RT info:eu-repo/semantics/article
T1 Molecular rotation spectrum of tetracyclic quinolizidines: Observation of trans-Matrine and the elusive cis-Matrine
A1 Juanes San José, Marcos
A1 Saragi, Rizalina Tama
A1 Enríquez Giraudo, María Lourdes
A1 Jaraíz Maldonado, Martín
A1 Lesarri Gómez, Alberto Eugenio
K1 Sensors
K1 Sensores
K1 Electromagnetic radiation
K1 Radiación electromagnética
K1 Organic compounds
K1 Compuestos orgánicos
K1 Molecular structures
K1 Estructuras moleculares
AB We characterized the bis-quinolizidine tetracyclic alkaloid (5S, 6S, 7R, 11R)-matrine in a supersonic jet expansion, using chirped-pulsed broadband microwave spectroscopy. Previous crystal diffraction analyses suggested 16 diastereoisomers associated with matrine’s four carbon stereocenters but were inconclusive whether the lactamic nitrogen atom would additionally produce separated trans-/cis- diastereoisomers or if both species may interconvert through low potential barriers. Our experiment simultaneously detected trans- and cis-matrine through their rotational spectrum, confirming the possibility of conformational rearrangement in matrine alkaloids. The two matrine conformers mainly differ in the envelope or half-chair lactamic ring, as evidenced by the experimental rotational and nuclear quadrupole coupling parameters. Molecular orbital calculations with ab initio (MP2) and density functional methods (B3LYP-D3(BJ) and MN15) were tested against the experiment, additionally offering an estimation of the cis-/trans- barrier of 24.9–26.9 kJ mol–1. The experiment illustrates the structural potential of chirped-pulsed broadband microwave spectroscopy for high-resolution rotational studies of biomolecules in the range of 20–40 atoms.
PB ACS Publications
SN 1520-6904
YR 2021
FD 2021
LK https://uvadoc.uva.es/handle/10324/47830
UL https://uvadoc.uva.es/handle/10324/47830
LA eng
NO The Journal of Organic Chemistry, 2021, vol. 86, n. 2. p. 1861–1867
NO Producción Científica
DS UVaDOC
RD 18-nov-2024