Imaging Single-Molecule Reaction Intermediates Stabilized by Surface Dissipation and Entropy

Nature Chemistry 8, 678 - 683 (2016)

Imaging Single-Molecule Reaction Intermediates Stabilized by Surface Dissipation and Entropy

A. Riss, A. Pérez Paz, S. Wickenburg, H-Z. Tsai, D. G. de Oteyza, A. J. Bradley, M. M. Ugeda, P. Gorman, H. Sae Jung, M. F. Crommie, A. Rubio, F. R. Fischer

Chemical transformations at the interface between solid/liquid or solid/gaseous phases of matter lie at the heart of key industrial-scale manufacturing processes. A comprehensive study of the molecular energetics and conformational dynamics that underlie these transformations is often limited to ensemble-averaging analytical techniques. Here we report the detailed investigation of a surface-catalysed cross-coupling and sequential cyclization cascade of 1,2-bis(2-ethynyl phenyl)ethyne on Ag(100). Using non-contact atomic force microscopy, we imaged the single-bond-resolved chemical structure of transient metastable intermediates. Theoretical simulations indicate that the kinetic stabilization of experimentally observable intermediates is determined not only by the potential-energy landscape, but also by selective energy dissipation to the substrate and entropic changes associated with key transformations along the reaction pathway. The microscopic insights gained here pave the way for the rational design and control of complex organic reactions at the surface of heterogeneous catalysts.

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A. Riss, A. Pérez Paz and S. Wickenburg have contributed equally to this work. Research supported by the U.S. Department of Energy Office of Basic Energy Sciences Nanomachine Program under contract no. DE-AC02-05CH11231 (STM and nc-AFM instrumentation development, AFM imaging), the Office of Naval Research BRC Program (molecular synthesis, characterization, and STM imaging), the ERC Advanced Grant DYNamo no. ERC-2010-AdG-267374 (computer resources and support), Spanish Grant no. FIS2013-46159-C3-1-P (MD calculations), and Grupos Consolidados UPV/EHU del Gobierno Vasco no. IT-578-13 (DFTB calculations). A.R. acknowledges fellowship support by the Austrian Science Fund (FWF) no. J3026-N16. A.P.P. acknowledges fellowship support from the "Ayuda para la Especialización de Personal Investigador del Vicerrectorado de Investigación de la UPV/EHU-2013". A.Ru. acknowledges fellowship support from the Miller Institute for Basic Research in Science of the University of California at Berkeley (Miller Visiting Research Professor program). We thank Pavel Jelinek and Prokop Hapala for their help with the nc-AFM simulations and Duncan J. Mowbray for useful discussions.

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