Cooperative Dehydrogenation of N‐Heterocycles Using a Carbon Nanotube–Rhodium Nanohybrid

Rhodium nanoparticles were anchored on carbon nanotubes and the resulting nanohybrid was studied as co‐catalyst, along with tert‐butylcatechol, for the dehydrogenation of various N‐heterocycles. The co‐catalytic system operates in high yields, under the mildest conditions reported so far, and can be applied to a wide variety of secondary amine‐containing scaffolds.     

Preparation of core–shell structure Fe3O4@SiO2 superparamagnetic microspheres immoblized with iminodiacetic acid as immobilized metal ion affinity adsorbents for His‐tag protein purification

The core–shell structure Fe₃O₄/SiO₂ magnetic microspheres were prepared by a sol–gel method, and immobiled with iminodiacetic acid (IDA) as metal ion affinity ligands for protein adsorption. The size, morphology, magnetic properties and surface modification of magnetic silica nanospheres were characterized by various modern analytical instruments. It was shown that the magnetic silica nanospheres exhibited superparamagnetism with saturation magnetization values of up to 58.1 emu/g. Three divalent metal ions, Cu²⁺, Ni²⁺ and Zn²⁺, were chelated on the Fe₃O₄@SiO₂–IDA magnetic microspheres to adsorb lysozyme. The results indicated that Ni²⁺‐chelating magnetic microspheres had the maximum adsorption capacity for lysozyme of 51.0 mg/g, adsorption equilibrium could be achieved within 60 min and the adsorbed protein could be easily eluted. Furthermore, the synthesized Fe₃O₄@SiO₂–IDA–Ni²⁺ magnetic microspheres were successfully applied for selective enrichment lysozyme from egg white and His‐tag recombinant Homer 1a from the inclusion extraction expressed in Escherichia coli. The result indicated that the magnetic microspheres showed unique characteristics of high selective separation behavior of protein mixture, low nonspecific adsorption, and easy handling. This demonstrates that the magnetic silica microspheres can be used efficiently in protein separation or purification and show great potential in the pretreatment of the biological sample. Copyright © 2015 John Wiley & Sons, Ltd.     

Effects of C3-aromatic heterocycles on 1,3,5-triaryl-2-pyrazoline sulfonium salt photoacid generators as light-emitting diode-sensitive cationic photoinitiators

Four 1,5-diphenyl-3-aromatic heterocyclyl-2-pyrazoline-based sulfonium salt photoacid generators (PAGs) with different aromatic heterocycles substituted on C3 atom and dimethyl sulfonium group on C5 atom were synthesized. These PAGs were highly photosensitive in the 365–425 nm light-emitting diode region, and the intramolecular charge transfer from the pyrazoline ring to sulfonium salts induced efficient photolysis and high Φ_H⁺. The heterocycles as well as their substituted positions significantly influenced the energy of the S₂ orbital, which was determined by the electrochemical and absorption properties of the PAGs. The raising of the S₂ orbital energy enlarged the energy gap of S₀–S₂ and S₁–S₂, resulting in blue shift of the absorption spectra and increase in the quantum yield of photoacid generation (Φ_H⁺), respectively. When the energy of excited electrons was higher than that of the S₂ orbital, the transition from S₀ to S₂ (π–π*) occurred before the C-S cleavage on S₁ and the PAGs showed high Φ_H⁺ values (0.52–0.72). The transition from S₀ to S₁ (π–σ*) occurred when the energy of electrons is lower than that of the S₂ orbital, and the PAGs showed low Φ_H⁺ value. The photopolymerization kinetics demonstrated that these PAGs were highly efficient cationic photoinitiators.     

Aggregation-Induced Generation of Reactive Oxygen Species: Mechanism and Photosensitizer Construction

Luminogens with aggregation-induced emission (AIEgens) have been widely applied in the field of photodynamic therapy. Among them, aggregation-induced emission photosensitizers (AIE–PSs) are demonstrated with high capability in fluorescence and photoacoustic bimodal imaging, as well as in fluorescence imaging-guided photodynamic therapy. They not only improve diagnosis accuracy but also provide an efficient theranostic platform to accelerate preclinical translation as well. In this short review, we divide AIE–PSs into three categories. Through the analysis of such classification and construction methods, it will be helpful for scientists to further develop various types of AIE–PSs with superior performance.     

Crosslinked polyaniline nanorods coupled with molybdenum disulfide on functionalized carbon cloth for excellent electrochemical performance

Journal of Solid State Electrochemistry - In this work, the binary nanocomposite of crosslinked polyaniline nanorods (CPANINRs) and molybdenum disulfide (MoS2) is first synthesized by in situ...     

Reaction for the preparation of unique cyclic polysiloxanes with large size and narrow distribution

Utilizing collective forces between reactant and multiple catalyst molecules has been unprecedented due to the difficulty in realizing high order catalysis. Inspired by the power of collective forces in enzymes and organic catalysts, herein we report a rare example of high order catalysis for ring opening reaction (ROR) of strained rings by methanol. ROR is an important way to produce various polysiloxanes, but usually suffers from serious side reactions especially at high conversion, and currently there is a need to design new reaction pathway to achieve low molecular dispersity. In our study, the judiciously designed strained spiral cyclosiloxanes enable a high order catalysis by methanol, and this new methodology leads to a cyclic polysiloxane with high molecular weight and low dispersity even at full conversion of reactants. Kinetic study indicates an extremely unusual high-order reaction involving multiple methanol molecules per reaction, also confirmed by quantum calculation which reveals the presence of zwitterionic ions stabilized by collecting force of hydrogen bonds by methanol molecules. The inherent driving force for this unusual phenomenon is dominated by enthalpy stabilization of the reactive intermediates through hydrogen bonding. The selective formation of Si O Si bonds, instead of silanol products, reflects the power of scientific design.     

Cooperative effect of Fe and Ti species over Fe–Ti–Ox catalysts on the catalytic hydrolysis performance of hydrogen cyanide

FeO_x, TiO₂, and Fe–Ti–O_x catalysts were synthesized and used in the catalytic hydrolysis of hydrogen cyanide (HCN). Nearly 100% HCN conversion was achieved at 250 °C over the Fe–Ti–O_x catalyst. TiO₂ rutile was detected over TiO₂, but not over Fe–Ti–O_x, which suggested that the interaction between Fe and Ti species could inhibit the TiO₂ phase transition. Furthermore, the interaction between Fe and Ti species over Fe–Ti–O_x could promote the selectivity of NH₃ and CO. The mechanism of hydrolysis of HCN over FeO_x, TiO₂, and Fe–Ti–O_x can be given as follows: HCN + H₂O → methanamide → ammonium formate → formic acid → H₂O + CO.     

Highly selective propylene dimerization catalyzed by C1‐symmetric zirconocene complexes

A series of ethylene‐bridged C₁‐symmetric ansa‐(3‐R‐indenyl)(fluorenyl) zirconocene complexes ( 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ) incorporating a pendant arene substituent on the 3‐position of indenyl ring have been synthesized. The structure of complex 4 was further confirmed by X‐ray diffraction analysis. When activated with methylaluminoxane, four sterically less encumbered complexes 1 , 2 , 4 and 5 could catalyze the dimerization of propylene in toluene at 100°C to afford 2‐methyl‐1‐pentene with high selectivities up to 95.7–98.4% and moderate activities of 2.00 × 10⁴ to 7.89 × 10⁴ g (mol‐Zr?h)^?1. Copyright © 2014 John Wiley & Sons, Ltd.