Prolific Polymorph Generator ROY in Its Liquid and Glass: Two Conformational Populations Mirroring the Crystalline-State Distribution,The Journal of Physical Chemistry B

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Prolific Polymorph Generator ROY in Its Liquid and Glass: Two Conformational Populations Mirroring the Crystalline-State Distribution
The Journal of Physical Chemistry B ( IF 2.8 ) Pub Date : 2021-08-31 , DOI: 10.1021/acs.jpcb.1c05834
Zhenxuan Chen ₁ , Yue Gui ₁ , Kai Cui ₂ , J R Schmit ₂ , Lian Yu ₁

Affiliation

5-Methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile, dubbed ROY for its numerous crystal polymorphs of red, orange, and yellow colors, has been studied in its liquid and glassy state by infrared spectroscopy. Two populations of conformers are observed, whose equilibrium is characterized by ΔH = 2.4 kJ/mol and ΔS = 8.0 J/K/mol. The two populations correspond to the global and local minima of the torsional energy surface and to the conformational preference of the 13 crystal polymorphs. The local minimum features a more coplanar arrangement of the two aromatic rings, greater π conjugation, and lower CN stretch frequency. In the gas phase, the lowest-energy path between the two minima has an energy barrier 3.9 kJ/mol above the global minimum, consistent with the rapid equilibration between the two populations. The relevance of our result for understanding the prolific polymorphism of ROY is discussed.

中文翻译：

液体和玻璃中的多晶型发生器 ROY：反映结晶态分布的两个构象群

5-甲基-2-[(2-硝基苯基)氨基]-3-噻吩甲腈因其具有红色、橙色和黄色的众多晶体多晶型物而被称为 ROY，已通过红外光谱对其液态和玻璃态进行了研究。观察到两个构象异构体群，其平衡特征为 Δ H = 2.4 kJ/mol 和 Δ S= 8.0 J/K/mol。这两个群体对应于扭转能量表面的全局和局部最小值以及 13 种晶体多晶型的构象偏好。局部最小值的特点是两个芳环的排列更共面，π共轭更大，CN 拉伸频率更低。在气相中，两个最小值之间的最低能量路径的能垒比全局最小值高 3.9 kJ/mol，与两个种群之间的快速平衡一致。讨论了我们的结果与理解 ROY 的多产多态性的相关性。

更新日期：2021-09-16

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