Persistence of Chirality for a Weakly Bound Adsorbate:  (R,R)- and (S,S)-Tartaric Acid/Ag(111)

Abstract

The interaction of tartaric acid (C4H6O6), including both (R,R) and (S,S) enantiomers, with Ag(111) has been studied using low-energy electron diffraction (LEED) and low-temperature scanning tunneling microscopy (STM). As evidenced by both diffraction and microscopy, this molecule binds very weakly to the Ag lattice, and the interadsorbate forces strongly dictate the formation of ordered monolayers that are globally chiral. In addition to a discussion of the role that hydrogen bonding plays in the formation of monolayer domains, comparisons of this system to the growth of tartaric acid on other metallic surfaces will be made.

Mechanisms for chemical transformations of (R,R)-tartaric acid on Cu(110): A first principles study

“…perimental study on the persistence of chirality for the intact biacid molecules of ͑R,R͒and ͑S,S͒-tartaric acids on Ag͑111͒ has also been reported. 20 Although the chemical transformations of ͑R,R͒-tartaric acid on a metal surface are expected to correlate closely with enantioselectivity in the hydrogenation of ␤-ketoesters, [8][9][10] to our knowledge, the mechanisms of these chemical transformations have not been previously studied from theoretical calculations. In this paper, we carry out first principles slab calculations to systematically investigate, for the first time, the mechanisms for the chemical transformations of ͑R,R͒tartaric acid on a model Cu͑110͒ surface.…”

Chiral Steering of Molecular Organization in the Limit of Weak Adsorbate−Substrate Interactions: Enantiopure and Racemic Tartaric Acid Domains on Ag(111)

“…Previous LEED and room temperature STM results showed that enantiopure films of tartaric acid are weakly bound to the Ag(111) substrate. 26 Room temperature STM studies for the racemic films confirm the same behavior, namely mobile domains whose perimeters are easily perturbed by repeated scanning of the STM tip. Therefore, in an effort to elucidate the molecular-level structure in the absence of thermally induced motion, the dual-component tartaric acid monolayers were imaged at cryogenic temperatures.…”

“…The relative chirality of the (S,S)-and (R,R)-tartaric acid domains is evidenced by structural modulation bands that arise for the enantiopure films. 26 These features, whose directionality are enantiomer dependent and, therefore, are a signature of a specific chiral arrangement for this system, are the result of a mismatch between the tartaric acid and the Ag(111) lattice and the spacings between the bands are sensitive to the local molecular density. The bright area between the two enantiopure domains is most likely the result of domain growth overlap, but the presence of separate chiral domains indicates that the formation of a single tartaric acid layer is preferred to direct multilayer growth.…”

“…24,25 In contrast to the chemisorption to Cu and Ni surfaces, tartaric acid enantiomers are only weakly bound to Ag(111). 26 It has been shown that tartaric acid enantiomers on Ag(111) experience intermolecular interactions that give rise to a sufficiently rigid adsorption geometry, allowing for the realization of global organizational chirality in a similar fashion to what has been observed for molecules with a strong interaction with the underlying surface. [26][27][28] The goal of the present study is to determine the exact influence of molecular chirality on twodimensional organization in the absence of strong chemical bonds to the surface.…”

“…26 It has been shown that tartaric acid enantiomers on Ag(111) experience intermolecular interactions that give rise to a sufficiently rigid adsorption geometry, allowing for the realization of global organizational chirality in a similar fashion to what has been observed for molecules with a strong interaction with the underlying surface. [26][27][28] The goal of the present study is to determine the exact influence of molecular chirality on twodimensional organization in the absence of strong chemical bonds to the surface. To further understand the stability and formation mechanism of the single component, enantiomerically pure domains, detailed low-temperature scanning tunneling microscopy (STM) studies were performed regarding the concurrent adsorption of both (S,S)-and (R,R)-tartaric acid enantiomers onto Ag(111).…”