Synthesis, Structure, Antioxidant, and Antiviral Studies on N₂H₅[Ln(edta)(H₂O)₃].5H₂O (Ln = Pr, Nd, and Sm)

Abstract

3 ].5H 2 O (Ln = Pr, Nd and Sm) have been prepared and the molecular structures of these crystals were determined by X-ray single crystal study. The Xray powder diffraction patterns of the three complexes reveal that they are isomorphous. These complexes are nine coordinated with a hexadentate edta 4− ion and three coordinated water molecules. However, the remaining five more water molecules present as lattice water. Hydrazinium cation, though capable of coordination with the metal ion, in the present case present outside the coordination sphere as primary valency. The Ln (III)N 2 O 4 O 3 parts in the complex anions have the same structures in all the three complexes. The crystals of Pr(III), Nd(III), and Sm(III) complexes belong to the orthorhombic crystal system and Fdd2 space group. The crystal data are as follows: Pr(III): a = 19.6712(5) Å, b = 35.6939(9) Å, c = 12.3079(4) Å, α = β = γ = 90 • , V = 8641.9(4) Å 3 , R = 0.0255, and Rw = 0.0728 for I>2σ (I) and 10119 reflections. Nd(III): a = 19.6414(3) Å, b = 35.6177(5) Å, c = 12.3212(2) Å, α = β = γ = 90 • , V = 8619.7(2) Å 3 , R = 0.0251, and Rw = 0.0693 for I > 2σ (I) and 7378 reflections. Sm(III): a = 19.5814(3) Å, b = 35.4617(7) Å, c = 12.2931(2) Å, α = β = γ = 90 • , V = 8536.2(3) Å 3 , R = 0.0233, and Rw = 0.0641 for I > 2σ (I) and 6766 reflections. These complexes show promising antioxidant activity as expected for lanthanide(III) ions with unpaired electrons.The antiviral screening also shows enhanced activities of these complexes than the respective non-hydrazinium and ammonium chelates. The crystals of the complexes in purest form were powdered and subjected to constant temperature degradation at 600 • C to yield pure fine powders of the respective oxides. The microstructures of the oxides were studied by scanning electron microscope photographs.

Aqueous Structure of Lanthanide–EDTA Coordination Complexes Determined by a Combined DFT/EXAFS Approach

“…Studies examining the complexation of lanthanides by EDTA have primarily used solid-phase XRD to determine coordination structure. The distances of inner-sphere coordinating atoms to the lanthanides determined from XRD were compared to the EXAFS results of this study in Figure . − ,,,− Considering that the lanthanide remains coordinated by 7 oxygen atoms and 2 nitrogen atoms, it is reasonable that a similar conformation would be adopted by the solid. However, there does appear to be a trend toward shorter distances in the XRD structures, especially for the water oxygen and EDTA nitrogen atoms.…”

“…Ethylenediaminetetraacetic acid (EDTA), a common transition-metal chelator utilized in REE ion exchange, − has been the subject of many structural studies. − Studies generally agree that light lanthanides (lanthanides with a lower atomic number) are 9-coordinate when binding with EDTA (6 sites taken by EDTA and 3 by water) before losing a water and becoming 8-coordinate for the heaviest lanthanides. ,, However, the organization of molecules and the distance of coordinating atoms to the lanthanide ion in solution remains unclear. Molecular simulations using molecular dynamics (MD) and density functional theory (DFT) have modeled the coordination structures of Ln-EDTA complexes. , Classical MD simulations of a La-EDTA complex resulted in an average first-shell La-EDTA distance considerably shorter than the distance of an AIMD simulation (2.53 ± 0.06 and 2.63 Å, respectively) indicating a need for structural confirmation from experimental data.…”

“…Molecular simulations using molecular dynamics (MD) and density functional theory (DFT) have modeled the coordination structures of Ln-EDTA complexes. , Classical MD simulations of a La-EDTA complex resulted in an average first-shell La-EDTA distance considerably shorter than the distance of an AIMD simulation (2.53 ± 0.06 and 2.63 Å, respectively) indicating a need for structural confirmation from experimental data. To determine the structure experimentally, single-crystal X-ray diffraction (SC-XRD) has been used for precipitated Ln-EDTA complexes. ,,,,− XRD structures show a steady trend toward shorter first-shell bond distances across the Ln series (2.62 and 2.54 Å for La and Nd, respectively). However, the solid crystals studied may not represent the actual structure of the complex in solution due to changes in geometry during crystallization (i.e., crystal packing forces) .…”

Highly water-soluble dimeric and trimeric lanthanide carbonates with ethylenediaminetetraacetates as precursors of catalysts for the oxidative coupling reaction of methane

“…1a, both La(1) and La(2) are deca-coordinated, while the La in the starting material of [La(EDTA)(H 2 O) 3 ] is nona-coordinated. 31 Table S2 (ESI †) shows the selected average bond distances of 1-5 with rare earth complexes. The bond lengths between Ln-O av (carboxy) and Ln-N av are substantially longer than the other lanthanide ethylenediaminetetraacetate compounds.…”

Αυθεντικότητα Τροφίμων

“…Επιπλέον, έχει αναφερθεί ότι οι σπάνιες γαίες μπορούν να έχουν αντι-ιική δράση [104][105][106][107]. Αυτό μπορεί να οφείλεται είτε στην υψηλή παραγωγή ιντερφερόνης (oι ιντερφερόνες είναι ένα σύνολο φυσικών πρωτεϊνών οι οποίες αποτελούν βασικό μέρος του ανοσοποιητικού μας συστήματος), [107], είτε στην άμεση αντι-ιική δραστηριότητα των σπανίων γαιών [105].…”