Time-resolved CIDNP: applications to radical and biradical chemistry

Journal Article · Mon Jul 01 00:00:00 EDT 1985 · Acc. Chem. Res.; (United States)

DOI:https://doi.org/10.1021/ar00115a001· OSTI ID:5187555

Closs, G L; Miller, R J; Redwine, O D

Nuclear magnetic resonance has long been one of the most useful tools for investigating reaction kinetics. The direct method follows resonance intensities as a function of time and correlates them with reactant or product concentrations. This approach can be applied only to slow reactions, although flow and stopped-flow techniques can reduce the time scale to approximately 10/sup -2/s. With use of line-shape analysis, kinetic measurements can be carried out under dynamic equilibrium conditions. With modern high-field spectrometers rates up to 10/sup 4/ s/sup -1/ can be measured in diamagnetic molecules. The fundamental limit for the time resolution is imposed by the weakness of the interactions of the nuclear spins with the molecular environment or the lattice. In systems containing unpaired electrons the strong hyperfine (hf) interactions allow measurements of diamagnetic-paramagnetic exchange rates up to 10/sup 10/ s/sup -1/. In this Account a new NMR method for measuring rates of irreversible reactions with a time resolution approaching 10/sup -8/ s is reviewed. This extends the previous limit for irreversible reactions by 5-6 orders of magnitude. The method is an extension of chemically induced dynamic nuclear polarization (CI-DNP) originating from radical pair chemistry via the hyperfine interaction. 25 references, 8 figures, 1 table.

• Research Organization: Univ. of Chicago, IL
• OSTI ID: 5187555
• Journal Information: Acc. Chem. Res.; (United States), Vol. 18:7
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
RADICALS
NUCLEAR MAGNETIC RESONANCE
CHEMICAL REACTION KINETICS
EXPERIMENTAL DATA
STRUCTURAL CHEMICAL ANALYSIS
TIME RESOLUTION
DATA
INFORMATION
KINETICS
MAGNETIC RESONANCE
NUMERICAL DATA
REACTION KINETICS
RESOLUTION
RESONANCE
TIMING PROPERTIES
400104* - Spectral Procedures- (-1987)
400301 - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)