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991.
A series of 4‐[2‐(alicyclic‐[1,2,4]oxadiazol‐3‐yl)phenoxy]‐butyric acids were synthesized from N‐hydroxy‐2‐isopropoxy benzamidine in 4 steps with good yields. These [1,2,4]oxadiazoles are novel platelet aggregation inhibitors preventing human platelet aggregation induced by thromboxane derivative U44,619 and adenosine diphosphate. A structure‐activity‐relationship study revealed that the potency for these 5‐oxadiazoles increases with the increase in the ring size of the alicylic rings. Derivative 8f may be useful as a template for the design of more potent anti‐platelet agents. 相似文献
992.
Long JW Logan MS Rhodes CP Carpenter EE Stroud RM Rolison DR 《Journal of the American Chemical Society》2004,126(51):16879-16889
We have developed crystalline nanoarchitectures of iron oxide that exhibit superparamagnetic behavior while still retaining the desirable bicontinuous pore-solid networks and monolithic nature of an aerogel. Iron oxide aerogels are initially produced in an X-ray-amorphous, high-surface-area form, by adapting recently established sol-gel methods using Fe(III) salts and epoxide-based proton scavengers. Controlled temperature/atmosphere treatments convert the as-prepared iron oxide aerogels into nanocrystalline forms with the inverse spinel structure. As a function of the bathing gas, treatment temperature, and treatment history, these nanocrystalline forms can be reversibly tuned to predominantly exhibit either Fe(3)O(4) (magnetite) or gamma-Fe(2)O(3) (maghemite) phases, as verified by electron microscopy, X-ray and electron diffraction, microprobe Raman spectroscopy, and magnetic analysis. Peak deconvolution of the Raman-active Fe-O bands yields valuable information on the local structure and vacancy content of the various aerogel forms, and facilitates the differentiation of Fe(3)O(4) and gamma-Fe(2)O(3) components, which are difficult to assign using only diffraction methods. These nanocrystalline, magnetic forms retain the inherent characteristics of aerogels, including high surface area (>140 m(2) g(-1)), through-connected porosity concentrated in the mesopore size range (2-50 nm), and nanoscale particle sizes (7-18 nm). On the basis of this synthetic and processing protocol, we produce multifunctional nanostructured materials with effective control of the pore-solid architecture, the nanocrystalline phase, and subsequent magnetic properties. 相似文献
993.
The complex, bis[N‐6‐aminopyridyl‐N‐(1S)‐(+)‐10‐camphorsulfonylamino]palladium, Pd[(S)‐APCS]2, 1 , was prepared by reaction of 2‐[(1S)‐(+)‐10‐camphorsulfonamino]‐6‐aminopyridine with PdCl2 in THF. Complex 1 has been characterized by spectroscopic methods and its structure has been determined by X‐ray crystallography. Crystal data: space group C2, a= 16.082 (2), b = 17.104 (2), c = 13.051 (2)Å, β = 99.95 (1)°, V = 3535.9 (8) Å3, Z = 2 with final residuals R1 = 0.0491 and wR2 = 0.0944. Two independent molecules, (S,S)‐Pd[(S)‐APCS]2, 1a , and (R,R)‐Pd[(S)‐APCS]2, 1b , were found in each asymmetric unit, which exchange to each other via a series of nitrogen inversion and C‐C bond rotation. The inversion energy (ΔGc1≠) and the energy barrier (δGc2≠) were 11.5 ± 0.1 Kcal mol?1 at 246 K and 9.8 ± 0.1 Kcal mol?1 at 199 K, respectively, calculated by dynamic NMR data. 相似文献
994.
A series of spiropyrans with a polyaromatic or heteroaromatic pendant was synthesized conveniently.Their photochromic behaviors were investigated with the aid of absorption spectral measurements.The results indicated that the compounds with the same parent spiropyran but different aromatic pendant show significantly different photochromic properties.This may be due to the π-π orbital interaction between the polyaromatic pendant and the open photomerocyanine form of spiropyran.The results obtained are very useful in the molecule design area. 相似文献
995.
