Bis(1,10‐phenanthroline)(thio­sulfato)­manganese(II) methanol solvate and catena‐poly­[[di­aqua(2,9‐di­methyl‐1,10‐phenanthroline)­manganese(II)]‐μ‐thio­sulfato]

The structure of bis(1,10‐phenanthroline‐κ²N,N′)(thio­sulfato‐κ²O:S)­manganese(II) methanol solvate, [Mn(S₂O₃)(C₁₂H₈N₂)₂]·CH₃OH, is made up of Mn²⁺ centers coordinated to two bidentate phenanthroline (phen) groups and an S,O‐chelating thio­sulfate anion, forming monomeric entities. The structure of catena‐poly­[[di­aqua(2,9‐di­methyl‐1,10‐phen­anthro­line‐κ²N,N′)­manganese(II)]‐μ‐thio­sulfato‐κ²O:S], [Mn(S₂O₃)(C₁₄H₁₂N₂)(H₂O)₂]_n, is polymeric, consisting of Mn(dmph)(H₂O)₂ units (dmph is 2,9‐di­methyl‐1,10‐phenanthroline) linked by thio­sulfate anions acting in an S,O‐chelating manner.     

Application of chemical and chemometric analytical techniques to the study of ancient ceramics from Dougga (Tunisia)

In the present paper chemical characterization has been carried out on 67 shards of archaeological pottery from Dougga (North Tunisia). The analysed shards, dated to the Byzantine period (VI–VII century A.D.), belong to the three ceramic classes African Red Slip Ware, Dougga Ware and African cooking Ware. Fourteen elements have been determined by both atomic emission spectroscopy with flame as source (AES) and by using an inductively coupled plasma source (ICP-OES). The data acquired have been treated by statistical techniques in order to define grouping for the examined shards. Both unsupervised and supervised methods have been employed in order to define groups of different pottery shards. As a comparison, some samples (control group) coming from Southern Tunisia have been examined. All the statistical methods employed have evidenced how the control group, as concerns the chemical composition, is clearly distinguishable from Ain Wassel samples which are highly homogeneous. In fact because of the compositional homogeneity of the Northern Tunisia productions, it is quite difficult to establish a good classification and distribution of the samples in well defined cluster. Nevertheless supervised analysis has evidenced how, among the three classes, the African cooking Ware is the more distinguishable one confirming the archaeologists' hypothesis that Dougga Ware is an imitation of African Red Slip Ware.     

UV-induced immobilization of tethered zirconocenes on H-terminated silicon surfaces

A tethered ethylenebis(indenyl) zirconocene was covalently immobilized on H-terminated Si(111) surfaces using UV-mediated alkene hydrosilylation, thus making possible the development of structured catalytic surfaces with highly controlled properties.     

Hydrolytic and photoinduced degradation of tribenuron methyl studied by HPLC-DAD-MS/MS

The paper studies, with the help of HPLC-DAD-MS/MS technique, the hydrolytic and photoinduced degradation processes that take place in aqueous solutions of tribenuron methyl, both when preserved in the dark and when undergoing solar box irradiation under conditions that simulate sun light. The results indicate that the degradation products formed by hydrolysis alone and by photoirradiation are the same, but kinetics of the hydrolysis reaction is much slower. The degradation products are identified as 2-methoxy-4-methylamino-6-methyl-1,3,5-triazine (P1), methyl 2-aminosulfonylbenzoate (P2), and saccharin (P3) and quantified. Ecotoxicological biotests performed on 0.1 microg L(-1) photoirradiated solutions of the herbicide give a border line toxicity situation comparable to that of the precursor and indicate that the herbicide is characterized by low persistence in the environment, as required. Its degradation, however, does not lead to mineralization but to the formation of products of comparable toxicity. To evaluate the matrix effects, the photodegradation of the herbicide is also studied in the presence of rice paddy waters: the process is slower than in ultrapure water but leads to the same products. Experiments performed for comparison by irradiating ultrapure water solutions with UV lamp (254 nm) show that the degradation process is not only faster with respect to sunlight, but gives a different pathway, without in anyway leading to mineralization.     

