Enantioselective Adsorption on Magnetic Surfaces

From the beginning of molecular theory, the interplay of chirality and magnetism has intrigued scientists. There is still the question if enantiospecific adsorption of chiral molecules occurs on magnetic surfaces. Enantiomer discrimination was conjectured to arise from chirality‐induced spin separat...

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Bibliographic Details
Published in:Advanced materials (Weinheim) 2024-04, Vol.36 (14), p.e2308666-n/a
Main Authors: Safari, Mohammad Reza, Matthes, Frank, Caciuc, Vasile, Atodiresei, Nicolae, Schneider, Claus M., Ernst, Karl‐Heinz, Bürgler, Daniel E.
Format: Article
Language:English
Subjects:
Adsorption
Aromatic hydrocarbons
Chemisorption
Chirality
CISS
Cobalt
Enantiomers
enantiospecific adsorption
Ferromagnetism
magnetic surfaces
Magnetization
Molecular theory
Scanning tunneling microscopy
Substrates
Surface chemistry
van der Waals interactions
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Summary:From the beginning of molecular theory, the interplay of chirality and magnetism has intrigued scientists. There is still the question if enantiospecific adsorption of chiral molecules occurs on magnetic surfaces. Enantiomer discrimination was conjectured to arise from chirality‐induced spin separation within the molecules and exchange interaction with the substrate's magnetization. Here, it is shown that single helical aromatic hydrocarbons undergo enantioselective adsorption on ferromagnetic cobalt surfaces. Spin and chirality sensitive scanning tunneling microscopy reveals that molecules of opposite handedness prefer adsorption onto cobalt islands with opposite out‐of‐plane magnetization. As mobility ceases in the final chemisorbed state, it is concluded that enantioselection must occur in a physisorbed transient precursor state. State‐of‐the‐art spin‐resolved ab initio simulations support this scenario by refuting enantio‐dependent chemisorption energies. These findings demonstrate that van der Waals interaction should also include spin‐fluctuations which are crucial for molecular magnetochiral processes. Racemic helical aromatic hydrocarbons are sublimed in vacuo onto ferromagnetic cobalt nanoislands. Spin‐ and chirality‐sensitive scanning tunneling microscopy on the single‐molecule scale reveals that molecules of opposite handedness preferentially adsorb on islands with opposite out‐of‐plane magnetization. Enantioselection occurs in a transiently occupied physisorbed precursor state, suggesting that spin‐ and chirality‐sensitive interactions at the van der Waals level play a role.
ISSN:0935-9648
1521-4095
DOI:10.1002/adma.202308666