Optimizing the high-field relaxivity by self-assembling of macrocyclic Gd(iii) complexes

Abstract

(2015) 'Optimizing the high-eld relaxivity by self-assembling of macrocyclic Gd(III) complexes.', Dalton transactions., 44 (11). pp. 4910-4917. Further information on publisher's website:http://dx.doi.org/10.1039/C4DT02971BPublisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication.Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. We will replace this Accepted Manuscript with the edited and formatted Advance Article as soon as it is available.You can find more information about Accepted Manuscripts in the Information for Authors. Table of contentsThe self-assembling of two macrocyclic Gd-chelates results in a small-size dimeric system characterized by a remarkably high relaxivity, r 1 . Using recognition moieties that bind to the inner co-ordination sphere of a monomeric DO3A-type di-aqua complex, dimeric poly(aminocarboxylate) gadolinium(III) compounds can be formed with greatly enhanced relaxivities, arising from optimized contributions of inner-and second spheres of hydration.

Developing High Field MRI Contrast Agents by Tuning the Rotational Dynamics: Bisaqua GdAAZTA‐based Dendrimers

“…These experimental results confirm the published theoretical predictions and simulations . With the increase of the magnetic field, r 1 no longer scales with τ R and relatively simple systems (dimer‐tetramers) afford optimal results, provided they are compact and characterized by predominantly isotropic rotation motion …”

“…[9] With the increase of the magnetic field, r 1 no longer scales with t R and relatively simple systems (dimer-tetramers) afford optimal results, provided they are compact and characterized by predominantly isotropic rotation motion. [26] Experimental Section All chemicals were purchased from Sigma-Aldrich Co. and were used without purification unless otherwise stated. NMR spectra were recorded on a on a JEOL Eclipse Plus 400 (operating at 9.4 Tesla; 1 H at 399.968, 13 C at 100.572 MHz) spectrometer.…”

New insights into water‐soluble and water‐coordinated copper 15‐metallacrown‐5 gadolinium complexes designed for high‐field magnetic resonance imaging applications

“…The synthesis of Ln Cu 15-metallacrown-5 complexes was performed using a modified procedure reported previously. [10][11][12] A general synthesis for 1(Ln)-4(Ln) complexes based on R-substituted aminohydroxamic acid (R =−H, −Me, −CH 2 Ph, −CH 2 PhOH) is described below for La(H 2 O) 4 [15-MC Cu(II)Glyha -5](Cl) 3 . The Gd(III) complexes were prepared similarly by using Gd(III) chloride instead of LaCl 3 .…”

“…However, the relaxation efficiency of classic Gd(III) contrast agents decreases with increasing magnetic field strengths. Gd–DTPA has a low relaxivity value of 4.4 s −1 mM −1 at 9.4 T and requires an injection dose of up to 0.1 mmol kg −1 body weight for clinical and preclinical applications . For these reasons, the development of contrast agents specifically designed for high‐field applications is required.…”

Optimizing the Relaxivity of MRI Probes at High Magnetic Field Strengths With Binuclear GdIII Complexes

“…The relaxivity enhancement of these systems as compared to monomeric Gd-complexes was often very much dependent on the water exchange rate or on the rigidity of the linker. We were also inspired by the recently reported self-assembling of two oppositely charged macrocyclic Gd-chelates that resulted in a small-sized dimeric system with high relaxivity at high frequencies thanks to improved inner- and second-sphere relaxivity contributions (Lawson et al, 2015 ). Remarkably, the additional contribution of about 30–40% from water molecules in the second coordination sphere was considered responsible of the increased performance of the ditopic probe.…”