Various Approaches to Studying the Phase Transition in an Octamethylcyclotetrasiloxane Crystal: From X-ray Structural Analysis to Metadynamics
The structure, thermodynamic parameters, and the character of thermal motion in octamethylcyclotetrasiloxane (D4) were investigated using the combination of experimental (single-crystal X-ray diffraction, thermochemistry) and theoretical (density functional theory calculations, ab initio molecular d...
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MDPI AG
2022-08-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/23/16/9073 |
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| author | Alexander D. Volodin Alexander F. Smol’yakov Alexander A. Korlyukov |
| author_facet | Alexander D. Volodin Alexander F. Smol’yakov Alexander A. Korlyukov |
| author_sort | Alexander D. Volodin |
| collection | DOAJ |
| description | The structure, thermodynamic parameters, and the character of thermal motion in octamethylcyclotetrasiloxane (D4) were investigated using the combination of experimental (single-crystal X-ray diffraction, thermochemistry) and theoretical (density functional theory calculations, ab initio molecular dynamics and metadynamics) methods. Single crystals of D4 were grown in a glass capillary in situ and the structures of high- (238–270 K) and low-temperature (100–230 K) phases were studied in detail. In the temperature interval 230–238 K, a phase transition with rather low enthalpy (−1.04(7) kcal/mol) was detected. It was found that phase transition is accompanied by change of conformation of cyclosiloxane moiety from boat-saddle (cradle) to chair. According to PBE0/6-311G(d,p) calculation of isolated D4, such conformation changes are characterized by a low barrier (0.07 kcal/mol). The character of molecular thermal motion and the path of phase transition were established with combination of periodic DFT calculations, including molecular dynamics and metadynamics. The effect of crystal field led to an increase in the calculated phase transition barrier (4.27 kcal/mol from low- to high-temperature phase and 3.20 kcal/mol in opposite direction). |
| first_indexed | 2024-03-09T13:17:26Z |
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| id | doaj.art-5d081952d7ff4d7280a0f0e0ddb0b3a7 |
| institution | Directory Open Access Journal |
| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-09T13:17:26Z |
| publishDate | 2022-08-01 |
| publisher | MDPI AG |
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| series | International Journal of Molecular Sciences |
| spelling | doaj.art-5d081952d7ff4d7280a0f0e0ddb0b3a72023-11-30T21:33:51ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672022-08-012316907310.3390/ijms23169073Various Approaches to Studying the Phase Transition in an Octamethylcyclotetrasiloxane Crystal: From X-ray Structural Analysis to MetadynamicsAlexander D. Volodin0Alexander F. Smol’yakov1Alexander A. Korlyukov2A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Science, Vavilova Street 28, 119991 Moscow, RussiaA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Science, Vavilova Street 28, 119991 Moscow, RussiaA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Science, Vavilova Street 28, 119991 Moscow, RussiaThe structure, thermodynamic parameters, and the character of thermal motion in octamethylcyclotetrasiloxane (D4) were investigated using the combination of experimental (single-crystal X-ray diffraction, thermochemistry) and theoretical (density functional theory calculations, ab initio molecular dynamics and metadynamics) methods. Single crystals of D4 were grown in a glass capillary in situ and the structures of high- (238–270 K) and low-temperature (100–230 K) phases were studied in detail. In the temperature interval 230–238 K, a phase transition with rather low enthalpy (−1.04(7) kcal/mol) was detected. It was found that phase transition is accompanied by change of conformation of cyclosiloxane moiety from boat-saddle (cradle) to chair. According to PBE0/6-311G(d,p) calculation of isolated D4, such conformation changes are characterized by a low barrier (0.07 kcal/mol). The character of molecular thermal motion and the path of phase transition were established with combination of periodic DFT calculations, including molecular dynamics and metadynamics. The effect of crystal field led to an increase in the calculated phase transition barrier (4.27 kcal/mol from low- to high-temperature phase and 3.20 kcal/mol in opposite direction).https://www.mdpi.com/1422-0067/23/16/9073in situ cryo-crystallizationX-ray structure determinationperiodic DFT calculationsquantum chemical calculationsBorn–Oppenheimer molecular dynamicsmetadynamics |
| spellingShingle | Alexander D. Volodin Alexander F. Smol’yakov Alexander A. Korlyukov Various Approaches to Studying the Phase Transition in an Octamethylcyclotetrasiloxane Crystal: From X-ray Structural Analysis to Metadynamics International Journal of Molecular Sciences in situ cryo-crystallization X-ray structure determination periodic DFT calculations quantum chemical calculations Born–Oppenheimer molecular dynamics metadynamics |
| title | Various Approaches to Studying the Phase Transition in an Octamethylcyclotetrasiloxane Crystal: From X-ray Structural Analysis to Metadynamics |
| title_full | Various Approaches to Studying the Phase Transition in an Octamethylcyclotetrasiloxane Crystal: From X-ray Structural Analysis to Metadynamics |
| title_fullStr | Various Approaches to Studying the Phase Transition in an Octamethylcyclotetrasiloxane Crystal: From X-ray Structural Analysis to Metadynamics |
| title_full_unstemmed | Various Approaches to Studying the Phase Transition in an Octamethylcyclotetrasiloxane Crystal: From X-ray Structural Analysis to Metadynamics |
| title_short | Various Approaches to Studying the Phase Transition in an Octamethylcyclotetrasiloxane Crystal: From X-ray Structural Analysis to Metadynamics |
| title_sort | various approaches to studying the phase transition in an octamethylcyclotetrasiloxane crystal from x ray structural analysis to metadynamics |
| topic | in situ cryo-crystallization X-ray structure determination periodic DFT calculations quantum chemical calculations Born–Oppenheimer molecular dynamics metadynamics |
| url | https://www.mdpi.com/1422-0067/23/16/9073 |
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