Semisynthesis of new D-seco-C-nor-taxane derivatives containing a polyfunctionalized furanosyl or cyclopentenyl or cyclopentyl C-ring

The synthesis of new D-seco-C-nor-taxane derivatives in which the D-ring has been deleted and the C-ring has been transformed into a new pentatomic ring, i.e., the polyfunctionalized tetrahydrofuranosyl and cyclopentenyl or cyclopentyl ring, was performed starting from baccatin III derivatives. The synthetic strategy adopted took advantage of the oxetane ring opening and disconnection of the C4-C5 bond, followed by an intramolecular condensation. The formation of furanosyl or cyclopentyl rings is strictly dependent on the presence of unprotected or protected oxygen at C-7 in the starting material. The reactions proceeded with good diastereoselectivity with control of the stereochemistry of one or two stereocenters.     

Mixed Co/Fe oxide nanoparticles in block copolymer micelles

Small iron oxide and Co-doped iron oxide nanoparticles (NPs) were synthesized in a commercial amphiphilic block copolymer, poly(ethylene oxide)-b-poly(methacrylic acid) (PEO 68-b-PMAA8), in aqueous solutions. The structure and composition of the micelles containing guest molecules (metal salts) or NPs (metal oxides) were studied using transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy, and X-ray powder diffraction. The enlarged micelle cores after incorporation of metal salts are believed to be formed by both PMAA blocks containing metal species and penetrating PEO chains. The nanoparticle size distributions in PEO 68-b-PMAA8 were determined using small-angle X-ray scattering (SAXS) in bulk. Two independent methods for SAXS data interpretation for comprehensive analysis of volume distributions of metal oxide NPs showed presence of both small particles and larger entities containing metal species which are ascribed to organization of block copolymer micelles in bulk. The magnetometry measurements revealed that the NPs are superparamagnetic and their characteristics depend on the method of the NP synthesis. The important advantage of the PEO 68-b-PMAA8 stabilized magnetic nanoparticles described in this paper is their remarkable solubility and stability in water and buffers.     

Cysteine-S-trityl a key derivative to prepare N-methyl cysteines

S-Trt Cys are used as precursors for the synthesis of protected NMe-Cys. N-Methylation of Alloc-Cys(Trt)-OH and Boc-Cys(Trt)-OH gives the corresponding N-methylated derivatives in good yields and purities, which can be further derivatized in solution to obtain a myriad of S-protected derivatives. To further broaden the scope of this methodology, the N (alpha)-amino protecting group of the NMe- S-protected Cys can be replaced easily either on the solid phase (from the Alloc precursor) or in solution (from the Boc precursor). Thus, this convenient route allows us to obtain many different protected NMe-Cys, which were of limited accessibility until now.     

Surface and structural analysis of epitaxial La1−xSrx (Mn1−yCoy)zO3 films

In the present study were studied the ferromagnetic La_1−xSr_x (Mn_1−yCo_y)_zO₃ (LSMCO) films with Co content y = 0 to 0.18, grown on LaAlO₃ substrates by advantageous pulsed-injection metalorganic chemical vapor deposition technique. The LSMCO films exhibit negative colossal magnetoresistance effect; therefore, they are interesting as potential material for the applications in magnetic field sensing. The changes of lattice volume in the investigated LSMCO films were monitored by X-ray diffraction measurements revealing a transition from tensile to compressive strain with increase of Co content. Additionally, from the atomic force microscopy images, the surface smoothening with increase of y was determined. Despite the reduction of the out-of-plane lattice parameter of LSMCO, the increase of lattice volume in the whole Co-doping range was observed. The X-ray photoelectron spectroscopy combined with Ar⁺ ion sputtering was used for the investigation of chemical composition of the LSMCO films and demonstrated the change and redistribution of oxidation states of Mn and Co on the surface and in the volume of the films. Regardless of the structural changes and charge distribution of Co and Mn cations, epitaxial LSMCO exhibits ferromagnetic properties and magnetoresistance values increases with augmenting Co content in the range of y = 0 to 0.18.     

XPS study of Cr segregation in a martensitic stainless steel

Cr martensitic steels are promising materials for structural applications in future nuclear fusion reactors. Because the embrittlement after tempering treatments can be a serious problem, the fracture mode of a steel with 10.5 wt% of Cr treated at 700°C for 18 h has been investigated through Charpy tests in the temperature range from −100°C to +150°C. X-ray photoelectron spectroscopy (XPS) analyses carried out on the fracture surfaces evidenced the segregation of Cr in both ductile and brittle (quasicleavage) fields. The unexpected result indicates that Cr segregation weakens the atomic bonds; thus, the fracture path in both the cases corresponds to the zones with higher Cr content.