Phosphorus-based p-tert-butylcalix[5]arene ligands

New calix[5]arene trivalent phosphorus derivatives have been synthesized which should be excellent ligands with which to study and control the interaction of a ligand atom with a metal. The larger cavity of the calix[5]arene (compared to calix[4]arene) provides a good balance between constraint and flexibility. Treatment of p-tert-butylcalix[5]arene with 2 equiv of either tris(dimethylamino)phosphine or dichlorophenylphosphine inserts two RP moieties into the calix[5]arene framework to give calix[5](PR)2(OH) (1, R = Me2N; 2, R = Ph). Further treatment of 1 with 4 equiv of HCl gives calix[5](PCl)2(OH) (3). Heating a solution of the monophosphorus compound calix[5](PNMe2)(OH)3 (4) releases dimethylamine to yield both monomeric calix[5](P)(OH)2 (6) and dimeric [calix[5](P)(OH)2](2) (7), the latter having a tubelike geometry. X-ray crystallographic studies confirm the structures and show that 1 and 2 have approximate cone conformations while 3 has an approximate 1,2-alternate conformation. The orientations of the phosphorus lone pairs and oxygen atoms in all derivatives provide a framework for both soft and hard ligand interactions within the calix[5]arene.     

Ligand location and biochemical productivity of silica-based immunoaffinity adsorbents.

Ligand location within particles, detected by immunogold labelling, was shown to influence the biochemical productivity of a silica-based solid phase, Sorbsil C-500, using a model ligand-biomolecule system (immobilised human immunoglobulin G-anti-human immunoglobulin G monoclonal antibody). The distribution of the ligand was in turn affected by the initial ligand challenge used to prepare the immunoadsorbents. Maximal productivity was achieved with adsorbents prepared with an initial challenge of about 3 mg human immunoglobulin G per ml: the ligand in these cases was shown to be more uniformally distributed within the adsorbent particles than adsorbents, exhibiting low productivity, prepared with either low (1 mg/ml) or high (9 mg/ml) concentrations of human immunoglobulin G. The ligand in the latter was restricted to the periphery of the particles.     

Euphorbiasteroid Abrogates EGFR and Wnt/β-Catenin Signaling in Non-Small-Cell Lung Cancer Cells to Impart Anticancer Activity

EGFR and Wnt/β-catenin signaling pathways play a prominent role in tumor progression in various human cancers including non-small-cell lung carcinoma (NSCLC). Transactivation and crosstalk between the EGFR and Wnt/β-catenin pathways may contribute to the aggressiveness of cancers. Targeting these oncogenic pathways with small molecules is an attractive approach to counteract various types of cancers. In this study, we demonstrate the effect of euphorbiasteroid (EPBS) on the EGFR and Wnt/β-catenin pathways in NSCLC cells. EPBS induced preferential cytotoxicity toward A549 (wildtype EGFR-expressing) cells over PC-9 (mutant EGFR-expressing) cells. EPBS suppressed the expression of EGFR, Wnt3a, β-catenin, and FZD-1, and the reduction in β-catenin levels was found to be mediated through the activation of GSK-3β. EPBS reduced the phosphorylation of GSK-3β^S9 with a parallel increase in β-TrCP and phosphorylation of GSK-3β^Y216. Lithium chloride treatment increased the phosphorylation of GSK-3β^S9 and nuclear localization of β-catenin, whereas EPBS reverted these effects. Forced expression or depletion of EGFR in NSCLC cells increased or decreased the levels of Wnt3a, β-catenin, and FZD-1, respectively. Overall, EPBS abrogates EGFR and Wnt/β-catenin pathways to impart its anticancer activity in NSCLC cells.     

Role of method of synthesis on the size of flakes,dispersion stability and thermophysical properties of aqua based reduced graphene oxide nanofluids

Journal of Thermal Analysis and Calorimetry - The role of method of synthesis on the size of flakes, dispersion stability and thermophysical properties of aqua based reduced graphene oxide (rGO)...     

