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1.
Crystals of Ba(2)Cu(PO(4))(2) have been grown in a low-temperature eutectic flux of 32% KCl and 68% CuCl (mp = 140 degrees C). The X-ray single-crystal structure analysis shows that this barium copper(II) phosphate crystallizes in a monoclinic lattice with a = 12.160(4) ?, b = 5.133(4) ?, c = 6.885(4) ?, beta = 105.42(4) degrees, and V = 414.3(4) ?(3); C2/m (No. 12); Z = 2. The structure has been refined by the least-squares method to a final solution with R = 0.020, R(w) = 0.026, and GOF = 1.05. The framework of the title compound consists of [Cu(PO(4))(2)](infinity) linear chains with Ba(2+) cations residing between these parallel chains. The chains are composed of an array of Cu(2+) cations that are doubly bridged by PO(4) anions. Each pair of bridging PO(4) tetrahedra are in a staggered configuration above and below the CuO(4) square plane, resulting in a linear chain with a long Cu---Cu separation distance, 5.13 ? ( identical withb). This quasi-one-dimensional framework is unusual among the Cu(2+)-based phosphates. Magnetic susceptibility data shows Curie-Weiss paramagnetic behavior in the range of ca. 190-300 K and a possible antiferro-to-ferromagnetic transition at approximately 8 K. In this paper, the synthesis, structure, and properties of the title compound are presented. A structural comparison to a closely related vanadyl (VO)(2+) phosphate, Ba(2)(VO)(PO(4))(2).H(2)O, as well as Na(2)CuP(2)O(7) will be discussed. 相似文献
2.
Hwu JR Jain ML Tsai FY Tsay SC Balakumar A Hakimelahi GH 《The Journal of organic chemistry》2000,65(17):5077-5088
Silica gel-supported ceric ammonium nitrate (CAN-SiO2) was found effective for rapid and selective cleavage of trityl (Tr), monomethoxytrityl (MMTr), and dimethoxytrityl (DMTr) groups from protected nucleosides and nucleotides under mild conditions. Efficiency of deprotections depended upon the stability of the resultant carbocationic species: DMTr+ > MMTr+ > Tr+. Use of a catalytic amount of this solid-supported reagent can also efficiently and selectively remove the tert-butyldimethylsilyl or the triisopropylsilyl group from a primary hydroxyl functionality in di- or trisilyl ethers of ribonucleosides. A comparative study of deprotection reactions by utilization of CAN alone or CAN-SiO2 indicates a remarkable increase in the rate of the reactions involving a solid support. The mechanism of electron-transfer processes is proposed for the use of CAN-SiO2 in the removal of these protective groups from organic molecules. 相似文献
3.
Nocardicin A analogues 30, 34 , and 38 as well as the highly strained quinone methide 43 were synthesized. β -Lactam 34 was found biologically active against several Gram-negative microorganisms in vitro; pyridinium N-oxide derivative 38 possessed activity against Gram-positive S. aureus bacterium. Masked p-quinone methide β -lactam 43 exhibited significant antimicrobial activity in vitro. A mechanism involving an oxidation in vivo is proposed for the unprecedented biological properties of nocardicins. 相似文献
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Hwu SJ Ulutagay-Kartin M Clayhold JA Mackay R Wardojo TA O'Connor CJ Krawiec M 《Journal of the American Chemical Society》2002,124(42):12404-12405
Two novel copper(II) arsenates Na5ACu4(AsO4)4Cl2 (A = Rb, Cs) were synthesized by conventional solid-state methods using reactive molten salt media. These compounds are isostructural and crystallize in an orthorhombic lattice (Fmmm, No. 69; Z = 8). The cell constants are a = 14.632(3) A, b = 18.872(2) A, c = 14.445(3) A, V = 3989(1) A3, for A = Rb; a = 14.638(3) A, b = 18.990(4) A, c = 14.418(3) A, V = 4008(1) A3, for A = Cs. Single-crystal structure studies reveal a new composite framework consisting of alternating covalent and ionic lattices. The covalent lattice contains highly oriented oligomeric mu-oxo [Cu4O12]16- tetrameric units with a cyclo-S8-like Cu4O4 magnetic core that resembles the building block of layered cuprates. The ionic slab consists of a novel framework of mixed alkali metal chloride lattice and rarely seen Na6O8 clusters. Similar to organic-inorganic hybrid materials, the title compounds present a new class of host-guest chemistry via salt inclusion reactions. 相似文献
6.
Vibrant blue crystals of Na(4)Mn(0.5)P(0.5)O(5) were synthesized via a sodium hydroxide flux. The X-ray structural analysis showed that this sodium manganese(VII) phosphorous oxide crystallizes in an orthorhombic lattice with a = 8.967(3) ?, b = 7.291(3) ?, c = 8.090(3) ?: Pnma (No. 62); Z = 4. The manganese and phosphorus cations equally share one crystallographic site and are tetrahedrally coordinated. The (Mn,P)O(4) tetrahedra are held together by sodium cations via Na-O bonds forming an ionic solid, [Na(4)O](2+)[(Mn(0.5)P(0.5))O(4)](2)(-). The synthesis, structure, thermal property and infrared spectroscopy of the title compound are presented in this paper. 相似文献
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8.
Gholam H. Hakimelahi Min-Jen Shiao Jih Ru Hwu Hady Davari 《Helvetica chimica acta》1992,75(6):1840-1847
Syntheses of the cis-configurated isopenam 9 (Scheme 1), isocephem 14 (Scheme 2), and isocephem 19 (Scheme 3) are described. The key step in the preparation of 14 and 19 involved a Pummerer-type rearrangement of the corresponding sulfoxides 12 and 18 . These β-lactams were found to possess biological activity against several pathogenic microorganisms in vitro. The electronic activation of the lactam moiety of 19 remarkably enhanced its biological activity. A retinoic moiety was attached to 19 via an amino linker. The resultant retinamido-β-lactam 21 showed significant cytostatic activity in tracheal organ cultures obtained from vitamin-A-deficient hamsters. 相似文献
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