ChemInform Abstract: CHEMICALLY INDUCED DYNAMIC ELECTRON AND NUCLEAR POLARIZATION. VII. SIMULTANEOUS CONTRIBUTIONS OF THE RADICAL PAIR AND PHOTOEXCITED TRIPLET MECHANISMS IN THE PHOTOLYSIS OF PYRUVIC ACID

1976 ◽  
Vol 7 (7) ◽  
pp. no-no
Author(s):  
K. Y. CHOO ◽  
J. K. S. WAN
Keyword(s):  
Pyruvic Acid ◽  
Nuclear Polarization ◽  
Radical Pair ◽  
Chemically Induced

scholarly journals Exploration of the close chemical space of tryptophan and tyrosine reveals importance of hydrophobicity in CW-photo-CIDNP performances

2021 ◽  
Vol 2 (1) ◽  
pp. 321-329
Author(s):  
Felix Torres ◽  
Alois Renn ◽  
Roland Riek
Keyword(s):  
Magnetic Field ◽  
Nuclear Polarization ◽  
Continuous Wave ◽  
Radical Pair ◽  
Chemical Space ◽  
Spin Dynamics ◽  
Basic Mechanism ◽  
Chemical Library ◽  
Chemically Induced ◽  
Small Chemical

Abstract. Sensitivity being one of the main hurdles of nuclear magnetic resonance (NMR) can be gained by polarization techniques including chemically induced dynamic nuclear polarization (CIDNP). Kaptein demonstrated 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-CIDNP of interest here the radical pair is between a dye and the molecule to be polarized. Here, we explore continuous-wave (CW) photo-CIDNP (denoted CW-photo-CIDNP) with a set of 10 tryptophan and tyrosine analogues, many of them newly identified to be photo-CIDNP active, and we observe not only signal enhancement of 2 orders of magnitude for 1H at 600 MHz (corresponding to 10 000 times in measurement time) but also reveal that polarization enhancement correlates with the hydrophobicity of the molecules. Furthermore, the small chemical library established indicates the existence of many photo-CIDNP-active molecules.

Chemically Induced Dynamic Nuclear Polarization During Irradiation of Phenol in the Presence of Amides

1975 ◽  
Vol 53 (16) ◽  
pp. 2459-2464
Author(s):  
Shiv P. Vaish ◽  
Holger E. Chen ◽  
Micha Tomkiewicz ◽  
Robert D. McAlpine ◽  
Michael Cocivera
Keyword(s):  
Carbonyl Group ◽  
Spin Polarization ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Spin ◽  
Nuclear Polarization ◽  
Radical Pair ◽  
Hydroxybenzoic Acid ◽  
Nuclear Spin Polarization ◽  
Ph Values ◽  
Chemically Induced

Irradiation of D2O solutions containing various phenols with aliphatic amides at pH values between 9 and 12 results in nuclear spin polarization which is observed as n.m.r. emission signals during irradiation. No polarization is observed for the phenols which include tyrosine, cresol, p-hydroxybenzoic acid, phenol, and others. For the amides which include acetamide, propionamide, N-methylacetamide, and N,N-dimethylacetamide, polarization was observed for only the protons on the carbon bonded to the carbonyl group. Because excited phenolate ions are known to eject electrons, it is proposed that the radical RĊ(O−)NR2 is formed by reaction of the amide with the hydrated electron. The polarization observed for the amides can be explained by reaction of RĊ(O−)NR2 with a benzosemiquinone radical via a radical pair.

Chemically Induced Dynamic Nuclear Polarization. X. On Effects of Nuclear Relaxation and the Magnetic Field Dependence

1972 ◽  
Vol 27 (8-9) ◽  
pp. 1300-1307 ◽  
Author(s):  
M. Lehnig ◽  
H Fischer
Keyword(s):  
Magnetic Field ◽  
Field Dependence ◽  
Magnetic Field Dependence ◽  
Nuclear Polarization ◽  
Radical Pair ◽  
Reaction Products ◽  
Theory Analysis ◽  
Alkyl Radicals ◽  
Chemically Induced ◽  
The Magnetic Field

Abstract The magnetic field dependence of CIDNP is presented for two reaction products of independently generated alkyl radicals. It is shown that nuclear spin relaxation of the products influences the intensity distributions within multiplets, and how this relaxation can be included in the calculation of CIDNP effects from the radical pair theory. Analysis of the experimental results supports the recent view that CIDNP is created in pairs of radicals which undergo many diffusive displacements before reencounter.

scholarly journals Molecular features toward high photo-CIDNP hyperpolariztion explored through the oxidocyclization of tryptophan

2021 ◽  
Vol 23 (11) ◽  
pp. 6641-6650
Author(s):  
Felix Torres ◽  
Alexander Sobol ◽  
Jason Greenwald ◽  
Alois Renn ◽  
Olga Morozova ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Nuclear Polarization ◽  
Radical Pair ◽  
Signal To Noise ◽  
Molecular Features ◽  
Chemically Induced

Photo-chemically induced nuclear polarization yields to NMR signal-to-noise enhancement and can be tuned by chemical modification of one of the radical-pair partners.

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