Solid-state thermolysis of [MnO]12 containing molecular clusters into novel MnO nano- and microparticles

Novel MnO nano- and microparticles including spherical nanoparticles and various micropolyhedra of pyramid-like, truncated rectangular pyramid-like, cubic, and rhombic dodecahedral particles, were controllably synthesized via solid-state thermolysis of inorganic core containing molecular clusters [Mn₁₂O₁₂(O₂CR)₁₆(H₂O)₄] (R=C₆H₅, CH₃, and C₆H₅OCH₂) in a conventional horizontal tube furnace. Among them, pyramid-like, truncated rectangular pyramid-like, cubic, and rhombic dodecahedral MnO submicroscale particles were reported for the first time. The products were characterized by XRD, XPS, Raman spectrum, SEM, EDX, TEM and HRTEM. During the reaction process, thermolysis temperature, reaction time, and different molecular clusters {Mn12} precursors with different organic ligands as well play important roles in determining the sizes and shapes of the final products. The formed MnO nanospheres from [Mn₁₂O₁₂(O₂CC₆H₅)₁₆(H₂O)₄] at 400 °C for 10 h exhibited weak ferromagnetic behavior at low temperature which may be due to the size-effect of nanomaterials. Furthermore, the possible formation mechanism was also discussed.     

The Relationship of Phthalocyanine 4 (Pc 4) Concentrations Measured Noninvasively to Outcome of Pc 4 Photodynamic Therapy in Mice

The ability to noninvasively measure photosensitizer concentration at target tissues will allow optimization of photodynamic therapy (PDT) and could improve outcome. In this study, we evaluated whether preirradiation tumor phthalocyanine 4 (Pc 4) concentrations, measured noninvasively by the optical pharmacokinetic system (OPS), correlated with tumor response to PDT. Mice bearing human breast cancer xenografts were treated with 2 mg kg⁻¹ Pc 4 iv only, laser irradiation (150 J cm⁻²) only, Pc 4 followed by fractionated irradiation or Pc 4 followed by continuous irradiation. Laser irradiation treatment was initiated when the tumor to skin ratio of Pc 4 concentration reached a maximum of 2.1 at 48 h after administration. Pc 4 concentrations in tumor, as well as in Intralipid in vitro , decreased monoexponentially with laser fluence. Pc 4-PDT resulted in significant tumor regression, and tumor response was similar in the groups receiving either fractionated or continuous irradiation treatment after Pc 4. Tumor growth delay following Pc 4-PDT correlated with OPS-measured tumor Pc 4 concentrations at 24 h prior to PDT ( R ² = 0.86). In excised tumors, OPS-measured Pc 4 concentrations were similar to the HPLC-measured concentrations. Thus, OPS measurements of photosensitizer concentrations can be used to assist in the scheduling of Pc 4-PDT.     

Three sandglass-type molybdophosphates obtained via a new route: Synthesis and characterization of X7[PMo8O30] (X=Na, K, NH4)

Three new polyoxometalates X₇[PMo₈O₃₀] (X=Na⁺, 1; K⁺, 2; NH₄⁺, 3) have been synthesized with the classical Keggin and/or Dawson heteropolymolybdophosphates and PCl₅ in acetonitrile-water solutions via hydrothermal treatment. The three compounds were characterized by different analyses including IR, ³¹P NMR spectroscopy, elemental analysis, electrochemistry, thermogravimetric analysis (TGA) and powder X-ray diffraction (XRD). Single crystal X-ray analyses were carried out on Na₇[PMo₈O₃₀] (1) and (NH₄)₇[PMo₈O₃₀] (3). Compound 1 and 3 crystallize in the orthorhombic system. The structure of compound 2 was confirmed by the IR spectra and powder XRD. All the three compounds contain the same octamolybdophosphate polyoxoanion [PMo₈O₃₀]⁷⁻, which consists of two Mo₄O₁₅ moieties linked by one central PO₄ tetrahedron, leading to a remarkable sandglass-like structure.     

Post-acquisition ETD spectral processing for increased peptide identifications

Tandem mass spectra (MS/MS) produced using electron transfer dissociation (ETD) differ from those derived from collision-activated dissociation (CAD) in several important ways. Foremost, the predominant fragment ion series are different: c- and z ^·-type ions are favored in ETD spectra while b- and y-type ions comprise the bulk of the fragments in CAD spectra. Additionally, ETD spectra possess charge-reduced precursors and unique neutral losses. Most database search algorithms were designed to analyze CAD spectra, and have only recently been adapted to accommodate c- and z ^·-type ions; therefore, inclusion of these additional spectral features can hinder identification, leading to lower confidence scores and decreased sensitivity. Because of this, it is important to pre-process spectral data before submission to a database search to remove those features that cause complications. Here, we demonstrate the effects of removing these features on the number of unique peptide identifications at a 1% false discovery rate (FDR) using the open mass spectrometry search algorithm (OMSSA). When analyzing two biologic replicates of a yeast protein extract in three total analyses, the number of unique identifications with a ∼1% FDR increased from 4611 to 5931 upon spectral pre-processing—an increase of ∼28. 6%. We outline the most effective pre-processing methods, and provide free software containing these algorithms.     

