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Neil Vasdev Raman Chirakal Rezwan Ashique Gary J. Schrobilgen Karen Gulenchyn 《Journal of fluorine chemistry》2003,121(1):9-14
The detection of 3-nitro-l-tyrosine has been used as a biomarker of “reactive nitrogen species” in biological matrices and has been an ongoing challenge in analytical chemistry. In this work, fluorine-18 labelled 5-fluoro-3-nitro-l-tyrosine (FNT) was synthesized as a potential radiotracer to probe the biological fate of 3-nitro-l-tyrosine. The synthesis of []FNT was carried out by reaction of []3-fluoro-l-tyrosine with NaNO3 in TFA solvent for 5 min at 4 °C. The radiochemical yield (RCY) of []FNT was 96±2% and []3-fluoro-l-tyrosine, was 29±1%, relative to []3-fluoro-l-tyrosine and []F2, respectively. The syntheses of []FNT were also accomplished by direct fluorination of 3-nitro-l-tyrosine with []F2 and by nitration of l-tyrosine with NaNO3, followed by fluorination, in TFA (4 °C) or anhydrous HF (−65 °C) solvent. The latter two synthetic routes produced []FNT in 13.5±1.5% RCY, within 1 h. Products were characterized by use of , and NMR spectroscopy and mass spectrometry. 相似文献
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The crystal structures of three new intermetallic ternary compounds in the LnNiSb3 (Ln=Pr, Nd and Sm) family have been characterized by single crystal X-ray diffraction. PrNiSb3, NdNiSb3 and SmNiSb3 all crystallize in an orthorhombic space group, Pbcm (No. 57), Z=12, with , , , and ; , , , and ; and , , , and , for Ln=Pr, Nd and Sm, respectively. These compounds consist of rare-earth atoms located above and below layers of nearly square, buckled Sb nets, along with layers of highly distorted edge- and face-sharing NiSb6 octahedra. Resistivity data indicate metallic behavior for all three compounds. Magnetization measurements show antiferromagnetic behavior with (PrNiSb3), 4.6 K (NdNiSb3), and 2.9 K (SmNiSb3). Effective moments of 3.62 μB, 3.90 μB and 0.80 μB are found for PrNiSb3, NdNiSb3 and SmNiSb3, respectively, and are consistent with Pr3+ (f 2), Nd3+ (f 3), and Sm3+ (f 4). 相似文献
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The rare-earth dicyanamides Ln[N(CN)2]3 (Ln=La, Ce, Pr, Nd, Sm, Eu) were obtained via ion exchange in aqueous medium and subsequent drying: The crystal structures were solved and refined based on X-ray powder diffraction data and they were found to be isotypic: Ln[N(CN)2]3; Cmcm (no. 63), Z=4, Ln=La: , , ; Ce: , , ; Pr: , , ; Nd: , , ; Sm: , , ; Eu: , , ). The compounds represent the first dicyanamides with trivalent cations. The Ln3+ ions are coordinated by three bridging N atoms and six terminal N atoms of the dicyanamide ions forming a three capped trigonal prism. The structure type is related to that of PuBr3. The novel compounds Ln[N(CN)2]3 have been characterized by IR and Raman spectroscopy (Ln=La) and the thermal behavior has been monitored by differential scanning calorimetry (Ln=Ce, Nd, Eu). 相似文献