title: Surface-assisted dehydrogenative homocoupling of porphine molecules.
abstract: The templated synthesis of porphyrin dimers, oligomers, and tapes has recently attracted considerable interest. Here, we introduce a clean, temperature-induced covalent dehydrogenative coupling mechanism between unsubstituted free-base porphine units yielding dimers, trimers, and larger oligomers directly on a Ag(111) support under ultrahigh-vacuum conditions. Our multitechnique approach, including scanning tunneling microscopy, near-edge X-ray absorption fine structure and photoelectron spectroscopy complemented by theoretical modeling, allows a comprehensive characterization of the resulting nanostructures and sheds light on the coupling mechanism. We identify distinct coupling motifs and report a decrease of the electronic gap and a modification of the frontier orbitals directly associated with the formation of triply fused dimeric species. This new on-surface homocoupling protocol yields covalent porphyrin nanostructures addressable with submolecular resolution and provides prospective model systems towards the exploration of extended oligomers with tailored chemical and physical properties.
authors: Physik Department E20, Technische Universität München , James-Franck-Straße 1, D-85748 Garching, Germany.
authors: Alissa
authors: A
authors: Wiengarten
authors: Knud
authors: K
authors: Seufert
authors: Willi
authors: W
authors: Auwärter
authors: David
authors: D
authors: Ecija
authors: Katharina
authors: K
authors: Diller
authors: Francesco
authors: F
authors: Allegretti
authors: Felix
authors: F
authors: Bischoff
authors: Sybille
authors: S
authors: Fischer
authors: David A
authors: DA
authors: Duncan
authors: Anthoula C
authors: AC
authors: Papageorgiou
authors: Florian
authors: F
authors: Klappenberger
authors: Robert G
authors: RG
authors: Acres
authors: Thien H
authors: TH
authors: Ngo
authors: Johannes V
authors: JV
authors: Barth
mesh_terms: D019281:Dimerization; D016252:Microscopy, Scanning Tunneling; D049329:Nanostructures / Q000737:chemistry; D056951:Photoelectron Spectroscopy; D011166:Porphyrins / Q000737:chemistry* / Q000378:metabolism; D012834:Silver / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy
chemical_list: D011166:Porphyrins; D012834:Silver; C107018:porphine