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61.
2-甲基-8-羟基喹啉和二溴丁烷在正丁基锂的存在下反应,生成标题化合物(C24H24N2O2, Mr = 372.46)。X-射线单晶结构分析表明此晶体属于单斜晶系,空间群P21/c, a = 5.7002(5), b = 12.186(1), c = 14.312(1) , b = 92.503(2), V = 993.2(2) 3, Z = 2, m = 0.080 mm-1, Dc = 1.245 g/cm3, F(000) = 396, R = 0.0505, wR = 0.0705. 结果表明,该化合物的2个配位端基2-甲基-8-羟基-喹啉基处于间隔基团-(CH2)4-的两侧,整个分子呈现中心对称的反式构象。此外,通过分子间的p…p 堆积作用和 CH…p 作用,使分子堆积成三维网络结构。 相似文献
62.
The exposure of populations of Ceratitis capitata (fruit fly), Bactrocera oleae (olive fly) and Stomoxis calcitrans (house fly) to a bait containing mumolar concentrations of porphyrin-type photosensitizers resulted in a significant accumulation of the porphyrin by the insects and a consequent development of photosensitivity upon exposure to visible light. The photoinsecticidal activity appeared to increase with increasing hydrophobicity of the porphyrin molecule: thus, the amphiphilic dicationic meso-di(cis-4N-methyl-pyridyl)-cis-diphenyl-porphine (n-octanol/water partition coefficient = 20) was markedly more efficient than its tricationic analogue or the dianionic hematoporphyrin (n-octanol/water partition coefficient = 12). The observed large decrease in the acetylcholinesterase activity of the photosensitized flies suggests that the damage of the nervous system gives an important contribution to the phototoxic action of porphyrins. Studies with C. capitata indicate that the photoinsecticidal action of porphyrins can be utilized to control the population of noxious insects also in open field conditions. 相似文献
63.
Joanna Aizenberg Gretchen Lambert Steve Weiner Lia Addadi 《Journal of the American Chemical Society》2002,124(1):32-39
The majority of invertebrate skeletal tissues are composed of the most stable crystalline polymorphs of CaCO(3), calcite, and/or aragonite. Here we describe a composite skeletal tissue from an ascidian in which amorphous and crystalline calcium carbonate coexist in well-defined domains separated by an organic sheath. Each biogenic mineral phase has a characteristic Mg content (5.9 and 1.7 mol %, respectively) and concentration of intramineral proteins (0.05 and 0.01 wt %, respectively). Macromolecular extracts from various biogenic amorphous calcium carbonate (ACC) skeletons are typically glycoproteins, rich in glutamic acid and hydroxyamino acids. The proteins from the crystalline calcitic phases are aspartate-rich. Macromolecules extracted from biogenic ACC induced the formation of stabilized ACC and/or inhibited crystallization of calcite in vitro. The yield of the synthetic ACC was 15-20%. The presence of Mg facilitated the stabilization of ACC: the protein content in synthetic ACC was 0.12 wt % in the absence of Mg and 0.07 wt % in the presence of Mg (the Mg content in the precipitate was 8.5 mol %). In contrast, the macromolecules extracted from the calcitic layer induced the formation of calcite crystals with modified morphology similar to that expressed by the original biogenic calcite. We suggest that specialized macromolecules and magnesium ions may cooperate in the stabilization of intrinsically unstable amorphous calcium carbonate and in the formation of complex ACC/calcite tissues in vivo. 相似文献
64.
Giulio Jori Marcella Folin Giorgio Gennari Guido Galiazzo Orfeo Buso 《Photochemistry and photobiology》1974,19(6):419-433
Abstract— Rare-earth metal ions give 1:1 complexes with hen's egg-white lysozyme. Spectroscopic and enzymic activity measurements suggest that the binding site consists of the side chains of glutamic-35 and aspartic-52. The spatial conformation of these complexes is practically identical to that of native lysozyme, especially as concerns the environment of the tryptophyl side chains. Irradiation of La3+ -lysozyme by visible light, in the presence of proflavine as photosensitizer, causes the oxidative modification of all the tryptophyl and methionyl residues at almost the same rate as in uncomplexed protein. On the other hand, when lanthanide ions with nonvanishing magnetic moments were coordinated with lysozyme, at least some tryptophans and methionines were protected from photooxidative attack. The distance of the protected residues from the coordination site increased with increasing magnetic moment of the bound metal ion, which suggests that inhibition of the photoprocess was mainly due to perturbation of the lifetime of the electronically excited intermediate species. On the basis of the atomic coordinates of lysozyme in the crystal state, it is thus possible to define a "quenching radius" for the various lanthanide ions; these radii could in turn be used to evaluate intramolecular distances in proteins of unknown tertiary structure, by identifying the amino acid residues that are protected or photooxidized upon irradiation of complexes between the given protein and several different lanthanide ions. Our studieson lysozyme allow us to define five radii of protection, ranging from 6·7 Å for Sm3+ to over 17 Å for Dy3+ , Ho3+ , Er3+ and Tb3+ . Therefore, this technique opens the possibility of mapping appreciably large regions of a protein molecule. 相似文献
65.