Chin‐Ping Yang Ruei‐Shin Chen Ming‐Jui Wang 《Journal of polymer science. Part A, Polymer chemistry》2002,40(8):1092-1102
A novel tetraimide dicarboxylic acid was synthesized with the ring‐opening addition of 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, 4,4′‐oxydianiline, and trimellitic anhydride in a 1/2/2 molar ratio in N‐methyl‐2‐pyrrolidone followed by azeotropic condensation to tetraimide dicarboxylic acid. A series of poly(amide imide imide)s (PAIIs) with inherent viscosities of 0.8–1.1 dL/g were prepared from tetraimide dicarboxylic acid with various aromatic diamines by direct polycondensation. Most of the PAIIs were readily soluble in a variety of amide polar solvents and even in less polar m‐cresol and pyridine. Solvent‐cast films had tensile strengths ranging from 99 to 106 MPa, elongations at break ranging from 8 to 13%, and initial moduli ranging from 2.0 to 2.3 GPa. The glass‐transition temperatures of these PAIIs were recorded at 244–276 °C. They had 10% weight losses at temperatures above 520 °C in air or nitrogen atmospheres. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1092–1102, 2002 相似文献
996.
The synthesis and oxygen atom transfer (OAT) photoreactivity of a diiron(III) mu-oxo meso-tripentafluorophenyl bisporphyrin appended to a dibenzofuran spacer are presented. Reaction of 4,6-diformyldibenzofuran under standard Lindsey conditions furnishes the parent cofacial porphyrin architecture in a single step. These cofacial porphyrins photocatalyze the oxidation of sulfides and olefins using visible light and molecular oxygen as the terminal oxidant. High turnover numbers reflect the enhanced stability of the electron-deficient diiron(III) mu-oxo bisporphyrin core appended to a dibenzofuran spacer under aerobic conditions. 相似文献
997.
An enantioselective synthesis of (+)‐β‐himachalene ( 2 ) was accomplished starting from (1S,2R)‐1,2‐epoxy‐p‐menth‐8‐ene ( 3 ) in 15 or 16 steps with an overall yield of ca. 6% (Schemes 3, 5, and 6). Key transformations include an Ireland–Claisen rearrangement, a Corey oxidative cyclization, and a ring expansion. 相似文献
998.
Herbert Schumann Sebastian Dechert Frank Girgsdies Bernd Heymer Markus Hummert Ji‐Young Hyeon Jens Kaufmann Stefan Schutte Sonja Wernik Birgit C. Wassermann 《无机化学与普通化学杂志》2006,632(2):251-263
Synthesis and Characterization of New Intramolecularly Nitrogen‐stabilized Organoaluminium‐ and Organogallium Alkoxides The intramolecularly nitrogen stabilized organoaluminium alkoxides [Me2Al{μ‐O(CH2)3NMe2}]2 ( 1a ), Me2AlOC6H2(CH2NMe2)3‐2,4,6 ( 2a ), [(S)‐Me2Al{μ‐OCH2CH(i‐Pr)NH‐i‐Pr}]2 ( 3a ) and [(S)‐Me2Al{μ‐OCH2CH(i‐Pr)NHCH2Ph}]2 ( 4 ) are formed by reacting equimolar amounts of AlMe3 and Me2N(CH2)3OH, C6H2[(CH2NMe2)3‐2,4,6]OH, (S)‐i‐PrNHCH(i‐Pr)CH2OH, or (S)‐PhCH2NHCH(i‐Pr)CH2OH, respectively. An excess of AlMe3 reacts with