Metal complexes of 1-oxa-4,7,10-triazacyclododecane-N,N′,N″-triacetic acid

Mt, Amorim; Delgado, Rita; Jj, da Silva; Cǎndida, M.; Ta, Vaz; Mf, Vilhena

doi:10.1016/0039-9140(88)80175-9

Cited by 26 publications

(2 citation statements)

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“…On the other hand, the basicity of the macrocyclic nitrogen atoms in DO3P is higher than that in DO3A resulting in a noticeably higher ligand basicity. The ligand ODO3A, derived from DO3A by substituting an etheric O-atom for the macrocyclic NH, also displays a drop in the Σ log β

value due to a change in the protonation sequence (Amorim et al, 1988 ).…”

Section: Resultsmentioning

confidence: 99%

“…The concentration of the MnCl 2 , CuCl 2 and ZnCl 2 solutions was determined by using standardized Na 2 H 2 EDTA solution and eriochrome black T (Mn(II)), murexide (Cu(II) and xylenolorange (Zn(II)) as indicator. The ligands were either prepared by following literature procedures (DOTAM, DO3A, DO3P, PCTA, ODO3A, PC3AM Gly ) (Amorim et al, 1988 ; Maumela et al, 1995 ; Aime et al, 1997 ; Siaugue et al, 2000 ; Sun et al, 2003 ; Rojas-Quijano et al, 2009 ; Nithyakumar and Alexander, 2016 ) or obtained from commercial sources (DO3AM H - CheMatech, Dijon (France)). The PC3AM H and PC3AM Pip ligands were prepared by alkylating the pyclen macrocycle prepared according to literature description (Stetter et al, 1981 ) with a suitable bromoacetamide derivative (see the Supplementary Material for the detailed synthesis and analytical data) available from commercial sources or prepared by following literature synthesis (Kaupang and Bonge-Hansen, 2013 ).…”

Section: Methodsmentioning

confidence: 99%

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Effect of the Nature of Donor Atoms on the Thermodynamic, Kinetic and Relaxation Properties of Mn(II) Complexes Formed With Some Trisubstituted 12-Membered Macrocyclic Ligands

et al. 2018

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During the past few years increasing attention has been devoted to Mn(II) complexes as possible substitutes for Gd(III) complexes as contrast agents in MRI. Equilibrium (log KMnL or pMn value), kinetic parameters (rates and half-lives of dissociation) and relaxivity of the Mn(II) complexes formed with 12-membered macrocyclic ligands were studied. The ligands were selected in a way to gain information on how the ligand rigidity, the nature of the donor atoms in the macrocycle (pyridine N, amine N, and etheric O atom), the nature of the pendant arms (carboxylates, phosphonates, primary, secondary and tertiary amides) affect the physicochemical parameters of the Mn(II) complexes. As expected, decreasing the denticity of DOTA (to afford DO3A) resulted in a drop in the stability and inertness of [Mn(DO3A)]− compared to [Mn(DOTA)]2−. This decrease can be compensated partially by incorporating the fourth nitrogen atom into a pyridine ring (e.g., PCTA) or by replacement with an etheric oxygen atom (ODO3A). Moreover, the substitution of primary amides for acetates resulted in a noticeable drop in the stability constant (PC3AMH), but it increased as the primary amides (PC3AMH) were replaced by secondary (PC3AMGly) or tertiary amide (PC3AMPip) pendants. The inertness of the Mn(II) complexes behaved alike as the rates of acid catalyzed dissociation increased going from DOTA (k1 = 0.040 M−1s−1) to DO3A (k1 = 0.45 M−1s−1). However, the rates of acid catalyzed dissociation decreased from 0.112 M−1s−1 observed for the anionic Mn(II) complex of PCTA to 0.0107 M−1s−1 and 0.00458 M−1s−1 for the cationic Mn(II) complexes of PC3AMH and PC3AMPip ligands, respectively. In spite of its lower denticity (as compared to DOTA) the sterically more hindered amide complex ([Mn(PC3AMPip)]2+) displays surprisingly high conditional stability (pMn = 8.86 vs. pMn = 9.74 for [Mn(PCTA)]−) and excellent kinetic inertness. The substitution of phosphonates for the acetate pendant arms (DOTP and DO3P), however, resulted in a noticeable drop in the conditional stability as well as dissociation kinetic parameters of the corresponding Mn(II) complexes ([Mn(DOTP)]6− and [Mn(DO3P)]4−) underlining that the phosphonate pedant should not be considered as a suitable building block for further ligand design while the tertiary amide moiety will likely have some implications in this respect in the future.

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value due to a change in the protonation sequence (Amorim et al, 1988 ).…”

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Effect of the Nature of Donor Atoms on the Thermodynamic, Kinetic and Relaxation Properties of Mn(II) Complexes Formed With Some Trisubstituted 12-Membered Macrocyclic Ligands

et al. 2018

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Polyaza‐Crown Macrocycles

1993

Chemistry of Heterocyclic Compounds: A Series of Monographs

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Stability and Toxicity of Contrast Agents

Brücher

Tircsó

Baranyai

et al. 2013

The Chemistry of Contrast Agents in Medical Magnetic Resonance Imaging

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Magnetic Resonance Imaging (MRI) derives directly from the phenomenon of Nuclear Magnetic Resonance (NMR [1][2][3][4]), which is widely used by chemists to determine molecular structure. The word "nuclear" was dropped in the switch to imaging to avoid alarming patients as NMR has nothing to do with radioactivity. This book is intended mainly for chemists, who are generally familiar with the NMR spectra. After a brief overview of the technique explaining the notion of relaxation time and saturation transfer used in MRI, we will describe localization techniques, which are less well-known in chemistry. The purpose of this short chapter is not to provide a complete theory of MRI [5][6][7][8], but to understand the rest of the book concerning the action of contrast agents. We will not go into the theoretical background of the phenomena, and while it is important to have some understanding of quantum mechanics, it is not our purpose to develop this aspect. This is a "nuts and bolts" description of MRI. Whenever possible, we refer to chemists' knowledge of NMR (for example, "2D NMR"). Theoretical basis of NMR Short description of NMRIn most cases, MRI focuses on one type of atomic nucleus, that of hydrogen in H 2 O. We will therefore only use this nucleus, termed the " 1 H proton."The physical phenomenon of NMR lies at the boundary between "conventional" and "quantum" treatment due to the small transition energies involved. Traditionally, the 1 H proton can be considered as a charged

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Metal complexes of 1-oxa-4,7,10-triazacyclododecane-N,N′,N″-triacetic acid

Cited by 26 publications

References 9 publications

Effect of the Nature of Donor Atoms on the Thermodynamic, Kinetic and Relaxation Properties of Mn(II) Complexes Formed With Some Trisubstituted 12-Membered Macrocyclic Ligands

Effect of the Nature of Donor Atoms on the Thermodynamic, Kinetic and Relaxation Properties of Mn(II) Complexes Formed With Some Trisubstituted 12-Membered Macrocyclic Ligands

Polyaza‐Crown Macrocycles

Stability and Toxicity of Contrast Agents

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