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991.
Fangyuan Zhang Fangfang Zhang Qun Jing Shilie Pan Zhihua Yang Dianzeng Jia 《无机化学与普通化学杂志》2015,641(7):1211-1215
The apatite‐type strontium vanadate fluoride Sr5(VO4)3F was synthesized by standard solid‐state reaction method and grown by spontaneous crystallization flux method. It crystallizes in the hexagonal space group P63/m with lattice constants a = 9.988(4) Å, c = 7.415(6) Å, Z = 2. The structure consists of infinite three‐dimensional [Sr(2)2(VO4)3]5+ framework with tunnels along the c axis, where Sr(1)2+ and F– ions are filled. Functional groups in the structure have been identified by IR spectroscopy and the very high thermal stability up to 1400 °C has been identified by TG and DSC analyses. UV/Vis/NIR diffuse reflectance spectroscopy and first‐principle theoretical studies were also carried out to aid the understanding of optical properties and electronic structure. 相似文献
992.
Al(OH)3- and ZrO(OH)2-coated magnetites were prepared and used for fluoride removal from aqueous samples. The influence of pH, sorbent mass, and ions such as chloride, sulfate, and phosphate on the removal of fluoride was characterized. The sorption process was highly pH dependent, and the optimal sorption was obtained from pH 4 to 5 for ZrO(OH)2- and pH 4 to 7 for Al(OH)3-coated magnetites. The sorption isotherm was well described by the Langmuir equation for the sorbents. The maximum adsorption capacity of ZrO(OH)2-coated magnetite (57.47?mg-F?g?1-sorbent) was higher than for Al(OH)3-coated magnetite (23.87?mg-F?g?1-sorbent). The ion-exchange reaction occurred in 5?min and more than 99% of fluoride was removed from solution. When the ZrO(OH)2-coated magnetite was used, the presence of foreign ions negatively affected the fluoride removal. The prepared sorbents showed an excellent performance for the removal of fluoride in water samples. 相似文献
993.
V. S. Minkov V. V. Ghazaryan E. V. Boldyreva A. M. Petrosyan 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(8):733-741
L‐Cysteine hydrogen fluoride, or bis(L‐cysteinium) difluoride–L‐cysteine–hydrogen fluoride (1/1/1), 2C3H8NO2S+·2F−·C3H7NO2S·HF or L‐Cys+(L‐Cys...L‐Cys+)F−(F−...H—F), provides the first example of a structure with cations of the `triglycine sulfate' type, i.e.A+(A...A+) (where A and A+ are the zwitterionic and cationic states of an amino acid, respectively), without a doubly charged counter‐ion. The salt crystallizes in the monoclinic system with the space group P21. The dimeric (L‐Cys...L‐Cys+) cation and the dimeric (F−...H—F) anion are formed via strong O—H...O or F—H...F hydrogen bonds, respectively, with very short O...O [2.4438 (19) Å] and F...F distances [2.2676 (17) Å]. The F...F distance is significantly shorter than in solid hydrogen fluoride. Additionally, there is another very short hydrogen bond, of O—H...F type, formed by a L‐cysteinium cation and a fluoride ion. The corresponding O...F distance of 2.3412 (19) Å seems to be the shortest among O—H...F and F—H...O hydrogen bonds known to date. The single‐crystal X‐ray diffraction study was complemented by IR spectroscopy. Of special interest was the spectral region of vibrations related to the above‐mentioned hydrogen bonds. 相似文献
994.
Dr. Boris D. Zlatopolskiy Johannes Zischler Elizaveta A. Urusova Priv.-Doz. Dr. Heike Endepols Dr. Elena Kordys Dr. Holm Frauendorf Prof. Dr. Felix M. Mottaghy Prof. Dr. Bernd Neumaier 《ChemistryOpen》2015,4(4):394-462
Invited for this months cover picture is the group of Professor Bernd Neumaier at the Institute of Radiochemistry and Experimental Molecular Imaging at the University Clinic of Cologne. The cover picture shows the differences in brain metabolism of a healthy young and a healthy old subject, as well as a patient suffering from Parkinsons disease (left to right) uncovered by 6-[18F]FDOPA-positron emission tomography (PET). Morbus Parkinson occurs when nerve cells that produce dopamine begin to die. The shortage of dopamine leads to movement problems in affected individuals. 6-[18F]FDOPA is extensively used to evaluate the progression of Parkinsons disease. Bold stick projections of this PET tracer, as well as a neuronal network, are seen in the background. Unfortunately, conventional procedures to produce 6-[18F]FDOPA are cumbersome. Thus, several recent developments aim at the simplification of this radiosynthesis. In our work, we studied the applicability of the recently reported Ni-mediated radiofluorination approach for daily routine production of 6-[18F]FDOPA. For more details, see the Full Paper on p. 457 ff. 相似文献
995.
