The Kinetics Of Chemically Induced Dynamic Nuclear Polarization

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Exploration of the close chemical space of tryptophan and

polarization techniques including chemically induced dynamic nuclear polarization (CIDNP). Kaptein demon-strated that the basic mechanism of the CIDNP arises from spin sorting based on coherent electron electron nuclear spin dynamics during the formation and the recombination of a radical pair in a magnetic field. In photo-

Non-classical disproportionation revealed by photo-chemically

Photo-chemically induced dynamic nuclear polarization (photo-CIDNP) was used to observe the light-induced disproportionation reaction of 6,7,8-trimethyllumazine starting out from its triplet state to gener-ate a pair of radicals comprising a one-electron reduced and a one-electron oxidized species. Our evidence is

Proton NMR and photochemically induced dynamic nuclear

Consequently, photochemically induced dynamic nu- clear polarization experiments show an increased ex- posure of Tyr-37 in the fragment of mouse epidermal growth factor containing residues 1-48. Nuclear Ov- erhauser data suggest that structural changes do occur on fragmentation but seem to be localized in the tiered-

ELECTRON PARAMAGNETIC RESONANCE

10.8.2 Chemically Induced Dynamic Electron Polarization / 345 10.9 Dynamic Nuclear Polarization / 347 10.10 Bio-Oxygen / 347 10.11 Summary / 347 References / 348 Notes / 351 Further Reading / 352 Problems / 353 11 NONCONTINUOUS EXCITATION OF SPINS 357 11.1 Introduction / 357 11.2 The Idealized B 1 Switch-on / 359 11.3 The Single B 1 Pulse / 362

Molecular features toward high photo-CIDNP hyperpolariztion

Photo-chemically induced dynamic nuclear polarization (photo-CIDNP) is a promising solution to the inherent lack of sensitivity in NMR spectroscopy. It is particularly interesting in biological systems since it operates in water, at room temperature, and it can be repeated if the bleaching of the system can be controlled.

Uniform illumination of optically dense NMR samples

including but not limited to: photo-CIDNP (chemically induced dynamic nuclear polarization) [1 3], metal ion release from photolabile cage compounds [4,5], photo-chemical kinetics [6 8], and studies of photoactive pro-teins [9 12]. One of the biggest technical challenges faced in such experiments is to deliver light efficiently into the

Basic principles and applications of spin chemistry

Polarization and Magnetic Effects in Radical Reactions. Elsevier, Amsterdam-Oxford-New York-Tokyo, 1984 2. U.E. Steiner and T. Ulrich. Magnetic Field Effects in Chemical Kinetics and Related Phenomena // Chem. Rev. 1989,89, p, 51-147 3. H. Hayashi. Introduction to Dynamic Spin Chemistry. Magnetic Field Effects on Chemical and Biochemical Reactions.

Mapping of Absolute Host Concentration and Exchange Kinetics

Jan 21, 2021 can be boosted even further by including methods of spin hyperpolarization. Dynamic nuclear polarization (DNP) and para-hydrogen-induced polarization (PHIP) preclude CEST detection because the spin label (most commonly 13C or 15N) is covalently bound to the molecule/metabolite of interest. It lacks a bulk pool that is in chemical exchange

BI RADICAL INTERMEDIATES

resolved esr and Raman spectroscopy, or chemically induced dynamic nuclear polarization (CIDNP). Our main tool to monitor biradicals under laboratory conditions comparable to preparative work is flash photolysis, using a Q switched Nd laser as an excitation source to study reactions in the time do-

Multiple Subsets of Side-Chain Packing in Partially Folded

The second is photochemically induced dynamic nuclear polariza-tion (photo-CIDNP), a technique involving the reaction of laser-induced photoexcited triplet molecules with surface-accessible tryptophan, tyrosine, and histidine residues to provide information on the accessibilities of specific side chains in the partially folded MG state (17, 18).

Level crossing analysis of chemically induced dynamic nuclear

Numerical simulation of free evolution in solid-state nuclear magnetic resonance using low-order correlations in Liouville space J. Chem. Phys. 133, 224501 (2010); 10.1063/1.3505455 Theoretical and experimental studies of chemically induced dynamic nuclear polarization kinetics in

Indirect NMR detection of transient guanosyl radical

explanation of the unusual behavior of the kinetics of CIDNP (chemically induced dynamic nuclear polarization) detected by us during the photoreaction of guanosine-50-monophosphate (GMP) with the photosensitizer, 3,30,4,40-tetracarboxy benzo-phenone (TCBP). The unusual behavior was a change in sign of

