Neptunium thiophosphate chemistry: intermediate behavior between uranium and plutonium

Black crystals of Np(PS(4)), Np(P(2)S(6))(2), K(11)Np(7)(PS(4))(13), and Rb(11)Np(7)(PS(4))(13) have been synthesized by the reactions of Np, P(2)S(5), and S at 1173 and 973 K; Np, K(2)S, P, and S at 773 K; and Np, Rb(2)S(3), P, and S at 823 K, respectively. The structures of these compounds have been characterized by single-crystal X-ray diffraction methods. Np(PS(4)) adopts a three-dimensional structure with Np atoms coordinated to eight S atoms from four bidentate PS(4)(3-) ligands in a distorted square antiprismatic arrangement. Np(PS(4)) is isostructural to Ln(PS(4)) (Ln = La-Nd, Sm, Gd-Er). The structure of Np(P(2)S(6))(2) is constructed from three interpenetrating diamond-type frameworks with Np atoms coordinated to eight S atoms from four bidentate P(2)S(6)(2-) ligands in a distorted square antiprismatic geometry. The centrosymmetric P(2)S(6)(2-) anion comprises two PS(2) groups connected by two bridging S centers. Np(P(2)S(6))(2) is isostructural to U(P(2)S(6))(2). A(11)Np(7)(PS(4))(13) (A = K, Rb) adopts a three-dimensional channel structure built from interlocking [Np(7)(PS(4))(13)](11-)-screw helices with A cations residing in the channels. The structure of A(11)Np(7)(PS(4))(13) includes four crystallographically independent Np atoms. Three are connected to eight S atoms in bicapped trigonal prisms. The other Np atom is connected to nine S atoms in a tricapped trigonal prism. A(11)Np(7)(PS(4))(13) is isostructural to A(11)U(7)(PS(4))(13). From Np-S bond distances and charge-balance, we infer that Np is trivalent in Np(PS(4)) and tetravalent in Np(P(2)S(6))(2) and A(11)Np(7)(PS(4))(13). Np exhibits a behavior intermediate between U and Pu in its thiophosphate chemistry.     

Syntheses, structures, and magnetic properties of Np3S5 and Np3Se5

Black prisms of Np(3)Q(5) (Q = S, Se) have been synthesized by the stoichiometric reactions between Np and Q at 1173 K in a CsCl flux. The structures of these compounds were characterized by single-crystal X-ray diffraction methods. The Np(3)Q(5) compounds are isostructural with U(3)Q(5). The structure of Np(3)Q(5) is constructed from layers of Np(1)Q(8) distorted bicapped trigonal prisms that share faces with each other on bc planes. Each Np(1)Q(8) layer further shares Q(2) edges with two adjacent identical neighbors to form a three-dimensional framework. The space inside each channel within this framework is filled by one single edge-sharing Np(2)Q(7) distorted 7-octahedron chain running along the b axis. Magnetic susceptibility measurements show that Np(3)S(5) and Np(3)Se(5) have antiferromagnetic orderings at 35(1) and 36(1) K, respectively. Above the magnetic ordering temperatures, both Np(3)S(5) and Np(3)Se(5) behave as typical Curie-Weiss paramagnets. The effective moments obtained from the fit of the magnetic data to a modified Curie-Weiss law over the temperature range 70 to 300 K are 2.7(2) μ(B) (Np(3)S(5)) and 2.9(2) μ(B) (Np(3)Se(5)).     

Theoretical study on low‐lying states of HAlO+ and HOAl+ cations

Some low‐lying states of HAlO⁺ and HOAl⁺ cations have been studied using the complete‐active‐space self‐consistent field (CASSCF) and multiconfiguration second‐order perturbation theory (CASPT2) methods with the contracted atomic natural orbital (ANO) basis sets. The geometries of all stationary points along the potential energy surfaces were optimized at the CASSCF/ANO and CASPT2/ANO levels. The ground and the first excited states of HAlO⁺ are predicted to be X²Π and A²Σ⁺ states, respectively. It was predicted that the ground state of HOAl⁺ is X²Σ⁺ state. The A²Π state of HOAl⁺ has unique imaginary frequency. A bent local minimum M1 was found along the 1²A″ potential energy surface, and the A²Π state of HOAl⁺ should be the transition state of the isomerization reactions for M1 ? M1. The CASPT2/ANO potential energy curves of isomerization reactions were calculated as a function of HAlO bond angle. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

The model of rough wetting for hydrophobic steel meshes that mimic Asparagus setaceus leaf

A comprehensive analytical model is proposed to provide a relationship between the macroscopic roughness and contact angle, which is used to develop macroscopic rough surface and to create biomimetic superhydrophobic surfaces. Using chemical surface modification of steel wires, an artificial hydrophobic surface was prepared. A steel mesh mimicking the Asparagus setaceus leaf was created by lowing the surface energy and enhancing macroscopic surface roughness. Water contact angles as high as 129.0° were achieved on the steel mesh with 200μm×200μm pore size. Bad agreement between the predictions based on the original Cassie-Baxter model and experiments was obtained. The version of the Cassie-Baxter model in current use could not be applied to this problem since the roughness magnitude changes from nano/microscopic to macroscopic. A new model, called macroscopic Cassie-Baxter (MCB) model, is constructed by the introduction of contact area density (δ) to original Cassie-Baxter model. It is shown that the measured data is in good agreement with the predicted data based on the MCB model. This model not only for solving macroscopic hydrophobic problems of meshes, but also can be used to solve that of other materials with macroscopic roughness.     

