L-tyrosine on Ag(111): Universality of the amino acid 2D zwitterionic bonding scheme?

Joachim Reichert, Agustin Eduardo Schiffrin, Wilhelm Auwarter, Alexander Weber-Bargioni, Matthias Marschall, Martina Dell'Angela, Dean Cvetko, Gregor Bavdek, Albano Cossaro, Alberto Morgante, Johannes V Barth

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36 Citations (Scopus)

Abstract

We present a combined study of the adsorption and ordering of the L-tyrosine amino acid on the close-packed Ag(111) noble-metal surface in ultrahigh vacuum by means of low-temperature scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. On this substrate the biomolecules self-assemble at temperatures exceeding 320 K into linear structures primarily following specific crystallographic directions and evolve with larger molecular coverage into two-dimensional nanoribbons which are commensurate with the underlying atomic lattice. Our high resolution topographical STM data reveal noncovalent molecular dimerization within the highly ordered one-dimensional nanostructures, which recalls the geometrical pattern already seen in the L-methionine/Ag(111) system and supports a universal bonding scheme for amino acids on smooth and unreactive metal surfaces. The molecules desorb for temperatures above 350 K, indicating a relatively weak interaction between the molecules and the substrate. XPS measurements reveal a zwitterionic adsorption, whereas NEXAFS experiments show a tilted adsorption configuration of the phenol moiety. This enables the interdigitation between aromatic side chains of adjacent molecules via parallel-displaced p-p interactions which, together with the hydrogen-bonding capability of the hydroxyl functionality, presumably mediates the emergence of the self-assembled supramolecular nanoribbons
Original languageEnglish
Pages (from-to)1218 - 1226
Number of pages9
JournalACS Nano
Volume4
Issue number2
DOIs
Publication statusPublished - 2010
Externally publishedYes

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