Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 64: Organic Molecules on Inorganic Substrates IV: Adsorption, Growth and Networks
O 64.8: Talk
Wednesday, March 18, 2020, 12:15–12:30, TRE Phy
Tailoring adsorbed porphyrins with reactive metal centers — •Francesco Allegretti1, David Duncan1,2, Peter Deimel1, Alissa Wiengarten1, Willi Auwärter1, Ari Seitsonen3, and Johannes Barth1 — 1Physics Department E20, Technical University of Munich, Germany — 2Diamond Light Source, Didcot, OX11 0DE, UK — 3Département de Chimie, École Normale Supérieure, F-75005 Paris, France
Endowing adsorbed metal complexes such as porphyrins and phthalocyanines with specific functionalities can be of paramount importance for a range of applications, including heterogeneous catalysis, solar cells, and chemical sensors. The exploitation of on-surface reactions following the adsorption of free-base macrocyclic species on metal substrates provides an elegant route to tailor reactive centers in clean environments. Here, we report on the formation of Titanium(II) tetraphenylporphyrin (TiTPP) molecules on a Ag(111) surface by on-surface metalation. Unlike other metalloporphyrins we have previously studied, these species are very reactive even in the monolayer limit, and readily react with molecular oxygen to form oxotitanium porphyrin (TiOTPP) molecules with Titanium(IV) centers. We characterize the TiTPP and TiOTPP products at the molecular scale by a combination of X-ray spectroscopy, scanning probe microscopy and density functional theory to unravel details of the self-assembly, the molecular conformation and the oxidation state of the metal centers. Both molecules are promising candidates for future studies into model catalytic and photocatalytic reactions at surfaces.