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High-Pressure Crystallization and Structural Transformations in Compressed R,S-Ibuprofen

机译:压缩R,S-布洛芬的高压结晶和结构转变

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摘要

R,S-Ibuprofen dissolved in chiral and achiral solvents recrystallizes at varied pressure and temperature in the same racemic form I of monoclinic space group P2(1)/c. At 4.0 GPa the crystal is compressed to 78% of its ambient-pressure volume. The main structural transformation is the compression of intermolecular van der Waals contacts, increasing the effects of intermolecular interactions in the crystal environment, which results in the more skew position of OH...O bonded carboxyl groups and more stabile H-atoms in the bistable H-bonds. Consequently, the H-atoms remain ordered in all pressure ranges investigated, despite the compression of the H-bonds by over 0.1 angstrom at 4 GPa. The crystal compression and thermal expansion obey the reverse relationship rule of temperature and pressure effects; however, the compression is considerably nonlinear due to the strong reduction of void volume up to about 0.8 GPa.
机译:溶解在手性和非手性溶剂中的R,S-布洛芬在不同的压力和温度下以单斜晶空间群P2(1)/ c的相同外消旋形式I重结晶。在4.0 GPa时,晶体被压缩到其环境压力体积的78%。主要的结构转变是分子间范德华接触的压缩,增加了晶体环境中分子间相互作用的影响,这导致OH ... O键合羧基更偏斜的位置以及双稳态中更稳定的H原子H键。因此,尽管在4 GPa下H键的压缩量超过0.1埃,但H原子在所有研究的压力范围内仍保持有序。晶体的压缩和热膨胀服从温度和压力效应的反向关系规律。然而,由于空隙体积最大减少至约0.8 GPa,压缩明显是非线性的。

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