Me2N(CH2)2OH, Me2N(CH2)3OH, C6H2[(CH2NMe2)3‐2,4,6]OH, and (S)‐i‐PrNHCH(i‐Pr)CH2OH producing the “pick‐a‐back” complexes [Me2AlO(CH2)2NMe2](AlMe3) ( 5 ), [Me2AlO(CH2)3NMe2](AlMe3) ( 1b ), [Me2AlOC6H2(CH2NMe2)3‐2,4,6](AlMe3)2 ( 2b ), and [(S)‐Me2AlOCH2CH(i‐Pr)NH‐i‐Pr](AlMe3) ( 3b ), respectively. The mixed alkyl‐ or alkenylchloroaluminium alkoxides [Me(Cl)Al{μ‐O(CH2)2NMe2}]2 ( 6 ) and [{CH2=C(CH3)}(Cl)Al{μ‐O(CH2)2NMe2}]2 ( 8 ) are to obtain from Me2AlCl and Me2N(CH2)2OH and from [Cl2Al{μ‐O(CH2)2NMe2}]2 ( 7 ) and CH2=C(CH3)MgBr, respectively. The analogous dimethylgallium alkoxides [Me2Ga{μ‐O(CH2)3NMe2}]2 ( 9 ), [(S)‐Me2Ga{μ‐OCH2CH(i‐Pr)NH‐i‐Pr}]n ( 10 ), [(S)‐Me2Ga{μ‐OCH2CH(i‐Pr)NHCH2Ph}]n ( 11 ), [(S)‐Me2Ga{μ‐OCH2CH(i‐Pr)N(Me)CH2Ph}]n ( 12 ) and [(S)‐Me2Ga{μ‐OCH2(C4H7NHCH2Ph)}]n ( 13 ) result from the equimolar reactions of GaMe3 with the corresponding alcohols. The new compounds were characterized by elemental analyses, 1H‐, 13C‐ and 27Al‐NMR spectroscopy, and mass spectrometry. Additionally, the structures of 1a , 1b , 2a , 2b , 3a , 5 , 6 and 8 were determined by single crystal X‐ray diffraction. 相似文献
999.
An electrochemical synthesis of oxazol‐2‐ones and imidazol‐2‐ones has been developed via 5‐exo‐dig cyclization of propargylic carbamates‐ and ureas‐derived amidyl radicals. The electrosynthesis relies on the dual function of 2,2,6,6‐tetramethylpiperidin‐ 1‐yl)oxyl (TEMPO) as a redox mediator for amidyl radical formation and an oxygen atom donor. The reactions are conducted under mild conditions using a simple setup and provide convenient access to functionalized oxazol‐2‐ones and imidazol‐2‐ones from readily available materials. 相似文献
1000.
Hydrogen storage in the dehydrated prussian blue analogues M3[Co(CN)6]2 (M = Mn, Fe, Co, Ni, Cu, Zn)
The porosity and hydrogen storage properties for the dehydrated Prussian blue analogues M3[Co(CN)6]2 (M = Mn, Fe, Co, Ni, Cu, Zn) are reported. Argon sorption isotherms measured at 87 K afford BET surface areas ranging from 560 m2/g for Ni3[Co(CN)6]2 to 870 m2/g for Mn3[Co(CN)6]2; the latter value is comparable to the highest surface area reported for any known zeolite. All six compounds show significant hydrogen sorption at 77 K and 890 Torr, varying from 1.4 wt % and 0.018 kg H2/L for Zn3[Co(CN)6]2 to 1.8 wt % and 0.025 kg H2/L for Cu3[Co(CN)6]2. Fits to the sorption data employing the Langmuir-Freundlich equation give maximum uptake quantities, resulting in a predicted storage capacity of 2.1 wt % and 0.029 kg H2/L for Cu3[Co(CN)6]2 at saturation. Enthalpies of adsorption for the frameworks were calculated from hydrogen isotherms measured at 77 and 87 K and found to increase with M varying in the order Mn < Zn < Fe < Co < Cu < Ni. In all cases, the binding enthalpies, which lie in the range of 5.3-7.4 kJ/mol, are higher than the 4.7-5.2 kJ/mol measured for Zn4O(1,4-benzenedicarboxylate)3. 相似文献