Nuclear Magnetic Resonance of Less Common Quadrupolar Nuclei

Abstract

This chapter reviews the developments in the field of Nuclear Magnetic Resonance (NMR) studies of less quadrupolar nuclei for the five-year period from mid-1978 to mid-1983. The 39K isotope is the one of the three potassium isotopes that have been used in NMR studies. Molten potassium salts at 200 °C have been studied and the 39K chemical shift is found to be quite sensitive to the nature of the counter-ion. 39K NMR have also been used to study the formation of complexes in non-aqueous media. In few cases, 39K has been used in biochemical and there is one report using 39K NMR to study polysaccharide gels. Rubidium is the least studied alkali metal even though it has two quadrupolar isotopes, 85Rb and 87Rb. 87Rb has reasonably high receptivity, however, its quadrupole moment, combined with the Sternheimer antishielding factor, results in lines that are seldom less than 200 Hz wide. The main development in the area of alkaline earth NMR has taken place in applications to biochemical problems. 40 25Mg and 43Ca NMR have been used to study the metal ion binding to prothrombin fragment 1 and pH titration studies have shown that the Mg2+ binding has pKa, values at 4.2 and above 7.