Chemically Induced Dynamic Nuclear Polarization

nuclear polarization. From a kinetic formulation of the pair mechanism equations for quantitative calculations of CIDNP patterns are derived. 1. Introduction After the discovery la>2 a of NMR emission and enhanced absorption of reaction products during radical reactions, the so-called chemically induced dynamic nuclear polarization (CIDNP

Theoretical Description of Protein NMR Saturation Transfer to

librium NMR polarization transfer, for instance, chemically induced dynamic nuclear polarization from a protein to its ligand. 1 Introduction For many years, nuclear magnetic resonance (NMR) is widely used for research of biological macromolecules and reactions they are involved in. At present, one of the

Stimulated nuclear polarization a new method for studying the

detection of such species - the method of stimulated nuclear polarization (SNP). This method has considerable advantages over the well-known technique of chemically induced dynamic nuclear polarization (CIDNP) (ref. 1). The SNP method is based on the resonance mw field effect on the singlet-triplet conversion in radical pairs (RP) (refs.

Structure and magnetic resonance parameters of the cation

While other well-known mechanisms of dynamic nuclear polarization, e.g. the Overhauser2,3 effect, rely on pumping of electron spin transitions this Chemically Induced Dynamic Nuclear Polarization (CIDNP) results from spin-selective reaction steps and it has been widely used for analyzing intermediate reaction stages.

Photo-chemically induced dynamic nuclear polarization

sensitivity. Nuclear spins are usually polarized by a strong magnetic field (up to 20 T), still resulting in just a smallspin polarization of order of 10 -5. One way to boost the NMR signal is to perform chemically induced dynamic nuclear polarization (CIDNP). allows to This increase spin polarization by up to three orders of magnitude.

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(chemically induced dynamic nuclear polarization) for these processes in dyads, including the drug, (S)- and (R)-naproxen and (S)-N-methyl pyrrolidine in solutions with strong and weak permittivity have been measured. The dramatic influence of solvent permittivity on the field dependence of the N-methyl pyrrolidine 1H CIDNP effects has been found.

Electron self-exchange activation parameters of diethyl

from the sulfides to excited 2,4,6-triphenylpyrylium cations, was investigated by time-resolved measurements of chemically induced dynamic nuclear polarization (CIDNP) in acetonitrile. The strongly negative activation entropies provide evidence for an associative dissociative electron exchange involving dimeric radical cations.

Photochemical primary process of photo-Fries rearrangement

cyclohexadienone.9 13 The reaction kinetics and intermediates of photo-Fries reactions have been continuously studied by means of product analysis, chemically induced dynamic nuclear polarization (CIDNP), laser flash photolysis, and magnetic isotope effects (MIEs).14 19 Nakagaki et al. reported that

Electron and hydrogen self-exchange of free radicals of

provided by measurements of chemically induced dynamic nuclear polarization (CIDNP) [10-15]. CIDNP arises from a spin-sorting process in radical pairs, which leads to opposite polarizations in the products of the two radicals of a pair with each other (geminate products) and the products of subsequent

The molten globule state of α‐lactalbumin

chemically induced dynamic nuclear polarization, and paramagnetic perturbation of the NMR spectra have also shown that Trp26 and Trpt#{176}4,buried in the native state, are buried in the molten globule (41, 48) so that some form of a hydrophobic core in the a-helical domain of the native structure may persist in the molten globule state.

Nanosecond-Flash N Photo-CIDNP MAS NMR on Reaction Centers of

electron polarization delocalized in the S 0 - T 0 manifold is detected as photo-chemically induced dynamic electron polarization [17, 18]. In this context, electron polarization of the radical pair corresponds to selective population of the two non-eigenstates having the magnetic quantum number m = 0 and being in the S 0 - T 0 manifold.

QUANTITATIVE DETERMINATION OF CHEMICAL PROCESSES BY DYNAMIC

CIDNP Chemically Induced Dynamic Nuclear Polarization CPD Composite Pulse Decoupling CW Continuous Wave DMSO Dimethyl sulfoxide DNP Dynamic Nuclear Polarization DPBD 1,4-dipheneylbutadiene DQ Double-Quantum ESR Electron Spin Resonance FID Free Induction Decay HMQC Heteronuclear Multiple-Quantum Correlation

THEPHOTOCHEMTSTRY OFSOME HALOSUBSTITUTED PHENYLALKYL KETONES

Rate constants have been calculated from competitive kinetics between the homolytic carbon-halogen cleavage reaction and the Norrish Type II photoelimination process. Irradiations of(S-halovalerophenones gave Norrish Type II products and an olefinic product resulting from halogen atom elimination from a -haloradical. Both products resulted

RSC CP c3cp52026a 3.

