Yayın:
5-Methylhydantoin: From isolated molecules in a low-temperature Aaon matrix to solid state polymorphs characterization

No Thumbnail Available
Tarih
2017-12
Yazarlar
Öğrüç Ildız, Gülce
Nogueira, Bernardo.A.
Canotilho J.
Eusébio MES
Henriques MSC
Paixão JA
Fausto R.
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayımcı
Araştırma Projeleri
Organizasyon Birimleri
Dergi Sayısı
Özet
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.
Açıklama
Anahtar kelimeler
Alıntı