NMR in operando monitoring of mechanochemically accelerated sublimations

Puccetti, Francesco; Rinesch, Torsten; Suljić, Sanel; Rahimi, Khosrow; Herrmann, Andreas; Bolm, Carsten

doi:10.1016/j.chempr.2023.02.022

Cited by 7 publications

(5 citation statements)

References 87 publications

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“…For mechanochemistry, it is important because it gives structural information by identifying phases, purities, crystallite sizes, and morphologies. [ 16 ] As a bulk technique, it has been widely used to investigate polymorphs of co‐crystals and their interconversions. [ 17 ] When studying mechanochemical reactions, the solids cannot only be analyzed ex situ at the starting and the end point of the process, but also while the transformation is occurring.…”

Section: Analytical Methods In Organic Mechanochemistrymentioning

confidence: 99%

“…Another example demonstrating the high value of ex situ solid-state NMR stems from a study with a-(trifluoromethyl)lactic acid (TFL). [16] This compound is known for its unusually high sublimation tendency, which can lead to a rapid alternation in the enantiomer composition of a scalemic sample. [62] Direct analyses of TFL mixtures by ex situ solid-state NMR pro-vides reliable data, since the optical pure phases can be distinguished from the racemic compound, [63] whereas solution-based NMR techniques cannot differentiate between those phases and come with the danger of losing parts of the product by sublimation, thereby changing the enantiomer ratio of the sample to be analyzed.…”

Section: Studying Milling Reaction Products By Ex Situ Solid-state Nm...mentioning

confidence: 99%

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Opportunities and Challenges in Applying Solid‐State NMR Spectroscopy in Organic Mechanochemistry

et al. 2023

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In recent years it was shown that mechanochemical strategies can be beneficial in directed conversions of organic compounds. Finding new reactions proved difficult, and due to the lack of mechanistic understanding of mechanochemical reaction events, respective efforts have mostly remained empirical. Spectroscopic techniques are crucial in shedding light on these questions. In this overview, the opportunities and challenges of solid‐state nuclear magnetic resonance (NMR) spectroscopy in the field of organic mechanochemistry are discussed. After a brief discussion of the basics of high‐resolution solid‐state NMR under magic‐angle spinning (MAS) conditions, seven opportunities for solid‐state NMR in the field of organic mechanochemistry are presented, ranging from ex‐situ approaches to structurally elucidate reaction products obtained by milling to the potential and limitations of in‐situ solid‐state NMR approaches. Particular strengths of solid‐state NMR, for instance in differentiating polymorphs, in NMR‐crystallographic structure‐determination protocols, or in detecting weak noncovalent interactions in molecular‐recognition events employing proton‐detected solid‐state NMR experiments at fast MAS frequencies, are discussed.This article is protected by copyright. All rights reserved

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Section: Analytical Methods In Organic Mechanochemistrymentioning

confidence: 99%

Section: Studying Milling Reaction Products By Ex Situ Solid-state Nm...mentioning

confidence: 99%

Opportunities and Challenges in Applying Solid‐State NMR Spectroscopy in Organic Mechanochemistry

et al. 2023

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“…Other applications, opportunities, and challenges of using solid-state NMR spectroscopy in the mechanochemistry of organic compounds have recently been extensively discussed by Bolm and colleagues. [49,50]…”

Section: Introductionmentioning

confidence: 99%

“…SS MAS NMR is particularly suitable for in situ monitoring processes when substances during transformation form low‐melting eutectic mixtures (e. g. cocrystal formation). Other applications, opportunities, and challenges of using solid‐state NMR spectroscopy in the mechanochemistry of organic compounds have recently been extensively discussed by Bolm and colleagues [49,50] …”

Section: Introductionmentioning

confidence: 99%

Solvent‐Free Mechanosynthesis of Oligopeptides by Coupling Peptide Segments of Different Lengths – Elucidating the Role of Cesium Carbonate in Ball Mill Processes

Wróblewska,

Bak‐Sypien,

Paluch

et al. 2024

Chemistry A European J

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We report an idea for the synthesis of oligopeptides using a solvent‐free ball milling approach. Our concept is inspired by block play, in which it is possible to construct different objects using segments (blocks) of different sizes and lengths. We prove that by having a library of short peptides and employing the ball mill mechanosynthesis (BMMS) method, peptides can be easily coupled to form different oligopeptides with the desired functional and biological properties. Optimizing the BMMS process we found that the best yields we obtained when TBTU and cesium carbonate were used as reagents. The role of Cs2CO3 in the coupling mechanism was followed on each stage of synthesis by 1H, 13C and 133Cs NMR employing Magic Angle Spinning (MAS) techniques. It was found that cesium carbonate acts not only as a base but is also responsible for the activation of substrates and intermediates. The unique information about the BMMS mechanism is based on the analysis of 2D NMR data. The power of BMMS is proved by the example of different peptide combinations, 2+2, 3+2, 4+2, 5+2 and 4+4. The tetra‐, penta‐, hexa‐, hepta‐ and octapeptides obtained under this project were fully characterized by MS and NMR techniques.

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“…Whether the organic compounds are natural products − or synthesized by chemists, it is extremely important to determine their structures and absolute conformations at the atomic level. Over the past few decades, numerous researchers have developed and refined many methods for the structural identification of organic molecules, such as nuclear magnetic resonance ( NMR ), − infrared spectroscopy ( IR ), − mass spectrometry ( MS ), − single crystal X-ray diffraction ( X-ray SCD ), − etc. Among them, X-ray SCD can provide direct and accurate structural information and is globally recognized as a fairly reliable method for the structural identification of organic compounds, including their stereochemical conformation.…”

mentioning

confidence: 99%

The Structure Determination of Organic Molecules by Co-crystallization of Anthracene-Based Crystallization Chaperone

Li,

Jiao,

Xie

et al. 2023

ACS Materials Lett.

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Single crystal X-ray diffraction is considered to be a highly reliable method for determining the molecular structures and absolute conformation at the atomic level, but this technique is limited to the application of oily organic molecules that are difficult to crystallize. Here, we report an anthracene-based crystallization chaperone TMAPA to overcome the above limitation, where 56 various oily organic guest molecules were cocrystallized with TMAPA in the organic solvent. As a result, 51 high-resolution co-crystal structures of organic guest molecules (chiral or achiral) with TMAPA were determined in a short time so that 51 refined structures of oily organic guest molecules can be readily determined. Importantly, anthracene moieties introduced in the TMAPA structure could not only extend the length of arms to increase the size of pores but also adaptively adopt different conformations leading to an efficient capture of the guest molecule during the co-crystallization process. It is expected that this work will open up new possibilities for structural identification and absolute conformation determination of unknown oily organic molecules.

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NMR in operando monitoring of mechanochemically accelerated sublimations

Cited by 7 publications

References 87 publications

Opportunities and Challenges in Applying Solid‐State NMR Spectroscopy in Organic Mechanochemistry

Opportunities and Challenges in Applying Solid‐State NMR Spectroscopy in Organic Mechanochemistry

Solvent‐Free Mechanosynthesis of Oligopeptides by Coupling Peptide Segments of Different Lengths – Elucidating the Role of Cesium Carbonate in Ball Mill Processes

The Structure Determination of Organic Molecules by Co-crystallization of Anthracene-Based Crystallization Chaperone

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