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Title: Adsorption and Structure of Chiral Epoxides on Pd(111): Propylene Oxide and Glycidol

Abstract

Here, the adsorption of enantiopure versus racemic propylene oxide (PO) on Pd(111) is studied by temperature-programmed desorption (TPD) to explore possible differences in their saturation coverage. It is found that that the saturation coverage of enantiopure PO on Pd(111) is identical to that of racemic PO, in contrast to results on Pt(111) where significant coverage differences were found. The surface structures of enantiopure PO on Pd(111) were characterized by scanning tunneling microscopy (STM), which shows the formation of linear chains and hexagonal structures proposed to be due to freely rotating PO, in contrast to the relatively disordered PO overlayers found on Pt(111). STM experiments were carried out for enantiopure glycidol, which contains the same epoxy ring as PO, but where the methyl group of propylene oxide is replaced by a -CH 2OH group to provide a hydrogen-bonding sites. Glycidol STM images show the formation of completely different surface structures; at low coverages, glycidol forms pseudohexagonal structures which assemble from glycidol dimers, while at high coverages the surface shows extensive hydrogen-bonded networks. Density functional theory (DFT) calculations were carried out to model the enantiopure PO linear chain and the glycidol dimers that are observed by STM. Similar calculations were carried outmore » for racemic PO and glycidol structures. The calculated interaction energies for the enantiopure and the racemic pairs reveal that there is no difference for homochiral versus heterochiral structures for both PO and glycidol on Pd(111).« less

Authors:
ORCiD logo [1]; ORCiD logo [2]
  1. Univ. of Wisconsin, Milwaukee, WI (United States). Dept. of Chemistry and Lab. for Surface Studies; Brookhaven National Lab. (BNL), Upton, NY (United States). Chemistry Division
  2. Univ. of Wisconsin, Milwaukee, WI (United States). Dept. of Chemistry and Lab. for Surface Studies
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
OSTI Identifier:
1430868
Report Number(s):
BNL-203415-2018-JAAM
Journal ID: ISSN 1932-7447; TRN: US1802762
Grant/Contract Number:  
SC0012704; SC008703
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 122; Journal Issue: 2; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY

Citation Formats

Mahapatra, Mausumi, and Tysoe, Wilfred T. Adsorption and Structure of Chiral Epoxides on Pd(111): Propylene Oxide and Glycidol. United States: N. p., 2018. Web. doi:10.1021/acs.jpcc.7b10852.
Mahapatra, Mausumi, & Tysoe, Wilfred T. Adsorption and Structure of Chiral Epoxides on Pd(111): Propylene Oxide and Glycidol. United States. doi:10.1021/acs.jpcc.7b10852.
Mahapatra, Mausumi, and Tysoe, Wilfred T. Wed . "Adsorption and Structure of Chiral Epoxides on Pd(111): Propylene Oxide and Glycidol". United States. doi:10.1021/acs.jpcc.7b10852. https://www.osti.gov/servlets/purl/1430868.
@article{osti_1430868,
title = {Adsorption and Structure of Chiral Epoxides on Pd(111): Propylene Oxide and Glycidol},
author = {Mahapatra, Mausumi and Tysoe, Wilfred T.},
abstractNote = {Here, the adsorption of enantiopure versus racemic propylene oxide (PO) on Pd(111) is studied by temperature-programmed desorption (TPD) to explore possible differences in their saturation coverage. It is found that that the saturation coverage of enantiopure PO on Pd(111) is identical to that of racemic PO, in contrast to results on Pt(111) where significant coverage differences were found. The surface structures of enantiopure PO on Pd(111) were characterized by scanning tunneling microscopy (STM), which shows the formation of linear chains and hexagonal structures proposed to be due to freely rotating PO, in contrast to the relatively disordered PO overlayers found on Pt(111). STM experiments were carried out for enantiopure glycidol, which contains the same epoxy ring as PO, but where the methyl group of propylene oxide is replaced by a -CH2OH group to provide a hydrogen-bonding sites. Glycidol STM images show the formation of completely different surface structures; at low coverages, glycidol forms pseudohexagonal structures which assemble from glycidol dimers, while at high coverages the surface shows extensive hydrogen-bonded networks. Density functional theory (DFT) calculations were carried out to model the enantiopure PO linear chain and the glycidol dimers that are observed by STM. Similar calculations were carried out for racemic PO and glycidol structures. The calculated interaction energies for the enantiopure and the racemic pairs reveal that there is no difference for homochiral versus heterochiral structures for both PO and glycidol on Pd(111).},
doi = {10.1021/acs.jpcc.7b10852},
journal = {Journal of Physical Chemistry. C},
issn = {1932-7447},
number = 2,
volume = 122,
place = {United States},
year = {2018},
month = {1}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Figures / Tables:

Figure 1: Figure 1:: TPD uptake profile following S-propylene oxide (PO) adsorption on a Pd(111) surface at ~125 K, using exposures of 0.4 (―), 1.0 (―), 1.6 (―), 2.2 (―), 2.8 (―) and 3.4 (―) L (1 L (Langmuir) = 1×10-6 Torr·s). The spectra were collected at 58 amu by using amore » linear heating rate of ~2 K/s.« less

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