Synthesis and biological evaluation of some new class of benzothiazole–pyrazole ligands containing arene ruthenium,rhodium and iridium complexes

Transition Metal Chemistry - Metal complexes 1–9 have been synthesized by reacting the benzothiazole–pyrazole derivative ligands (L1, L2 and L3) with the metal precursors of ruthenium...     

Stereochemical applications of mass spectrometry: 1—The utility of electron impact and chemical ionization mass spectrometry in the differentiation of stereoisomeric benzoin oximes and phenylhydrazones

A study of the electron impact and chemical ionization (H₂, CH₄, and iso-C₄H₁₀) mass spectra of stereoisomeric benzoin oximes and phenylhydrazones indicates that while the former can be distinguished only by their chemical ionization mass spectra the latter are readily distinguishable by both their electron impact and chemical ionization mass spectra. The electron impact mass spectra of the isomeric oximes are practically identical; however, the chemical ionization spectra show that the E isomer forms more stable [MH]⁺ and [MH? H₂O]⁺ ions than the Z isomer for which both the [MH]⁺ and [MH? H₂O]⁺ ions are relatively unstable. In electron impact the Z-phenylhydrazone shows a lower [M]⁺˙ ion abundance and more facile loss of H₂O than does the E isomer. This more facile H₂O loss also is observed for the [MH]⁺ ion of the Z isomer under chemical ionization conditions.     

Chemical ionization mass spectra of mononitroarenes

The H₂ and CH₄ chemical ionization mass spectra of a selection of substituted nitrobenzenes have been determined. It is shown that reduction of the nitro group to the amine is favoured by high source temperatures and the presence of water in the ion source. The H₂ chemical ionization mass spectra are much more useful for distinguishing between isomeric compounds than the CH₄ CI mass spectra because of the more extensive fragmentation. For ortho substituents bearing a labile hydrogen abundant [MH ? H₂O]⁺ fragments are observed. When the substituent is electron-releasing both ortho and para substituted nitrobenzenes show abundant [MH? OH]⁺ fragment ions while meta substituted compounds show abundant loss of NO and NO₂ from [MH]⁺. The latter fragmentation is interpreted in terms of protonation para to the substituent or ortho to the vitro function, while the first two fragmentation routes arise from protonation at the nitro group. When the substituent is electron-attracting the chemical ionization mass spectra of isomers are very similar except for the H₂O loss reaction for ortho compounds.     

Comparative Study of Natural Terpenoid Precursors in Reactive Plasmas for Thin Film Deposition

If plasma polymer thin films are to be synthesised from sustainable and natural precursors of chemically heterogeneous composition, it is important to understand the extent to which this composition influences the mechanism of polymerisation. To this end, a well-studied monoterpene alcohol, terpinen-4-ol, has been targeted for a comparative study with the naturally occurring mix of terpenes (viz. Melaleuca alternifolia oil) from which it is commonly distilled. Positive ion mode mass spectra of both terpinen-4-ol and M. alternifolia oil showed a decrease in disparities between the type and abundance of cationic species formed in their respective plasma environments as applied plasma power was increased. Supplementary biological assay revealed the antibacterial action of both terpinen-4-ol and M. alternifolia derived coatings with respect to S. aureus bacteria, whilst cytocompatibility was demonstrated by comparable eukaryotic cell adhesion to both coatings. Elucidating the processes occurring within the reactive plasmas can enhance the economics of plasma polymer deposition by permitting use of the minimum power, time and precursor pre-processing required to control the extent of monomer fragmentation and fabricate a film of the desired thickness and functionality.     

A novel and simple route for the synthesis of 3,4‐disubstituted pyrroles

A new class of 3,4‐disubstituted pyrroles has been prepared by the reaction of 1‐aroyl‐2‐arylsul‐fonylethenes and 1,2‐diarylsulfonylethenes with tosyl methyl isocyanide.