The crystal and molecular structure oftrans-Di(methylsulphito)bis-(triphenylphosphine)platinum(II)

Summary The crystal and molecular structure oftrans-di(methylsulphito)bis(triphenylphosphine)platinum(II), Pt(SO₃Me)₂ (PPh₃)₂, derived from the reaction of Pt(PPh₃)₂ (O₂) with SO₂ in MeOH and in the presence of sodium tetraphenylborate(III), has been determined from diffractometer data. The complex crystallizes in the space group P ¯1- (C_i ¹) with one molecule in a unit cell of dimensionsa = 9.744(2) Å,b = 10.062(3) Å,c = 11.153(2) Å; = 68.59(2)°, = 82.69(2)° and = 62.25(2)°. Leastsquares refinement has led to a value of the conventional R index (on F) of 0.031 for the 3308 reflections having F²>3(F₀ ²). The complex is a typical square-planar platinum(II) complex with the platinum atom lying on a crystallographically imposed centre of symmetry. The important structural parameters are Pt-P 2.369(1) Å, Pt-S 2.308(1) Å, and the oxygen atoms complete an approximate tetrahedron about the sulphur atoms with S-O 1.448(5) Å and S-O(Me) 1.620(5) Å.     

Evaluation of resazurin microtiter plate assay and HPLC- photodiode array analysis of the roots of Asparagus adscendens

Asparagus adscendens Roxb. (Asparagaceae), is native to the Himalayas. The present study, for the first time, was undertaken to explore the antimicrobial potential, to determine the minimum inhibitory concentration (MIC) values of the methanol extract of the roots of A. adscendens and its solid-phase extraction (SPE) fractions using resazurin microtitre assay against Gram-positive and negative bacterial-registered strains and to carry out HPLC-photodiode array analysis of the SPE fractions. The methanol extract and all SPE exhibited considerable level of antibacterial potential against Gram-positive bacteria (MIC: 2.5–0.009 mg/mL) than against Gram-negative bacteria (MIC: 1.25–2.5 mg/mL). The use of microtitre plates has the advantage of lower cost, fast and quantitative results. Like other Asparagus species, the presence of phenolic compounds in all SPE fractions was evident in the HPLC-PDA data.     

Phosphite addition to organometallic cations to give phosphonium adducts

Addition of tri-n-butylphosphite to [(C₆H₇)Fe(CO)₃]BF₄, [(C₆H₆OMe)-Fe(CO)₃]BF₄, and [(C₇H₇)Cr(CO)₃]BF₄ has yielded novel phosphonium salts; which are remarkably stable.     

Elastic and inelastic effects in proton-proton scattering from states of pure spin

Modified phase-shift analyses of pp scattering are presented at p_L = 1.25 and 1.66 GeV/c and shown to give large negative elastic effects in Δσ_L^tot. Using a combination of phase-shift analyses from low energies up to 1.66 GeV/c and simple models of both elastic (pp → pp) and inelastic (pp → NΔ) scattering we conclude that the measured behaviour of Δσ_T^tot is mostly inelastic, but the large negative value of Δσ_L^tot is predominantly elastic with fluctuations produced by inelastic effects. We find no evidence for a dibaryon resonance.     

Modification of fluorophore photophysics through peptide-driven self-assembly

We describe the formation of self-assembling nanoscale fibrillar aggregates from a hybrid system comprising a short polypeptide conjugated to the fluorophore fluorene. The fibrils are typically unbranched, approximately 7 nm in diameter, and many microns in length. A range of techniques are used to demonstrate that the spectroscopic nature of the fluorophore is significantly altered in the fibrillar environment. Time-resolved fluorescence spectroscopy reveals changes in the guest fluorophore, consistent with energy migration and excimer formation within the fibrils. We thus demonstrate the use of self-assembling peptides to drive the assembly of a guest moiety, in which novel characteristics are observed as a consequence. We suggest that this method could be used to drive the assembly of a wide range of guests, offering the development of a variety of useful, smart nanomaterials that are able to self-assemble in a controllable and robust fashion.