Synthesis and lanthanide coordination chemistry of trifluoromethyl derivatives of phosphinoylmethyl pyridine N-oxides.

A synthetic route for the formation of 2-[bis(2-trifluoromethylphenyl)phosphinoylmethyl]pyridine N-oxide (1c) and 2-[bis(3,5-trifluoromethylphenyl)phosphinoylmethyl]pyridine N-oxide (1d) was developed and the new ligands characterized by spectroscopic methods and single-crystal X-ray diffraction analyses. The coordination chemistry of 1c was examined with Yb(NO3)3 and the molecular structure of one complex, [Yb(1c)(NO3)3(DMF)].DMF.0.5H2O, was determined by single-crystal X-ray diffraction methods. The ligand is found to coordinate in a bidentate fashion, and this is compared against lanthanide coordination chemistry observed for the related ligand, [Ph2P(O)CH2] C5H4NO.

Synthesis and coordination properties of trifluoromethyl decorated derivatives of 2,6-bis[(diphenylphosphinoyl)methyl]pyridine N-oxide ligands with lanthanide ions.

Phosphinoyl Grignard-based substitutions on 2,6-bis(chloromethyl)pyridine followed by N-oxidation of the intermediate 2,6-bis(phosphinoyl)methylpyridine compounds with mCPBA give the target trifunctional ligands 2,6-bis[bis(2-trifluoromethylphenyl)phosphinoylmethyl]pyridine 1-oxide (2a) and 2,6-bis[bis(3,5-bis(trifluoromethyl)phenyl)phosphinoylmethyl]pyridine 1-oxide (2b) in high yields. The ligands have been spectroscopically characterized, the molecular structures confirmed by single crystal X-ray diffraction methods, and the coordination chemistry surveyed with lanthanide nitrates. Single crystal X-ray diffraction analyses are described for the coordination complexes Nd(2a)(NO(3))(3), Nd(2a)(NO(3))(3) x (CH(3)CN)(0.5), Eu(2a)(NO(3))(3), and Nd(2b)(NO(3))(3) x (H(2)O)(1.25); in each case the ligand binds in a tridentate mode to the Ln(III) cation. These structures are compared with the structures found for lanthanide coordination complexes of the parent NOPOPO ligand, [Ph(2)P(O)CH(2)](2)C(5)H(3)NO.

Iron loading into ferritin can be stimulated or inhibited by the presence of cations and anions: a specific role for phosphate.

Phosphate and other oxo-anions have been shown to stimulate the rate of iron loading into ferritin (J. Polanams, A.D. Ray, R.K. Watt, Inorg. Chem. 44 (2005) 3203-3209). This study was undertaken to determine if accelerated iron loading was a specific effect for phosphate and closely associated oxo-anions or if it was a general anion effect. Controls were also performed with mono-valent cations to determine the effect of these cations on iron loading into ferritin. Cations were shown to slow the rate of iron loading into ferritin. Fluoride and iodide were shown to slow the iron loading process of ferritin. Sulfate was also shown to slow iron loading into ferritin to a more significant extent than the cations or halides tested. The trigonal planar oxo-anions, carbonate and nitrate, did not inhibit or stimulate iron loading. We conclude that the increased rate of iron loading into ferritin is specific to phosphate and other closely associated tetrahedral oxo-anion analogs, that the effect is driven by the insolubility of the iron and anion complex, and that in general, cations and anions slow the rate of iron loading into ferritin.

Nanophase iron phosphate, iron arsenate, iron vanadate, and iron molybdate minerals synthesized within the protein cage of ferritin.

Nanoparticles of iron phosphate, iron arsenate, iron molybdate, and iron vanadate were synthesized within the 8 nm interior of ferritin. The synthesis involved reacting Fe(II) with ferritin in a buffered solution at pH 7.4 in the presence of phosphate, arsenate, vanadate, or molybdate. O2 was used as the oxidant to deposit the Fe(III) mineral inside ferritin. The rate of iron incorporation into ferritin was stimulated when oxo-anions were present. The simultaneous deposition of both iron and the oxo-anion was confirmed by elemental analysis and energy-dispersive X-ray analysis. The ferritin samples containing iron and one of the oxo-anions possessed different UV/vis spectra depending on the anion used during mineral formation. TEM analysis showed mineral cores with approximately 8 nm mineral particles consistent with the formation of mineral phases inside ferritin.