Asymmetry Induction by Cooperative Intermolecular Hydrogen Bonds in Surface-Anchored Layers of Achiral Molecules

The mesoscale induction of two‐dimensional supramolecular chirality (formation of 2D organic domains with a single handedness) was achieved by self‐assembly of 1,2,4‐benzenetricarboxylic (trimellitic) acid on a Cu(100) surface at elevated temperatures. The combination of spectroscopic [X‐ray photoel...

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Bibliographic Details
Published in:	Chemphyschem 2006-10, Vol.7 (10), p.2197-2204
Main Authors:	Dmitriev, Alexandre, Spillmann, Hannes, Stepanow, Sebastian, Strunskus, Thomas, Wöll, Christof, Seitsonen, Ari P., Lingenfelder, Magali, Lin, Nian, Barth, Johannes V., Kern, Klaus
Format:	Article
Language:	eng
Subjects:	Chemistry chirality density functional calculations Exact sciences and technology General and physical chemistry hydrogen bonds photoelectron spectroscopy scanning probe microscopy Surface physical chemistry
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Summary:	The mesoscale induction of two‐dimensional supramolecular chirality (formation of 2D organic domains with a single handedness) was achieved by self‐assembly of 1,2,4‐benzenetricarboxylic (trimellitic) acid on a Cu(100) surface at elevated temperatures. The combination of spectroscopic [X‐ray photoelectron spectroscopy (XPS) and near‐edge X‐ray absorption fine structure (NEXAFS)], real‐space‐probe [scanning tunneling microscopy (STM)], and computational [density functional theory (DFT)] methods allows a comprehensive characterization of the obtained organic adlayers, where details of molecular adsorption geometry, intermolecular coupling, and surface chemical bonding are elucidated. The trimellitic acid species, comprising three functional carboxylic groups, form distinct stable mirror‐symmetric hydrogen‐bonded domains. The chiral ordering is associated with conformational restriction in the domains: molecules anchor to the substrate with an ortho carboxylate group, providing two para carboxylic acid moieties for collective lateral interweaving through H bonding, which induces a specific tilt of the molecular plane. The ease of molecular symmetry switching in domain formation makes homochiral‐signature propagation solely limited by the terrace width. The molecular layer modifies the morphology of the underlying copper substrate and induces μm‐sized strictly homochiral terraces. Mesoscale supramolecular chirality induction is achieved by self‐assembly of achiral trimellitic acid molecules on a Cu(100) surface. The appreciable substrate–adsorbate interactions induce changes in the surface morphology, which result in the formation of homochiral R and S terrace patterns (see figure).
ISSN:	1439-4235 1439-7641