Syntheses and magnetic properties of iron(III) complexes with imidazole groups

Iron(III) complexes with the general formula of [Fe (R-Himap)₂]X and [Fe(R-Himat)₂]X (Himap = shiff-base prepared from the condensation of 4-formylimidazole and 2-aminophenol, Himat = shiff base prepared from the condensation of 4-formylimidazole and 2-aminobenzenethiol, and R = H, Me, Ph; X = ClO₄, NO₃, BPh₄) have been synthesized. The complexes have an N₄O₂ donor set or an N₄S₂ donor set. These complexes have 5 and 5 member rings around an iron(III) atom per one chelate ring, that is, "5-5 member rings". The crystal structure, Mössbauer spectra, magnetic properties and absorption spectra of the complexes were examined. In addition, [Fe (Himsa)₂]ClO₄ having "5-6 member rings" of an N₄O₂ donor set and [Fe (Ph-Himap)(Ph-imap)] obtained by the deprotonation of [Fe (Ph-Himap)₂]ClO₄ have been also synthesized, and the Mössbauer spectra and magnetic properties of those complexes were examined. The X-ray structure of a single crystal of [Fe (Himap)₂]BPh₄ was determined: C₄₄H₃₆N₆BO₂Fe, triclinic, space group P(# 2), a = 12.452(2) Å, b = 12.748(2) Å, c = 11.996(2) Å, = 103.97(1)°, = 90.78(1)°, = 84.70(1)° and Z = 2. The moiety of an iron atom of [Fe(Himap)₂]BPh₄ was a pseudo octahedron with an FeN₄O₂ geometry. [Fe(R-Himap)₂]X was in high-spin state (about 5.9 B.M. at 80 K in solid state), and [Fe(R-Himat)₂]X was in low-spin state (about 2.0 B.M. at 293 K). The complex [Fe(Himsa)₂]ClO₄ with "5-6 member rings" and the deprotonated complex [Fe(Ph-Himap)(Ph-imap)] were in the high-spin state (6.0 B.M. at 80 K). It is concluded that the ligand field strength of an N₄S₂ donor set is stronger than that of an N₄O₂ donor set.     

Pseudogap formation in the intermetallic compounds (Fe1-xVx)3Al

Optical conductivity data of the intermetallic compounds (Fe1-xVx)3Al ( 0相似文献   

Full automatic synthesis of [<Superscript>18</Superscript>F]THK-5351 for tau protein PET imaging in Alzheimer’s disease patients: 1 year experience

[¹⁸F]THK-5351, a new candidate for tau protein imaging, is based on an aryl quinoline structure. We report the full automatic synthesis using disposable cassettes under pH controlled [¹⁸F]fluorination. After the trapping of 88.5 ± 21.9 GBq of [¹⁸F]fluoride, it was eluted with potassium methansulfonate (KOMs) (pH 7.8)/K₂₂₂. After drying, 3 mg of the precursor was added to 1 mL DMSO and subjected to [¹⁸F]fluorination at 110 °C for 10 min. After hydrolysis, the final product was purified by HPLC. The overall radiochemical yield was 31.9 ± 11.1% (n = 22), satisfying all quality control criteria. It was stable for up to 6 h with high radiochemical purity as 99.8 ± 0.5%.     

Kaempferol glycosides in the flowers of carnation and their contribution to the creamy white flower color

Three flavonol glycosides were isolated from the flowers of carnation cultivars 'White Wink' and 'Honey Moon'. They were identified from their UV, MS, 1H and 13C NMR spectra as kaempferol 3-O-neohesperidoside, kaempferol 3-O-sophoroside and kaempferol 3-O-glucosyl-(1 --> 2)-[rhamnosyl-(1 --> 6)-glucoside]. Referring to previous reports, flavonols occurring in carnation flowers are characterized as kaempferol 3-O-glucosides with additional sugars binding at the 2 and/or 6-positions of the glucose. The kaempferol glycoside contents of a nearly pure white flower and some creamy white flower lines were compared. Although the major glycoside was different in each line, the total kaempferol contents of the creamy white lines were from 5.9 to 20.9 times higher than the pure white line. Thus, in carnations, kaempferol glycosides surely contribute to the creamy tone of white flowers.     

