Zwitterionic self-assembly of L-methionine nanogratings on the Ag(111) surface

Agustin Schiffrin, Andreas Riemann, Willi Auwärter, Yan Pennec, Alex Weber-Bargioni, Dean Cvetko, Albano Cossaro, Alberto Morgante, Johannes V. Barth

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The engineering of complex architectures from functional molecules on surfaces provides new pathways to control matter at the nanoscale. In this article, we present a combined study addressing the self-assembly of the amino acid L-methionine on Ag(111). Scanning tunneling microscopy data reveal spontaneous ordering in extended molecular chains oriented along high-symmetry substrate directions. At intermediate coverages, regular biomolecular gratings evolve whose periodicity can be tuned at the nanometer scale by varying the methionine surface concentration. Their characteristics and stability were confirmed by helium atomic scattering. X-ray photoemission spectroscopy and high-resolution scanning tunneling microscopy data reveal that the L-methionine chaining is mediated by zwitterionic coupling, accounting for both lateral links and molecular dimerization. This methionine molecular recognition scheme is reminiscent of sheet structures in amino acid crystals and was corroborated by molecular mechanics calculations. Our findings suggest that zwitterionic assembly of amino acids represents a general construction motif to achieve biomolecular nanoarchitectures on surfaces. 

Original languageEnglish
Pages (from-to)5279-5284
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number13
Publication statusPublished - 27 Mar 2007
Externally publishedYes


  • Nanochemistry
  • Scanning tunneling microscopy
  • Supramolecular engineering
  • Surface chemistry
  • X-ray photoemission spectroscopy

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