Capilliposide-A, a rare secondary saponin found in Lysimachia capillipes, has been reported to exhibit good biological activities. However, it is difficult to obtain a sufficient of capilliposide-A for further research through column chromatography and chemical synthesis. The aim of this work was to establish an efficient approach for the convenient preparation of this steroid saponin based on alkaline hydrolysis. The hydrolysis conditions were optimized by response surface methodology after a preliminary investigation of the affecting factors by single-factor experiments. Under the optimal conditions, the macroporous resin that adsorbed capilliposide-B and capilliposide-C was hydrolyzed in an 8% (w/v) NaOH solution at 35 °C for 65 h, and the yield of capilliposide-A was 68.90%. The results demonstrated that this newly developed approach is efficient for the preparation of capilliposide-A, and this approach is also crucial for further development and clinical applications.
Reactions of (NH4)2WS4 with CuCN, CuCN/1,2-bis(4-pyridyl)propane (bppa) or [Cu(MeCN)4]PF6/bppa under different reaction conditions afforded a set of two- or three-dimensional W/Cu/S cluster-based coordination polymers including {[Et4N]2[WS4Cu4(μ-CN)2(μ-I)2]}n ( 1 ), [WS4Cu4(μ-CN)2(bppa)2]n ( 2 ) and {[WS4Cu4(bppa)4](PF6)2}n ( 3 ), respectively. Compound 2 can be readily formed from reaction of 1 with bppa under solvothermal conditions. Compounds 1 and 2 feature two-dimensional networks with a “sql” topology, while 3 possesses a two-fold interpenetrated three-dimensional net with a rare “reo” topology. Compounds 1 – 3 in DMF exhibited different third-order nonlinear optical responses, and they all showed a reverse saturable absorption while 2 held a strong self-focusing effect. 相似文献
In this paper, a novel improvement in the catalytic Fenton reaction system named MHACF-NH2-MIL-101(Cr) was constructed based on H2 and Pd/NH2-MIL-101(Cr). The improved system would result in an accelerated reduction in FeIII, and provide a continuous and fast degradation efficiency of the 10 mg L-1 4-chlorophenol which was the model contaminant by using only trace level FeII. The activity of Pd/NH2-MIL-101(Cr) decreased from 100% to about 35% gradually during the six consecutive reaction cycles of 18 h. That could be attributed to the irreversible structural damage of NH2-MIL-101(Cr). 相似文献
The dynamics of random sequential partitioning of a square into ever smaller mutually exclusive rectangular blocks, which we call weighted planar stochastic lattice (WPSL), is governed by infinitely many conservation laws. Recently, we have shown one of the infinitely many conservation laws can be used as multifractal measure. In this article, we show that except the conservation of total area, each of the infinitely many non-trivial conservation laws is actually a multifractal measure and hence WPSL is a multi-multifractal. We then look at the block size distribution function and find that it exhibits dynamic scaling revealing that the spatial patterns of WPSL of different sizes are statistically self-similar. Besides, we investigate how the mean area ⟨A⟩k of blocks with k neighbours and the average number of neighbours mk of a typical cell that neighbours a k-sided block behaves with k. These results suggest that the Lewis law, ⟨A⟩k∝k, is obeyed for up to k ≈ 8 and the Aboav–Weaire law, kmk∝k, is violated for the entire range of k. 相似文献
The [3 + 2] cycloaddition reaction between sodium azide and various organic nitriles proceeds smoothly in the presence of amine salts as catalyst in dimethylformamide. The corresponding 5-substituted 1-H tetrazoles were obtained under mild condition in good to excellent yields. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献
Fractals equipped with intrinsic arithmetic lead to a natural definition of differentiation, integration, and complex structure. Applying the formalism to the problem of a Fourier transform on fractals we show that the resulting transform has all the required basic properties. As an example we discuss a sawtooth signal on the ternary middle-third Cantor set. The formalism works also for fractals that are not self-similar. 相似文献