Kernresonanz-Emissionslinien während rascher Radikalreaktionen

Bargon, Joachim; Fischer, Heinz; Johnsen, U.

doi:10.1515/zna-1967-1014

Cited by 224 publications

(73 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…7. CIDNP of ethane (in emission at 0.8 ppm) and of methane (in emission, not shown since outside of the depicted range to the left) observed during the decompostion of diacetyl peroxide (left) and multiplet effect in CH 2 In addition to this pleasing consequence, it had now become apparent that my observations in the field of NMR spectroscopy did not only involve processes of nuclei, but radical electrons also accounted for part of the action. This, however, was the domain of Hanns Fischer, who indeed had considerable experience, lecturing about ESR.…”

mentioning

confidence: 84%

The Discovery of Chemically Induced Dynamic Polarization (CIDNP)

Bargon

2006

Helvetica Chimica Acta

View full text Add to dashboard Cite

mentioning

confidence: 84%

The Discovery of Chemically Induced Dynamic Polarization (CIDNP)

Bargon

2006

Helvetica Chimica Acta

View full text Add to dashboard Cite

“…12,13 Nuclear spins can influence the course of chemical reactions that involve radical pairs as intermediates. As a result, nuclei with different spin states can be sorted into different reaction products.…”

Section: Photochemically Induced Dynamic Nuclear Polarization (Photo-mentioning

confidence: 99%

“…For spin=1/2 nuclei (e.g. 1 H, 13 C, 15 N), α and β nuclear spin states are the eigenstates of the Zeeman Hamiltonian. Even in high-field magnets, the α and β states are nearly equally populated due to their similar energy levels, and the difference in population gives rise to NMR signals.…”

mentioning

confidence: 99%

Sensitivity Enhancement in Solution NMR via Photochemically Induced Dynamic Nuclear Polarization

Im¹,

Lee²

2017

Journal of the Korean Magnetic Resonance Society

View full text Add to dashboard Cite

Enhancements in NMR sensitivity have been the main driving force to extend the boundaries of NMR applications. Recently, techniques to shift the thermally populated nuclear spin states are employed to gain high NMR signals. Here, we introduce a technique called photochemically induced dynamic nuclear polarization (photo-CIDNP) and discuss its progresses in enhancing the solution-state NMR sensitivity.

show abstract

“…-Ever since its accidental discovery [1] [2] in the form of intense emission and enhanced absorption lines in NMR spectra ca. 40 years ago, the nuclear-spinpolarization phenomenon termed chemically induced dynamic nuclear polarization (CIDNP) has been used to investigate a great variety of free-radical reactions.…”

Section: In Memoriam Professor Hanns Fischermentioning

confidence: 99%

“…We attribute this phenomenon to the different T 1 nuclear-relaxation times, which are known to be short for macromolecular systems. A quite promising, potential alternative is to transfer the CIDNP-derived initial 1 H spin polarization to heteronuclei, in particular to 13 C. For certain heteronuclei, notably for 13 C, the T 1 nuclear-relaxation times are considerably longer than those of the corresponding protons. Hence, we have investigated the feasibility and rules for transferring nuclear polarization from 1 H to 13 C or to 19 F, respectively.…”

mentioning

confidence: 99%

Photo‐CIDNP Studies of Hydroxy Ketones and Higher‐Molecular‐Weight Systems

Bargon¹,

Kuhn

2006

Helvetica Chimica Acta

View full text Add to dashboard Cite

In memoriam Professor Hanns FischerIn situ NMR spectroscopy can be applied to investigate chemical reactions during which free radicals occur as intermediates. In chemical systems of low molecular weight, nuclear-spin polarization results from the spin selectivity of free-radical reactions, because a pair of radicals has to obey the exclusion principle according to Pauli; therefore, this system reacts in a spin-selective manner when forming a chemical single bond. As a consequence, strong transient absorption and emission lines occur in the NMR spectra acquired during free-radical reactions. This phenomenon is known as chemically induced dynamic nuclear polarization (CIDNP). However, long correlation times associated with short proton spin-lattice relaxation times T 1 render it difficult to observe CIDNP in macromolecules. Therefore, in these and in many other cases, it can be attractive to utilize the simultaneously occurring heteronuclear polarization or to selectively transfer the 1 H polarization to heteronuclei, since their T 1 times can be substantially shorter than those of protons.In this paper, we present examples of how CIDNP can be observed both in low-molecular-weight systems as well as in systems exhibiting a rather macromolecular character. Also, CIDNP can assist in obtaining useful information about macromolecular systems that normally is very difficult to obtain otherwise. Since CIDNP is primarily a qualitative method by which free-radical intermediates may be identified, we have developed a procedure allowing the quantitative determination of the magnetic properties of the intermediate free radicals. This process is especially useful for very short-lived radicals, which are frequently elusive to ESR spectroscopy conducted in solution. In particular, g values of a variety of radical ions have been determined in this fashion by CIDNP-NMR spectroscopy. The data thus obtained provide an alternative to ESR and, hence, complement this traditional method (manuscript in preparation).Introduction. -Ever since its accidental discovery [1] [2] in the form of intense emission and enhanced absorption lines in NMR spectra ca. 40 years ago, the nuclear-spinpolarization phenomenon termed chemically induced dynamic nuclear polarization (CIDNP) has been used to investigate a great variety of free-radical reactions. Especially attractive is its application to determine structural details of biochemically important molecules both in the steady state as well as during the progression of folding or unfolding [3]. The observation of CIDNP requires in situ NMR spectroscopy, which allows one to investigate chemical reactions during which free radicals occur as intermediates. At least in chemical systems of low molecular weight, nuclear-spin polarization results from the spin selectivity of free-radical reactions, because a pair of radicals

show abstract

Kernresonanz-Emissionslinien während rascher Radikalreaktionen

Cited by 224 publications

References 0 publications

The Discovery of Chemically Induced Dynamic Polarization (CIDNP)

The Discovery of Chemically Induced Dynamic Polarization (CIDNP)

Sensitivity Enhancement in Solution NMR via Photochemically Induced Dynamic Nuclear Polarization

Photo‐CIDNP Studies of Hydroxy Ketones and Higher‐Molecular‐Weight Systems

Contact Info

Product

Resources

About