Dresden 2017 – scientific programme

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O: Fachverband Oberflächenphysik

O 72: Oxide and Insulator Surfaces: Adsorption I

O 72.2: Talk

Wednesday, March 22, 2017, 10:45–11:00, WIL C107

Hungry Porphyrins: Protonation and Self-Metalation of Tetraphenylporphrin on TiO₂(110) - 1 × 1 — •Julia Köbl¹, Tao Wang², Cici Wang², Martin Drost¹, Fan Tu¹, Qian Xu², Huanxin Ju², Daniel Wechsler¹, Matthias Franke¹, Haibin Pan², Hubertus Marbach¹, Hans-Peter Steinrück¹, Junfa Zhu², and Ole Lytken¹ — ¹Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, D-91058 — ²National Synchrotron Radiation Laboratory, 42 S Hezuohua Road, Hefei, 230029, China

In order to obtain a detailed understanding of organic electronic devices such as dye-sensitized solar cells, one has to characterize the interactions of organic molecules with oxide substrates at the atomic level. Thus, we have studied the adsorption and self-metalation of tetraphenylporphyrin (2HTPP) on TiO₂(110) - 1 × 1 with X-ray Photoelectron Spectroscopy (XPS) and Scanning Tunneling Microscopy (STM). Upon adsorption at room temperature, the first monolayer of 2HTPP is protonated, forming porphyrin diacid (4HTPP²⁺). As the surface is heated to 400 K, all unprotonated 2HTPP molecules in the second layer metalate, forming titanyl tetraphenylporphyrin (TiOTPP), but the protonated molecules in the first layer stay intact. As the surface is heated further to 550 K even the protonated 4HTPP²⁺ molecules metalate and only TiOTPP remain on the surface^a. Supported by the DFG through FOR 1878 (funCOS), the Chinese Scholarship Council and BayCHINA.
^aKöbl et al., Chemistry Select, 2016, 1, 6103 - 6105.