74199-09-0Relevant articles and documents
Picolinate-containing macrocyclic Mn2+ complexes as potential MRI contrast agents
Molnar, Eniko,Camus, Nathalie,Patinec, Veronique,Rolla, Gabriele A.,Botta, Mauro,Tircso, Gyula,Kalman, Ferenc K.,Fodor, Tamas,Tripier, Raphael,Platas-Iglesias, Carlos
, p. 5136 - 5149 (2014)
We report the synthesis of the ligand Hnompa (6-((1,4,7-triazacyclononan-1- yl)methyl)picolinic acid) and a detailed characterization of the Mn2+ complexes formed by this ligand and the related ligands Hdompa (6-((1,4,7,10-tetraazacyclododecan-1-yl)methyl)picolinic acid) and Htempa (6-((1,4,8,11-tetraazacyclotetradecan-1-yl)methyl)picolinic acid). These ligands form thermodynamically stable complexes in aqueous solution with stability constants of logKMnL = 10.28(1) (nompa), 14.48(1) (dompa), and 12.53(1) (tempa). A detailed study of the dissociation kinetics of these Mn 2+ complexes indicates that the decomplexation reaction at about neutral pH occurs mainly following a spontaneous dissociation mechanism. The X-ray structure of [Mn2(nompa)2(H2O) 2](ClO4)2 shows that the Mn2+ ion is seven-coordinate in the solid state, being directly bound to five donor atoms of the ligand, the oxygen atom of a coordinated water molecule and an oxygen atom of a neighboring nompa- ligand acting as a bridging bidentate carboxylate group (μ-η1-carboxylate). Nuclear magnetic relaxation dispersion (1H NMRD) profiles and 17O NMR chemical shifts and transverse relaxation rates of aqueous solutions of [Mn(nompa)]+ indicate that the Mn2+ ion is six-coordinate in solution by the pentadentate ligand and one inner-sphere water molecule. The analysis of the 1H NMRD and 17O NMR data provides a very high water exchange rate of the inner-sphere water molecule (kex 298 = 2.8 × 109 s-1) and an unusually high value of the 17O hyperfine coupling constant of the coordinated water molecule (AO/h = 73.3 ± 0.6 rad s-1). DFT calculations performed on the [Mn(nompa)(H2O)]+· 2H2O system (TPSSh model) provide a AO/h value in excellent agreement with the one obtained experimentally.
TETRACYCLIC TETRAAMINES BY GLYOXAL-MACROCYCLIC TETRAAMINE CONDENSATION
Weisman, Gary R.,Ho, Suzzy C. H.,Johnson, Van
, p. 335 - 338 (1980)
A series of new tetracyclic tetraamines have been synthesized in good to moderate yield by glyoxal-macrocyclic tetraamine condensation.
Trans-Methylpyridine cyclen versus cross-bridged trans-methylpyridine cyclen. Synthesis, acid-base and metal complexation studies (metal = Co 2+, Cu2+, and Zn2+)
Bernier, Nicolas,Costa, Judite,Delgado, Rita,Felix, Vitor,Royal, Guy,Tripier, Raphael
, p. 4514 - 4526 (2011)
The synthesis of the cross-bridged cyclen CRpy2 {4,10-bis((pyridin-2-yl)methyl)-1,4,7,10-tetraazabicyclo[5.5.2]tetradecane}, a constrained analogue of the previously described trans-methylpyridine cyclen Cpy2 is reported. The additional ethylene bridge confers to CRpy 2 proton-sponge type behaviour which was explored by NMR and potentiometric studies. Transition metal complexes have been synthesized (by complexation of both ligands with Co2+, Cu2+ and Zn 2+) and characterized in solution and in the solid state. The single crystal X-ray structures of [CoCpy2]2+, [CuCpy 2]2+ and [ZnCpy2]2+ complexes were determined. Stability constants of the complexes, including those of the cross-bridged derivative, were determined using potentiometric titration data and the kinetic inertness of the [CuCRpy2]2+ complex in an acidic medium (half-life values) was evaluated by spectrophotometry. The pre-organized structure of the cross-bridged ligand imposes an additional strain for the complexation leading to complexes with smaller thermodynamic stability in comparison with the related non-bridged ligand. The electrochemical study involving cyclic voltammetry underlines the importance of the ethylene cross-bridge on the redox properties of the transition metal complexes.
Definition of the Labile Capping Bond Effect in Lanthanide Complexes
Rodríguez-Rodríguez, Aurora,Regueiro-Figueroa, Martín,Esteban-Gómez, David,Rodríguez-Blas, Teresa,Patinec, Véronique,Tripier, Rapha?l,Tircsó, Gyula,Carniato, Fabio,Botta, Mauro,Platas-Iglesias, Carlos
supporting information, p. 1110 - 1117 (2017/02/05)
Two macrocyclic ligands containing a cyclen unit, a methyl group, a picolinate arm, and two acetate pendant arms attached to two nitrogen atoms of the macrocycle either in trans (1,7-H3Medo2 ampa = 2,2′-(7-((6-carboxypyridin-2-yl)methyl)-10-met
Incorporation of Cobalt-Cyclen Complexes into Templated Nanogels Results in Enhanced Activity
Jorge, Ana Rita,Chernobryva, Mariya,Rigby, Stephen E.J.,Watkinson, Michael,Resmini, Marina
, p. 3764 - 3774 (2016/03/08)
Recent advances in nanomaterials have identified nanogels as an excellent matrix for novel biomimetic catalysts using the molecular imprinting approach. Polymerisable Co-cyclen complexes with phosphonate and carbonate templates have been prepared, fully characterised and used to obtain nanogels that show high activity and turnover with low catalytic load, compared to the free complex, in the hydrolysis of 4-nitrophenyl phosphate, a nerve agent simulant. This work demonstrates that the chemical structure of the template has an impact on the coordination geometry and oxidation state of the metal centre in the polymerisable complex resulting in very significant changes in the catalytic properties of the polymeric matrix. Both pseudo-octahedral cobalt(III) and trigonal-bipyramidal cobalt(II) structures have been used for the synthesis of imprinted nanogels, and the catalytic data demonstrate that: i) the imprinted nanogels can be used in 15 % load and show turnover; ii) the structural differences in the polymeric matrices resulting from the imprinting approach with different templates are responsible for the molecular recognition capabilities and the catalytic activity. Nanogel P1, imprinted with the carbonate template, shows >50 % higher catalytic activity than P2 imprinted with the phosphonate.