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2H-TPP on Ag: carbon de-hydrogenation and geometrical adaptation
We observe a selective carbon de-hydrogenation, the formation of new aryl-aryl bonds between phenyl groups and the macrocycle, as well as the rotation of the phenyl rings in a flat conformation. Experiments and theoretical calculations prove this chemical reaction. |
 In our recent investigations we have demonstrated that one monolayer of 2H-TPP, prepared by thermal desorption of the corresponding multilayer at 550 K on Ag(111), adsorbs with the macrocycle and the phenyl flat. This information has been directly addressed by means of X-ray absorption and photoemission experiments. |
Theoretical calculations suggest a possible molecular reaction and modification of porphyrins, in order to explain this adsorption conformation: the de-hydrogenation of eight carbon atoms in the remaining monolayer after the multilayer desorption, with the formation of four new aryl-aryl carbon bonds. While the reaction takes place also in the deposited monolayer annealed at 550 K, the initial presence of the multilayer favors a decrease of the aryl-aryl coupling barrier and the selection of a spiral conformation in the de-hydrogenated molecule. The chemical reaction produces a stable molecule that forms a patterned square lattice on Ag(111) and that can be further modified by the introduction of central metal atoms. |
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Supramolecular Engineering through Temperature-Induced Chemical Modification of 2H-Tetraphenylporphyrin on Ag(111): Flat Phenyl Conformation and Possible Dehydrogenation Reactions
1INSTM—Micro & Nano-Carbon Laboratory, Sincrotrone Trieste S.C.p.A. s.s.14 km. 163.5, 34149 Trieste (Italy), Fax: +(39) 040-3758565Empa, Swiss Federal Laboratiories for 2Materials Science and Technology nanotech@surfaces Laboratory, Ueberlandstrasse 129, 8600 Dübendorf (Switzerland)
3Dipartimento di Matematica e Fisica and Interdisciplinary Laboratories for Advanced Materials Physics, Università Cattolica del Sacro Cuore, Brescia (Italy)
4Istituto Officina dei Materiali-CNR, Lab. TASC, s.s. 14 km 163.5, 34149 Trieste (Italy)
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Chemistry - A European Journal vol 17, Issue 51, 14354, December 16, 2011
DOI: 10.1002/chem.201102268
Publication Date (Web): November 23, 2011
Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
