Details
| Original language | English |
|---|---|
| Pages (from-to) | 1055-1061 |
| Number of pages | 7 |
| Journal | ChemPhysChem |
| Volume | 7 |
| Issue number | 5 |
| Publication status | Published - 3 May 2006 |
Abstract
Using a combination of ab initio and semiempirical methods, adsorption problems on surfaces with large unit cells and low symmetry can still be studied. Here, a hybrid approach of density functional theory (DFT) and Hartree-Fock (HF) was used. As an example, we determined the geometry and the electronic properties of benzoic acid (BA), salicylic acid (SA) and pata-salicylic acid (p-SA) adsorbed on MgSO4·H2O (100), which are used as conditioner molecules for the electrostatic separation of minerals. Contrary to general expectations, these molecules are chemisorbed, with binding energies around 1.9 eV, forming bonds through the carboxylic O atom of the COOH groups in a nonplanar geometry, although the surface is a stoichiometric wide-band-gap insulator and the molecules stay intact. In contrast, a planar adsorption geometry turned out to be nonbonding. Bonding takes place by means of surface-molecule resonances due to the overlap of the valence band with molecular orbitals, assisted by a small charge-transfer molecule to the surface of around 0.15e. These combined interactions cause an intramolecular twist between the COOH group and the benzene ring.
Keywords
- ab initio calculations, Adsorption, Chemisorption, Insulating surfaces, Single-molecule studies
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Atomic and Molecular Physics, and Optics
- Chemistry(all)
- Physical and Theoretical Chemistry
Cite this
- Standard
- Harvard
- Apa
- Vancouver
- BibTeX
- RIS
In: ChemPhysChem, Vol. 7, No. 5, 03.05.2006, p. 1055-1061.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Adsorption of functionalized benzoic acids on MgSO4· H2O (100)
AU - Maslyuk, Volodymyr
AU - Tegenkamp, Christoph
AU - Pfnür, Herbert
AU - Bredow, Thomas
PY - 2006/5/3
Y1 - 2006/5/3
N2 - Using a combination of ab initio and semiempirical methods, adsorption problems on surfaces with large unit cells and low symmetry can still be studied. Here, a hybrid approach of density functional theory (DFT) and Hartree-Fock (HF) was used. As an example, we determined the geometry and the electronic properties of benzoic acid (BA), salicylic acid (SA) and pata-salicylic acid (p-SA) adsorbed on MgSO4·H2O (100), which are used as conditioner molecules for the electrostatic separation of minerals. Contrary to general expectations, these molecules are chemisorbed, with binding energies around 1.9 eV, forming bonds through the carboxylic O atom of the COOH groups in a nonplanar geometry, although the surface is a stoichiometric wide-band-gap insulator and the molecules stay intact. In contrast, a planar adsorption geometry turned out to be nonbonding. Bonding takes place by means of surface-molecule resonances due to the overlap of the valence band with molecular orbitals, assisted by a small charge-transfer molecule to the surface of around 0.15e. These combined interactions cause an intramolecular twist between the COOH group and the benzene ring.
AB - Using a combination of ab initio and semiempirical methods, adsorption problems on surfaces with large unit cells and low symmetry can still be studied. Here, a hybrid approach of density functional theory (DFT) and Hartree-Fock (HF) was used. As an example, we determined the geometry and the electronic properties of benzoic acid (BA), salicylic acid (SA) and pata-salicylic acid (p-SA) adsorbed on MgSO4·H2O (100), which are used as conditioner molecules for the electrostatic separation of minerals. Contrary to general expectations, these molecules are chemisorbed, with binding energies around 1.9 eV, forming bonds through the carboxylic O atom of the COOH groups in a nonplanar geometry, although the surface is a stoichiometric wide-band-gap insulator and the molecules stay intact. In contrast, a planar adsorption geometry turned out to be nonbonding. Bonding takes place by means of surface-molecule resonances due to the overlap of the valence band with molecular orbitals, assisted by a small charge-transfer molecule to the surface of around 0.15e. These combined interactions cause an intramolecular twist between the COOH group and the benzene ring.
KW - ab initio calculations
KW - Adsorption
KW - Chemisorption
KW - Insulating surfaces
KW - Single-molecule studies
UR - http://www.scopus.com/inward/record.url?scp=33646754902&partnerID=8YFLogxK
U2 - 10.1002/cphc.200500486
DO - 10.1002/cphc.200500486
M3 - Article
AN - SCOPUS:33646754902
VL - 7
SP - 1055
EP - 1061
JO - ChemPhysChem
JF - ChemPhysChem
SN - 1439-4235
IS - 5
ER -