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Comparison of the equilibrium, kinetic and water exchange properties of some metal ion-DOTA and DOTA-bis(amide) complexes.

Abstract：

:The 1,7-diacetate-4,10-diacetamide substituted 1,4,7,10-tetraazacyclododecane structural unit is common to several responsive Magnetic Resonance Imaging (MRI) contrast agents (CAs). While some of these complexes (agents capable of sensing fluctuations in Zn2+, Ca2+ etc. ions) have already been tested in vivo, the detailed physico-chemical characterization of such ligands have not been fully studied. To fill this gap, we synthesized a representative member of this ligand family possessing two acetate and two n-butylacetamide pendant side-arms (DO2A2MnBu = 1,4,7,10-tetraazacyclodoecane-1,7-di(acetic acid)-4,10-di(N-butylacetamide)), and studied its complexation properties with some essential metal and a few lanthanide(III) (Ln(III)) ions. Our studies revealed that the ligand basicity, the stability of metal ion complexes, the trend of stability constants along the Ln(III) series, the formation rates of the Ln(III) complexes and the exchange rate of the bound water molecule in the Gd(III) complex fell between those of Ln(DOTA)- and Ln(DOTA-tetra(amide))3+ complexes (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, DOTAM = 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane). The only exception is the stability of Cu(DO2A2MnBu) which was found to be only slightly lower than that of Cu(DOTA)2- (log KCuL = 19.85 vs. 21.98). This is likely reflects exclusive coordination of the negatively charged acetate donor atoms to the Cu2+ ion forming an octahedral complex with the amides remaining uncoordinated. The only anomaly observed during the study was the rates of acid assisted dissociation of the Ln(III) complexes, which occur at a rate similar to those observed for the Ln(DOTA)- complexes. These data indicate that even though the Ln(DO2A2MnBu)+ complexes have lower thermodynamic stabilities, their kinetic inertness should be sufficient for in vivo use.

journal_name

J Inorg Biochem

journal_title

Journal of inorganic biochemistry

authors

Tircsó G,Tircsóné Benyó E,Garda Z,Singh J,Trokowski R,Brücher E,Sherry AD,Tóth É,Kovács Z

doi

10.1016/j.jinorgbio.2020.111042

subject

Has Abstract

pub_date

2020-05-01 00:00:00

pages

111042

eissn

0162-0134

issn

1873-3344

pii

S0162-0134(20)30070-2

journal_volume

206

pub_type

杂志文章

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Comparison of the equilibrium, kinetic and water exchange properties of some metal ion-DOTA and DOTA-bis(amide) complexes.