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https://hdl.handle.net/10316/99974
Título: | 5-Methylhydantoin: from Isolated Molecules in a Low-Temperature Argon Matrix to Solid State Polymorphs Characterization | Autor: | Nogueira, Bernardo Albuquerque Ildiz, Gulce O Lage, João Carlos Canotilho Eusébio, Maria Ermelinda da Silva Henriques, Marta Sofia C Paixao, Jose A Fausto, Rui |
Data: | 2017 | Volume: | 121 | Número: | 28 | Resumo: | The molecular structure, vibrational spectra and photochemistry of 5-methylhydantoin (C4H6N2O2; 5-MH) were studied by matrix isolation infrared spectroscopy and theoretical calculations at the DFT(B3LYP)/6-311++G(d,p) theory level. The natural bond orbital (NBO) analysis approach was used to study in detail the electronic structure of the minimum energy structure of 5-MH, namely the specific characteristics of the σ and π electronic systems of the molecule and the stabilizing orbital interactions. UV irradiation of 5-MH isolated in argon matrix resulted in its photofragmentation through a single photochemical pathway, yielding isocyanic acid, ethanimine, and carbon monoxide, thus following a pattern already observed before for the parent hydantoin and 1-methylhydantoin molecules. The investigation of the thermal properties of 5-MH was undertaken by differential scanning calorimetry (DSC), polarized light thermal microscopy (PLTM) and Raman spectroscopy. Four different polymorphs of 5-MH were identified. The crystal structure of one of the polymorphs, for which it was possible to grow up suitable crystals, was determined by X-ray diffraction (XRD). Two of the additional polymorphs were characterized by powder XRD, which confirmed the molecules pack in different crystallographic arrangements. | URI: | https://hdl.handle.net/10316/99974 | ISSN: | 1089-5639 1520-5215 |
DOI: | 10.1021/acs.jpca.7b05030 | Direitos: | openAccess |
Aparece nas coleções: | I&D CQC - Artigos em Revistas Internacionais |
Ficheiros deste registo:
Ficheiro | Descrição | Tamanho | Formato | |
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5-METH~1.PDF | 5.58 MB | Adobe PDF | Ver/Abrir |
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