Self-assembly of photonic crystals from polymer colloids

This article reviews recent developments in self-assembly of polymer colloids into colloidal crystals, a good candidate material for photonic crystals. Self-assembly strategy has developed as a facile and efficient method to fabricate colloidal crystals. Much research work has been focused on controlling the morphology and improving the quality, as well as finding applications of the colloidal crystals.     

Investigation of FeB alloy prepared by an electric arc method and used as the anode material for alkaline secondary batteries

High active FeB alloy was prepared by an electric arc method, and used as the anode material for alkaline secondary batteries. The structural characteristics of the as-prepared FeB alloy were studied using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and the electrochemical performances were investigated using cyclic voltammetry (CV) and charge–discharge test. The FeB alloy achieves an excellent reversible capacity of 312 mA h/g as well as a good cycleability, and is proved to be a promising low-cost and high performance anode material for alkaline secondary batteries.     

Theoretical studies on electronic structures and spectroscopic properties of a series of novel β-diketonate Os(II) complexes

The geometries, electronic structures, and spectroscopic properties of a series of [Os^(II)(CO)₃(tfa)(acac(X)₂)] (tfa = trifluoroacetate; acac = acetoylacetonate; X = H (1), CF₃ (2), C₆H₅ (3), and C₁₀H₇ (4)) complexes have been investigated theoretically. The ground and excited state geometries were optimized at the B3LYP/LANL2DZ and CIS/LANL2DZ levels, respectively. The optimized geometry structural parameters agreed well with the corresponding experimental results. As indicated in this paper, the highest occupied molecular orbitals were dominantly localized on the Os atom, ctfa (abbv. of CO and tfa), and acac ligand for 1 and 2, acac ligand and X substituent for 3 and 4, while the lowest unoccupied molecular orbitals were mainly composed of acac ligand and X substituent. Under the time-dependent density functional theory (TDDFT) level with the polarized continuum model (PCM), the absorption and phosphorescence in CH₂Cl₂ media were calculated based on the optimized ground- and excited-state geometries, respectively. The calculated results show that the lowest energy absorptions at 317 (1), 342 (2), 377 (3), and 420 nm (4) are attributed to a change of ππ*/MLCT mixing transition to pure ππ* transition for 1–4, while their phosphorescence emission have similar transition properties. This indicates that the absorption and emission transition characters could be altered by adjusting the π electron-donating ability.     

Hydrogen‐Bond‐Selective Phase Transfer of Nanoparticles across Liquid/Gel Interfaces

In the swim : Colloidal nanoparticles coated with polylactide (PLA, red) and poly(ethylene glycol) brushes (PEG, black) can transfer from organic to aqueous phases across liquid/liquid or liquid/gel interfaces during degradation of the PLA coating (see picture: first step), which is driven selectively by the hydrogen bonding of the PEG coating with the aqueous phase (second step).

     

A study of the interaction between enantiomers of zolmitriptan and hydroxypropyl-beta-cyclodextrin by capillary electrophoresis

The enantioresolution of zolmitriptan was performed using cyclodextrin (CD)-modified capillary zone electrophoresis (CZE) with hydroxypropyl-β-CD (HP-β-CD) as the chiral selector. The influence of experimental conditions on the enantioseparation of zolmitriptan, such as pH, temperature, applied voltage, and concentrations of running electrolyte and CD, was systematically investigated, obtaining a baseline separation of two enantiomers by the use of a 25 mM sodium dihydrogen phosphate (SDPH) running electrolyte (pH 2.4) containing 30 mM HP-β-CD at 15 °C. Binding constants for each enantiomer–HP-β-CD pair at different temperatures, as well as thermodynamic parameters for binding, were calculated. A nonlinear van’t Hoff plot was obtained, indicating that the thermodynamic parameters of complexation were temperature-dependent for zolmitriptan enantiomers. The significant contribution of the enthalpy difference to the Gibbs free energy change suggested a stereomeric barrier mechanism for chiral recognition. Figure Resolution of zolmitriptan enantiomers was achieved by using CD-modified CZE Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.