Practical hints and tips for solution of pseudo-merohedric twins: three case studies
Twinning by pseudo-merohedry is a common phenomenon in small-molecule crystallography. In cases where twin-component volume fractions are markedly different, structure solution is often no more difficult than for non-twinned structures of similar complexity. When twin-component volume fractions are...
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| Format: | Article |
| Language: | English |
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International Union of Crystallography
2021-05-01
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| Series: | Acta Crystallographica Section E: Crystallographic Communications |
| Subjects: | |
| Online Access: | http://scripts.iucr.org/cgi-bin/paper?S205698902100342X |
| _version_ | 1819276203698159616 |
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| author | S. R. Parkin |
| author_facet | S. R. Parkin |
| author_sort | S. R. Parkin |
| collection | DOAJ |
| description | Twinning by pseudo-merohedry is a common phenomenon in small-molecule crystallography. In cases where twin-component volume fractions are markedly different, structure solution is often no more difficult than for non-twinned structures of similar complexity. When twin-component volume fractions are similar, however, structure solution can be much more of a problem. This paper presents hints and tips for such cases by means of three worked examples. The first example presents the most common (and simplest) case of a two-component pseudo-orthorhombic twin. The second example describes structure solution of a reticular threefold pseudo-hexagonal twin that benefits from use of an unconventional space-group setting. The third example covers structure solution of a reticular fourfold pseudo-tetragonal twin. All three structures are ultimately shown to be monoclinic crystals that twin as a consequence of unit-cell metrics that mimic those of higher symmetry crystal systems. |
| first_indexed | 2024-12-23T23:36:29Z |
| format | Article |
| id | doaj.art-7e3f5fc404c14c7daff8f32a8bd4bc0c |
| institution | Directory Open Access Journal |
| issn | 2056-9890 |
| language | English |
| last_indexed | 2024-12-23T23:36:29Z |
| publishDate | 2021-05-01 |
| publisher | International Union of Crystallography |
| record_format | Article |
| series | Acta Crystallographica Section E: Crystallographic Communications |
| spelling | doaj.art-7e3f5fc404c14c7daff8f32a8bd4bc0c2022-12-21T17:25:51ZengInternational Union of CrystallographyActa Crystallographica Section E: Crystallographic Communications2056-98902021-05-0177545246510.1107/S205698902100342Xhb7973Practical hints and tips for solution of pseudo-merohedric twins: three case studiesS. R. Parkin0Department of Chemistry, University of Kentucky, Lexington, KY 40506, USATwinning by pseudo-merohedry is a common phenomenon in small-molecule crystallography. In cases where twin-component volume fractions are markedly different, structure solution is often no more difficult than for non-twinned structures of similar complexity. When twin-component volume fractions are similar, however, structure solution can be much more of a problem. This paper presents hints and tips for such cases by means of three worked examples. The first example presents the most common (and simplest) case of a two-component pseudo-orthorhombic twin. The second example describes structure solution of a reticular threefold pseudo-hexagonal twin that benefits from use of an unconventional space-group setting. The third example covers structure solution of a reticular fourfold pseudo-tetragonal twin. All three structures are ultimately shown to be monoclinic crystals that twin as a consequence of unit-cell metrics that mimic those of higher symmetry crystal systems.http://scripts.iucr.org/cgi-bin/paper?S205698902100342Xpseudo-merohedrypseudo-orthorhombicpseudo-tetragonalpseudo-hexagonalreticulartwinninghklf 5 format |
| spellingShingle | S. R. Parkin Practical hints and tips for solution of pseudo-merohedric twins: three case studies Acta Crystallographica Section E: Crystallographic Communications pseudo-merohedry pseudo-orthorhombic pseudo-tetragonal pseudo-hexagonal reticular twinning hklf 5 format |
| title | Practical hints and tips for solution of pseudo-merohedric twins: three case studies |
| title_full | Practical hints and tips for solution of pseudo-merohedric twins: three case studies |
| title_fullStr | Practical hints and tips for solution of pseudo-merohedric twins: three case studies |
| title_full_unstemmed | Practical hints and tips for solution of pseudo-merohedric twins: three case studies |
| title_short | Practical hints and tips for solution of pseudo-merohedric twins: three case studies |
| title_sort | practical hints and tips for solution of pseudo merohedric twins three case studies |
| topic | pseudo-merohedry pseudo-orthorhombic pseudo-tetragonal pseudo-hexagonal reticular twinning hklf 5 format |
| url | http://scripts.iucr.org/cgi-bin/paper?S205698902100342X |
| work_keys_str_mv | AT srparkin practicalhintsandtipsforsolutionofpseudomerohedrictwinsthreecasestudies |