PARAMAGNETIC-COMPLEXES AS NOVEL NMR PH INDICATORS

The remarkable pH dependence of the chemical shift separation (7.0 +/- 0.1 ppm/pH unit) observed between the outer H-1 NMR resonances on the spectrum of the paramagnetic complex [Yb(dotp)](5-) [H(8)dotp = 1,4,7 ,10-tetraazacyclododecane-N, N',N '',N triple prime-tetrakis(methylene phosphonic acid)] in the pH range 5.0-7.5 at 39 degrees C enables this compound to be considered as a potential NMR probe for in vivo pH mea surements.