Berlin 2024 – scientific programme

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O: Fachverband Oberflächenphysik

O 65: Poster: Molecular Nanostructures on Surfaces

O 65.14: Poster

Wednesday, March 20, 2024, 18:00–20:00, Poster C

Visualising the steps in a chemical reaction: On-surface reactivity of brominated tetraphenyl porphyrin on Cu(111) — •Ailish Gray, Michael Clarke, Matthew Edmondson, and Alex Saywell — School of Physics & Astronomy, University of Nottingham, UK

Scanning probe microscopy techniques have been extensively employed to provide details of on-surface reactions [1] and can provide significant insight into the effects of substrate and molecular chemistry upon the reaction products of on-surface synthesis.[2] The Ullmann-type coupling of brominated tetraphenyl porphyrin (BrxTPP) on Au(111) [3] is a seminal work, demonstrating molecular characterisation of on-surface covalent coupling. However, on Cu(111) the reaction progress is different,[4] and for various substrates a variety of reactions (including; ring-closing, metalorganic coordination, and self-metalation) may occur. Here, we detail a low-temperature ultra-high vacuum scanning tunnelling microscopy (STM) study of BrxTPP (x=0-4) on Cu(111). We observe multiple steps in an on-surface reaction; debromination, formation of metal-organic frameworks, ring opening, self-metalation, and covalent coupling. Systematic, temperature controlled, investigation reveals step-wise evolution of the reaction, with the intermediate reaction stages probed using STM imaging and manipulation.

[1] A. Sweetman, N.R. Champness, A. Saywell, Chem. Soc. Rev., 2020, 49, 4189 [2] L. Grill, S. Hecht, Nat. Chem. 2020, 12, 115 [3] L. Grill et.al, Nat. NanoTech., 2007, 2, 687 [4] C.M. Doyle et. al, Chem. Commun. Camb., 2011, 28, 12134

Keywords: On-surface synthesis; STM; Porphyrin; Cu(111)