Publication: Structure-spectroscopic relationship of co-crystals between a rare chromone structure type of barakol and some organic acids
Issued Date
2013-10-22
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ISSN
00222860
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2-s2.0-84885489031
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Mahidol University
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SCOPUS
Bibliographic Citation
Journal of Molecular Structure. Vol.1054-1055, (2013), 188-198
Suggested Citation
T. Chimsook, T. Teerawatananond, N. Ngamrojnavanich, N. Chaichit, P. Kongsaeree, N. Muangsin Structure-spectroscopic relationship of co-crystals between a rare chromone structure type of barakol and some organic acids. Journal of Molecular Structure. Vol.1054-1055, (2013), 188-198. doi:10.1016/j.molstruc.2013.08.053 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/31507
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Title
Structure-spectroscopic relationship of co-crystals between a rare chromone structure type of barakol and some organic acids
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Abstract
Barakol, extracted from Cassia siamea Lamk. having an anxiolytic property, consists of a rare chromone core structure, therefore, in this work we investigate relation between the X-ray crystallography and physical properties such as spectroscopic data and the intermolecular interactions of the keto-enol forms based on the CSD search, especially e.g. hydrogen bonding, π-π interactions, ionic interactions and acid-base interactions and clarifies their ambiguous spectroscopic properties. The 1:1 molecular complexes of barakol and carboxylic acid (phthalic acid and 3-hydroxybenzoic acid) were prepared and the X-ray crystallographic studies revealed that the barakol-phthalate complex exists in an ion-pair complex. The formation of barakol-phthalate ion-pair complex is stabilized by the complementary of ion-ion interactions, π-π interactions and hydrogen bonding. The barakol-3-hydroxybenzoic acid complex is a π-π molecular complex. The co-crystallization of barakol-3- hydroxybenzoic acid complex is solely stabilized by π-π interactions. The spectroscopic studies including IR,1H NMR and13C NMR are consistent with the results from the X-ray analysis. The1H NMR spectrum of the barakol and phthalic acid complex in a mixture of CDCl3-CD3OD showed a dramatic spectral changes with downfield shifts of the ortho-protons of phthalic acid (ΔδH(ppm) = 0.37), and the proton resonances of barakol (ΔδH(ppm) = 0.31 for proton H3, 0.53 for proton H4, 0.57 for proton H6 and 0.33 for proton H9). © 2013 Elsevier B.V. All rights reserved.