Chemically induced dynamic nuclear polarizations

Lawler R G 1967 Chemically Induced dynamic nuclear polarization J. Am. Chem. Soc. 89 5519-21... 

Kaptein R and Oosterhoff J L 1969 Chemically Induced dynamic nuclear polarization III (anomalous multiplets of radical coupling and disproportionation products) Chem. Phys. Lett. 4 214-16... 

Goez M 1995 An introduction to chemically induced dynamic nuclear polarization Concepts Magn. Reson. 7 69-86... 

Kaptein R 1971 Simple rules for chemically induced dynamic nuclear polarization J. Chem. See. Chem. Commun. 732-3... 

Morozova O B, Tsentalovich Y P, Yurkovskaya A V and Sagdeev R Z 1998 Consecutive biradicals during the photolysis of 2,12-dihydroxy-2,12-dimethylcyclododecanone low- and high-field chemically induced dynamic nuclear polarizations (CIDNP) study J. Rhys. Chem. A 102 3492-7... 

Carboxamides, formation from ArNj 243 2-Carboxybenzenediazonium zwitterion, see 2-Diazoniobenzenecarboxylate Carboxy-de-diazoniation 241 f. Carcinogenicity 319 Chemically induced dynamic nuclear polarization, see CIDNP Chloro-de-diazoniation 194, 230ff., 247, 270, 277... 

CIDNP chemically induced dynamic nuclear polarization... 

Kaptein, R. (1971b). Chemically Induced Dynamic Nuclear Polarization , Thesis, Leiden. 

Chemically Induced Dynamic Nuclear Polarization Complete Neglect of Differential Overlap cyclopentadienyl diethyl azodicarboxylate... 

Observation of spin-polarized products resulting from these radical pairs by the method of chemically induced dynamic nuclear polarization (CIDNP)<67) was accomplished by photolysis in the probe of an NMR spectrometer using perfluoromethylcyclohexane as solvent. The results obtained were consistent with nuclear spin polarization steps involving radical pairs formed from dissociated radicals and also directly from excited states, although the former could not be detected in carbon tetrachloride, probably due to radical scavenging by the solvent. It was not possible to determine the fraction of the reaction proceeding by singlet and triplet radical pairs.<68)... 

The chemically induced dynamic nuclear polarization (DNP) opened perspective to study products formed from free radicals [102], The basis of this study is the difference in NMR spectra of normal molecules and those formed from free radicals and radical pairs. The molecules formed from radicals have an abnormal NMR spectrum with lines of emission and abnormal absorption [102]. DNP spectra help to obtain the following mechanistic information ... 

On the other hand, in accord with the free radical mechanism peroxynitrite is dissociated into free radicals, which are supposed to be genuine reactive species. Although free radical mechanism was proposed as early as in 1970 [111], for some time it was not considered to be a reliable one because a great confusion ensued during the next two decades because of misinterpretations of inconclusive experiments, sometimes stimulated by improper thermodynamic estimations [85]. The latest experimental data supported its reliability [107-109]. Among them, the formation of dityrosine in the reaction with tyrosine and 15N chemically induced dynamic nuclear polarization (CIDNP) in the NMR spectra of the products of peroxynitrite reactions are probably the most convincing evidences (see below). 

Finally, Podoplelov and coworkers41 have prepared trimethyltin hydride and benzyltrimethyltin labelled with tin-117 from a tin sample enriched to 92% in 117Sn. The photochemical reaction between dibenzyl ketone and trimethyltin-117 hydride was used to investigate the chemically induced dynamic nuclear polarization of tin-containing radicals. 

For more complex spin systems, a computer program PHIP+ has been developed [13, 45] which allows the expected PHIP spectra to be calculated from the chemical shifts and coupling constants of the products. Depending upon which proton pair in the product molecule stems from p-H2, different - but characteristic - polarization patterns result [14]. The patterns also depend on the sign of the coupling constants. Simple sign rules governing the relative sequence of the emission and absorption lines in the PHIP spectra (i.e., their phase ) can be formulated in similar manner to the Kaptein Rules of chemically induced dynamic nuclear polarization (CIDNP) [15]. 

Further evidence for the formation of alkene radical cations derives from the work of Giese, Rist, and coworkers who observed a chemically induced dynamic nuclear polarization (CIDNP) effect on the dihydrofuran 6 arising from fragmentation of radical 5 and electron transfer from the benzoyl radical within the solvent cage (Scheme 6) [67]. 

The PFR of para-cresyl para-chlorobenzoate (30) (Scheme 12) has been studied by means of chemically induced dynamic nuclear polarization (CIDNP) [46]. The... 

Chemically Induced Dynamic Nuclear Polarization Effects... 

Among NMR methods providing insight into radical ions, chemically induced dynamic nuclear polarization (CIDNP) has proved especially useful it results in enhanced transient signals, in absorption or emission CIDNP effects were first reported in 1967 their application was soon extended to radical ions. The method lends itself to modest time resolution. 

These assignments are consistent with PES data ° and supported by theoretical calculations " in C2v symmetry, IS " " has two low-lying radical cationic states, and Ai. " The state is the ground state of IS " " the calculated hyperfine coupling constants (B3LYP/6-31G //MP2/6-31G ) are compatible with chemically induced dynamic nuclear polarization (CIDNP) and ESR/ENDOR results. No spin... 

H. D. Roth, Chemically induced dynamic nuclear polarization, in Encyclopedia of Nuclear Magnetic Resonance, Vol. 2, D. M. Grant, R. K. Harris, Eds., 1996, John Wiley Sons, Inc., New York, pp. 1337-1350. 

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