Zn(II)–D-(−)penicillamine complexes in aqueous solution. Zn-67 nuclear magnetic resonance study

Abstract

ALFRED DELVILLE and CHRISTIAN DETELLIER. Can. J . Chem. 64, 1845 (1986). D-(-)-Penicillarnine interactions with Zn(I1) have been studied in aqueous solutions as a function of pH, penicillamine concentration, and temperature, using Zn-67 nuclear magnetic resonance. Longitudinal and transverse relaxation rate measurements show the presence in solution of complexes in fast exchange with the aquated Zn(I1) cation, and belonging to the extreme narrowing regime. Using equilibrium constant values from the literature, the relaxation behaviour was modelled. Characteristic Zn-67 line width values for the two complexes Zn(Pen) (v = (6200 2 500) Hz) and [Zn(Pen HI]+ ( v = (6000 2 1000) Hz) were found. Equality of the two values is in agreement with zinc chelation by the sulfhydryl and the amino groups.

Interactions of Silicate Ions with Zinc(II) and Aluminum(III) in Alkaline Aqueous Solution

“…Silicate − Zincate Interactions: 67 Zn Spectra. The quadrupolar 67 Zn nucleus has low receptivity and gives notoriously broad NMR spectra in solution in all but the most symmetrical environments, such as Zn(H 2 O) 6 2+ . − The reference solution, 1.5 mol L -1 Zn(ClO 4 ) 2 in 20% D 2 O (δ( 67 Zn) = 0), gave a line width of 46 Hz at 280 K, but 0.63 mol L -1 Zn(OH) 4 2- in 10.0 mol L -1 KOH at 280 K gave a single peak at δ( 67 Zn) = +220 ppm with line width of 554 Hz, suggesting either that the symmetry of the Zn II site in this anion is far from the commonly supposed T d or that solution viscosity or hydrogen bonding between zincate and solvent water cause the line broadening. Cain et al suggest that polynuclear aggregation of zincate in highly alkaline solution (albeit at [Zn II ] somewhat higher than ours) might also contribute to the large 67 Zn line width through the effect of increased molecular mass on T 1 .…”

67Zn QCPMG Solid-State NMR Studies of Zinc Complexes as Models for Metalloproteins

“…Zinc plays a key role in the active binding site for a range of important metalloproteins . For example, Zn 2+ is important for the function of pencillamine, insulin, carboxypeptidase A, thermolysin, and phospholipase C . To understand the enzymatic function of these metalloproteins, it is of interest to study the Zn 2+ coordination environment with a variety of ligands, i.e., N, O, and S donor atoms.…”

Zinc-67 NMR study of tetrahedral and octahedral zinc sites with symmetrical oxygen, nitrogen, and sulfur ligands

“…In addition to the low intrinsic sensitivity, solution state 67 Zn NMR is further hampered by the fact that molecular tumbling motion always induces efficient 67 Zn quadrupole relaxation, resulting in short life times of Zeeman energy levels, which lead to broad NMR lines. To date, 67 Zn NMR of liquid samples has been limited to studies of either highly symmetric species or unsymmetrical complexes undergoing rapid exchange with large excessive [Zn(H 2 O) 6 ] 2+ (3)(4)(5)(6). Despite the biological relevance of zinc ions, the aforementioned practical difficulties have made 67 Zn NMR a nearly forgotten area.…”