66.
Tsuneaki Maeda 《中国化学快报》2010,21(6):730-733
<正>Triacontyl modified silica gel as a sorbent coupled with gas chromatography-mass spectrometry(GC-MS) was developed to determine EPA prior 16 polycyclic aromatic hydrocarbons(PAHs) in water samples.Various parameters of solid-phase extraction such as organic modifier solvent,eluent,sample flow rate and volume were optimized.The developed method was found to yield a linear calibration curve in the concentration range of 0.05-8μg/L with respect to naphthalene,acenaphthylene,acenaphthene and 0.01-8μg/L for dibenz[a,h]anthracene and 0.05-14μg/L for fluorene,phenanthrene,anthracene and 0.01-14μg/L for the rest of analytes.Furthermore,the good accuracy and repeatability of the method made sure the requirements for achieving reliable analysis of PAHs in the environmental water samples,and the recoveries of optimal method were in the range of 80-120%except to higher volatility PAHs.C_(30)-bonded silica was proved to be an efficient sorbent for extraction of high molecular weight PAHs. 相似文献
67.
The giant polyelectrolyte glycosaminoglycan hyaluronan (1-10 MDa) is a major component of the pericellular coat on a variety of cells, where it is an important modulator and mediator of early cell adhesion events. This pericellular layer can reach 5 mum thickness on cells that produce cartilage (chondrocytes), and up to 2 mum on Xenopus laevis kidney epithelial cells (A6). We are interested in generating model systems for the pericellular coat in order to learn more about the structure and function of hyaluronan on biological or artificial surfaces. We report here the synthesis of model systems where a coat of coordinatively cross-linked hyaluronan of up to 2 mum thickness was covalently photografted onto polystyrene microspheres. The hydrated coat was imaged directly by environmental scanning electron microscopy (ESEM) at close to 100% relative humidity. The key feature of the procedure is the reversible reverse-temperature phase transition of hyaluronan induced by trivalent lanthanide cations, which is exploited to achieve sufficient density for grafting of thick layers. The microsphere-grafted coat shows a temperature-dependent swelling when labeled with lanthanide ions (Gd(3+) or Tb(3+)). We directly observed a volume contraction of 20% with increasing temperature between 1 and 11 degrees C by wet-mode ESEM. 相似文献
68.
Ying Lu Yu Xian Li Chang Qiang Ke Chun Ping Tang Xin Zhou Yang Xi Qiang Li Yang Ye 《中国化学快报》2010,21(6):709-711
<正>A new iridoid glucoside,allamanoid(1),was isolated from the aerial parts of Allamanda neriifolia,together with three known glucosides,plumieride,protoplumericin,and nicotiflorin.Their structures were elucidated by 1D and 2D spectroscopic analyses, hydrolysis,and comparison with literature data. 相似文献
69.
<正>One new dammarane-type triterpene saponin,named(20S)-3β,20,21-trihydroxydammar-24-ene 3-O-[α-L-rhamnopyranosyl- (1→2)][β-D-xylopyranosyl(1→3)]-β-D-glucopyranoside(1),was isolated from the aerial parts of Gynostemma pentaphyllum (Thunb.) Makino.Its structural elucidation was accomplished mainly on the basis of the interrelation of spectroscopic methods, such as IR,HR-TOF-MS,NMR. 相似文献
70.
Cheng Bo Zhang Ying Li Wen Ke Liu Hai Quan Zhang Huai Yang Qing Shan Li Guang Zhong Xing 《中国化学快报》2009,20(12):1423-1426
The trimeric phenylenevinylene with the symmetrical chiral end-groups(ChTPV) was synthesized.The liquid crystalline and luminescent properties of the ChTPV have been studied by differential scanning calorimetry(DSC),polarized optical microscopy (POM),absorption and photoluminescence spectra.The results indicated that the ChTPV exhibits mesophase over a wide temperature range and a typical optical texture of smectic phase.In contrast with the spectra of the solution,that of the film showed blue-shift in m... 相似文献