Preparation and characterization of the argentates: [Ag[P(CF(3))(2)](2)](-), [Ag[(micro-P(CF(3))(2))M(CO)(5)](2)](-) (M = Cr, W), and [Ag[(micro-P(C(6)F(5))(2))W(CO)(5)](2)](-): X-ray crystal structure of [K(18-crown-6)][Ag[(micro-P(CF(3))(2))Cr(CO)(5)](2)

The first example of a mononuclear diphosphanidoargentate, bis[bis(trifluoromethyl)phosphanido]argentate, [Ag[P(CF(3))(2)](2)](-), is obtained via the reaction of HP(CF(3))(2) with [Ag(CN)(2)](-) and isolated as its [K(18-crown-6)] salt. When the cyclic phosphane (PCF(3))(4) is reacted with a slight excess of [K(18-crown-6)][Ag[P(CF(3))(2)](2)], selective insertion of one PCF(3) unit into each silver phosphorus bond is observed, which on the basis of NMR spectroscopic evidence suggests the [Ag[P(CF(3))P(CF(3))(2)](2)](-) ion. On treatment of the phosphane complexes [M(CO)(5)PH(CF(3))(2)] (M = Cr, W) with [K(18-crown-6)][Ag(CN)(2)], the analogous trinuclear argentates, [Ag[(micro-P(CF(3))(2))M(CO)(5)](2)](-), are formed. The chromium compound [K(18-crown-6)][Ag[(micro-P(CF(3))(2))Cr(CO)(5)](2)] crystallizes in a noncentrosymmetric space group Fdd2 (No. 43), a = 2970.2(6) pm, b = 1584.5(3) pm, c = 1787.0(4), V = 8.410(3) nm(3), Z = 8. The C(2) symmetric anion, [Ag[(micro-P(CF(3))(2))Cr(CO)(5)](2)](-), shows a nearly linear arrangement of the P-Ag-P unit. Although the bis(pentafluorophenyl)phosphanido compound [Ag[P(C(6)F(5))(2)](2)](-) has not been obtained so far, the synthesis of its trinuclear counterpart, [K(18-crown-6)][Ag[(micro-P(C(6)F(5))(2))W(CO)(5)](2)], was successful.     

Optimised isolation of polysaccharides from Lentinula edodes strain NCBI JX915793 using response surface methodology and their antibacterial activities

Mycelial growth in a defined medium by submerged fermentation is a rapid and alternative method for obtaining fungal biomass of consistent quality. Biomass, exopolysaccharides (EPS) and intracellular polysaccharides (IPS) production were optimised by response surface methodology in Lentinula edodes strain LeS (NCBI JX915793). The optimised conditions were pH 5.0, temperature 26°C, incubation period of 25 days and agitation rate of 52 r/min for L. edodes strain LeS. Under the calculated optimal culture conditions, biomass production (5.88 mg mL^? 1), EPS production (0.40 mg mL^? 1) and IPS production (12.45 mg g^? 1) were in agreement with the predicted values for biomass (5.93 mg mL^? 1), EPS (0.55 mg mL^? 1) and IPS production (12.64 mg g^? 1). Crude lentinan exhibited highest antibacterial effects followed by alcoholic, crude and aqueous extracts. The results obtained may be useful for highly effective yield of biomass and bioactive metabolites.     

Interpenetrated structure and compressibility studies in pressure frozen pentafluoropyridine crystals at 0.3 and 1.1 GPa

Pentafluoropyridine has been pressure frozen in situ in a diamond-anvil cell (DAC) and its structure determined at 0.30(5) and 1.10(5) GPa and at room temperature by single-crystal X-ray diffraction. The freezing pressure of pentafluoropyridine has been determined to be 0.10(5) GPa. The crystals are monoclinic, space group P2₁/c. The crystal packing is governed by F?F and C/N?F van der Waals contacts, but no ring stacking is observed. The intermolecular interactions are non-directional, and the crystal compresses nearly isotropically between 0.3 and 1.1 GPa.     