Xiongyi Huang Dr. Wei Liu Prof. Jacob M. Hooker Prof. John T. Groves 《Angewandte Chemie (International ed. in English)》2015,54(17):5241-5245
We describe the first catalytic decarboxylative fluorination reaction based on the nucleophilic fluoride ion. The reported method allows the facile replacement of various aliphatic carboxylic acid groups with fluorine. Moreover, the potential of this method for PET imaging has been demonstrated by the successful 18F labeling of a variety of carboxylic acids with radiochemical conversions up to 50 %, representing a targeted decarboxylative 18F labeling method with no‐carrier‐added [18F]fluoride. Mechanistic probes suggest that the reaction proceeds through the interaction of the manganese catalyst with iodine(III) carboxylates formed in situ from iodosylbenzene and the carboxylic acid substrates. 相似文献
996.
Hydroxy‐Directed,Fluoride‐Catalyzed Epoxide Hydrosilylation for the Synthesis of 1,4‐Diols
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Dr. Yong‐Qiang Zhang Nico Funken Peter Winterscheid Prof. Dr. Andreas Gansäuer 《Angewandte Chemie (International ed. in English)》2015,54(23):6931-6934
A novel highly regioselective, fluoride‐catalyzed hydrosilylation of β‐hydroxy epoxides has been developed. The reaction is modular and applicable to the synthesis of a broad range of 1,4‐diols. Fluoride is crucial for two reasons: First, it promotes the formation of a silyl ether (which contains a Si‐H bond) and, second, it enables ring opening by an intramolecular SN2 reaction through activation of the silane. The reaction can be performed under air. 相似文献
997.
Dr. Theresa Soltner M. Sc. Jonas Häusler Prof. Dr. Andreas J. Kornath 《Angewandte Chemie (International ed. in English)》2015,54(46):13775-13776
Calcium tricyanomethanide reacts with hydrogen fluoride under formation of tricyanomethane and Ca(HF2)2. Tricyanomethane is stable below ?40 °C and was characterized by IR, Raman, and NMR spectroscopy. The vibrational spectra were compared to the quantum‐chemical frequencies at the PBE1PBE/6‐311G(3df,3dp) level of theory and confirm the predicted C3v symmetry of the molecule with regular C? H (109.8 pm), C? C (146.7 pm), and C?N (114.7 pm) bonds. 相似文献
998.
Yogesh B. Wagh Yogesh A. Tayade Swapnil A. Padvi Bhupesh S. Patil Nilesh B. Patil Dipak S. Dalal 《中国化学快报》2015,26(10):1273-1277
A rapid, one-pot and highly efficient protocol for the synthesis of pharmaceutically interesting functionalized 2-amino-3-cyano-4H-pyran and spirooxindole derivatives has been developed using commercially available Cs F as a catalyst in the reaction of malononitrile and aryl aldehydes or isatins with 1,3-cyclohexanediones. The major advantages of this methodology are excellent yield at ambient temperature, very short reaction time(5–10 min), and use of an inexpensive catalyst. 相似文献
999.
Poly(vinylidene fluoride-co-hexaflouro propylene) is a well-known material for polymer electrolyte membranes (PEMs) due to its low cost, high mechanical integrity and excellent chemical resistance; however, its pure form has limited characteristics that require further modification to achieve optimum results. Therefore, the different dosages of polyaniline (PANI) (10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt%) were incorporated into PVDF-HFP blend to fabricate PVDF-HFP/PANI polymer electrolyte membrane by using breath-figure method. The FTIR peaks of PVDF-HFP and PVDF-HFP/PANI membrane confirms the successful incorporation of PANI into PVDF-HFP blend, while TGA, DSC and XRD analysis shows the PANI effect on stability and ionic conductivity of PVDF-HFP membrane. The PVDF-HFP/PANI membrane with 30 wt% PANI found superior with the highest porosity of 83%, electrolyte uptake of 270% and ionic conductivity of 1.96 mS cm−1; however, the other concentrations of PANI were also effective and enhanced the performance of PVDF-HFP membrane. This shows the improved performances of PVDF-HFP membrane were attributed to successful incorporation of PANI and the proposed membrane can be a suitable alternative PEM or a separator for energy devices. 相似文献
1000.
Glatfelter A Dybowski C Kragten DD Bai S Perry DL Lockard J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,66(4-5):1361-1363
Solid-state 207Pb NMR studies have been conducted on mixed lead(II) halides of the type PbFX, where X=Cl, Br, or I. NMR data for the mixed halides are compared to the solid-state NMR data for the divalent, binary lead halides, PbX2 (X=F, Cl, Br, I). The NMR data are evaluated in the context of the structures of the compounds and the effects of the mixed halides on the electronic structure of the divalent lead. Data sets for the mixed halides are discussed and compared to those for the regular lead(II) halides. 相似文献