Uniform NH4TiOF3 mesocrystals prepared by an ambient temperature self-assembly process and their topotaxial conversion to anatase

For the first time, we describe a simple, room-temperature surfactant-mediated route to inorganic mesocrystals of NH(4)TiOF(3) and their remarkable topotaxial conversion by washing or annealing to TiO(2) as anatase mesocrystals.     

Phase transitions in perovskite-like oxyfluorides (NH4)3WO3F3 and (NH4)3TiOF5

Calorimetric and X-ray measurements have been performed on ammonium oxyfluorides (NH₄)₃WO₃F₃ and (NH₄)₃TiOF₅ from 120 up to 300 K. Two and one structural phase transitions were found for the former and latter compounds, respectively. In accordance with the entropy parameters both compounds undergo phase transitions of order–disorder type.     

A facile conversion of ethoxydihydropyrans to 4-cyanoethylisoxazoles

The reaction of ethoxydihydropyrans 2 , which were prepared from 2-methylene-1,3-dicarbonyl compounds 1 with ethyl vinyl ether, and hydroxylamine hydrochloride gave 4-cyanoethylisoxazoles 3 whose substituents at the 3 and 5 positions were transformed from substituent at the 2 position and the acyl group of 2 regioselectively.     

A facile synthesis of trans (+)-4-carboxymethyl-3-ethylazetidin-2-one and its conversion into natural PS-5

A novel simple synthesis of trans-4-carboxymethyl-3-ethylazetidin-2-one $\text{2}$ is described together with its optical resolution. The (+) acid was converted in five steps into the natural carbapenem antibiotic (+) PS-5.     

A facile synthesis of 3-aryl-4-pyrazoleacetic acids and of their 4,5-dihydro derivatives

N-1-Unsubstituted-3-aryl-4-pyrazoleacetic acids and their 4,5-dihydro derivatives can conveniently be prepared by cyclization of 3-benzoyl-3-butenoic acids with hydrazine hydrate in acetic acid and subsequent treatment with bromine in acetic acid or, respectively, with diluted mineral acids.     

A facile synthesis of C2,N3-disubstituted-4-quinazolone

A simple and efficient methodology for the synthesis of C(2),N(3)-disubstituted-4 quinazolones from anilines and N-acylanthranilic acids was developed. The new cyclization conditions are much milder than any other reported protocols and resulted in excellent yields (87-98%) without chromatography.     

A facile synthesis of methyl 2-substituted-4-benzoxazolecarboxylates

Methyl 2-substituted-4-benzoxazolecarboxylates were synthesized from methyl 2-amino-3-hydroxybenzoate and the corresponding acid chloride or ortho acetal with pyridinium p-toluenesulfonate as an acid catalyst. Decomposition due to hydration at the 2-position was seen for some compounds during purification.     

A facile synthesis of hierarchical flower-like TiO2 with enhanced photocatalytic activity

The hierarchical flower-like TiO₂ has been achieved by using a simple solvothermal process without any surfactants or colloidal crystals as a template. The structures of the products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption–desorption analysis. The relationship between hierarchical structure and photocatalytic performance has been presented based on detailed characterizations. It was found that the hierarchical flower-like structure was a benefit for light absorption and significantly enhanced the photocatalytic activity.     

A facile solution-phase synthesis of high quality water-soluble anatase TiO2 nanocrystals

Water-soluble anatase TiO(2) nanocrystals (NCs) were synthesized by a simple sol-gel method. The reaction time is greatly reduced even under mild conditions. High-resolution transition electron microscopy (HRTEM), X-ray diffraction (XRD) and UV-vis were used to characterize the synthesized NCs and proved that the NCs are anatase phase and about 2 nm with near spherical shape. Surface photovoltage spectroscopy (SPS) experiments show that the synthesized anatase NCs have good photovoltaic properties compared with that of poly(vinyl pyrrolidone) (PVP) coated NCs synthesized by the similar method.     

A new approach to the facile synthesis of 2-substituted-quinazolin-4(3H)-ones

A new approach to the facile synthesis of 2-substituted-quinazolin-4(3H)-ones and its derivatives using the condensation reaction of substituted 2-aminobenzamide and orthoesters is reported.     

