Micellar nucleation differential microemulsion polymerization

Polymer nanoparticles within the range of 2–5 nm with a solid content of more than 13 wt.% and a narrow molecular weight polydispersity (Mw/Mn ∼ 1.1) were for the first time prepared using a micellar nucleation differential microemulsion polymerization system emulsified by sodium dodecyl sulfate (SDS), with SDS/monomer (methyl methacrylate) and SDS/H₂O weight ratios of up to 1:16 and 1:100, respectively. It was found that for benzoyl peroxide (BPO), micellar nucleation is more favorable for the synthesis of smaller polymer nanoparticles than ammonium persulfate (APS) which gives rise to homogeneous nucleation and 2,2′-azobisisobutyronitrile (AIBN) which involves partially heterogeneous nucleation. In the polymerization process, there exists a critical stability concentration (CSC) of SDS, above which the size of the nanoparticles is to be minimized and stabilized. With an increase in the monomer addition rate, the polymerization system changes from a microemulsion system to an emulsion system. A mechanism was proposed to describe the micellar nucleation process of differential microemulsion polymerization. This study may contribute to the development of fine polymer nanoparticles for drug delivery systems.     

Layer-by-layer self-assembly polytungstogermanate multilayer films and their photocatalytic properties under sunlight irradiation

Seven different types of thio- and/or amine-modified cellulose resin materials were synthesized and their mercury (II) ion adsorption properties determined. All seven resins showed good mercury (II) adsorption capability in the more neutral pH regions. However, the o-benzenedithiol- and o-aminothiophenol-modified cellulosic resins were found to be very effective in removing mercury (II) ions from strongly acidic media. For example, 93.5-100% mercury (II) ion recoveries from very acid aqueous solutions (nitric acid concentration ranged from 0.1 to 2.0 mol/L) were obtained using the o-benzenedithiol-modified resin while recoveries ranged from ca. 50% to 60% for the o-aminothiophenol-modified resin. An adsorption capacity of 23 mg (as Hg atoms) per gram of resin was observed for the o-benzenedithiol-modified cellulose in the presence of 1.0 mol/L nitric acid. This same resin shows very good selectivity for mercury (II) as only ruthenium (II) also somewhat adsorbed onto it out of 14 other metal ions studied (Ag(+), Al(3+), As(3+), Co(2+), Cd(2+), Cr(3+), Cu(2+), Fe(3+), Mn(2+), Ni(2+), Pt(2+), Pb(2+), Ru(2+), and Zn(2+)).     

Multimetallic synergic sedation of a labile sodium atrane: synthesis and characterization of a tetranuclear sodium atrane cation complex

A series of sodium and aluminum atrane complexes of Na(3)L(THF)(5) (1), [AlLMe][Na(4)L(THF)(6)] (2), AlL(THF) (3), AlNaLMe(THF)(2) (4), and AlNaLOBn(THF)(2) (5), wherein L = tris(2-oxy-4,6-di-tert-butyl-benzyl)amine, were synthesized and characterized by NMR, X-ray crystallography, and elemental analysis. The trinuclear sodium atrane complex of Na(3)L(THF)(5) (1) is labile at room temperature; however, the tetranuclear sodium atrane cation in complex 2 can be stabilized by a multimetallic synergetic effect due to a firm interaction ring of -[Na-O-benzene](3)-. Complex 2 is also the first example of a sodatrane and alumatrane ion-paired complex in which both the cationic and anionic moieties contain an atrane ligand.     

Donor/acceptor complex of triphenylene and trinitrotoluene on Au(111): a scanning tunneling microscopy study

The co-adsorption of trinitrotoluene (TNT), a typical π-electron acceptor, and triphenylene (TP), a typical π-electron donor, on a Au(111) surface was investigated by in situ Electrochemical Scanning Tunneling Microscopy (ECSTM). DFT calculations proved that parallelly stacked and well-overlapped TP and TNT molecules can form Donor-Acceptor dyads through intermolecular π-π charge transfer, which agree well with the experimental results in the present work.     

Copper-mediated methylthiolation of aryl halides with DMSO

A copper-mediated methylthiolation of aryl halides with the widely available DMSO is described. The procedure tolerates a series of functional groups such as methoxy, nitro, chloro, fluoro, trifluoromethyl, formyl and methoxycarbonyl groups. Thus, it represents a simple and facile methylthiolation procedure.     

Nearly monodispersed core-shell structural Fe3O4@DFUR-LDH submicro particles for magnetically controlled drug delivery and release

Nearly monodispersed magnetic Fe(3)O(4)@DFUR-LDH submicro particles containing the anticancer agent DFUR were prepared via a coprecipitation-calcination-reconstruction strategy of LDH materials over the surface of Fe(3)O(4) particles, and present well-defined core-shell structure, strong magnetization and obvious magnetically controlled drug delivery and release properties.     

Enantioselective intramolecular Rauhut-Currier reaction catalyzed by chiral phosphinothiourea

Chiral organophosphine-catalyzed enantioselective Rauhut-Currier reaction has been disclosed for the first time. With L-valine-derived phosphinothiourea, the intramolecular Rauhut-Currier reaction of bis(enones) was achieved in good yields (up to 99%) with excellent enantioselectivities (up to 99.4% ee).     

A novel catalyst precursor K2TiF6 with remarkable synergetic effects of K, Ti and F together on reversible hydrogen storage of NaAlH4

A synergetic effect of K, Ti and F together on improving the reversible hydrogen storage properties of NaAlH(4) is found by intruding K(2)TiF(6) as catalyst precursor. Around 4.4 wt% of hydrogen can be released from the NaAlH(4)-0.025 K(2)TiF(6) sample within 40 min at 140 °C.     

Recognizing ortho-, meta- or para-positional isomers of S-methyl methoxylphenylmethylenehydrazine dithiocarboxylates by ESI-MS2: The positional effect of the methoxyl substituent

The dissociation chemistry of the ortho-, meta- or para-isomers of protonated S-methyl methoxyl- (or chloro-) benzenylmethylenehydrazine dithiocarboxylate, RPhCHN–NHC(S)–SCH₃ (R = MeO– or Cl–), has been investigated by collision induced dissociation experiments and DFT theoretical calculations. The three methoxyl-substituted isomers were easily differentiated according to the different abundance of the characteristic ion at m/z 136, resulting from the varying reactivity of the (NSC)SCH₃ elimination. This fragmentation is triggered by the positive charge upon protonation on the imine N2. Relative to the meta isomer, the positive charge on N2 in the para isomer is dispersed due to the electron donating resonance of the methoxyl group, which leads to higher energy barrier in the dissociation reaction and the less abundant product ion (m/z 136) in the MS/MS. (NSC)SCH₃ elimination of the ortho- isomer is further suppressed due to both the resonance effect and the “ortho effect” (an intramolecular hydrogen bond), with much higher energy barrier and extremely lower abundance of the fragment ion (m/z 136, 0.4%). The chloro substituted isomers, however, are short of the above positional effects due to the weak electronic effect of the substituent, and share the similar tandem mass spectrum.