Synthesis, characterization and properties of a novel fluorinated methacrylate polymer

A fluorinated monomer of 2-(2,2,2-trifluoroethoxy)ethyl methacrylate (FEMA) was prepared by a “one pot” process and then a novel fluorinated methacrylate polymer, poly[2-(2,2,2-trifluoroethoxy)ethyl methacrylate] (PFEMA), was successfully synthesized via miniemulsion polymerization using cetyltrimethyl ammonium bromide (CTAB) as emulsifier, hexadecane (HD) as co-stabilizer and 2,2′-azobisisobutyronitrile (AIBN) as initiator. The chemical structure of PFEMA was characterized by FT-IR, ¹H NMR and ¹⁹F NMR. GPC results show that the number average molecular weight (M_n) of PFEMA was as high as 8.5 × 10⁵ g/mol and the polydispersity index (PDI) was only 1.3. SEM and DLS characterizations showed that the morphology of PFEMA latex was uniform spheres with the diameter of about 110–125 nm. It was also found that PFEMA has high thermo-stability (T_d > 200 °C), low glass transition temperature (T_g = 13.0 °C), and nice hydrophobicity (θ_water = 99.9°). Comparison studies on PFEMA and poly(2,2,2-trifluoroethyl methacrylate) show that an introduced functional group (–CH₂CH₂O–) has a significant effect on lowering T_g and improving hydrolysis resistance without impairing surface properties.     

The variable role of clay on the crystallization behavior of DMDBS-nucleated polypropylene

The effect of clay on the nucleating behavior of 1,3:2,4-bis(3,4-dimethylbenzylidene) sorbitol(DMDBS) in cryatallization of isotactic polypropylene(iPP) was investigated by means of differential scanning calorimetry(DSC), dynamic rheology and polarized light microscopy(PLM).It is interesting to note that the incorporation of layered clay nanoparticles into DMDBS-nucleated iPP may induce a synergetic nucleation effect while the DMDBS content is below 0.1 wt%,otherwise it restricts the crystallization rate prominently as the DMDBS content increases up to 0.3 wt%,which has exceeded the content threshold to yield a nucleating agent(NA) network.As shown by dynamic rheological investigations, the clay nanoparticles demonstrate an obstructive effect of disturbing the consistency of DMDBS fibrils network.Moreover, to further demonstrate the importance of NA network formation in the crystallization of iPP,we used another NA named HPN-20e,which can not form network structure at all over the concentration studied,for comparison.In this case,the nucleated-crystallization rate is independent on the addition of clay nanoparticles,as the nucleating mechanism is an individual nuclei manner without NA network forming.     

Enantioselective synthesis of optically pure β-amino ketones and γ-aryl amines by Rh-catalyzed asymmetric hydrogenation

A series of optically pure β-amino ketones have been synthesized in high enantioselectivities (ee > 99%) by Rh-DuanPhos-catalyzed asymmetric hydrogenation of readily prepared β-keto enamides. Further reduction of these β-amino ketones with hydrogen and Pd/C leads to the formation of a variety of protected enantiomerically pure γ-aryl amines (ee > 99%), which are key building blocks in many bioactive molecules.     

Reassemblable quasi-chip free-flow electrophoresis with simple heating dispersion for rapid micropreparation of trypsin in crude porcine pancreatin

An increasing number of small biosamples (e.g. proteins and enzymes) need micropreparation in lab. However, neither large-scale free-flow electrophoresis (LS-FFE) nor chip FFE (C-FFE) could fit the growing demands. Herein, a simple quasi-chip FFE (QC-FFE) was constructed. In contrast to C-FFE, the features of QC-FFE are as follows: (i) its separation chamber is reassemblable and rewashable avoiding discard of C-FFE due to blockage of solute precipitation in chamber; (ii) its chamber size is 45 mm × 30 mm × (80-500) μm (108-654 μL volume) having function of micropreparation; (iii) there are up to 16 outlets in QC-FFE bestowing fine fraction for micropurification. The QC-FFE was used for the micropurification of model enzyme of self-digestible trypsin in crude pancreatin. Under the given conditions, the purification factor of enzyme was 11.7, the specific activity reached 6236 U/mg, the run time for 19 μL sample purification was 45 s and the throughput of trypsin was 3.34 mg/h, and the yield of pure trypsin was 55.2%. All of the results show the feasibility of enzyme micropreparation via QC-FFE. The developed device and procedure have potential use to other micropurification of protein or peptide sample.     

A potent antitumor Zn2+ tetraazamacrocycle complex targeting DNA: the fluorescent recognition, interaction and apoptosis studies

A Zn(2+) tetraazamacrocycle complex (2) bearing three naphthalene moieties has been prepared. Complex 2 recognizes, binds and causes damage to DNA, and shows considerable cytotoxicity against human cervical (HeLa), breast (MCF-7) and lung (NCI-H157) cancer cell lines with a different apoptotic pathway from that of cisplatin.     

Aspergiolides C and D: spirocyclic aromatic polyketides with potent protein kinase c-Met inhibitory effects

Variation of the cultivation conditions for Aspergillus glaucus led to the discovery of two novel spirocyclic aromatic polyketides, aspergiolides C (3) and D (4). Their constitutions were elucidated by a combination of spectroscopic methods and isotope-labeling experiments. Aspergiolides C (3) and D (4) occur as racemic mixtures, the resolution of which was succeeded by HPLC on a chiral phase. The absolute configurations of their enantiomers were assigned online, from the peaks in the chromatogram, by a combination of HPLC-CD and quantum chemical CD calculations. Both compounds were found to inhibit the kinase activities of the receptor tyrosine kinases (RTKs) c-Met, Ron, and c-Src with low-micromolar IC(50)s. The enantiomers of 3 were resolved by HPLC on a chiral phase. Both enantiomers showed a comparable inhibition of the HGF-induced autophosphorylation of c-Met and of subsequent cell migration.