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NMR studies of anion-induced conformational changes in diindolylureas and diindolylthioureas

Markuc, D., Hiscock, Jennifer R., Light, Mark E., Gale, Philip A., Plavec, J. (2011) NMR studies of anion-induced conformational changes in diindolylureas and diindolylthioureas. Beilstein Journal of Organic Chemistry, 7 . pp. 1205-1214. ISSN 1860-5397. (doi:10.3762/bjoc.7.140) (KAR id:70823)

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http://dx.doi.org/10.3762/bjoc.7.140

Abstract

The conformational properties of 1,3-diindolylureas and thioureas were studied by a combination of heteronuclear NMR spectroscopy and quantum mechanics calculations. NOE experiments showed that the anti–anti conformer along the C7–N7? bonds was predominant in DMSO-d6 solution in the absence of anions. Anion-induced changes in the 1H and 15N chemical shifts confirm the weak binding of chloride anions with negligible conformational changes. Strong deshielding of ureido protons and moderate deshielding of indole NH was observed upon the addition of acetate, benzoate, bicarbonate and dihydrogen phosphate, which indicated that the predominant hydrogen bond interactions occurred at the urea donor groups. Binding of oxo-anions caused conformational changes along the C7–N7? bonds and the syn–syn conformer was preferred for anion–receptor complexes. The conformational changes upon anion binding are in good agreement with energetic preferences established by ab initio calculations.

Item Type: Article
DOI/Identification number: 10.3762/bjoc.7.140
Uncontrolled keywords: anion recognition; conformation analysis; host–guest systems; NMR spectroscopy
Subjects: Q Science > QD Chemistry
Divisions: Divisions > Division of Natural Sciences > School of Physical Sciences
Depositing User: Jennifer Hiscock
Date Deposited: 07 Dec 2018 16:26 UTC
Last Modified: 16 Feb 2021 14:00 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/70823 (The current URI for this page, for reference purposes)
Hiscock, Jennifer R.: https://orcid.org/0000-0002-1406-8802
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