Temperature dependence of conformation, chemical state, and metal-directed assembly of tetrapyridyl-porphyrin on Cu(111)

F. Klappenberger, A. Weber-Bargioni, W. Auwärter, M. Marschall, A. Schiffrin, J. V. Barth

Research output: Contribution to journalArticleOther

91 Citations (Scopus)

Abstract

We present a combined scanning tunneling microscopy (STM), near-edge x-ray-absorption fine-structure, and x-ray photoemission spectroscopy (XPS) study on the bonding and ordering of tetrapyridyl-porphyrin molecules on the Cu(111) surface in the 300-500 K temperature range. Following deposition at 300 K the molecules are adsorbed with a pronounced conformational adaptation of the anchored species featuring a saddle-shaped macrocycle and terminal groups pointing toward the substrate. Upon moderate annealing supramolecular chains evolve that are stabilized by metal-ligand interactions between the mesopyridyl substituents and copper adatoms resulting in twofold copper coordination. Annealing to temperatures exceeding 450 K strongly alters the molecular appearance in high-resolution STM data. This modification was also induced by controlled voltage pulses and related to a deprotonation of the molecule by XPS. Under appropriate conditions a novel binding motif leads to honeycomb structures coexisting with the chain segments. The conformation withstands annealing without large modification. 

Original languageEnglish
Article number214702
JournalThe Journal of Chemical Physics
Volume129
Issue number21
DOIs
Publication statusPublished - 2008
Externally publishedYes

Cite this