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91.
Sautter A Kaletas BK Schmid DG Dobrawa R Zimine M Jung G van Stokkum IH De Cola L Williams RM Würthner F 《Journal of the American Chemical Society》2005,127(18):6719-6729
A molecular square with dimensions of about 4 nm, incorporating sixteen pyrene chromophores attached to four ditopic bay-functionalized perylene bisimide chromophores, has been synthesized by coordination to four Pt(II) phosphine corner units and fully characterized via NMR spectroscopy and ESI-FTICR mass spectrometry. Steady-state and time-resolved emission as well as femtosecond transient absorption studies reveal the presence of a highly efficient (>90%) and fast photoinduced energy transfer (k(en) approximately equal to 5.0 x 10(9) s(-1)) from the pyrene to the perylene bisimide chromophores and a very fast and efficient electron transfer (>94%, k(et) approximately equal to 5 x 10(11) up to 43 x 10(11) s(-1)). Spectrotemporal parametrization indicates upper excited-state electron-transfer processes, various energy and electron-transfer pathways, and chromophoric heterogeneity. Temperature-dependent time-resolved emission spectroscopy has shown that the acceptor emission lifetime increases with decreasing temperature from which an electron-transfer barrier is obtained. The extremely fast electron-transfer processes (substantially faster and more efficient than in the free ligand) that are normally only observed in solid materials, together with the closely packed structure of 20 chromophoric units, indicate that we can consider the molecular square as a monodisperse nanoaggregate: a molecularly defined ensemble of chromophores that partly behaves like a solid material. 相似文献
92.
Bixing Fang Lina Dong Xingwei Ding YingZi Ren Zhongsheng Lv Kuan Liu Feng Zhang Wei Zhang Jianjian Deng Hongbo Xin Xiaolei Wang 《中国化学快报》2019,30(6):1178-1181
Black fungus aerogel (BFA) exhibited interesting double-faced properties. Weexplored the diverse properties of each side of the black fungus in three aspects:water contact angle measurements, liquid selective absorption capacity and air pollutant adsorption abilities. 相似文献
93.
A bismuth ion-selective electrode has been used to determine the nature and stability of the complexes formed by bismuth with citric acid and malic acid, by measurement of the response of the electrode to different total bismuth concentrations at various combinations of pH and total ligand concentration. The values found were beta(2) = 3 x 10(13) for Bi(Cit)(2)(3-) and beta(3) = 8 x 10(9) for Bi(Mal)(2)(3-). 相似文献
94.
95.
Codée JD Litjens RE den Heeten R Overkleeft HS van Boom JH van der Marel GA 《Organic letters》2003,5(9):1519-1522
Diphenylsulfoxide in combination with triflic anhydride provides a very potent thiophilic glycosylation promotor system, capable of activating disarmed thioglycosides. The usefulness of this novel thiophilic activator is illustrated in a successful chemoselective glycosylation sequence in which the donor thioglycoside in the first condensation step may be either armed or disarmed. [reaction: see text] 相似文献
96.
Maria A Girault JP Saatov Z Harmatha J Dinan L Lafont R 《Journal of chromatographic science》2005,43(3):149-157
Ecdysteroid glycosides are found in both animals and plants. The chromatographic behavior of these molecules is characteristic, as they appear much more polar than their corresponding free aglycones when analyzed by normal-phase high-performance liquid chromatography (HPLC), whereas the presence of glycosidic moieties has a very limited (if any) impact on polarity when using reversed-phase HPLC. Biological activity is greatly reduced because the presence of this bulky substituent probably impairs the interaction with ecdysteroid receptor(s). 2-Deoxy-20-hydroxyecdysone 22-O-beta-D-glucopyranoside, which has been isolated from the dried aerial parts of Silene nutans (Caryophyllaceae), is used as a model compound to describe the rationale of ecdysteroid glycoside purification and identification. 相似文献
97.
Wang Y Deng K Gui L Tang Y Zhou J Cai L Qiu J Ren D 《Journal of colloid and interface science》1999,213(1):270-272
Nanoscopic particles of oxovanadium phthalocyanine (VOPc, phase-II) with different particle sizes are prepared by aggregation of VOPc molecules in the presence of surfactants for the first time. A size effect in the region of nanoscale was observed in the UV-visible spectra. The photoconductivity of the nanoscopic VOPc is much higher than that of bulk VOPc. Copyright 1999 Academic Press. 相似文献
98.
Bi-Sr-Ca-Cu-O超导材料中存在110K和80K2个超导相。其组成是Bi_2Sr_2Ca_2Cu_3O_y和Bi_2Sr_2CaCu_2O。但迄今为止,在按2223组成比合成的未掺杂Bi系超导材料中从未得到过纯的110K相,也未见过组成为2223,零电阻温度在100K以上材料的报道。为了探索形成110K相的最佳条件,本文以2223组成比为参考,合成了5个系列材料:Bi_xSr_2Ca_2Cu_3O_y,Bi_2Sr_xCa_2Cu_3O_y,Bi_2Sr_2Ca_xCu_3O_y,Bi_2Sr_2Ca_2Cu_xO_y,Bi_i Sr_uCa_yCu_wO_s。 相似文献
99.
A liquid chromatographic-tandem mass spectrometric (LC-MS/MS) assay was developed and validated to determine tripdiolide in human whole blood using dexamethasone acetate as an internal standard (I.S.). Liquid-liquid extraction with ethyl acetate was used to isolate them from the biological matrix. Detection was performed on a mass spectrometer coupled with a negative atmospheric pressure chemical ionization (APCI) in the multiple-reaction monitoring (MRM) mode. The calibration curve was linear (r2 = 0.9973) in the concentration range of 0.5-100.0 ng/mL in human whole blood with a lower limit of quantification of 0.5 ng/mL. Intra-day and inter-day relative standard deviations (R.S.D.s) were less than 7.0 and 10.1%, respectively. Extraction recoveries of tripdiolide ranged from 80.5 to 90.1%. This assay can be used to determine trace tripdiolide in human whole blood. 相似文献
100.
The equilibrium geometries, electronic structures, as well as one- and two-photon absorption cross sections of a series of octupolar chromophores with Zn(2+) or Cu(+) as coordinate centers and 4,4'-bis(dibutylaminostyryl)-[2,2']-bis(bipyridyl) as ligands have been determined by using B3LYP/6-31G and ZINDO methods. These molecules are designed by controlled combination of two or three bipyridyl ligands with the metal centers. The results show that Zn(2+) is an effective template for the design of octupolar structures which enable it to form tetrahedral and octahedral coordinated complexes; while Cu(+) only exists in a tetrahedral coordinated complex, comparing the tetrahedral complex with Zn(2+) as the center with that of Cu(+) as the center, it is found that the complex with the Cu(+) center is a better two-photon absorption material than the former as far as the transparency/nonlinearity is concerned. Furthermore, for the same metal center of Zn(2+), both one- and two-photon absorptions of the tetrahedral complex are redshifted relative to those of the octahedral complex, is attributed to the spiroconjugation effect in the tetrahedral complex. Our theoretical findings are consistent with recent experimental observations and provide an important foundation for the design of improved transparency-nonlinearity two-photon absorption materials. 相似文献