1. Purpose

This experiment demonstrates the technique used to observe the Chemically Induced Dynamic Nuclear Polarization. Although the name CIDNP based on an early misinterpretation is somewhat misleading, it has become established in the literature. The effect has been widely used to prove the existence of a radical pair intermediate during a chemical reaction. Other applications include the signal assignment of aromatic amino acids in proteins, which uses the photochemical CIDNP technique. Currently, a related field of polarization studies is emerging, where the phenomenom is caused by para-hydrogen during hydrogenation [9]. Here we demonstrate the experiment by which the effect was originally discovered [1].

2. Literature

J. Bargon, H. Fischer, U. Johnsen, Z. Naturforsch. A 1967, 22, 1551–1555.
H. R. Ward, R. G. Lawler, J. Am. Chem. Soc. 1967, 89, 5518–5519.
R. Kaptein, Adv. Free Radical Chem. 1975, 5, 319–380.
G. L. Closs, R. J. Miller, O. D. Redwine, Acc. Chem. Res. 1985, 18, 196–202.
P. J. Hore, R. W. Broadhurst, Prog. NMR Spectrosc. 1993, 25, 345–402.
M. Goez, Concepts Magn. Reson. 1995, 7, 263–279; ibid. 137–152.
M. Goez, Adv. Photochem. 1997, 23, 63–163.
M. Lehnig, K. Jakobi, J. Chem. Soc. Perkin 2, 2000, 2016–2021.
M. Stephan, O. Kohlmann, H. G. Niessen, A. Eichhorn, J. Bargon, Magn. Reson. Chem. 2002, 40, 157–160.

3. Pulse Scheme and Phase Cycle

Carbon-13 CIDNP pulse sequence with composite pulse proton decoupling