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991.
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Mauricio Navarro Villalobos Susan Jeong Cristy Lindberg Benson Steven M. Zeman Catherine McCarty Matthew M. Weiss Analee Salcedo Jonathan Jenkins 《Tetrahedron》2009,65(39):8091-1520
The first total syntheses of (−)-syringolide 3, (+)-syributin 3 and their unnatural enantiomers (+)-syringolide 3 and (−)-syributin 3 using a common intermediate as starting material are described. In addition, total syntheses of (−)- and (+)-syributins 1 and 2 were accomplished by means of the same methodology. 相似文献
995.
We investigated the structure and stability of dodecane-in-water emulsions stabilised by partially hydrophobised silica particles after dilution of the emulsions in solutions of sodium dodecyl sulfate and sodium chloride. The emulsions were stable to coalescence on dilution in salt solutions, but did cream over time. The rate and extent of creaming gradually decreased as the salt concentration in the diluted emulsion increased. Dilution in low concentrations of the anionic surfactant did not affect the emulsion stability to coalescence or alter the creaming behaviour of the emulsion. At surfactant concentrations above the critical micelle concentration, however, the rate and extent of creaming and flocculation of the drops were enhanced. 相似文献
996.
Toussaint G Brisbois M Grandjean J Cloots R Henrist C 《Journal of colloid and interface science》2009,329(1):120-126
The surface modification of lamellar silica prepared by liquid crystal templating has been investigated. Two hydrophilic surface modifier agents, 2-glycidoxypropyltrimethoxysilane and 2-[methoxy(polyethyleneoxy)propyl)]trimethoxysilane, have been tested. Characterizations of the modified silica include thermal analysis, (13)C and (29)Si solid state NMR, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The different characterizations confirmed the preservation of the lamellar morphology and the successful surface modification with both silanes along with the template elimination. The results also indicate that the structure and length of the silanes influence the final lamellar organization as well as the grafting yields and mechanisms. 相似文献
997.
998.
Andreas Sofetis Fotini Fotopoulou Catherine P. Raptopoulou Theodoros F. Zafiropoulos Spyros P. Perlepes Nikolaos Klouras 《Polyhedron》2009
The reaction of [TiIV(Cp)2Cl2] (Cp− = η5-C5H5−) and 2,6-bis(3,5-dimethylpyrazolyl-1-yl)pyridine (bdmpp) in Me2CO has afforded complex [TiIVCl2(O2)(bdmpp)] (1). The complex can also be prepared from the 1:1:1 [Ti(Cp)2Cl2]/bdmpp/H2O2 reaction mixture in various solvents. Single-crystal, X-ray crystallography has revealed that the TiIV center is in a distorted pentagonal bipyramidal environment in both of the two, crystallographically independent molecules that are present in the asymmetric unit; the equatorial positions are occupied by the two O atoms of the side-on (η2) O22− group and the three N-atoms of the tridentate chelate, while the two chloro ligands are on the axial positions. IR, Raman, electronic and 1H NMR data are discussed in terms of the known structure and the coordination modes of the peroxo and bdmpp ligands. 相似文献
999.
Konstantis F. Konidaris Michalis Kaplanis Catherine P. Raptopoulou Spyros P. Perlepes Evy Manessi-Zoupa Eugenia Katsoulakou 《Polyhedron》2009
The initial employment of pyridine-3-carbaldehyde oxime, (3-py)C(H)NOH, and pyridine-4-carbaldehyde oxime, (4-py)C(H)NOH, in zinc(II) carboxylate chemistry is reported. The syntheses, crystal structures and IR characterization are described for [Zn3(O2CPh)6{(3-py)C(H)NOH}2] (1) and [Zn2(O2CPh)4{(4-py)C(H)NOH}2] (2). The trinuclear molecule of 1 has a linear structure, with one monoatomically bridging η1:η2:μ and two syn, syn-η1:η1:μ benzoate groups spanning each pair of ZnII ions; the terminal metal ions are each capped by one (3-py)C(H)NOH ligand coordinating through its pyridyl nitrogen. Complex 2 exhibits a dinuclear paddle–wheel structure with a Zn···Zn distance of 2.990(2) Å; each ZnII ion has a square pyramidal geometry with four carboxylate oxygens in the basal plane and the pyridyl nitrogen of one monodentate (4-py)C(H)NOH ligand at the apex. Both complexes form 1D architectures by virtue of hydrogen bonding interactions involving the free oxime group as donor and the oxime nitrogen (1) or carboxylate oxygens (2) as acceptors. IR data are discussed in terms of the known structures and coordination modes of the ligands. 相似文献
1000.
Constantinos G. Efthymiou Constantina Papatriantafyllopoulou Nadia I. Alexopoulou Catherine P. Raptopoulou Roman Boča Jerzy Mrozinski Evangelos G. Bakalbassis Spyros P. Perlepes 《Polyhedron》2009
The reactions of 2-(hydromethyl)pyridine, hmpH, with Ni(O2CMe)2·4H2O in H2O, in the absence of counterions, have been investigated. The synthetic study has led to the two new complexes [Ni(O2CMe)2(hmpH)2] (1) and [Ni4(O2CMe)4(hmp)4(H2O)2] (2). Complex 1 can also be transformed into 2 by reacting with an excess of NaOH in H2O. The structures of 1 and 2·2.25H2O·0.5(1,4-dioxane) have been solved by single-crystal, X-ray crystallography. The octahedral NiII center in centrosymmetric 1 is coordinated by two 1.10 (Harris notation) MeCO2− groups and two N,O-chelating (1.11) hpmH ligands. The tetranuclear cluster molecule of 2·2.25H2O·0.5(1,4-dioxane) possesses a distorted cubane {Ni4(μ3-OR′)4}4+ core [R′ = (2-pyridyl)CH2–] with the NiII ions and the oxygen atoms from the 3.31 hmp− ligands occupying alternate vertices of the cube. Two 2.11 MeCO2− groups cap two opposite faces of the cube, while two 1.10 MeCO2− ions and two aqua ligands complete the octahedral coordination sphere of the metal centers. Characteristic IR bands for the two complexes are discussed in terms of the nature of bonding and the structures of the two complexes. The variable-temperature magnetic properties of 2 have been modeled with two J values, and reveal antiferromagnetic exchange interactions between the four NiII ions to give a diamagnetic ground state. 相似文献