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¹⁹F NMR fingerprints: identification of neutral organic compounds in a molecular container.

Zhao Y, Markopoulos G, Swager TM - J. Am. Chem. Soc. (2014)

Bottom Line: We report a new approach to effectively "fingerprint" neutral organic molecules by using (19)F NMR and molecular containers.Spatial proximity of the analyte to the (19)F is important to induce the most pronounced NMR shifts and is crucial in the differentiation of analytes with similar structures.This new scheme allows for the precise and simultaneous identification of multiple analytes in a complex mixture.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.

ABSTRACT
Improved methods for quickly identifying neutral organic compounds and differentiation of analytes with similar chemical structures are widely needed. We report a new approach to effectively "fingerprint" neutral organic molecules by using (19)F NMR and molecular containers. The encapsulation of analytes induces characteristic up- or downfield shifts of (19)F resonances that can be used as multidimensional parameters to fingerprint each analyte. The strategy can be achieved either with an array of fluorinated receptors or by incorporating multiple nonequivalent fluorine atoms in a single receptor. Spatial proximity of the analyte to the (19)F is important to induce the most pronounced NMR shifts and is crucial in the differentiation of analytes with similar structures. This new scheme allows for the precise and simultaneous identification of multiple analytes in a complex mixture.

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3D scatter of analytesbased on the shifts of 19F resonancesupon bonding: x axis, o-19F (−Δδ × 1000); y axis, p-19F (−Δδ × 1000); z axis, m-19F (−Δδ× 1000). The sphere radius is correlated to imido-19F (−Δδ × 1000) with a factorof 0.04.
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fig9: 3D scatter of analytesbased on the shifts of 19F resonancesupon bonding: x axis, o-19F (−Δδ × 1000); y axis, p-19F (−Δδ × 1000); z axis, m-19F (−Δδ× 1000). The sphere radius is correlated to imido-19F (−Δδ × 1000) with a factorof 0.04.

Mentions: Athree-dimensional plot is shown in Figure 9, with the o-, p-, and m-19F NMR signals as the axes and the relativeshift of the imido-19F NMR signal representedby the radius of a sphere. The highly dispersed data points demonstratedthe ability of 5a to resolve all the analytes. As expected,nitriles with similar structures display 19F NMR signalsthat are close to one another. For example, acetonitrile and propionitrile(Figure 8d,e) induce similar but differentiatedresponses. It should be mentioned that the radii of the spheres inFigure 9 correlate with the shift of imido-fluorine and can further differentiate analytes thatproduce similar spectral differences in the other 19F NMRsignals, such as ethyl (R)-4-cyano-3-hydroxybutyrate(Figure 8h) and C8H17CN (Figure 8f).


¹⁹F NMR fingerprints: identification of neutral organic compounds in a molecular container.

Zhao Y, Markopoulos G, Swager TM - J. Am. Chem. Soc. (2014)

3D scatter of analytesbased on the shifts of 19F resonancesupon bonding: x axis, o-19F (−Δδ × 1000); y axis, p-19F (−Δδ × 1000); z axis, m-19F (−Δδ× 1000). The sphere radius is correlated to imido-19F (−Δδ × 1000) with a factorof 0.04.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4120996&req=5

fig9: 3D scatter of analytesbased on the shifts of 19F resonancesupon bonding: x axis, o-19F (−Δδ × 1000); y axis, p-19F (−Δδ × 1000); z axis, m-19F (−Δδ× 1000). The sphere radius is correlated to imido-19F (−Δδ × 1000) with a factorof 0.04.
Mentions: Athree-dimensional plot is shown in Figure 9, with the o-, p-, and m-19F NMR signals as the axes and the relativeshift of the imido-19F NMR signal representedby the radius of a sphere. The highly dispersed data points demonstratedthe ability of 5a to resolve all the analytes. As expected,nitriles with similar structures display 19F NMR signalsthat are close to one another. For example, acetonitrile and propionitrile(Figure 8d,e) induce similar but differentiatedresponses. It should be mentioned that the radii of the spheres inFigure 9 correlate with the shift of imido-fluorine and can further differentiate analytes thatproduce similar spectral differences in the other 19F NMRsignals, such as ethyl (R)-4-cyano-3-hydroxybutyrate(Figure 8h) and C8H17CN (Figure 8f).

Bottom Line: We report a new approach to effectively "fingerprint" neutral organic molecules by using (19)F NMR and molecular containers.Spatial proximity of the analyte to the (19)F is important to induce the most pronounced NMR shifts and is crucial in the differentiation of analytes with similar structures.This new scheme allows for the precise and simultaneous identification of multiple analytes in a complex mixture.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.

ABSTRACT
Improved methods for quickly identifying neutral organic compounds and differentiation of analytes with similar chemical structures are widely needed. We report a new approach to effectively "fingerprint" neutral organic molecules by using (19)F NMR and molecular containers. The encapsulation of analytes induces characteristic up- or downfield shifts of (19)F resonances that can be used as multidimensional parameters to fingerprint each analyte. The strategy can be achieved either with an array of fluorinated receptors or by incorporating multiple nonequivalent fluorine atoms in a single receptor. Spatial proximity of the analyte to the (19)F is important to induce the most pronounced NMR shifts and is crucial in the differentiation of analytes with similar structures. This new scheme allows for the precise and simultaneous identification of multiple analytes in a complex mixture.

Show MeSH
Related in: MedlinePlus