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91.
Catalytic Enantioselective 1,3‐Alkyl Shift in Alkyl Aryl Ethers: Efficient Synthesis of Optically Active 3,3′‐Diaryloxindoles
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Amol B. Gade Pradip N. Bagle Popat S. Shinde Vipin Bhardwaj Subhrashis Banerjee Dr. Ajit Chande Dr. Nitin T. Patil 《Angewandte Chemie (International ed. in English)》2018,57(20):5735-5739
Reported is the first organocatalytic asymmetric 1,3‐alkyl shift in alkyl aryl ethers for the synthesis of chiral 3,3′‐diaryloxindoles using a chiral Brønsted acid catalyst. Preliminary results showed that each enantiomer of the 3,3′‐diaryloxindole, and a racemic mixture, showed different antiproliferative activities against HeLa cell lines by using an MTT assay. 相似文献
92.
Reaction of iron(III) chloride with 1,2-ethanebis(diphenylphosphine oxide) in an ethanol/chloroform mixture formed a 11 adduct of stoichiometry FeCl3(L-L) which has been characterized by X-ray crystallography as [FeCl2(L-L)2] [FeCl4]. The structure was solved by the heavy atom method, using MoK diffractometer data and refined by full-matrix least squares toR=0.044 for 8506 observed reflections. The coordination is slightly distorted octahedral for the cation with acis-arrangement of the chlorine atoms and a seven-membered chelate ring formation by Ph2P(O)CH2CH2P(O)Ph2 with the donor O atoms also in acis arrangement. The Fe-Cl distances are equal at 2.306(1) Å but the Fe-O distances differ significantly in each of the two ligands, (avg. 2.076(2) Å; avg. 1.975(3) Å). 相似文献
93.
A study of the PbS-based vitreous semiconductors: (PbS)x(GeS)0.7?x(GeS)0.3 has been made. The presence of Pb atoms is found to induce structural changes in the network. These semiconductors display chemical ordering which depends upon the relative concentration of the constituent atoms. This property influences the electronic behavior of the semiconductors. For x = 0.23 the composition exhibits different features in its electrical conductivity and photoconductivity, as compared with the other compositions. 相似文献
94.
In this paper a new class of higher order (F,ρ,σ)-type I functions for a multiobjective programming problem is introduced, which subsumes several known studied classes. Higher order Mond-Weir and Schaible type dual programs are formulated for a nondifferentiable multiobjective fractional programming problem where the objective functions and the constraints contain support functions of compact convex sets in Rn. Weak and strong duality results are studied in both the cases assuming the involved functions to be higher order (F,ρ,σ)-type I. A number of previously studied problems appear as special cases. 相似文献
95.
AOT-based water-in-oil microemulsions display an anomalous maximum in the viscosity with X, the water to surfactant ratio. Several explanations for this phenomenon have been offered. In this work, we investigate viscosity and droplet interactions in Ca(AOT)(2)/water/n-decane and KAOT/water/n-decane microemulsions and compare our results with the commonly studied NaAOT/water/oil system. The Ca(AOT)(2) system demonstrates a maximum in relative viscosity and droplet attraction near X=15, similar to the NaAOT system, although the maximum occurs at a higher value of X in the Ca(AOT)(2) system. By contrast, the viscosity and interparticle interactions in the KAOT system do not strongly depend on the amount of water in the system. We attribute the differences in behavior between the two systems to different hydration characteristics of the counterion, and we believe that our results are consistent with a previously proposed model that attributes interdroplet attractions to charge fluctuations and surfactant exchange. Our findings support the connection between the viscosity anomaly and interparticle interactions. 相似文献
96.
Agrawal SK Sanabria-Delong N Tew GN Bhatia SR 《Langmuir : the ACS journal of surfaces and colloids》2008,24(22):13148-13154
ABA triblock copolymers in solvents selective for the midblock are known to form associative micellar gels. We have modified the structure and rheology of ABA triblock copolymer gels comprising poly(lactide)-poly(ethylene oxide)-poly(lactide) (PLA-PEO-PLA) through addition of a clay nanoparticle, laponite. Addition of laponite particles resulted in additional junction points in the gel via adsorption of the PEO corona chains onto the clay surfaces. Rheological measurements showed that this strategy led to a significant enhancement of the gel elastic modulus with small amounts of nanoparticles. Further characterization using small-angle X-ray scattering and dynamic light scattering confirmed that nanoparticles increase the intermicellar attraction and result in aggregation of PLA-PEO-PLA micelles. 相似文献
97.
