CONFORMATIONAL VARIABILITY IN A NEW TERPENOID-LIKE BISCHALCONE: STRUCTURE AND THEORETICAL STUDIES
W.B. Fernandes1, L.A. Malaspina2, F.T. Martins3, L.M. LiГЈo3, A.J. Camargo1, C. Lariucci2, C. Noda-Perez3, H.B. Napolitano1
1Ciências Exatas e Tecnológicas, Universidade Estadual de Goiás, 75001-970 Anápolis, GO, Brazil
hamilton@ueg.br
2Instituto de Física, Universidade Federal de Goiás, 74001-970 Goiânia, GO, Brazil
3Instituto de Química, Universidade Federal de Goiás, 74001-970 Goiânia, GO, Brazil
Ключевые слова: terpenoid-like bischalcone, X-ray diffraction, disorder modeling
Страницы: 1082-1091
Подраздел: СТРУКТУРА БИОЛОГИЧЕСКИ АКТИВНЫХ СИСТЕМ
Аннотация
A new terpenoid-like bischalcone (1E,4E)-1-(4-nitrophenyl)-5-(2,6,6-trimethylcyclohex-1-enyl)-penta-1,4-dien-3-one was synthesized from a b-ionone and 4-nitrobenzaldehyde by Claisen—Schmidt condensation reaction and its structure was determined by single crystal X-ray diffraction analysis. Additionally, this compound was featured by powder X-ray diffraction,
1H,
13C NMR and IR spectroscopy techniques. The molecule in the asymmetric unit showed disordered occupancy sites over two positions for the trimethylcyclohexene atoms. These two conformations were related by a rotation of about 180° around the axis of the C—C bond linking the six-membered ring and the olefin carbons. Single-molecule calculations using the DFT method have strengthened this structural finding, since our theoretical approaches also suggest two well-defined conformations of similar energies which resemble the molecular geometries determined by X-ray diffraction. Furthermore, the inspection of the crystal packing revealed that the hydrogen bonding patterns are different for each conformation of the compound reported here.
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