| Autor: |
Woodall, Christopher H., Brayshaw, Simon K., Schiffers, Stefanie, Allan, David R., Parsons, Simon, Valiente, Rafael, Raithby, Paul R. |
| Jazyk: |
angličtina |
| Rok vydání: |
2014 |
| Předmět: |
|
| Zdroj: |
Woodall, C H, Brayshaw, S K, Schiffers, S, Allan, D R, Parsons, S, Valiente, R & Raithby, P R 2014, ' High-pressure crystallographic and spectroscopic studies on two molecular dithienylethene switches ', CrystEngComm, vol. 16, no. 11, pp. 2119-2128 . https://doi.org/10.1039/c3ce41933a |
| DOI: |
10.1039/c3ce41933a |
| Popis: |
Single crystals of the dithienylethene compounds, 1,2-bis(2-methylbenzothiophen-3-yl) perfluorocyclopentene 1 and 1,2-bis(2,5-dimethylthiophen-3-yl)perfluorocyclopentene 2 undergo pressure-induced single-crystal to single-crystal phase transitions between 4.45-5.35 GPa and 4.15-5.70 GPa, respectively. For 1, there is a smooth reduction in unit-cell volume of similar to 20% from ambient pressure to 4.45 GPa, followed by a dramatic reduction in volume that coincides with a 7.7% increase in the b axis length. Above the pressure of 5.38 GPa a smooth volume reduction continues. In contrast, for 2, there is a continuous change in unit-cell volume with an observed space group change from C2/c to P21/c, between the pressures of 4.15 and 5.70 GPa. In the crystals of 1 between 4.45 and 5.38 GPa adjacent molecules slide over each other and the dominant stacking interaction changes from a thiophene···thiophene interaction at 4.45 GPa to a benzothiophene. benzothiophene interaction at 5.38 GPa and, within each molecule, the benzothiophene groups show a significant reorientation at the phase transition. In 2 there is a loss of molecular symmetry, concomitant with the change in space group, at the phase transition with the asymmetric unit changing from containing half a unique molecule to two independent molecules. The molecules show significant reorientations of their ring systems. The nature of the observed transition in 1 was investigated using solid-state computational methods to prove the superior thermodynamic stability of the high-pressure phase to the lower pressure phase at pressures above 5.38 GPa. Solid state UV-Vis spectroscopy of 1, over the pressure range from ambient to 15.4 GPa showed that the compound displayed piezochromism with a significant red shift in the π-π* absorption band and a colour change in the crystal from colourless to red with increasing pressure. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