problem is using non-thermal spin polarization, also called hyper-polarization. Among the techniques based on this approach are Dynamic Nuclear Polarization (DNP), 1 4 Chemically Induced Dynamic Nuclear Polarization (CIDNP) 5 and Para-Hydrogen Induced Polarization (PHIP).6 8 Allthesemethodsemploystrongly

High-resolution liquid- and solid-state nuclear magnetic

transfer of this polarization to deposited organic or biologi-cal compounds has not been taken up yet.15,16 In liquids, nuclear hyperpolarization by chemically in-duced radical pairs has proven to be much more accessible.17 19 This chemically induced dynamic nuclear po-larization CIDNP has been used extensively to study

Reduction of Guanosyl Radical by Cysteine and Cysteine

chemically induced dynamic nuclear polarization (CIDNP). Radicals were generated photochemically by pulsed laser irradiation of a solution containing the photosensitizer 2,2′-dipyridyl, guanosine-5′-monophosphate, and the amino acid or peptide. In neutral and basic aqueous solution, the neutral guanosyl radical is formed via electron or

HYDROGEN ATOM IN RADIOLYSIS OF LIQUIDS, SOLIDS AND ORDERED

Chemically Induced Dynamic Electron Polarization (CIDEP), additional insights into the mechanisms of radiolytic generation of H atoms and their fate can be obtained. With this considerable experience we embarked on the study of H atoms in zeolites and mesoporous solids to address the following questions: (1) What is the source of H atoms -

Spin Relaxation Effects in Photochemically Induced Dynamic

induced dynamic nuclear polarization (CIDNP)3,4 and chemically induced dynamic electron polarization (CIDEP),4,5 which rely on a delicate interplay between spin dynamics and chemical kinetics. Here we explore, both theoretically and experimentally, the effect of nuclear spin relaxation, cross-relaxation, and cross-correlation induced by the

STRUCTURES AND REACTIVITIES OF ORGANOLITHIUM COMPOUNDS

obtained by chemically induced dynamic nuclear polarization (CIDNP). T extensive researches on organolithium compounds of the past decade provide a basis for understanding in detail the chemistry of these compounds. The purpose of this contribution is to review the various lines of evidence

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the joint analysis of the chemically induced dynamic nuclear polarization (CIDNP) and fluorescence data. The 1H CIDNP effects in this system appear in the back electron transfer in the biradical zwitterion (BZ), which is formed via dyad photoirradiation. The rate constants of individual steps in the proposed scheme and the fluorescence

Photochemical Pump and NMR Probe: Chemically Created NMR

gases,14−16 dynamic nuclear polarization,17,18 and photochemi-cally induced dynamic nuclear polarization (photo-CIDNP).19−21 In the photo-CIDNP method, a spin-correlated radical pair is used to generate NMR signal enhancements on the order of 102. The photo-CIDNP approach has been used to observe short-lived radicals and to monitor

Free Radical Production From Criegee Ozonides.

7.6 observation of chemically induced dynamic nuclear polarization (cidnp) during the thermal decomposition of abo 133 discussion - part ii 139 8.1 mechanism of abo decomposition 139 8.1.1 decomposition of abo in the presence

Photooxidation of Chlorins by Quinones Studied by Nuclear

preparation). The appearance kinetics of this pair suggest that it is formed from 3Chl*. In recent years, a new technique, chemically induced dy-namic nuclear polarization (CIDNP), has been applied suc-cessfully in the study of photoreactions proceeding via radi-cal pairs or radical ion pairs (9, 10). This technique is based

Chemically Induced Dynamic Nuclear Polarization during the

Apr 08, 2019 Chemically Induced Dynamic Nuclear Polarization during the Thermolysis of Alkoxyamines: A New Approach to Detect the Occurrence of H-Transfer Reactions Maria Edeleva 1,2, Sylvain R. A. Marque 3,*, Denis Bertin 3, Didier Gigmes 3, Yohann Guillaneuf 3 and Elena Bagryanskaya 2,*

Electron spin echo study of CIDEP in photolysis of di-t-butyl

from the equilibrium ones. This phenomenon is known as the chemically induced dynamic electron polarization (CIDEP) (ref.1) or, more generally, as the electron spin polarization (ESP), two main mechanisms aooounthg for the majority of its observations. The first is triplet mechanism (TIY) (ref.2). It operates on the fast

The persistent radical effect in controlled radical

structure, and reaction kinetics both in low and macromolecular chemis-try. Experimental methods include electron spin resonance, chemically induced dynamic nuclear polarization (invented with J. Bargon in 1967), optical spectroscopy, and muon spin rotation. Special honors include the Centenary Medal and Lectureship of the Chemical Society