A series of aromatic oligoamide foldamers based on 8-fluoro amino-quinoline carboxyl acid have been synthe- sized and characterized. Studies show that these foldamers self-assemble to form well-defined twisted helical mi- crofibers in chloroform-methanol （1 ： 1, V/V） binary solvent due to the intermolecular π-π stacking and van der Waals forces of aliphatic chains, which are supported by SEM, TEM and XRD. It is also revealed that the assembly morphologies show strong dependence on the length of alkyl chains.
It is found that 5,10,15,20-tetrakis(4-sulfonatophenyl) porphyrin(TPPS),which is known to form J aggregates in water under low pH value,acts as a template for the hydrolyzing of organosilane.The nanotube structures of silica with 4 8 nm inner diameters are obtained,which is consistent with the height of TPPS J aggregates,indicating that TPPS J aggregates are indeed acting as the template for the sol-gel transcription.The TPPS J aggregation disappear when the medium pH value is shifted from acidic to basic,consequently formed silica nanostructures are amorphous nanosphere rather than nanofiber structures.In contrast,the copper phthalocyanine(TSCuPc),which does not exist as linear J aggregates,cannot induce the silica to form one dimensional nanofiber structures,implying that the templating effect of TPPS J aggregates for inorganic nanostructures.
A facile method is presented for preparing TiO2/reduced graphite oxide （RGO） nanocomposites with phase-controlled TiO2 nanoparticles via redox reaction between the reductive titanium （III） precursor and graphite oxide （GO）, and a series of TiO2/RGO composites with various TiO2 phase compositions were obtained. In all the titania/RGO composites, the TiO2 nanoparticles were uniformly distributed on the surface of the RGO. The TiO2 consisted of anatase phase particles in the form of square-plates with edges less than 10 nm and the rutile phase nanorods in diameters less than 10 nm. The performances of the as-prepared TiO2/RGO composites were investigated on catalytically degrading phenol under visible light irradiation. The TiO2/RGO composites can effectively degrade phenol under visible light irradiation, and the phase composition of TiO2 in the composites significantly influences the activities of these catalysts.
The use of green solvents (including supercritical fluids and ionic liquids) in the synthesis of nanomaterials is highlighted. The methods described can not only reduce or eliminate the use or generation of substances hazardous to health and the environment, but can also be used to efficiently prepare nanomaterials with high performances. The unique characteristics of green solvents are responsible for the green features and unusual advantages of these approaches.
This paper reports the chitosan-mediated synthesis of porous hematite nanoparticles with FeCl3 as the precursor via a hydrothermal approach at 160℃.A series of porous chitosan/iron oxide hybrid nanoparticles were obtained via changing the ratio of chitosan to FeCl3,FeCl3 concentration and pH value of the reaction solution,and producing porous iron oxide nanoparticles after calcination.The as-prepared samples were characterized by means of X-ray diffraction,transmission electron microscopy,thermal gravimetric analysis,Fourier transform infrared,and N2 sorption.The particle sizes of these metal oxides were less than 100 nm,and the pore sizes were in the range of 2-16 nm.It was demonstrated that chitosan played a key role in the formation of the porous structures.The resultant α-Fe2O3 nanoparticles were used as the support to immobilize Au or Pd nanoparticles,producing Au/α-Fe2O3 or Pd/α-Fe2O3 nanoparticles.The as-prepared α-Fe2O3 nanocatalyst exhibited high selectivity towards cyclohexanone and cyclohexanol for catalyzing cyclohexane oxidation with O2 at 150℃.
