| Summary: | 碩士 === 高雄醫學院 === 藥學研究所 === 86 === Three linear derivatives of diethylenetriamine-N,N,N, N,N
-pentaacetic acid(DTPA), N,N-ethylene- N,N-tri-
methylenetriamine- N,N,N,N,N-pentaacetic acid(ETTPA), N,N
-trimethylene- N,N-trimethylenetriamine- N,N,N,N,N-
pentaacetic acid(TETTPA) and N,N-trimethylene- N,N-tetra-
methylenetriamine- N,N,N,N,N-pentaacetic acid (TMTTPA)
were synthesized. Their protonation constants were determined by
potentiometric titration in 0.10 mol dm-3 Me4NNO3 and by NMR pH
titration at 25.0 0.1C. The stability constants of calcium(
II), zinc(II), copper(II) and gadolinium(III) complexes with
those ligands were also investigated quantitatively by the
potentiometric technique. The selectivity constants of the
ETTPA, TETTPA and TMTTPA for Gd(III) over endogenously available
metal ions(i.e. Ca2+, Zn2+ and Cu2+) were calculated and
discussed. Spin-lattice relaxivity R1(20MHz, 37.0 0.1C)
for Gd(III) complexes was also determined at different pH range.
The [Gd(ETTPA)]2-, [Gd(DTPA)]2- and [Gd(DTPA-BMA)] complexes
have similar relaxivity values, suggesting that they have
similar inner-sphere water molecule and coordination numbers.
17O NMR shifts showed that the [Dy(ETTPA)]2- complex had one
inner-sphere water molecule. The observed relaxivity values
decrease with increasing pH in the acid region below pH 3, when
a [Gd(ETTPA)]2- complex become fully formed, the relaxivity
value became invariant. The influence of R1 values at different
temperature range was also discussed.
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