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Anion-induced conformational changes in 2,7-disubstituted indole-based receptors

Anion-induced conformational changes in 2,7-disubstituted indole-based receptors
Anion-induced conformational changes in 2,7-disubstituted indole-based receptors
The conformational preorganization and anion-induced conformational changes of indole-based receptors functionalized with an amide group at the 2-position and a variety of amide, urea and thiourea moieties at the 7-position have been studied by the means of NMR spectroscopy. NOE experiments showed that anti–anti orientation across C2–C2 and C7–N7 bonds is preferred for receptors 1–4 in acetone solution in the absence of anions. Anion–receptor interactions have been evaluated through 1H and 15N chemical shift changes. In 2,7-bis-carboxamido functionalized indoles the interaction with chloride and bromide anions primarily occurs at the indole H1 proton. The introduction of urea and thiourea moieties increases the number of hydrogen bond donor sites which manifests itself in a distribution of halide–receptor interactions among the H1, H7 and H7 protons. Acetate anions also interact strongly with indole and urea NH donor groups, whereas nitrate anions interact solely with H7 and H7 urea/thiourea protons. NOE enhancements in the presence of anions revealed that anion–receptor complexes favour the syn–syn conformation of the C2 and C7 substituents.
1477-0520
3505-3511
Makuc, Damjan
0587d709-5f7a-44c7-9b74-1940285b933d
Lenarčič, Martina
64b01925-e28c-4190-b206-d37c7efc53fd
Bates, Gareth W.
784ac62e-67f5-400a-ab9a-42615be9ec9d
Gale, Philip A.
c840b7e9-6847-4843-91af-fa0f8563d943
Plavec, Janez
7a5f325c-d357-40b2-87ab-7482f862b7f0
Makuc, Damjan
0587d709-5f7a-44c7-9b74-1940285b933d
Lenarčič, Martina
64b01925-e28c-4190-b206-d37c7efc53fd
Bates, Gareth W.
784ac62e-67f5-400a-ab9a-42615be9ec9d
Gale, Philip A.
c840b7e9-6847-4843-91af-fa0f8563d943
Plavec, Janez
7a5f325c-d357-40b2-87ab-7482f862b7f0

Makuc, Damjan, Lenarčič, Martina, Bates, Gareth W., Gale, Philip A. and Plavec, Janez (2009) Anion-induced conformational changes in 2,7-disubstituted indole-based receptors. Organic & Biomolecular Chemistry, 7 (17), 3505-3511. (doi:10.1039/B908947K).

Record type: Article

Abstract

The conformational preorganization and anion-induced conformational changes of indole-based receptors functionalized with an amide group at the 2-position and a variety of amide, urea and thiourea moieties at the 7-position have been studied by the means of NMR spectroscopy. NOE experiments showed that anti–anti orientation across C2–C2 and C7–N7 bonds is preferred for receptors 1–4 in acetone solution in the absence of anions. Anion–receptor interactions have been evaluated through 1H and 15N chemical shift changes. In 2,7-bis-carboxamido functionalized indoles the interaction with chloride and bromide anions primarily occurs at the indole H1 proton. The introduction of urea and thiourea moieties increases the number of hydrogen bond donor sites which manifests itself in a distribution of halide–receptor interactions among the H1, H7 and H7 protons. Acetate anions also interact strongly with indole and urea NH donor groups, whereas nitrate anions interact solely with H7 and H7 urea/thiourea protons. NOE enhancements in the presence of anions revealed that anion–receptor complexes favour the syn–syn conformation of the C2 and C7 substituents.

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Published date: September 2009

Identifiers

Local EPrints ID: 144913
URI: http://eprints.soton.ac.uk/id/eprint/144913
ISSN: 1477-0520
PURE UUID: 32a2f2f6-6d85-4780-b3ee-9df39c4cbe5f
ORCID for Philip A. Gale: ORCID iD orcid.org/0000-0001-9751-4910

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Date deposited: 15 Apr 2010 12:54
Last modified: 19 Nov 2019 01:52

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