1939-36-2Relevant articles and documents
Chelating properties of EDTA-type ligands containing six-membered backbone ring toward copper ion: Structure, EPR and TD-DFT evaluation
?endi?, Marina,Deeth, Robert J.,Meetsma, Auke,Garribba, Eugenio,Sanna, Daniele,Matovi?, Zoran D.
, p. 215 - 228 (2017)
The P-APC ligands (EDTA-like aminopolycarboxylate ligands comprising 1,3-propanediamine backbone) H4pdta, H4pd3ap, H4pddadp and H4pdtp (H4pdta?=?1,3-propanediamine-N,N,N′,N′-tetraacetatic acid; H4pd3ap?=?1,3-propanediamine-N,N,N′-triacetic-N′-3-propionic acid; H4pddadp?=?1,3-propanediamine-N,N′-diacetatic-N,N′-di-3-propionic acid; H4pdtp?=?1,3-propanediaminetetra-3-propionic acid) were investigated. The chelating ligands coordinate to copper(II) via five or six donor atoms affording distorted trigonal-bipyramid and octahedral structures that were verified by X-ray analysis for Ba[Cu(pd3ap)]·6H2O (1) and trans(O6)-Ba[Cu(pddadp)]·8H2O (2) complexes respectively. The impact of counter-ions on the P-APC complexes is shown in detail together with the analysis of another strain parameters. EPR spectral results confirm the penta-coordination of 1 and hexa-coordination of 2 in aqueous solution, even if several Cu(II) species with different protonation degree exist as a function of pH, and indicate that a hexa-coordinated structure is favored when the two axial COO?donors close five-membered chelate rings. We also present here the results of molecular mechanics (LFMM) calculations based on our previously-developed force field along with results of DFT (Density Functional Theory). On the basis of extensive DFT and TD-DFT calculations the B1LYP/6-311++G(d,p) level has been seen as an accurate theory for calculating and predicting the UV–Vis spectra in case of copper–P-APC compounds.
A high and constant hydration of the nuclear magnetic resonance imaging contrast agent and its preparation method
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Paragraph 0058; 0075, (2018/03/01)
The invention relates to a nuclear magnetic resonance imaging contrast agent with a high hydration constant and a preparation method of the nuclear magnetic resonance imaging contrast agent. The nuclear magnetic resonance imaging contrast agent with the high hydration constant is a gadolinium (III) complex containing nitrogen oxygen groups. The nuclear magnetic resonance imaging contrast agent prepared by the gadolinium (III) complex has the advantages of high hydration constant, relatively good stability and high relaxation rate.
Crystal structure, configurational and density functional theory analysis of nickel(II) complexes with pentadentate 1,3-pd3a-type ligands
Belo?evi?, Svetlana,?endi?, Marina,Djuki?, Maja,Vasojevi?, Miorad,Meetsma, Auke,Matovi?, Zoran D.
, p. 146 - 153 (2013/06/27)
The O-O-N-N-O-type pentadentate ligands H31,3-pd3a and H 31,3-pd2ap (H31,3-pd3a stands for 1,3-propanediamine-N,N, N′-triacetic acid; H31,3-pd2ap stands for 1,3-propanediamine-N, N′-diacetic-N-3-propionic acid) and the corresponding novel octahedral nickel(II) complexes have been prepared and characterized. H31,3-pd3a and H31,3-pd2ap ligands coordinate to nickel(II) ion via five donor atoms (three deprotonated carboxylate atoms and two amine nitrogens) affording octahedral geometry in case of all investigated Ni(II) complexes. A sixth place within octahedra has been occupied by the molecule of water. A six coordinate, octahedral geometry has been established crystallographically for the K[Ni(1,3-pd3a)(H2O)]·3H2O complex. Structural data correlating similar chelate Ni(II) complexes have been used for an extensive strain analysis. This is discussed in relation to information obtained for similar complexes. The infra-red and electronic absorption spectra of the complexes are interpreted and compared with related complexes of known geometries. Density functional theory (DFT) has been used to model the most stable geometry isomer and Natural Energy Decomposition Analysis (NEDA) to reveal the energetic relationship of these compounds. The results from density functional studies have been compared with X-ray data. NEDA has been done for the [LNi]- and [H2O] units.
Kinetics of dissociation of trivalent actiniae chelates of TMDTA
Muscatello, Anthony C.,Choppin, Gregory R.,D'Olieslager, Willem
, p. 993 - 997 (2008/10/08)
Measurements by a radiotracer technique show that the dissociation of TMDTA (trimethylenediamine-N,N-tetraacetic acid) chelates with Am, Cm, Bk, Cf, and Eu proceeds through an acid-catalyzed pathway. The rates of dissociation of An(TMDTA)- are 2 orders of magnitude faster than those of the corresponding EDTA chelates, presumably due to the greater lability of the nitrogen atom in the six-membered nitrogen-metal-nitrogen ring of TMDTA chelates. The rate of dissociation also decreased with decreasing metal ion radius. A proton-catalyzed mechanism similar to that for dissociation of EDTA complexes of lanthanide and actinide cations is consistent with the rate data.
