C-13 NMR-STUDY OF POLY(N-VINYLPYRROLIDONE)-CU(II) COMPLEX IN AQUEOUS-SOLUTION

Structural and dynamic properties of the poly(N-vinylpyrrolidone) Cu(I I) complex in aqueous solution are studied by C-13 NMR relaxation meas urements. At pH 4, the spin-lattice relaxation rate of the carbonyl ca rbon increases remarkably with increasing Cu(II) concentration. This i ndicates that Cu(II) interacts with the carbonyl group at low pH. The temperature dependence of relaxation rate is explained in terms of the electron-C-13 dipolar interaction, the H-1-C-13 dipolar interaction, and the chemical shift anisotropy interaction, The distance between Cu (II) and the carbonyl carbon is evaluated to be 4.0 angstrom at pH 4.