Effect of Molecule-Substrate Interactions on the Adsorption of meso-Dibenzoporphycene Tautomers Studied by Scanning Probe Microscopy and First-Principles Calculations

Tomoko K. Shimizu, Carlos Romero-Muñiz, Oleksandr Stetsovych, Jaime Carracedo-Cosme, Michael Ellner, Pablo Pou, Koji Oohora, Takashi Hayashi, Ruben Perez, Oscar Custance

研究成果: Article査読

抄録

meso-Dibenzoporphycene molecules adsorbed on the Ag(111) surface and on 2-monolayer-thick NaCl films were studied using submolecular resolution atomic force microscopy (AFM), scanning tunneling microscopy (STM), and first-principles calculations to clarify their stability and tautomerization behavior. We have found that the bonding of the molecules with the surface is determined by the interplay of different contributions, including the interaction of the π-aromatic orbitals of the benzene rings and the metal-coordination bond of the lone-pair electrons of the imine nitrogen atoms with the metal atoms (Ag, Na) on each substrate. The strength of the latter ultimately governs the molecular adsorption configuration and determines the nature and energy barriers for tautomerization. On Ag(111), the interaction of the imine nitrogen atoms with the Ag atoms deforms the macrocycle of porphycene, leading to a distinct AFM contrast that allows a clear identification of the molecule in its cis tautomeric form. In contrast, on NaCl films, the weaker interaction with the Na atoms leads to a flatter geometry and very similar adsorption configurations for the cis- and trans-forms, which cannot be distinguished in AFM experiments. Although weak, the dominant role of this local N-Na interaction, compared to the essentially nondirectional dispersive interactions, results in a new type of tautomerization process. In this case, the transfer of hydrogen atoms within the porphycene cavity is accompanied by a significant displacement of the whole molecule to a new site to reach a new minimum energy adsorption configuration. Our theoretical calculations indicate that this lateral translation, rather than the intramolecular H transfer, dominates the activation energy on NaCl. This novel tautomerization behavior, which we have identified on a rather inert ionic surface, might also be present on other weakly interacting substrates.

本文言語English
ページ(範囲)26759-26768
ページ数10
ジャーナルJournal of Physical Chemistry C
124
49
DOI
出版ステータスPublished - 2020 12 10

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • エネルギー(全般)
  • 物理化学および理論化学
  • 表面、皮膜および薄膜

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