Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Reversible Anion-Driven Switching of an Organic 2D Crystal at a Solid–Liquid Interface
AU - Cui, K.
AU - Mali, K.S.
AU - Wu, D.
AU - Feng, X.
AU - Müllen, K.
AU - Walter, M.
AU - De Feyter, S.
AU - Mertens, S.F.L.
PY - 2017/12/13
Y1 - 2017/12/13
N2 - Ionic self-assembly of charged molecular building blocks relies on the interplay between long-range electrostatic forces and short-range, often cooperative, supramolecular interactions, yet has been seldom studied in two dimensions at the solid–liquid interface. Here, we demonstrate anion-driven switching of two-dimensional (2D) crystal structure at the Au(111)/octanoic acid interface. Using scanning tunneling microscopy (STM), three organic salts with identical polyaromatic cation (PQPC 6 + ) but different anions (perchlorate, anthraquinonedisulfonate, benzenesulfonate) are shown to form distinct, highly ordered self-assembled structures. Reversible switching of the supramolecular arrangement is demonstrated by in situ exchange of the anion on the pre-formed adlayer, by changing the concentration ratio between the incoming and outgoing anion. Density functional theory (DFT) calculations reveal that perchlorate is highly mobile in the adlayer, and corroborate why this anion is only resolved transiently in STM. Surprisingly, the templating effect of the anion persists even where it does not become part of the adlayer 2D fabric, which we ascribe to differences in stabilization of cation conformations by the anion. Our results provide important insight into the structuring of mixed anion–cation adlayers. This is essential in the design of tectons for ionic self-assembled superstructures and biomimetic adaptive materials and valuable also to understand adsorbate–adsorbate interactions in heterogeneous catalysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
AB - Ionic self-assembly of charged molecular building blocks relies on the interplay between long-range electrostatic forces and short-range, often cooperative, supramolecular interactions, yet has been seldom studied in two dimensions at the solid–liquid interface. Here, we demonstrate anion-driven switching of two-dimensional (2D) crystal structure at the Au(111)/octanoic acid interface. Using scanning tunneling microscopy (STM), three organic salts with identical polyaromatic cation (PQPC 6 + ) but different anions (perchlorate, anthraquinonedisulfonate, benzenesulfonate) are shown to form distinct, highly ordered self-assembled structures. Reversible switching of the supramolecular arrangement is demonstrated by in situ exchange of the anion on the pre-formed adlayer, by changing the concentration ratio between the incoming and outgoing anion. Density functional theory (DFT) calculations reveal that perchlorate is highly mobile in the adlayer, and corroborate why this anion is only resolved transiently in STM. Surprisingly, the templating effect of the anion persists even where it does not become part of the adlayer 2D fabric, which we ascribe to differences in stabilization of cation conformations by the anion. Our results provide important insight into the structuring of mixed anion–cation adlayers. This is essential in the design of tectons for ionic self-assembled superstructures and biomimetic adaptive materials and valuable also to understand adsorbate–adsorbate interactions in heterogeneous catalysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
KW - adlayer
KW - adsorption
KW - anion
KW - ionic self-assembly
KW - switching
KW - Adsorbates
KW - Adsorption
KW - Biomimetic materials
KW - Biomimetics
KW - Catalysis
KW - Crystal structure
KW - Density functional theory
KW - Design for testability
KW - Electrostatic force
KW - Inorganic compounds
KW - Negative ions
KW - Phase interfaces
KW - Positive ions
KW - Scanning tunneling microscopy
KW - Self assembly
KW - Supramolecular chemistry
KW - Switching
KW - Vapor deposition
KW - Adlayers
KW - Adsorbate interactions
KW - Ionic self- assembly
KW - Molecular building blocks
KW - Self assembled structures
KW - Supramolecular arrangement
KW - Supramolecular interactions
KW - Two-dimensional (2D) crystals
KW - Ions
U2 - 10.1002/smll.201702379
DO - 10.1002/smll.201702379
M3 - Journal article
VL - 13
JO - Small
JF - Small
SN - 1613-6810
IS - 46
M1 - 1702379
ER -