Related Experiment Video
Updated: Dec 20, 2025
08:01
Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo
Published on: September 26, 2016
9.7K
Chemical exchange induced Hahn echo modulation in pulsed electron paramagnetic resonance experiment
1In Vivo Multifunctional Magnetic Resonance Center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA; Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
Summary
Monophosphonated triarylmethyl (TAM) radicals are effective probes for studying microenvironments using pulse electron paramagnetic resonance (EPR). Their relaxation properties, influenced by chemical exchange, allow for quantitative pH and exchange rate determination.
Area of Science:
- Physical Chemistry
- Chemical Physics
- Biophysical Chemistry
Background:
- Triarylmethyl (TAM) radicals possess long relaxation times, making them suitable for pulse electron paramagnetic resonance (EPR) studies.
- Pulse EPR is a powerful technique for probing molecular dynamics and microenvironment parameters.
Purpose of the Study:
- To investigate the relaxation properties of monophosphonated TAM radicals.
- To study the influence of chemical exchange processes on TAM radical relaxation.
- To establish a method for quantitative determination of chemical exchange rates and solution pH using pulse EPR.
Main Methods:
- Utilized pulse electron paramagnetic resonance (EPR) spectroscopy.
- Performed Hahn echo and inversion recovery experiments.
- Analyzed the dependence of echo intensity on solution pH and chemical exchange rate.
Main Results:
- Observed modulation of Hahn echo intensity due to chemical exchange in TAM radical solutions.
- Demonstrated the quantitative determination of chemical exchange rates from Hahn echo decay analysis.
- Showed the correlation between echo decay and solution pH.
Conclusions:
- Monophosphonated TAM radicals exhibit relaxation behavior sensitive to chemical exchange.
- Pulse EPR, specifically Hahn echo analysis, provides a quantitative method to determine chemical exchange rates and pH.
- This study enhances the utility of TAM radicals as probes in complex chemical and biological systems.
More Related Videos
Related Concept Videos
01:12Double Resonance Techniques: Overview
603
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
Spin decoupling is usually achieved by...
603
01:27π Electron Effects on Chemical Shift: Overview
1.5K
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0,...
1.5K
01:17Electron Paramagnetic Resonance (EPR) Spectroscopy: Organic Radicals
3.2K
Ideally, an unpaired electron shows a single peak in the EPR spectrum due to the transition between the two spin energy states. However, coupling interactions can occur between the spins of the unpaired electron and any neighboring spin-active nuclei. This hyperfine coupling results in hyperfine splitting, where the EPR signal is split into multiplets. The signals split into 2nI + 1 peaks, where n is the number of equivalent nuclei and I is the nuclear spin. These splitting patterns provide...
3.2K
01:15Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)
903
Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) is an advanced Nuclear Magnetic Resonance (NMR) technique specifically designed to detect and enhance the signals of low-abundance nuclei, such as carbon-13 and nitrogen-15, in small molecules. The fundamental principle behind INEPT is the transfer of polarization from a more abundant and highly polarizable nucleus, typically hydrogen-1, to the low-abundance nucleus of interest. This process effectively boosts the NMR signal of the...
903
01:06Nuclear Overhauser Enhancement (NOE)
1.3K
Irradiation of a spin-active nucleus causes an increase or decrease in the signal intensity of neighboring nuclei that are not necessarily chemically bonded or involved in J-coupling. This phenomenon, called the nuclear Overhauser enhancement (NOE), results from through-space interactions between the nuclear spins. The NOE effect decreases with increasing internuclear distance and is generally not observed beyond 4 angstroms. In NOE, dipole-dipole interactions between neighboring spin-active...
1.3K
01:17NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences
1.6K
A pulse is a short burst of radio waves distributed over a range of frequencies that simultaneously excites all the nuclei in the sample. Upon passing a radio frequency pulse along the x-axis, the nuclei absorb energy corresponding to their Larmor frequencies and achieve resonance. This shifts the net magnetization vector from the z-axis toward the transverse plane. This angle of rotation of the magnetization vector, or the flip angle, is proportional to the duration and intensity of the pulse.
1.6K