Synthesis and reactions of phenylimidotrimethyl-bis(trimethylphosphine)-rhenium(V). Synthesis and X-ray crystal structure of bis(trimethylsilylmethyl)oxo-rhenium(V)-μ-oxo-tetrakis(trimethylphosphine)rhenium (I)-(trimethylsilylmethyl)dioxorhenium(V), (ReRe)

The interaction of phenylimidotrichloro bis(trimethylphosphine) with dimethylmagnesium gives the trimethyl compound, Re(NPh)Me₃(PMe₃)₂. Exchange reactions between the trichloro and trimethyl compounds are studied by ¹H nuclear magnetic resonance and the intermediates Re(NPh)Me₂Cl(PMe₃)₂ and Re(NPh)MeCl₂(PMe₃)₂ isolated.The trimethyl reacts with fluoroboric acid to give a phenylamido complex [Re(NHPh)Me₂F(PMe₃)₂]BF₄, with acetic acid to give Re(NPh)Me(CO₂Me₃)₂, and with trityltetrafluoroborate to give [Re(NPh)Me₂(PMe₃)₂]BF₄.The interaction of Re(NPh)Cl₃(PMe₃)₂ with excess of bis(trimethylsilylmethyl)magnesium and of trimethyl-phosphine in tetrahydrofuran gives an unusual tri-rhenium compound, (Me₃SiCH₂)₃(O)Re-μ-O-Re(PMe₃)₄Re(O)₂(CH₂SiMe₃) whose structure as a thf solvate, has been determined by X-ray crystallography. Crystals of the latter are monoclinic, space group P2₁/n with a = 15.512(3), b = 15.392(2), c = 21.506(4) Å, β = 100.19(2)°, Z = 4. The structure has been refined to an R of 0.07 for 5028 observed diffractometer data. The molecule is tri-nuclear with the central rhenium carrying four PMe₃ groups being bound to the second rhenium by a short ReRe bond and to the third by an asymmetric oxygen bridge. The end rhenium bound to the bridge oxygen carries two CH₂SiMe₃ groups and an oxygen atom, while the other has one CH₂SiMe₃ group and two oxygen atoms.     

Potential for microbial growth in arid subsurface sediments

To determine if bacterial populations could be increased for bioremediation of contaminants, the microbial growth arising in 200 h from the solid material from the vadose zone at an arid site after addition of water and nutrients was determined. Initial bacterial populations and activities at the site were very low. Bacteria grew in the interbed sands and silts with the higher carbon contents (0.08–1.1%), but did not respond in the basalts and interbed material with lower carbon content (undetectable). In longer term studies, to 30 d, there was evidence for bacterial activity in less than 25% of either the basalts or interbed material.

     

Evaluation of Anthocyanin Content,Antioxidant Potential and Antimicrobial Activity of Black,Purple and Blue Colored Wheat Flour and Wheat-Grass Juice against Common Human Pathogens

The present study aimed to analyze the antioxidant and antimicrobial activity of anthocyanins extracted from colored wheat flour and wheat-grass juice against human pathogens. The total anthocyanin content and antioxidant potential in colored wheat flour and wheat-grass juice extracts were significantly higher than white flour and wheat-grass juice extracts. Ultra-performance liquid chromatography showed the maximum number of anthocyanin peaks in black wheat, with delphinidin-3-o-galactoside chloride, delphinidin-3-o-glucoside chloride, and cyanindin-3-o-glucoside chloride as the major contributors. Among flour extracts, maximum zones of inhibition against Staphylococcus aureus (MTCC 1934), Pseudomonas aeruginosa (MTCC 1434), Escherichia coli, and Candida albicans (MTCC 227) were produced by black flour extract, having the highest anthocyanin content. It exhibited a minimum microbicidal concentration (MMC) of 200 mg/mL against E. coli and C. albicans; and 100 and 150 mg/mL against S. aureus and P. aeruginosa, respectively. Black and purple flour extracts exhibited a minimum inhibitory concentration (MIC) of 50 mg/mL against S. aureus and P. aeruginosa. White flour extracts did not show MMC against E. coli and C. albicans. Among wheat-grass juice extracts, black wheat-grass was most effective and showed an MIC of 100–150 mg/mL against all pathogens. It exhibited an MMC of 200 mg/mL against S. aureus and P. aeruginosa. Hence, anthocyanin-rich colored wheat could be of nutraceutical importance.     

Enantioselective S−H Insertion Reactions of α‐Carbonyl Sulfoxonium Ylides

The first example of enantioselective S?H insertion reactions of sulfoxonium ylides is reported. Under the influence of thiourea catalysis, excellent levels of enantiocontrol (up to 95 % ee) and yields (up to 97 %) are achieved for 31 examples in S?H insertion reactions of aryl thiols and α‐carbonyl sulfoxonium ylides.     

One‐pot solvent and catalyst‐free synthesis of functionalized 1,8‐naphthyridines and quinolines by microwave irradiation

A series of functionalized, aryl substituted naphthyridines and quinolines has been synthesized by microwave‐assisted one‐pot two‐component synthesis under solvent‐free conditions in good yields by the reaction of a variety of aryl or heteroaryl amines and aryl vinyl ketones. A combinatorial type approach for a one‐step microwave reaction has been developed where a ring‐closing condensation is followed by a spontaneous aromatization to afford the functionalized aryl substituted 1,8‐naphthyridines and quinolines.     

Studies of β-turn opening with model peptides containing non-coded α-amino isobutyric acid

Single crystal X-ray diffraction studies show that among the three terminally protected model tripeptides I-III, Boc-Ile-Aib-Xx-OMe (Xx in peptide I: Val; II: Leu; III: Phe) with a centrally placed non-coded amino acid Aib (Aib: α-amino isobutyric acid), peptide I displays a conformational preference for β-turn, peptide II forms a hydrated β-turn representing the solvent mediated intermediate for the interconversion between β-turn and β-strand and peptide III adopts a completely unfolded β-strand like structure. By varying the steric bulk of the third residue, Xx(3), various conformations related to the structural interconversion between the β-turn and β-strand have been isolated. The peptide conformations in the solution phase have been probed by solvent dependent NMR titration and CD spectroscopy. Morphological studies with scanning electron microscopy (SEM) reveal that among the three peptides only peptide III can form filamentous fibrils in the solid state.     

Polarizations on abelian subvarieties of principally polarized abelian varieties with dihedral group actions

For any $n\ge 2$ we study the group algebra decomposition of an $([\frac{n}{2}]+1)$ -dimensional family of principally polarized abelian varieties of dimension $n$ with an action of the dihedral group of order $2n$ . For any odd prime $p, n=p$ and $n=2p$ we compute the induced polarization on the isotypical components of these varieties and some other distinguished subvarieties. In the case of $n=p$ the family contains a one-dimensional family of Jacobians. We use this to compute a period matrix for Klein’s icosahedral curve of genus 5.