Origin of 6-fold coordinated aluminum at (010)-type pyrophyllite edges
To better understand the aqueous chemical reactivity of clay mineral edges we explored the relationships between hydration and the structure of (010)-type edges of pyrophyllite. In particular, we used density functional theory and the quantum theory of atoms in molecules to evaluate the stability of...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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AIP Publishing LLC
2017-05-01
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| Series: | AIP Advances |
| Online Access: | http://dx.doi.org/10.1063/1.4983213 |
| _version_ | 1819209533189259264 |
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| author | M. Okumura M. Sassi K. M. Rosso M. Machida |
| author_facet | M. Okumura M. Sassi K. M. Rosso M. Machida |
| author_sort | M. Okumura |
| collection | DOAJ |
| description | To better understand the aqueous chemical reactivity of clay mineral edges we explored the relationships between hydration and the structure of (010)-type edges of pyrophyllite. In particular, we used density functional theory and the quantum theory of atoms in molecules to evaluate the stability of 6-fold coordinated hydrated aluminum at the edge in terms of the electron density distribution. Geometrical optimization revealed an intra-edge hydrogen bond network between aluminol hydroxyls and water ligands completing the aluminum coordination shell. From the electron density isosurfaces one water ligand is not covalently bonded to aluminum. Bader charge analysis revealed that OH2 ligands have small negative charge. In addition, it is also found that the charge of the 6-fold coordinated aluminum is larger than one of the 5-fold aluminum. From these results, the charging of the OH2 ligands is interpreted as charge transfer originated from the formation of the hydrogen bond network and not from Al-OH2 interaction per se. This suggests that the weakly bound water ligand in question, and more generally 6-fold hydrated edge Al coordination, is stabilized primarily by the hydrogen bond network which in turn leads to weak ionic attraction to the aluminum center itself. The finding highlights the importance of cooperative effects between solvent structure and the coordination of metal cations exposed at clay mineral edges. |
| first_indexed | 2024-12-23T05:56:47Z |
| format | Article |
| id | doaj.art-2365854ca441425b811faedc7f36f3a2 |
| institution | Directory Open Access Journal |
| issn | 2158-3226 |
| language | English |
| last_indexed | 2024-12-23T05:56:47Z |
| publishDate | 2017-05-01 |
| publisher | AIP Publishing LLC |
| record_format | Article |
| series | AIP Advances |
| spelling | doaj.art-2365854ca441425b811faedc7f36f3a22022-12-21T17:57:46ZengAIP Publishing LLCAIP Advances2158-32262017-05-0175055211055211-910.1063/1.4983213012705ADVOrigin of 6-fold coordinated aluminum at (010)-type pyrophyllite edgesM. Okumura0M. Sassi1K. M. Rosso2M. Machida3Center for Computational Science and e-Systems, Japan Atomic Energy Agency, 178-4-4 Wakashiba, Kashiwa, Chiba 277-0871, JapanPhysical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, USAPhysical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, USACenter for Computational Science and e-Systems, Japan Atomic Energy Agency, 178-4-4 Wakashiba, Kashiwa, Chiba 277-0871, JapanTo better understand the aqueous chemical reactivity of clay mineral edges we explored the relationships between hydration and the structure of (010)-type edges of pyrophyllite. In particular, we used density functional theory and the quantum theory of atoms in molecules to evaluate the stability of 6-fold coordinated hydrated aluminum at the edge in terms of the electron density distribution. Geometrical optimization revealed an intra-edge hydrogen bond network between aluminol hydroxyls and water ligands completing the aluminum coordination shell. From the electron density isosurfaces one water ligand is not covalently bonded to aluminum. Bader charge analysis revealed that OH2 ligands have small negative charge. In addition, it is also found that the charge of the 6-fold coordinated aluminum is larger than one of the 5-fold aluminum. From these results, the charging of the OH2 ligands is interpreted as charge transfer originated from the formation of the hydrogen bond network and not from Al-OH2 interaction per se. This suggests that the weakly bound water ligand in question, and more generally 6-fold hydrated edge Al coordination, is stabilized primarily by the hydrogen bond network which in turn leads to weak ionic attraction to the aluminum center itself. The finding highlights the importance of cooperative effects between solvent structure and the coordination of metal cations exposed at clay mineral edges.http://dx.doi.org/10.1063/1.4983213 |
| spellingShingle | M. Okumura M. Sassi K. M. Rosso M. Machida Origin of 6-fold coordinated aluminum at (010)-type pyrophyllite edges AIP Advances |
| title | Origin of 6-fold coordinated aluminum at (010)-type pyrophyllite edges |
| title_full | Origin of 6-fold coordinated aluminum at (010)-type pyrophyllite edges |
| title_fullStr | Origin of 6-fold coordinated aluminum at (010)-type pyrophyllite edges |
| title_full_unstemmed | Origin of 6-fold coordinated aluminum at (010)-type pyrophyllite edges |
| title_short | Origin of 6-fold coordinated aluminum at (010)-type pyrophyllite edges |
| title_sort | origin of 6 fold coordinated aluminum at 010 type pyrophyllite edges |
| url | http://dx.doi.org/10.1063/1.4983213 |
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