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根据芳环上酰胺和氢键受体位置的不同,氢键介质的芳酰胺和酰肼折叠体可以产生折叠、螺旋、"之"字型、直线型及其他扩展型的构象.由于氢键具有较高的稳定性及芳酰胺固有的平面性特征,这一系列的芳酰胺寡聚体拥有较高的可预测的构象.芳酰胺骨架本身可以通过简单的酰胺键偶合反应构筑,而不同的官能团也可以选择性地引入到特定的骨架内部或其侧... 相似文献
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Natarajan Raju Rama S. Ranganathan Mike F. Tweedle Rolf E. Swenson 《Tetrahedron letters》2005,46(9):1463-1465
Synthesis of a new scaffold derived from iminodipropionic acid for the preparation of peptide dimers and tetramers is described. 相似文献
55.
The synthesis of a third generation phosphorus-containing dendrimer possessing 24 chiral iminophosphine end groups derived from (2S)-2-amino-1-(diphenylphosphinyl)-3-methylbutane is described. In situ complexation of this dendrimer by [Pd(η3-C3H5)Cl]2 affords a catalyst, which is used in asymmetric allylic alkylations of rac-(E)-diphenyl-2-propenyl acetate and pivalate. The percentage of conversion, the yield of isolated 2-(1,3-diphenylallyl)-malonic acid dimethyl ester, and its enantiomeric excess have been measured in each case, and were found to be good to very good (ee from 90% to 95%). Furthermore, the dendritic catalyst can be recovered and reused at least two times, with almost the same efficiency. 相似文献
56.
Edwin C. Constable Deborah Gusmeroli Catherine E. HousecroftMarkus Neuburger Silvia Schaffner 《Polyhedron》2007
Strategies for the construction of TMS-protected first generation star and dendritic polyynes, which are subsequently metallated to give multiple Co2C2(CO)6 clusters, are reported. In the absence of crystallographic data, well-resolved 13C NMR spectroscopy is a powerful technique for confirming the presence of core, inner and peripheral cluster domains. 相似文献
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《Electroanalysis》2018,30(8):1659-1668
PAMAM dendrimer/reduced graphene oxide nanocomposite modified pencil graphite electrode (PAMAM/RGO/PGE) was used to fabricate an electrochemical DNA biosensor for determination of Rituxan (RTX) at low concentrations, for the first time. The fabricated biosensor was characterized with FE‐SEM, EIS, and CV techniques. The ds‐DNA/PAMAM/RGO/PGE was used as a working electrode to study the interaction between the RTX and salmon sperm ds‐DNA by DPV technique. Because of the interaction between the drug and DNA leads to a decrease in the guanine oxidation peak current, it was used as an indicator for the determination of the RTX. Under the optimized experimental conditions, a wide linear relationship between RTX concentration and guanine signal was obtained within the range of 7.0 to 60.0 μmol L−1 and 60.0 to 300.0 μmol L−1 with a low detection limit (0.56 μmol L−1). To clarify the interaction mechanism between the RTX and the ds‐DNA, DPV and UV‐Vis measurements were used. The reproducibility, stability, and performance of the constructed biosensor was examined by quantitative measuring RTX in pharmaceutical and human serum samples with good precision (RSD; 2.0–6.0 %) and acceptable recoveries (100.04–101.95 %). 相似文献
59.
The emulsion polymerization of methyl methacrylate (MMA) and styrene (St) were investigated with using polyamidoamine (PAMAM) dendrimer as seed, potassium persulfate as initiator and sodium dodecyl sulfate as emulsifier. The effects of 4.0GPAMAM dendrimer concentration, initiator concentration, emulsifier concentration, monomer concentration, and polymerization temperature on the monomer conversion and polymerization rate were investigated. At the same time, the influence of the generation of PAMAM dendrimer on latex particle size was studied also. The results showed that the monomer conversion and polymerization rate increased with increasing initiator concentration, emulsifier concentration, monomer concentration, and polymerization temperature. But polymerization rate increased firstly with an increase in the 4.0GPAMAM dendrimer from 0.03 g to 0.09 g and then decreased with further increase to 0.12 g. When the concentration of 4.0GPAMAM dendrimer less than 1.449 × 10?4 mol/L, the kinetic equation can be expressed by Rp∝[4.0GPAMAM]0.772[SDS]0.562[KPS]0.589[M]0.697, and the activation energy (Ea) of emulsion polymerization is 62.56kJ/mol. In additional, the copolymer latex particle size decreased and possessed monodispersity with increasing the generation of PAMAM dendrimer. According to FT-IR spectrum analysis, PAMAM dendrimer is successfully incorporated into the poly(PAMAM-St–MMA) latex particles. 相似文献
60.
A series of dendrons and dendrimers skeleton-constructed with azobenzene moiety were synthesized and doped in a high Tg polycarbonate (PC) as a host for nonlinear optical (NLO) materials. The optimal loading density and poling conditions were investigated using UV-vis spectral and second-harmonic generation (SHG) measurements. The results showed that the dendrons and dendrimers have good solubility in PC host, which increased with the generation increased. Moreover, the SHG measurements indicated that the dendrons possess higher nonlinearity than the dendrimers. The chromophores of lower generation dendrons were easier to orient along the poling electric field and gave a cone shape with the azobenzene branching units, which coherently contributed to the molecular hyperpolarizability and resulted in the higher SHG intensity. The temporal stability of the dendrons with 15% loading density was also investigated, and showed that the decaying in nonlinearity was slower for higher generation dendrons. 相似文献