In 2019,Dalton Transactions included an article by Janicki, Rafal; Mondry, Anna. Safety of 1,4,7,10,13-Pentaoxacyclopentadecane. The article was titled 《Structural and thermodynamic aspects of hydration of Gd(III) systems》. The information in the text is summarized as follows:
X-ray crystal structures of Gd(III) and Lu(III) aqua ions as well as their complexes with polyaminopolycarboxylates (EDTA, CDTA, EGTA, DTPA, DOTA) were determined: [Gd(H2O)9](CF3SO3)3, [Gd(H2O)8]Cl3·C10H20O5, [Lu(H2O)8]Cl3·C12H24O6·4H2O, [C(NH2)3][Gd(EDTA)(H2O)3], [C(NH2)3]2[Lu(EDTA)(H2O)2]ClO4·6H2O, [C(NH2)3][Lu(CDTA)(H2O)2]·6H2O, [C(NH2)3][Gd(EGTA)(H2O)]·2H2O, [C(NH2)2(N2H4)][Gd(HDTPA)(H2O)]·2H2O, Na[Gd(DOTA)(H2O)]·4H2O, and K2[Lu(DOTA)]Cl·4.6H2O. The weighted sums of UV absorption spectra of appropriate crystals were used to reproduce the spectra of the Gd(III) aqueous solutions in the temperature range 276-363 K. In aqueous solution the Gd(III)-EGTA, Gd(III)-DTPA and Gd(III)-DOTA complexes exist as almost pure monohydrate [GdL(H2O)]n- species, while in the case of the Gd(III) aqua ion, Gd(III)-EDTA and Gd(III)-CDTA systems the equilibrium between variously hydrated species were found. The derived molar fractions of these species were used to determine the ΔG, ΔH and ΔS of hydration. These thermodn. functions may be derived not only from the spectra of the hypersensitive transitions, but from other f-f transitions as well. Next the ΔG, ΔH and ΔS values of hydration for the other Ln(III)-EDTA systems (Ln = Pr, Nd, Sm, Eu) were determined The ΔG298 values of the dehydration reaction for Ln(III)-EDTA complexes (Ln = Pr, Nd, Sm, Eu, Gd, Ho, Er) were almost linearly dependent on the number of 4f electrons in the whole series of lanthanides. Also, the point, where the ratio of [LnL(H2O)n] : [LnL(H2O)n-1] is 1, shifts along the lanthanide series depending on the ligand denticity – the higher the ligand denticity, the farther the point of the equimolar ratio in the lanthanide series. The presented results are the 1st systematic exptl. study on the thermodn. description of the hydration equilibrium of Gd(III) compounds In the experiment, the researchers used many compounds, for example, 1,4,7,10,13-Pentaoxacyclopentadecane(cas: 33100-27-5Safety of 1,4,7,10,13-Pentaoxacyclopentadecane)
1,4,7,10,13-Pentaoxacyclopentadecane(cas: 33100-27-5) is a member of crown ether Ligands. Crown-ethers are macrocyclic polyethers capable of forming host-guest complexes, especially with inorganic and organic cations. Crown-ethers can incorporate protonated primary amine compounds by formation of ion-dipole bonds with the oxygen atoms of the chiral selector. Crown-ethers have been widely used for the separation of several pharmaceuticals both in aqueous and non-aqueous media. Safety of 1,4,7,10,13-Pentaoxacyclopentadecane
Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem