Tutor: Prof. Martin Dračínský Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
This workshop will provide a brief overview of the most commonly used 2D NMR experiments, with an emphasis on techniques particularly suitable for the structure elucidation of small organic molecules. Practical examples and interactive exercises based on the web platform nmr-challenge.com will be presented. The workshop will also demonstrate how the platform can be effectively integrated into teaching and training workflows, with a particular focus on developing problem-solving skills for the elucidation of unknown molecular structures using 2D NMR spectroscopy. Because the platform systematically records both success rates and incorrect submissions for individual challenges, it enables data-driven analysis of common errors encountered during structure elucidation. One frequently observed difficulty is the correct assignment of substituent positions on benzene rings. Several representative examples illustrating these challenges will be discussed during the workshop.
Tutor : Prof. Greg Stanisz Sunnybrook Research Institute University of Toronto
description will be given soon
Tutor : Dr eng. Rafał Konefał NanoBioMedical Centre Adam Mickiewicz University, Poznań, Poland
Diffusion nuclear magnetic resonance (NMR) spectroscopy is a powerful technique for measuring molecular diffusion and probing translational mobility in solution. By combining diffusion measurements with conventional chemical shift information, diffusion NMR provides an additional dimension of spectral separation, commonly referred to as diffusion-ordered spectroscopy (DOSY). This approach enables the differentiation of species in complex mixtures based on their diffusion coefficients. In a typical DOSY experiment, pulsed magnetic field gradients are used to encode and decode spatial information about nuclear spins. The diffusion delay is positioned between the encoding and decoding gradient pulses. If molecular diffusion does not occur during this delay, the gradient pulses generate a perfect gradient echo and a strong signal is observed. However, when molecules diffuse during the delay period, the spatially encoded phase of the spins becomes partially randomized. As a result, the gradient echo is attenuated, leading to a reduction in signal intensity. The extent of signal attenuation depends on several experimental and molecular parameters, including the strength of the applied gradients, the gyromagnetic ratio of the observed nuclei, the diffusion delay, and the molecular diffusion coefficients. By systematically varying the gradient strength and analyzing the resulting signal decay, diffusion coefficients of individual species can be quantitatively determined. Consequently, diffusion NMR and DOSY experiments provide valuable insights into molecular size, intermolecular interactions, aggregation phenomena, and transport properties in a wide range of chemical and biological systems
Tutor: dr Jacek Jenczyk NanoBioMedical Centre, Adam Mickiewicz University, Poznań, Poland
In April 1948, G. E. Pake published his landmark paper in the Journal of Chemical Physics entitled “Nuclear Resonance Absorption in Hydrated Crystals: Fine Structure of the Proton Line”, in which he demonstrated that water molecules embedded in the CaSO₄·2H₂O crystal can be treated as semi-isolated proton pairs. Accordingly, these crystals constitute a perfect model system for describing the anisotropic nature of dipolar interactions. The aim of this workshop will be to explore the scientific problem addressed by G. E. Pake and thereby explain the fundamentals of dipolar interactions. I will also attempt to visualize the tensor formalism used to describe this interaction and, in an intuitive way, show the direct relationship between molecular orientation relative to the laboratory reference frame and the evolution of the NMR spectrum. Finally, I will explain what happens to tensors under magic-angle spinning conditions and how MAS affects and modulates the effective shielding and dipolar coupling.
Fig. 1. left) proton pair with D tensor in the laboratory reference frame, right) semi-isolated water molecules within gypsum crystal – unit cell.
Tutor : Dr Albert Smith-Penzel Universitat Lepizig
Tutor : Prof. Pedro José Sebastião University of Lisbon, Instituto Superior Técnico, CeFEMA
The analysis of NMR relaxation data can be a challenging task, ranging from the evaluation of spin–lattice relaxation components in multi-component magnetization decays to the analysis of spin–lattice relaxation profiles over many decades of Larmor frequencies. Numerous software tools are available to assist users in performing these tasks, and fitteia.org has gained some popularity within the NMRD community [1–2]. Its main difference with respect to other alternatives is that it requires only a web browser to access the fitteia.org servers; no software installation or maintenance is needed. In addition, its user-friendly graphical user interface is particularly well suited for model fitting of NMRD profiles, taking advantage of its relaxation model library [3]. Nevertheless, there is a growing demand for alternative interfaces to fitteia’s powerful numerical fitting engine. The OneFit-Engine (OFE) [4,5], available on GitHub, provides users with a software package and installation tools that significantly expand the possibilities offered by fitteia, enabling the automation of data fitting processes as well as its embedding or integration into other applications. In this tutorial, we will present a few examples illustrating how to use fitteia for multiexponential magnetization decay fitting and for the analysis of spin–lattice relaxation profiles. Some user-specific problems may also be addressed during the tutorial for the benefit of the audience, provided that interested participants register in advance at fitteia.org and have already uploaded their case-study datasets to the system. Acknowledgements EU’s Horizon Europe programme under the HORIZON-MSCA-DN-2021 FC-RELAX project, grant agreement 101072758, and HORIZON-MSCA-2022-SE-01-01 NMR-IMPROV project, grant agreement 101131564. References [1] "The art of model fitting to experimental results", P.J. Sebastião, Eur. J. Phys. 35, 15017 (2014) [2] "The art of fitting ordinary differential equations models to experimental results" P.J. Sebastiao et al. , Eur. J. Phys. 43, 035807 (2022) [3] http://NMRDpedia.org [4] https://github.com/fitteia/OneFit-Engine [5] http://onefite-t.vps.tecnico.ulisboa.pt:3000
Tutor : tba Magritec
The description will be given soon
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