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- Title
Effect of the solvent on the conformation of monocrotaline as determined by isotropic and anisotropic NMR parameters.
- Authors
Melo Sousa, Cleyton Marcos; Giordani, Raquel Brandt; Almeida, Wamberto Alristenio Moreira; Griesinger, Christian; Gil, Roberto R.; Navarro‐Vázquez, Armando; Hallwass, Fernando
- Abstract
The conformation in solution of monocrotaline, a pyrrolizidine alkaloid presenting an eleven‐membered macrocyclic diester ring, has been investigated using a combination of isotropic and anisotropic nuclear magnetic resonance parameters measured in four solvents of different polarity (D2O, DMSO‐d6, CDCl3, and C6D6). Anisotropic nuclear magnetic resonance parameters were measured in different alignment media, based on their compatibility with the solvent of interest: cromoglycate liquid crystal solution was used for D2O, whereas a poly (methyl methacrylate) polymer gel was chosen for CDCl3 and C6D6, and a poly (hydroxyethyl methacrylate) gel for DMSO‐d6. Whereas the pyrrolizidine ring shows an E6exo‐puckered conformation in all of the solvents, the macrocyclic eleven‐membered ring adopts different populations of syn‐parallel and anti‐parallel relative orientation of the carbonyl groups according to the polarity of the solvent.
- Subjects
MONOCROTALINE; METHYL methacrylate; POLYMER liquid crystals; NUCLEAR magnetic resonance; SOLVENTS; PYRROLIZIDINES
- Publication
Magnetic Resonance in Chemistry, 2021, Vol 59, Issue 5, p561
- ISSN
0749-1581
- Publication type
Article
- DOI
10.1002/mrc.4968