Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Proton (¹H) NMR: Chemical Shift01:07

Proton (¹H) NMR: Chemical Shift

Organic molecules primarily contain carbon and hydrogen atoms. While all the hydrogen isotopes are NMR-active, protium or hydrogen-1 is the most abundant. It has a significant energy separation between its nuclear spin states due to its large gyromagnetic ratio. As per Boltzmann's distribution, an increase in the energy separation implies a greater excess population of nuclei available for excitation, resulting in a strong NMR absorption signal.
Absorption signals of all the protium nuclei in a...
¹H NMR: Complex Splitting01:13

¹H NMR: Complex Splitting

A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution00:52

¹H NMR of Conformationally Flexible Molecules: Temporal Resolution

At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
¹H NMR of Labile Protons: Temporal Resolution01:10

¹H NMR of Labile Protons: Temporal Resolution

Protons bonded to heteroatoms such as nitrogen and oxygen exhibit a range of chemical shift values. This is due to the varying degree of hydrogen bonding between the proton and the heteroatom in other molecules. The extent of hydrogen bonding affects the electron density around the proton, thereby giving different chemical shift values for the protons in the proton NMR spectrum.
The –OH proton in alcohols typically appears in the range of δ 2 to 5 ppm but can vary depending on the specific...
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR01:15

¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR

The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.
NMR Spectroscopy Of Amines01:19

NMR Spectroscopy Of Amines

In proton NMR spectroscopy, primary amines and secondary amines showcase their N–H protons as a broad signal in the chemical shift range between δ 0.5 and 5 ppm. The exact position in this range depends on several factors, including sample concentration, hydrogen bonding, and the type of solvent used. Since amine protons undergo fast proton exchange in solution, the protons are labile and therefore do not participate in any splitting with adjacent protons. Thus, the observed peak is broad and...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Development and evaluation of RADA-PDGF2 self-assembling peptide hydrogel for enhanced skin wound healing.

Frontiers in pharmacology·2023
Same author

A study of out-of-plane cation dynamics in a bis-thiourea pyridinium chloride inclusion compound.

Physical chemistry chemical physics : PCCP·2011
Same author

A hybrid method for estimation of molecular dynamics of diazepam-density functional theory combined with NMR and FT-IR spectroscopy.

International journal of pharmaceutics·2010
Same author

Molecular dynamics in solid pyridoxine as studied by 1H NMR.

Solid state nuclear magnetic resonance·2003
Same author

Molecular dynamics in solid riboflavin as studied by 1H NMR.

Solid state nuclear magnetic resonance·2001
Same author

Molecular dynamics in solid pregnenolone studied by 1H spin-lattice relaxation.

Solid state nuclear magnetic resonance·2000

Related Experiment Video

Updated: Jul 19, 2026

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
14:55

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy

Published on: September 17, 2017

Molecular dynamics in solid L-adrenaline by proton NMR

E R Andrew1, B Peplinska, M Kempka

  • 1Department of Physics, University of Florida, Gainesville 32611, USA.

Solid State Nuclear Magnetic Resonance
|April 29, 1998
PubMed
Summary

Proton NMR studies reveal molecular dynamics in L-adrenaline. Methyl group reorientation dominates relaxation between 70-250 K, while lower temperatures show tunneling effects and higher temperatures indicate side-chain conformational motion.

More Related Videos

Paramagnetic Relaxation Enhancement for Detecting and Characterizing Self-Associations of Intrinsically Disordered Proteins
07:24

Paramagnetic Relaxation Enhancement for Detecting and Characterizing Self-Associations of Intrinsically Disordered Proteins

Published on: September 23, 2021

NMR 15N Relaxation Experiments for the Investigation of Picosecond to Nanoseconds Structural Dynamics of Proteins
09:25

NMR 15N Relaxation Experiments for the Investigation of Picosecond to Nanoseconds Structural Dynamics of Proteins

Published on: November 1, 2024

Related Experiment Videos

Last Updated: Jul 19, 2026

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
14:55

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy

Published on: September 17, 2017

Paramagnetic Relaxation Enhancement for Detecting and Characterizing Self-Associations of Intrinsically Disordered Proteins
07:24

Paramagnetic Relaxation Enhancement for Detecting and Characterizing Self-Associations of Intrinsically Disordered Proteins

Published on: September 23, 2021

NMR 15N Relaxation Experiments for the Investigation of Picosecond to Nanoseconds Structural Dynamics of Proteins
09:25

NMR 15N Relaxation Experiments for the Investigation of Picosecond to Nanoseconds Structural Dynamics of Proteins

Published on: November 1, 2024

Area of Science:

  • Solid-state Nuclear Magnetic Resonance (NMR) Spectroscopy
  • Molecular Dynamics
  • Physical Chemistry

Background:

  • Understanding molecular motion in organic compounds is crucial for predicting their physical and chemical properties.
  • Polycrystalline L-adrenaline's complex structure suggests potential for diverse molecular dynamics.
  • Proton Nuclear Magnetic Resonance (NMR) is a powerful technique for probing molecular motion in solids.

Purpose of the Study:

  • To investigate the molecular dynamics of polycrystalline L-adrenaline using Proton NMR.
  • To characterize different motional processes and their associated energy barriers.
  • To determine the temperature dependence of relaxation times (T1 and T1D).

Main Methods:

  • Proton NMR measurements were performed on polycrystalline L-adrenaline.
  • Spectra, second moment, spin-lattice relaxation time (T1), and dipolar relaxation time (T1D) were measured.
  • Measurements were conducted at 14 and 25 MHz over a temperature range of 55 K to 400 K.

Main Results:

  • Between 70 K and 250 K, relaxation is primarily governed by C3 reorientation of the methyl group, with an activation energy of 8.3±0.3 kJ/mole.
  • Below 70 K, tunneling-assisted relaxation becomes significant, characterized by an excitation energy of 1.9±0.2 kJ/mole.
  • Above 250 K, conformational motion of the methylene group in the ethylamine side chain becomes dominant, exhibiting an activation energy exceeding 28 kJ/mole.

Conclusions:

  • Multiple molecular motions, including methyl group reorientation, tunneling, and side-chain conformational changes, contribute to the relaxation dynamics of L-adrenaline.
  • The study quantifies the energy barriers associated with these distinct motional processes.
  • Proton NMR provides detailed insights into the complex dynamic behavior of L-adrenaline across a wide temperature range.