Chapter 8
Interpreting Nuclear Magnetic Resonance Spectra
![Chemical Shift: Internal References and Solvent Effects](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/14596.jpg)
In an NMR sample, precise measurement of the absolute absorption frequencies of nuclei is difficult. A standard internal reference compound is added,…
![NMR Spectroscopy: Chemical Shift Overview](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/12991.jpg)
The position of the absorption signal of a sample is reported relative to the position of the signal of tetramethylsilane (TMS), which is added as an…
![Inductive Effects on Chemical Shift: Overview](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/12272.jpg)
The protons in unsubstituted alkanes are strongly shielded with chemical shifts below 1.8 ppm. Methine, methylene, and methyl protons appear at…
![π Electron Effects on Chemical Shift: Overview](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/12996.jpg)
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field…
![<sup>1</sup>H NMR Chemical Shift Equivalence: Homotopic and Heterotopic Protons](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13000.jpg)
Protons in identical electronic environments within a molecule are chemically equivalent and have the same chemical shift. The replacement test is a…
![<sup>1</sup>H NMR Chemical Shift Equivalence: Enantiotopic and Diastereotopic Protons](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13001.jpg)
Replacing each alpha-hydrogen in chloroethane by bromine (or a different functional group) yields a pair of enantiomers. Such protons are called…
![NMR Spectroscopy: Spin–Spin Coupling](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13004.jpg)
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the…
![<sup>1</sup>H NMR Signal Multiplicity: Splitting Patterns](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13005.jpg)
When protons A and X are coupled, their nuclear spin energy levels are slightly modified. This is because the energy required to excite proton A to a…
![Spin–Spin Coupling Constant: Overview](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13008.jpg)
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the…
![Spin–Spin Coupling: One-Bond Coupling](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13010.jpg)
Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the…
![Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13012.jpg)
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily…
![<sup>1</sup>H NMR: Long-Range Coupling](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13014.jpg)
The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in…
![<sup>1</sup>H NMR: Pople Notation](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13015.jpg)
The Pople nomenclature system classifies spin systems based on the difference between their chemical shifts. Coupled spins are denoted by capital…
![<sup>1</sup>H NMR: Interpreting Distorted and Overlapping Signals](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/12276.jpg)
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These…
![<sup>13</sup>C NMR: <sup>1</sup>H–<sup>13</sup>C Decoupling](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13018.jpg)
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak…
![<sup>13</sup>C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/12283.jpg)
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is…
![High-Temperature and High-Pressure In situ Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy](https://cloudfront.jove.com/files/thumbs/61794_t.png)
Nuclear magnetic resonance (NMR) spectroscopy represents an important technique to understand the structure and bonding environments of molecules.…
![Measuring Interactions of Globular and Filamentous Proteins by Nuclear Magnetic Resonance Spectroscopy (NMR) and Microscale Thermophoresis (MST)](https://cloudfront.jove.com/files/thumbs/58537_t.png)
Measuring Interactions of Globular and Filamentous Proteins by Nuclear Magnetic Resonance Spectroscopy (NMR) and Microscale Thermophoresis (MST)
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Filamentous proteins such as vimentin provide organization within cells by providing a structural scaffold with sites that bind proteins containing…
![Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy](https://cloudfront.jove.com/files/thumbs/55779_t.png)
Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
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Supramolecular protein assemblies play fundamental roles in biological processes ranging from host-pathogen interaction, viral infection to the…