Octave-spanning carrier-envelope phase stabilized visible pulse with sub-3-fs pulse duration

The visible second harmonic of the idler output from a noncollinear optical parametric amplifier was compressed using adaptive dispersion control with a deformable mirror. The amplifier was pumped by and seeded in the signal path by a common 400 nm second-harmonic pulse from a Ti:sapphire regenerative amplifier. Thus, both the idler output and the second harmonic of the idler were passively carrier-envelope phase stabilized. The shortest pulse duration achieved was below 3 fs.     

Laser-induced fluorescence and infrared spectroscopic studies on the specific solvation of tris(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)europium(III) in an ionic liquid

The extraction constant and the two-phase stability constant (K_D,Mβ₃) of tris(2-thenoyltrifluoroacetonato)europium(III) between 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C₄mim][Tf₂N]) as an ionic liquid and an aqueous phase were determined by considering the extraction equilibria including anionic tetrakis(2-thenoyltrifluoroacetonato)europate(III). Specific solute-solvent interactions between the neutral Eu(III) chelate and [C₄mim][Tf₂N] molecules were revealed from the relationships between the distribution constant of the enol form of 2-thenoyltrifluoroacetone (Htta) as a proton chelate and the distribution constant (K_D,M) of the neutral Eu(III) chelate because the [C₄mim][Tf₂N] system gave the high K_D,Mβ₃ value compared with those in conventional molecular solvents such as benzene and 1,2-dichloroethane. The coordination environment of Eu³⁺ in the neutral Eu(III) chelate in [C₄mim][Tf₂N] was investigated by time-resolved laser-induced fluorescence spectroscopy and infrared absorption spectroscopy. Both methods consistently indicated that not only the Eu(III) chelate extracted but also Eu(tta)₃(H₂O)₃ synthesized as a solid crystal were almost completely dehydrated in [C₄mim][Tf₂N] saturated with water. Consequently, the higher K_D,M or extractability of the neutral Eu(III) chelate in the [C₄mim][Tf₂N] system can be ascribed to the dehydration of the Eu(III) chelate, which is caused by the specific solvation with [C₄mim][Tf₂N] molecules.     

Evaluation of ionic pollutants of acid fog and rain using a factor analysis and back trajectories.

Fog and rain water samples were collected at the same time in the Akita Hachimantai mountain range in northern Japan from June to September in 1998 and 1999. The various ion concentrations in these samples were analyzed, and the fog droplet sizes were measured for each fog event. As the fog droplet size increased, the ion concentration decreased. The slope of log-log plots of the concentration versus the droplet size differed with the kind of ion. In order to characterize the air pollutant, moreover, these data were quantitatively analyzed by an oblique rotational factor analysis. We found that three factors were extracted as the air pollutant source: (NH4)2SO4, acids (HNO3 + H2SO4) and sea-salt. Combining the factor analysis with the 72 h back-trajectory at 850 hPa level, we found that the contribution of each factor varied with the transport pattern of air masses.     

2-reducible cycles containing three consecutive edges in (2k + 1)-edge-connected graphs

LetG be ak-edge-connected graph and letf ₁,f ₀,f ₂ be consecutive edges. We call a cycleC (not necessarily simple) 2-reducible ifG – E(C) is (k – 2)-edge-connected. We here characterize the graphsG having no 2-reducible cycle containingf ₁,f ₀ andf ₂.     

Design and stereoselective synthesis of four peptide nucleic acid monomers with cyclic structures in backbone

Four isomers of the monomer of peptide nucleic acid (PNA) were derived from (2S,4R)‐4‐hydroxyproline; they had different stereochemistries at the C² and C⁴ positions in the pyrrolidine ring. These different backbone conformations corresponding to four different stereochemistries were realized through a combination of inversions at the C² and the C⁴ positions in pyrrolidine ring. The obtained backbone frameworks were reacted with N‐benzoyl thymine to give the corresponding PNA monomers. Spectroscopic comparison of the resultant monomers confirmed their stereochemistries. J. Heterocyclic Chem., (2011).