe microscopy to self-organized nanostructure fabrication, and nano-bio systems documented in more than 560 peer reviewed publications and 58 patents.
Prof. Harald Fuchs was the speaker of the first large scale collaborative research Sino-German basic research project, SFB/TRR 61, jointly funded by DFG and NSFC. H. Fuchs is a co-founder of two start-up companies.
Prof. Harald Fuchs is an elected member of the German National Academy of Science ‘Leopoldina’, the German National Academy of Science and Engineering ‘acatech’, and ‘TWAS’. He received the Chinese Friendship Award in 2019.
Abstract
Surfaces and interfaces represent low-dimensional spatial confinements opening unique pathways towards on-surface chemical reaction schemes with regio-selective and kinetic control that is not available in conventional liquid- or gas-phase chemistry. In addition, surfaces may be catalytically active, and by surface reconstruction or faceting the spatial confinement may display one- or zero-dimensional character.
Beyond pure mechanical support, surfaces may also promote ordering by self-assembly of educts and products and may stabilize them by molecule-substrate interactions. We have studied numerous novel chemical surface reaction types including metal-organic compounds, precursors for generating graphdiynes, and peroxides, otherwise unstable in liquid or gas phases. By using on-surface chemistry techniques intermediate states can be analyzed with high resolution techniques such as low-temperature STM and AFM under ultrahigh vacuum condition.
This approach also opens the pathway for controlled orthogonal reactions. Beyond all that, we found a fascinating new and powerful potential of on-surface chemistry which allows to set up a new strategy for the generation of intelligent functional systems. In this context, we recently introduced a molecular swarm like system performing a coordinated surface restructuring.
It is based on N‐heterocyclic carbenes (NHC) binding to a single noble metal atom such as of an Au(111) surface after vacuum deposition. Depending on the type of N-ligands, NHCs are able to pull a single atom out of the surface after forming a covalent bond and then travel in the so-called ‘ballbot’- motion type across the surface, eventually forming densely packed islands. The ballbots form spontaneously on the surface.
We discovered that on an Au(1×2) reconstructed surface ballbot-NHcs are able to autonomously re-organize that surface atom by atom in a well-controlled and ‘swarm-like’ manor. No external supporting measures are required such as lithography or STM and AFM probes. Rather, the cooperative restructuring occurs in a special zipper-mode by the molecular machines which are re-arranging Au atoms with atomic precision and in a massive parallel scheme.
As a result, the Au(1×2) surface is transferred at room temperature into an Au(1×3) -‘Added Row (AR)’ structure. It is known that the Au(1×3)-AR surface displays a higher chemical reactivity than the native Au(1×2) structure and does not spontaneously transform back to the (1×2) reconstruction as does the conventional Au(1×3) reconstruction occurring at temperatures around 800 K on a clean Au (111) surface.
This observation opens the door for the generation of ‘programmed’ and autonomously acting molecular species possibly allowing to optimize surfaces in a cooperative way, for example, for catalysis applications. All these studies require the intense collaboration of physicists, chemists and theoreticians. For high resolution analysis we apply advanced LT-UHV Scanning probe techniques such as LT-STM and nc-AFM allowing us a detailed sub-molecularly resolved analysis of on-surface chemical reaction schemes, including the characterization of intermediates.
A novel type of noncontact-AFM tip developed in our group which is based on a single oxygen atom located at the apex of a copper tip allows us to quantitatively characterize individual chemical bonds and even bond-orders with unprecedented precision.
Graphical Abstract
This talk was delivered in the webinar organized by Vebleo