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Physicochemical Characterization of Four Gadolinium(III) DTPA‐like Complexes
Author(s) -
Ou MingHung,
Cheng TsanHwang,
Liu GinChung,
Wang YunMing
Publication year - 2005
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200500125
Subject(s) - chemistry , gadolinium , rotational correlation time , diethylenetriamine , aqueous solution , lanthanum , diamagnetism , analytical chemistry (journal) , nuclear magnetic resonance , molecule , chromatography , inorganic chemistry , magnetic field , physics , organic chemistry , quantum mechanics
The analysis of 17 O NMR transverse relaxation rates and EPR transverse electronic relaxation rates for aqueous solutions of the four DTPA‐like (DTPA = diethylenetriamine‐ N,N,N ′ ,N ″, N ″‐pentaacetic acid) complexes, [Gd(DTPA‐PY)(H 2 O)] − (DTPA‐PY = N′ ‐(2‐pyridylmethyl)), [Gd(DTPA‐HP)(H 2 O) 2 ] − (DTPA‐HP = N ′‐(2‐hydroxypropyl)), [Gd(DTPA‐H1P)(H 2 O) 2 ] − (DTPA‐H1P = N ′‐(2‐hydroxy‐1‐phenylethyl)) and [Gd(DTPA‐H2P)(H 2 O) 2 ] (DTPA‐H2P = N ′‐(2‐hydroxy‐2‐phenylethyl)), at various temperatures allows us to understand the water exchange dynamics of these four complexes. The water‐exchange lifetime (τM) parameters for [Gd(DTPA‐PY)(H 2 O)] − , [Gd(DTPA‐HP)(H 2 O) 2 ] − , [Gd(DTPA‐H1P)(H 2 O) 2 ] − and [Gd(DTPA‐H2P)(H 2 O) 2 ] are of 585, 98, 163, and 69 ns, respectively. Compared with [Gd(DTPA)(H 2 O)] 2− (τM = 303 ns), the τM value of [Gd(DTPA‐PY)(H 2 O)] − is slightly higher, but the other three complexes values are significantly lower than those of [Gd(DTPA)(H 2 O)] 2− . This difference is explained by the fact that the gadolinium(III) complexes of DTPA‐HP, DTPA‐H1P, and DTPA‐H2P have two inner‐sphere waters. The 2 H longitudinal relaxation rates of the labeled diamagnetic lanthanum complex allow the calculation of its rotational correlation time (τR). The τR values calculated for DTPA‐PY, DTPA‐HP, DTPA‐H1P, and DTPA‐H2P are of 127, 110, 142 and 147 ps, respectively. These four values are higher than the value of [La(DTPA)] 2− (τR = 103 ps), because the rotational correlation time is related to the magnitude of its molecular weight.