RP-LC Resolution of (R,S)-Atenolol via Diastereomerization with Marfey’s Reagent and Its Structural Variants Under Conventional and Microwave Heating

(R,S)-Atenolol was derivatized with Marfey’s reagent, (MR; 1-fluoro-2,4-dinitrophenyl-5-l-alanine amide or FDNP-l-Ala-NH₂) and its four structural variants (FDNP-l-Phe-NH₂, FDNP-l-Val-NH₂, FDNP-l-Leu-NH₂ and FDNP-l-Pro-NH₂). MR reacts quantitatively with 1° and 2° amino groups and atenolol has a secondary amino group. The derivatization reactions were carried out under conventional and microwave heating and compared. The resulting diastereomers were separated on RP-TLC and on a C18 column with detection at 340 nm. (R)-Isomer eluted before (S). The conditions of derivatization and chromatographic separation were optimized. The method was validated for linearity, repeatability, limits of detection and limit of quantification.     

Liquid azide salts

Ionic liquid azides from azidoethyl, alkyl, and alkenyl substituted derivatives of 1,2,4- and 1,2,3-amino-triazoles were prepared and examined for the first time to investigate their structural and physical properties. All reported salts possess melting points below 100 degrees C. The unique character of these newly discovered ionic liquid azides is based upon the fact that these molecules are not simple protonated salts like previously reported substituted hydrazinium azides. The presence of quaternary nitrogen confers both thermal stability and negligible volatility.     

Mechanistic study of the oxidation of <Emphasis Type="SmallCaps">l</Emphasis>-phenylalanine by hexacyanoferrate(III) catalyzed by iridium(III) in aqueous alkaline medium

The oxidation of l-phenylalanine by hexacyanoferrate(III) (abbreviated as HCF) catalyzed by Ir(III) has been studied spectrophotometrically at 35 °C and at a constant ionic strength of 0.50 mol dm⁻³. The main oxidation product was identified as phenylpyruvic acid by physico-chemical and spectroscopic methods. The stoichiometry was found to be 2:1, i.e. 2 mol of hexacyanoferrate(III) reacted with 1 mol of phenylalanine. The reaction was first order with respect to both HCF and alkali concentration. The order with respect to [Phe] changed from first to zero as the concentration was increased. The effect of ionic strength was also investigated. Thermodynamic parameters were evaluated by studying the reaction at four different temperatures between 35 and 50 °C. Based on the experimental results, a suitable mechanism involving complex formation has been proposed.     

Direct TLC Resolution of the Enantiomers of Three β-Blockers by Ligand Exchange with Cu(II)–l-Amino Acid Complex, Using Four Different Approaches

TLC experiments have been performed to resolve the enantiomers of three β-blockers by complexation chiral TLC with Cu(II) cation and five l amino acids. Loading was carried out by using the Cu(II)–l amino acid complex as chiral mobile phase additive with untreated silica gel plates; by mixing the Cu complex with silica gel before preparing the TLC plates; by ascending development of untreated plates with solutions of the Cu complex; and by using a solution of Cu(II) acetate as mobile phase additive for plates prepared by mixing the l amino acid with silica gel. Spots were located by use of iodine vapour.     

Nano-sized polycrystalline bismuth silicon oxide powder by sol–gel technique

Bismuth silicon oxide (Bi₁₂SiO₂₀, BSO) nano crystalline powder was prepared by sol–gel technique using bismuth nitrate and tetraethyl orthosilicate as starting materials. The prepared samples were sintered at various temperatures (750 °C maximum) and characteristic sillenite single cubic phase with crystallite size ~38 nm (calculated from room temperature powder XRD measurements) was realized at 750 °C sintering temperature. SEM analysis showed that the powder contains the nano-sized particles with almost spherical morphology. The observed frequencies in room temperature FTIR spectrum could be assigned to Bi–O, Si–O and Bi–O–Si bonds. The FWHM (full width at half maximum) of the diffraction peaks decreased while the intensity of FTIR absorption lines increased with the increase in the sintering temperature indicating better bond formation and crystallization. The thermograph of the samples recorded in the temperature range 50–1,000 °C showed almost no weight loss after ~575 °C further confirmed the conclusion arrived at from XRD and FTIR analysis. The samples sintered at 750 °C showed about 50% absorbance in 400–600 nm region which was consistent with the pale yellow color of the sample. Broad blue emission centered ~478 nm was observed when excited by 350 nm radiation from a Xe-lamp. The intensity of this broad emission band increased while its FWHM decreased with the increase in sintering temperature. Self-trapped excitons could be responsible for this emission.