Microemulsion Synthesis of Nanosized TiO2 Particles Doping with Rare-Earth and their Photocatalytic Activity

Microemulsion is the easiest and cleanest of the popular methods of synthesizing nanomaterial. This work synthesized the nanosized La-TiO₂ and Ce-TiO₂ particles through the hydrolyzation of tetrabutyl titanate in a Triton X-100/n-hexanol/cyclohexane/water reverse microemulsion. The particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR) and thermogravimetry (TG). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) under ultraviolet light and visible light irradiation. The results showed that reverse microemulsion produced the nanosized and well-separated particles, which are obviously in degrading MO. Comparing the pure TiO₂ with doping TiO₂, the doping ones are smaller and have better photocatalytic activity, which was best at the molar content of 0.1% for La, whereas for Ce it was 0.5%.     

Chiral solvating agents for carboxylic acids based on the salen moiety

A series of chiral salen C₂-symmetric aminophenols 1–4, which were derived from (1R,2R)- or (1S,2S)-1,2-diphenylethane-1,2-diamine with the corresponding salicylic aldehyde through a [2+2] condensation reaction, have been prepared. The NMR studies demonstrated that they can function as chiral solvating agents for the determination of the enantiomeric purity of chiral carboxylic acids.     

Quantification of taurine and amino acids in mice single fibrosarcoma cell by microchip electrophoresis coupled with chemiluminescence detection

A method based on MCE coupled with chemiluminescence (CL) detection was developed for the determination of taurine (Tau) and amino acids including alanine (Ala), glycine (Gly), tryptophan (Trp), glutamic acid (Glu) and aspartic acid (Asp) present in mice single fibrosarcoma (S180) cells. Cell injection, loading, cytolysis, electrophoretic separation and CL detection were integrated onto a simple double‐T microfluidic chip. The intracellular constituents were electrophoretically separated within 150 s. The CL detection was based on the enhancement effects of Tau and amino acids on the CL reaction of luminol with H₂O₂ and Cu²⁺. The average amounts of Tau, Trp, Gly, Ala, Glu and Asp in per S180 cell from a cell population were 4.73, 1.23, 2.65, 1.94, 1.61 and 1.99 fmol. Ten S180 cells were analyzed, and the contents of Tau, Trp, Gly, Ala, Glu and Asp in mice single S180 cells were found to be in the range of 1.78–8.84, 0.95–2.31, 1.08–6.87, 1.03–4.05, 0.84–2.61 and 0.82–3.68 fmol, respectively. This work demonstrates that MCE coupled with CL detection is a useful analytical tool that is simple, quick and highly sensitive for single‐cell analysis.     

Facile,efficient functionalization of polyethylene via regioselective copolymerization of ethylene with cyclic dienes

The copolymerizations of ethylene with cyclic dienes [dicyclopentadiene (DCPD) and 2,5‐norbornadiene (NBD)] using bis(β‐enaminoketonato)titanium complexes [PhN = C(R₂)CHC(R₁)O]₂TiCl₂ ( 1a : R₁ = CF₃, R₂ = CH₃; 1b : R₁ = t‐Bu, R₂ = CF₃; 1c : R₁ = Ph, R₂ = CF₃) have been investigated. In the presence of modified methylaluminoxane, these complexes exhibited high catalytic activities in the copolymerization of ethylene with DCPD or NBD, affording high molecular weight copolymers with unimodal molecular weight distributions. ¹H and ¹³C‐NMR spectra reveal ethylene/DCPD copolymerizations by catalysts 1a – c proceeds through the enchainment of norbornene ring. Catalysts 1a and 1c showed a tendency to afford alternating copolymers. More noticeably, catalysts 1b and 1c bearing bulky substituents on the ligands promote ethylene/NBD copolymerization without crosslinking, affording the copolymer containing intracyclic double bonds. The NBD incorporation as high as 27.2 mol % has been achieved by catalyst 1c . Moreover, the microstructures of the copolymers were further confirmed by the measurement of reactivity ratios and dyad monomer sequences as well as mean sequence lengths. The intracyclic double bonds of ethylene/DCPD or ethylene/NBD copolymers can be fully converted into polar groups such as epoxy, amine, silane, and hydroxyl groups under mild conditions. Convenient synthesis of hydroxylated polyethylene can be provided for the first time through the ring opening reaction of epoxide. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1764–1772, 2010     

Raman studies of some cyanobiphenyl derivatives under pressure

We present the results of an experimental study of the Raman depolarization ratio for the cyano stretching mode in two mesogens, 5CB and 80CB, under variable temperature and pressure. In contrast to previous observations, the Raman results do not yield any indication of molecular association, even in such an expectedly strongly associated liquid crystal as 80CB, which has a re-entrant nematic phase at elevated pressure. Possible explanations for this are discussed.     

Preparation and characterization of novel hyperbranched poly(amido amine)s from Michael addition polymerizations of trifunctional amines with diacrylamides

Novel hyperbranched poly(amido amine)s containing tertiary amines in the backbones and acryl as terminal groups were synthesized via the Michael addition polymerizations of trifunctional amines with twofold molar diacrylamide. The hyperbranched structures of these poly(amido amine)s were verified by ¹³C NMR (INVGATE). The polymerization mechanisms were clarified by following the polymerization process with NMR method, and the results show that the reactivity of secondary amine formed in situ is much lower than that of the secondary amine in 1‐(2‐aminoethyl) piperazine (AEPZ) ring and the primary amine. The secondary amine formed in situ was almost kept out of the reaction before the primary and secondary amines in AEPZ were consumed, leading to the formation of the AB2 intermediate, and the further reaction of the AB2 yielded the hyperbranched polymers. The molecular weights and properties of poly(amindo amine)s obtained were characterized by GPC, DSC, and TGA, respectively. Based on the reaction of active acryl groups in the polymers obtained with glucosamine, hyperbranched polymers containing sugar were formed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5127–5137, 2005