title: Surface-Assisted Cyclodehydrogenation; Break the Symmetry, Enhance the Selectivity.
abstract: Selectivity in chemical reactions is a major objective in industrial processes to minimize spurious byproducts and to save scarce resources. In homogeneous catalysis the most important factor which determines selectivity is structural symmetry. However, a transfer of the symmetry concept to heterogeneous catalysis still requires a detailed comprehension of the underlying processes. Here, we investigate a ring-closing reaction in surface-confined meso-substituted porphyrin molecules by scanning tunneling microscopy, temperature-programmed desorption, and computational modeling. The identification of reaction intermediates enables us to analyze the reaction pathway and to conclude that the symmetry of the porphyrin core is of pivotal importance regarding product yields.
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).
authors.forename: Alissa
authors.initials: A
authors.lastname: Wiengarten
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).|Current address: Department of Materials Engineering, Monash University Clayton Campus, VIC 3800 (Australia).
authors.forename: Julian A
authors.initials: JA
authors.lastname: Lloyd
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).|Current address: Karl-Franzens-Universität Graz, Hainrichstrasse 28 V, 8010 Graz (Austria).
authors.forename: Knud
authors.initials: K
authors.lastname: Seufert
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany). joachim.reichert@tum.de.
authors.forename: Joachim
authors.initials: J
authors.lastname: Reichert
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).
authors.forename: Willi
authors.initials: W
authors.lastname: Auwärter
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).
authors.forename: Runyuan
authors.initials: R
authors.lastname: Han
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).|Current address: Diamond Light Source, Didcot, OX11 0DE (UK).
authors.forename: David A
authors.initials: DA
authors.lastname: Duncan
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).
authors.forename: Francesco
authors.initials: F
authors.lastname: Allegretti
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).
authors.forename: Sybille
authors.initials: S
authors.lastname: Fischer
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).
authors.forename: Seung Cheol
authors.initials: SC
authors.lastname: Oh
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).|Current address: Faculty of Engineering and Computer Sciences, Izmir University of Economics, Sakarya Cad.156, Balcova, Izmir (Turkey).
authors.forename: Özge
authors.initials: Ö
authors.lastname: Sağlam
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).
authors.forename: Li
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).|Current address: Corrosion and materials protection division CSIR - Central Electrochemical Research Institute, Karaikudi-630 003, Tamilnadu (India).
authors.forename: Saranyan
authors.initials: S
authors.lastname: Vijayaraghavan
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).|Current address: IMDEA NANOSCIENCE, 28049 Madrid (Spain).
authors.forename: David
authors.initials: D
authors.lastname: Écija
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany). a.c.papageorgiou@tum.de.
authors.forename: Anthoula C
authors.initials: AC
authors.lastname: Papageorgiou
authors.affiliation: Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).
authors.forename: Johannes V
authors.initials: JV
authors.lastname: Barth
keywords: heterogeneous catalysis; porphyrins; ring-closing reaction; selectivity; symmetry