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MNCL Highlights

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


Giovanni Di Santo1, Stephan Blankenburg2, Carla Castellarin-Cudia1, Mattia Fanetti1, Patrizia Borghetti3, Luigi Sangaletti3, Luca Floreano4, Alberto Verdini4, Elena Magnano4, Federica Bondino4, Carlo A. Pignedoli2, Manh-Thuong Nguyen2, Roberto Gaspari2, Daniele Passerone2, Andrea Goldoni1,*


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)

*E-mail:
 

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


 

Last Updated on Monday, 29 September 2014 18:21