Nuclear magnetic resonance line broadening studies

Rates of rapid ligand exchange reactions by nuclear magnetic resonance line broadening studies. /. Am. Chem. Soc.,... 

Nuclear magnetic resonance (NMR) has been used to study segmental motions in block copolymer solutions. The mobility of protons in polymer chains in dilute solutions has been probed using high-resolution H NMR. Association of chains into micelles leads to a reduction in mobility in the core, which leads to a broadening of the respective NMR lines that has been studied for a number of systems, as described by Tuzar and Kratochvil (1993). The sol-gel transition in concentrated solutions has been located via ]H transverse relaxation time experiments, as outlined in Chapter 4. 

Reversible reactions involving second-order steps in both directions. The following examples are taken from the many studies based on line-broadening analyses from nuclear magnetic resonance (NMR) and electron spin resonance (ESR) spectroscopy, respectively. 

Because of its high sensitivity, sodium-23 nuclear magnetic resonance (NMR) is useful for the study of ion-substrate interactions(1). Complex formation induces a relaxation enhancement of the nuclear spins manifested by line broadening whereas the position of the peak is little affected. Under sane conditions, such relaxation measurements can be used to determine the forward and the reverse rate constants for conplex formation. In this paper we present exan5)les of the determination of kinetic parameters by NMR. 

The use of NMR spectroscopy to characterize diamagnetic transition metal and posttransition metal complexes has increased tremendously in the past decade (111, 129). Mercury has two NMR-active isotopes, Hg (natural abundance = 13.22%) and (natural abundance = 16.84%). The former is quadrupolar (nuclear spin, / = ), and consequently, much more difficult to observe, due to line broadening. The latter, on the other hand, is one of approximately 20 nuclides in the periodic table with the preferred spin I = i. Its receptivity, a measure of relative signal strength, is five times that of C for comparison, " Cd, the most widely studied of the posttransition nuclei, has a receptivity of only 8 relative to C. Magnetic resonance frequencies are intimately connected with the quantity and dis-... 

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