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Self-Metalation of 2H-Tetraphenylporphyrin on Cu(111) Studied with XSW: Influence of the Central Metal Atom on the Adsorption Distance

DOI: 10.1021/jp503046w DOI Help

Authors: Christoph Buerker (University of Tuebingen) , Antoni Franco Canellas (University of Tuebingen) , Katharina Broch (Uni Tuebingen) , Tien-lin Lee (Diamond Light Source) , Alexander Gerlach (University of Tuebingen) , Frank Schreiber (Uni Tuebingen)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Physical Chemistry C , VOL 118 (25) , PAGES 13659–13666

State: Published (Approved)
Published: May 2014
Diamond Proposal Number(s): 8450

Abstract: We present a systematic X-ray standing wave (XSW) study of the π-conjugated organic compound 2H-tetraphenylporphyrin (2HTPP) and copper(II)-tetraphenylporphyrin (CuTPP) on Cu(111) at room and low temperatures. We exploit the feature of thermally activated self-metalation of 2HTPP to CuTPP to study the influence of the central metal atom on the bonding distance of the molecule to the substrate surface. Comparison between the average adsorption distances of the carbon and nitrogen atoms of 2HTPP reveals a distorted molecule with the nitrogen atoms being closer to the surface than the carbon ones on average. Additionally, the measured positions of the two chemically inequivalent types of nitrogen atoms (iminic and aminic) of 2HTPP indicate a distorted porphyrin ring. After the chemical reaction from 2HTPP to CuTPP at 500 K, no change of the adsorption distance of the carbon skeleton is seen, but the entire molecule becomes flattened. Despite the changes upon metalation, adsorption distances for both molecules show a strong interaction with the substrate in comparison to similar π-conjugated molecules.

Journal Keywords: XSW; porphyrin; metalation; self-metalation; organic molecule; interface; metal substrate; molecule-substrate interaction

Subject Areas: Physics, Chemistry

Instruments: I09-Surface and Interface Structural Analysis