Some new DTPA-N,N″-bis(amides) functionalized by alkyl carboxylates: Synthesis, complexation and stability properties

Autor: Suk-Kyung Kim, Daksha B. Patel, Yongmin Chang, Sujit Dutta, Tae-Jeong Kim
Rok vydání: 2007
Předmět:
Zdroj: Polyhedron. 26:3799-3809
ISSN: 0277-5387
DOI: 10.1016/j.poly.2007.04.027
Popis: A new series of DTPA- N , N ″-bis(amide) ligands functionalized by alkyl carboxylates on the amide side-arms ( 1a – 1l ) and their Gd(III) complexes of the type [Gd( 1 )(H 2 O)] · x H 2 O ( 2a – 2l ) were synthesized and characterized by analytical and spectroscopic techniques. Potentiality of 2a – 2l as contrast agent for magnetic resonance imaging (MRI CA) was investigated by measuring some relevant physicochemical properties such as (i) the protonation constants of 1a – 1l , (ii) thermodynamic and conditional stability constants of 2a – 2l , (iii) the selectivity (pGd) of 1a – 1l for the Gd(III) ion over the endogenous metal ions such as Zn(II), Ca(II), and Cu(II), and (iv) the relaxivities ( R 1 and R 2 ) of 2a – 2l in aqueous and aqueous HP-β-CD solutions. Comparative studies reveal that most of new Gd(III) complexes show enhanced thermodynamic stability and selectivity as compared with those of [Gd(DTPA-BMA)(H 2 O)] (DTPA-BMA = N , N ″-di(methylcarbamoylmethyl)diethylenetriamine- N , N ′, N ″-triacetate). Also enhanced with 1a – 1l (except 1f and 1h ) is affinity for Gd(III) as compared with [DTPA-BMA] 3− under physiological conditions. The relaxivities ( R 1 and R 2 ) of aqueous solutions of 2a – 2l , on the other hand, drop significantly as compared with [Gd(DTPA-BMA)(H 2 O)] although they increase dramatically (6–10 fold) in aqueous hydroxypropyl-β-cyclodextrin (HP-β-CD) solutions.
Databáze: OpenAIRE
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