Sharma PK Reilly MJ Jones DN Robinson PM Bhatia SR 《Colloids and surfaces. B, Biointerfaces》2008,61(1):53-60
We present results on the effects of various hydrophobic drugs and additives on the micellar structure of Pluronic F127 solutions. Small-angle neutron scattering experiments on 5wt% F127 solutions were used to measure micelle core size (R(1)), micelle corona size (R(2)), intermicellar interaction distance (R(int)), polydispersity (sigma), and aggregation number (N(agg)); dynamic light scattering was used to measure critical micelle concentration (CMC); and ultraviolet spectroscopy was used to measure drug solubility and apparent micelle-water partition coefficient (K(mw)). The core and corona size were found to generally increase in the presence of the drugs, as did R(int). Both sigma and N(agg) were found to decrease in the presence of most of the drugs, and the CMC was found to vary considerably with no clear correlation. A design of experiments (DOE) approach was used to analyze the results and build empirical correlations. All of the parameters from the SANS experiments were found to depend strongly on drug solubility, with a weak dependence on K(mw) in most cases. The aggregation number, however, was found to depend strongly on both K(mw) and solubility. The correlations can be used to roughly predict the structural parameters of F127 micelles for other hydrophobic drugs. 相似文献
98.
Surfaces of simple fcc metals such as Cu with nonzero and unequal Miller indices are intrinsically chiral. Density functional theory (DFT) calculations are a useful way to study the enantiospecific adsorption of small chiral molecules on these chiral metal surfaces. We report DFT calculations of seven chiral molecules on several structurally distinct chiral Cu surfaces. These surfaces include two surfaces with (111)-oriented terraces and one with (100)-oriented terraces. Calculations are also described on a surface that was modified to mimic the surface structures that typically appear on real metal surfaces following thermally driven fluctuations in step edges. Our results provide initial information on how variation in the surface structure of intrinsically chiral metal surfaces can affect the enantiospecific adsorption of small molecules on these surfaces. 相似文献
99.
Dr. Vinod Khatri Dr. Badri Parshad Prof. Ashok K. Prasad Dr. Sumati Bhatia 《European journal of organic chemistry》2023,26(9):e202201360
In the last decades, various efforts have been made to synthesize optimal glycotripods for targeting trimeric glycoproteins like asialoglycoprotein receptor, hemagglutinin, and langerin. All these trimeric glycoproteins have sugar binding pockets which are highly selective for a particular carbohydrate ligand. Optimized glycotripods are high affinity binders and have been used for delivering drugs or even applied as drug candidates. The selection of the tripodal base scaffold together with the length and flexibility of the linker between the scaffold and sugar residue, as important design parameters are discussed in this review. 相似文献
100.
Bruno Voigt Twinkle Bhatia Julia Hesselbarth Dr. Monika Baumann Prof. Dr. Carla Schmidt Dr. Maria Ott Prof. Dr. Jochen Balbach 《Chemphyschem》2023,24(19):e202300439
Nucleation and growth of amyloid fibrils were found to only occur in supersaturated solutions above a critical concentration (ccrit). The biophysical meaning of ccrit remained mostly obscure, since typical low values of ccrit in the sub-μM range hamper investigations of potential oligomeric states and their structure. Here, we investigate the parathyroid hormone PTH84 as an example of a functional amyloid fibril forming peptide with a comparably high ccrit of 67±21 μM. We describe a complex concentration dependent prenucleation ensemble of oligomers of different sizes and secondary structure compositions and highlight the occurrence of a trimer and tetramer at ccrit as possible precursors for primary fibril nucleation. Furthermore, the soluble state found in equilibrium with fibrils adopts to the prenucleation state present at ccrit. Our study sheds light onto early events of amyloid formation directly related to the critical concentration and underlines oligomer formation as a key feature of fibril nucleation. Our results contribute to a deeper understanding of the determinants of supersaturated peptide solutions. In the current study we present a biophysical approach to investigate ccrit of amyloid fibril formation of PTH84 in terms of secondary structure, cluster size and residue resolved intermolecular interactions during oligomer formation. Throughout the investigated range of concentrations (1 μM to 500 μM) we found different states of oligomerization with varying ability to contribute to primary fibril nucleation and with a concentration dependent equilibrium. In this context, we identified the previously described ccrit of PTH84 to mark a minimum concentration for the formation of homo-trimers/tetramers. These investigations allowed us to characterize molecular interactions of various oligomeric states that are further converted into elongation competent fibril nuclei during the lag phase of a functional amyloid forming peptide. 相似文献