A facile approach to synthesize CoO-Co3O4/TiO2 NAs for reinforced photoelectrocatalytic water oxidation

Journal of Solid State Electrochemistry - Photoelectrocatalytic (PEC) water splitting technology is used to convert solar energy into hydrogen energy, and has the potential to alleviate energy...     

Preparation and properties of NH4Ti2P3O12 in the pseudobinary system NH4H2PO4TiO2

Phase equilibria in the system NH₄H₂PO₄TiO₂ were studied and a new compound (NH₄Ti₂P₃O₁₂) with Nasicon-type structure was synthesized. Its stability range was established. X-Ray and thermal properties were investigated and another new compound (Ti₄P₆O₂₃) with the Nasicon-type structure was obtained by heat treatment at 770°C.     

Hydrothermal synthesis of single-crystal CeCO3OH and their thermal conversion to CeO2

Hexagonal single-crystalline cerium carbonate hydroxide （CeCO3OH） precursors with dendrite morphologies have been synthesized by a facile hydrothermal method at 180 C using CeCl3-7H2O as the cerium source, triethylenetetramine as both an alkaline and carbon source, with triethylenete- tramine also playing an important role in the formation of the dendrite structure. Polycrystalline ceria （CeO2） have been obtained by calcining the precursor at 500 C for 4 h. Tile morphology of the precursor was partly maintained during the heating process. The optical absorption spectra indicate the CeO2 nano/microstructures have a direct band gap of 2.92 eV, which is lower than values of the bulk powder due to the quantum size effect. The high absorption in the UV region for CeO2 nano/microstructure indicated that this material was expected to be used as UV-blocking materials.     

TiO2 mesocrystals: Synthesis, formation mechanisms and applications

Mesocrystals, which are assemblies of crystallographically oriented nanocrystals, have received increasing attention due to their unique properties such as high crystallinity, high porosity, oriented subunit alignment, and similarity to highly sophisticated biominerals. However, the controlled synthesis of TiO 2 mesocrystals has not been realized until recently, probably because of the difficulty in accurately controlling the reaction processes that produce TiO 2 crystals. In this review, recent advances in the synthesis and applications of TiO 2 mesocrystals are summarized with particular attention paid to the mechanisms of their formation. Three typical pathways for the preparation of TiO 2 mesocrystals are discussed, namely topotactic transformation, direct synthesis in solution, and growth on supports. The potential applications of TiO 2 mesocrystals in lithium ion batteries, photocatalysis, enzyme immobilization, and antireflection materials are also described.     

Investigation of oxofluorotitanates (NH4)3TiOF5 and Rb2KTiOF5 by vibrational spectroscopy and quantum-chemical methods

The phase transition effects in (NH₄)₃TiOF₅ and Rb₂KTiOF₅ were studied by vibrational spectroscopy over a wide range of temperatures. Changes in the spectra of these crystals were found for a PT in the region of the internal vibrations of the [TiOF₅]^3? ion. Quantum-chemical simulation of the vibrational spectra of (NH₄)₃TiOF₅ was performed, and band assignments were carried out. The structure of the compound and the mechanism of the structural phase transition were examined. It is shown that the vibrational spectra of the compounds at room temperature depend on the dynamic disordering of the complex anion.     

A facile one-pot synthesis of uniform core-shell silver nanoparticle@mesoporous silica nanospheres

The uniform core-shell silver nanoparticle@mesoporous silica nanospheres have been prepared by a simple one-pot synchronous method, which combines several steps into one, including the generation of silver nanocrystals and mesoporous silica, transfer and aggregation of silver nanoparticles in an incompact silica framework.     

A facile synthesis of 1,2-oxaphospholenes and stereoselective conversion into oxaphospholanes

Treatment of α-acylallylphosphonates with m-CPBA in the presence of MgSO₄, afforded 1,2-oxaphosphol-3-enes 2-oxides and the subsequent cuprate addition produced 1,2-oxaphospholanes stereoselectively.     

A facile synthesis of azoviolet@Mn3O4 nanoparticles for supercapacitor

Russian Journal of Physical Chemistry A - The azoviolet@Mn3O4 nanoparticles have been successfully synthesized using the azoviolet as a stable absorbed reagent for the supercapacitor. The prepared...