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Published on: August 9, 2022
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Pressure induced transformations in sorbic acid
G D Saraiva1, J R Maia2, J A Lima3
1Faculdade de Educação Ciências e Letras do Sertão Central, Universidade Estadual do Ceará, CEP 63.900-000, Quixadá, CE, Brazil.
Summary
High pressure causes sorbic acid to disorder gradually, maintaining its molecular structure. Upon pressure release, it reverts to its original crystalline phase without decomposition.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Spectroscopy
Background:
- Sorbic acid is a widely used food preservative.
- Understanding its behavior under pressure is crucial for material science applications.
- Previous studies have not fully explored its high-pressure phase transitions.
Purpose of the Study:
- To investigate the pressure-dependent structural and vibrational changes in sorbic acid.
- To understand the disordering process and phase transitions under high pressure.
- To elucidate the role of crystal structure in sorbic acid's response to pressure.
Main Methods:
- High-pressure Raman spectroscopy up to 10.0 GPa.
- Unpolarized Raman spectra collected in the 20-3000 cm-1 range.
- Density Functional Theory (DFT) calculations for vibrational properties.
Main Results:
- Sorbic acid exhibits a gradual disordering process under increasing pressure.
- At ~10 GPa, Raman spectra show a single bending mode and broad stretching modes, indicating significant disorder.
- The crystal structure reverts to the ambient-pressure phase upon pressure release, with internal and external modes confirming molecular integrity and crystalline memory.
- DFT calculations show significant decreases in unit cell volume and beta angle up to 8.0 GPa, correlating with increased Raman band broadening.
Conclusions:
- Sorbic acid undergoes reversible pressure-induced disordering without decomposition.
- The monoclinic crystal structure of sorbic acid shows significant changes in unit cell parameters under pressure.
- Raman spectroscopy and DFT calculations provide insights into the vibrational dynamics and structural stability of sorbic acid under extreme conditions.
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