Polymorphism in 1-methylhydantoin: investigation by periodic DFT calculations and characterization of the third polymorph,CrystEngComm

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Polymorphism in 1-methylhydantoin: investigation by periodic DFT calculations and characterization of the third polymorph
CrystEngComm ( IF 2.6 ) Pub Date : 2020-09-04 , DOI: 10.1039/d0ce01016b
Bernardo A. Nogueira _{1,

2,

3,

4,

5} , Alberto Milani _{6,

7,

8,

9,

10} , Gulce O. Ildiz _{1,

2,

3,

4,

5} , José A. Paixão _{3,

5,

11,

12,

13} , Chiara Castiglioni _{6,

7,

8,

9,

10} , Rui Fausto _{1,

2,

3,

4,

5}

Affiliation

In previous studies [Puszyńska-Tuszkanow et al. Polyhedron, 2011, 30(12), 2016; Nogueira et al. J. Phys. Chem. A, 2014, 118(31), 5994; Nogueira et al., J. Mol. Struct., 2017, 1148, 111], two different polymorphs of 1-methylhydantoin (1-MH, C₄H₆N₂O₂) were identified (forms I and II) and characterized using infrared and Raman spectroscopies, as well as by X-ray diffraction. In this work, a new polymorph of the compound (form III) is described. The new polymorph was characterized spectroscopically and its structure was determined for the first time by single crystal X-ray diffraction. Very interestingly, the crystal of polymorph III was found to exhibit a high-Z′ (Z′ = 3) asymmetric unit and 12 molecules in the unit cell (Z = 12), which contrasts with the simpler crystal structures found previously for forms I and II (Z = 4; Z′ = 1). Besides, a thorough study of the polymorphism of 1-MH was performed with the help of state-of-the-art first principles fully periodic calculations of the structure, as well as infrared and Raman spectra of the different polymorphs of the compound. Marker-bands in the infrared and Raman spectra of the polymorphs are proposed for fast spectroscopic identification of the polymorphs.

中文翻译：

1-甲基乙内酰脲的多态性：定期的DFT计算研究和第三个多态性的表征

在以前的研究中[Puszyńska-Tuszkanow等。多面体，2011，30（12），2016; Nogueira等。J.物理化学甲，2014，118（31），5994; Nogueira等。，J。Mol。结构。，2017，1148，111 ]，鉴定了两种不同的1-甲基乙内酰脲多晶型物（1-MH，C ₄ H ₆ N ₂ O ₂）（形式I和II），并使用红外和拉曼光谱以及X进行了表征射线衍射。在这项工作中，该化合物的新多晶型物（形式III）进行了说明。用光谱表征了新的多晶型物，并通过单晶X射线衍射首次确定了其结构。非常有趣的是，发现多晶型物III的晶体表现出高Z '（Z '= 3）不对称单元，并且在晶胞中具有12个分子（Z = 12），这与之前针对晶型I的较简单晶体结构形成了对比。和II（Z = 4; Z′= 1）。此外，借助于先进的第一原理对化合物的不同多晶型物进行结构，周期计算以及红外光谱和拉曼光谱分析，对1-MH多晶型物进行了深入研究。提出了多晶型物的红外和拉曼光谱中的标记带，用于快速光谱鉴定多晶型物。

更新日期：2020-10-05

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