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Type: Artigo
Title: Controlling the self-metalation rate of tetraphenylporphyrins on Cu(111) via cyano functionalization
Author: Lepper, M.
Kobl, J.
Zhang, L.
Meusel, M.
Holzel, H.
Lungerich, D.
Jux, N.
Siervo, A. de
Meyer, B.
Steinruck, H. P.
Marbach, H.
Abstract: The reaction rate of the self-metalation of free-base tetraphenylporphyrins (TPPs) on Cu(111) increases with the number of cyano groups (n=0, 1, 2, 4) attached at the para positions of the phenyl rings. The findings are based on isothermal scanning tunneling microscopy (STM) measurements. At room temperature, all investigated free-base TPP derivatives adsorb as individual molecules and are aligned with respect to densely packed Cu substrate rows. Annealing at 400K leads to the formation of linear dimers and/or multimers via CN-Cu-CN bonds, accompanied by self-metalation of the free-base porphyrins following a first-order rate equation. When comparing the non-cyano-functionalized and the tetracyano-functionalized molecules, we find a decrease of the reaction rate by a factor of more than 20, corresponding to an increase of the activation energy from 1.48 to 1.59eV. Density functional theory (DFT) calculations give insights into the influence of the peripheral electron-withdrawing cyano groups and explain the experimentally observed effects.
Subject: Porfirinas
Microscopia de tunelamento de elétrons
Química de superfície
Scanning tunneling microscopy
Surface chemistry
Country: Alemanha
Editor: Wiley-VCH Verlag
Rights: fechado
Identifier DOI: 10.1002/anie.201803601
Date Issue: 2018
Appears in Collections:IFGW - Artigos e Outros Documentos

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