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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Thermodynamic stability, kinetic inertness and relaxometric properties of monoamide derivatives of lanthanide(III) DOTA complexes
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Thermodynamic stability, kinetic inertness and relaxometric properties of monoamide derivatives of lanthanide(III) DOTA complexes

机译：镧系元素（DOTA）配合物单酰胺衍生物的热力学稳定性，动力学惰性和弛豫特性

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摘要

A complete thermodynamic and kinetic solution study on lanthanide(III) complexes with monoacetamide (DOTAMA, L1) and monopropionamide (DOTAMAP, L2) derivatives of DOTA (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) was undertaken with the aim to elucidate their stability and inertness in aqueous media. The stability constants of GdL1 and GdL2 are comparable, whereas a more marked difference is found in the kinetic inertness of the two complexes. The formation of the Eu(III) and Ce(III) complexes takes place via the formation of the protonated intermediates which can deprotonate and transform into the final complex through a OH-assisted pathway. GdL2 shows faster rates of acid catalysed decomplexation with respect to GdL1, which has a kinetic inertness comparable to GdDOTA. Nevertheless, GdL2 is one order of magnitude more inert than GdDO3A. A novel DOTAMAP-based bifunctional chelating ligand and its deoxycholic acid derivative (L5) were also synthesized. Since the coordinated water molecule in GdL2 is characterized by an exchange rate ca. two orders of magnitude greater than in GdL1, the relaxivity of the macromolecular derivatives of GdL5 should not be limited by the slow water exchange process. The relaxometric properties of the supramolecular adduct of GdL5 with human serum albumin (HSA) were investigated in aqueous solution by measuring the magnetic field dependence of the H-1 relaxivity which, at 20 MHz and 298 K, shows a 430% increase over that of the unbound GdL5 chelate. Thus, Gd(III) complexes with DOTAMAP macrocyclic ligands can represent good candidates for the development of stable and highly effective bioconjugate systems for molecular imaging applications.
机译：镧系元素（III）与DOTA的单乙酰胺（DOTAMA，L1）和单丙酰胺（DOTAMAP，L2）衍生物（DOTA = 1,4,7,10-四氮杂环十二烷-1,4,7,10）的完整热力学和动力学溶液研究为了阐明其在水性介质中的稳定性和惰性而进行了研究。 GdL1和GdL2的稳定性常数是可比较的，而在两种配合物的动力学惰性方面发现了更明显的差异。 Eu（III）和Ce（III）配合物的形成通过质子化中间体的形成而发生，该中间体可以去质子化并通过OH辅助途径转化为最终的配合物。与GdL1相比，GdL2显示出更快的酸催化分解速率，而GdL1具有与GdDOTA相当的动力学惰性。然而，GdL2的惰性比GdDO3A高一个数量级。还合成了基于DOTAMAP的新型双功能螯合配体及其脱氧胆酸衍生物（L5）。由于GdL2中的配位水分子的特征在于交换率ca。相比于GdL1高两个数量级，GdL5大分子衍生物的弛豫性不应受到缓慢的水交换过程的限制。通过在20 MHz和298 K下测量H-1弛豫性的磁场依赖性，研究了GdL5与人血清白蛋白（HSA）的超分子加合物的弛豫特性，该H-1弛豫性的磁场依赖性比H-1弛豫性高出430％。未结合的GdL5螯合物。因此，具有DOTAMAP大环配体的Gd（III）配合物可以代表开发用于分子成像应用的稳定高效的生物共轭体系的良好候选者。

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