Tircsó, GyulaRegueiro-Figueroa, MartínNagy, ViktóriaGarda, ZoltánGarai, TamásKálmán, FerencEsteban-Gómez, DavidTóth, ÉvaPlatas-Iglesias, Carlos2017-10-302017-10-302016-01-08Tircsó, G., Regueiro-Figueroa, M., Nagy, V., Garda, Z., Garai, T., Kálmán, F. K., Esteban-Gómez, D., Tóth, E. and Platas-Iglesias, C. (2016), Approaching the kinetic inertness of macrocyclic gadolinium(III)-based MRI contrast agents with highly rigid open-chain derivatives. Chem. Eur. J., 22: 896-901.0947-65391521-3765http://hdl.handle.net/2183/19665[Abstract] A highly rigid open-chain octadentate ligand (H4cddadpa) containing a diaminocylohexane unit to replace the ethylenediamine bridge of 6,6′-[(ethane-1,2 diylbis{(carboxymethyl)azanediyl})bis(methylene)] dipicolinic acid (H4octapa) was synthesized. This structural modification improves the thermodynamic stability of the Gd3+ complex slightly (log KGdL=20.68 vs. 20.23 for [Gd(octapa)]−) while other MRI-relevant parameters remain unaffected (one coordinated water molecule; relaxivity r1=5.73 mm−1 s−1 at 20 MHz and 295 K). Kinetic inertness is improved by the rigidifying effect of the diaminocylohexane unit in the ligand skeleton (half-life of dissociation for physiological conditions is 6 orders of magnitude higher for [Gd(cddadpa)]− (t1/2=1.49×105 h) than for [Gd(octapa)]−. The kinetic inertness of this novel chelate is superior by 2–3 orders of magnitude compared to non-macrocyclic MRI contrast agents approved for clinical use.engThis is the peer reviewed version of the following article: Tircsó, G., Regueiro-Figueroa, M., Nagy, V., Garda, Z., Garai, T., Kálmán, F. K., Esteban-Gómez, D., Tóth, E. and Platas-Iglesias, C. (2016), Approaching the kinetic inertness of macrocyclic gadolinium(III)-based MRI contrast agents with highly rigid open-chain derivatives. Chem. Eur. J., 22: 896-901, which has been published in final form at https://doi.org/10.1002/chem.201503836. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Contrast agentsCoordination compoundsGadoliniumLanthanidesNMR imagingjournal articleopen access