Related Experiment Video
Updated: Jul 17, 2025

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Synergistic Combination of NAPROC-13 and NMR 13C DFT Calculations: A Powerful Approach for Revising the Structure of
Hugo A Sánchez-Martínez1, Juan A Morán-Pinzón1, Esther Del Olmo Fernández2
1CIPFAR, Departamento de Farmacología Facultad de Medicina, University of Panama, Avenue Octavio Mendez Pereira, Panamá City 0801, Panamá.
Abstract:
This article describes the structure revision of nine triterpenoids that have been reported corresponding to the same 13C NMR data set. In addition, 13C NMR calculation shows that some chemical shift assignments must be swapped. Our analysis improves the fit between the experimental and calculated data. Correcting misassigned structures and correctly assigning each signal is essential for elucidating new structurally related compounds. Furthermore, the ambiguity of several compounds, the structure of which differs in the literature and the Sci-Finder database, has been eliminated. Misassigned structures were found by chemical shift searches in NAPROC-13, and the results provide two or more different compounds with the same 13C NMR data. The process to determine the correct, most likely structural proposal in agreement with the experimental 13C NMR data was carried out by DFT calculations.
More Related Videos
Related Concept Videos
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
¹³C NMR: ¹H–¹³C Decoupling
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
NMR Spectroscopy of Aromatic Compounds
Carbon-13 (¹³C) NMR: Overview
NMR and Mass Spectroscopy of Carboxylic Acids
While α protons of carboxylic acids absorb at 2–2.5 ppm, β protons absorb further upfield.
Carboxylic acids are easily identified by dissolving them in deuterium oxide, which results in a rapid exchange of the acidic protons with deuterium. This leads to the...
Nuclear Overhauser Enhancement (NOE)

