Here we demonstrate a simple and cost effective synthetic route for selective esterification of aldehydes with high productivity in the presence of molecular oxygen (O 2 ) on a gold supported lanthanum oxide (Au/La 2 O 3 ) nanoparticle catalyst. Au nanoparticles with sizes of 2−7 nm supported on 1D La 2 O 3 nanorods with diameters between 20 and 50 nm were synthesized by a room-temperature surfactantassisted single-step preparation method. The as-synthesized catalyst was thoroughly characterized by powder XRD, SEM, HR-TEM, H 2 -TPR, XPS, TGA/DTA, FTIR, BET, EXAFS, and UV−visible spectroscopy. This prepared nanostructured catalyst was found to be highly effective in the liquid phase synthesis of methyl methacrylate (MMA) via direct oxidative esterification of methacrolein (MA) with a high turnover number of ∼1136. The effect of various reaction controlling parameters like reaction temperature, pressure, and time of reaction was investigated and studied. High methacrolein conversion of 89% with high methyl methacrylate selectivity of 98% was attained without the use of any external additives. The synergistic effect between the surface AuNPs and La 2 O 3 nanorods plays an important role toward the activity of the catalyst.

No abstract

Highly dispersed Ag-supported α-Fe2O3 is found to be a recyclable and efficient catalyst for one-pot conversion of aniline to azoxybenzene.

Herewith, we have prepared poly(vinylpyrrolidone)-assisted waterbased synthesis of the nanocrystalline spinel NiCo 2 O 4 nanocatalyst by a one-pot hydrothermal route. The formation of the synthesized spinel NiCo 2 O 4 nanoparticle has been confirmed by X-ray diffraction, scanning electron microscopy (SEM), energy-dispersive spectrometry, transmission electron microscopy, X-ray photoelectron spectroscopy, and extended X-ray absorption fine structure (EXAFS) analyses. The SEM results confirmed the formation of the three-dimensional octahedron structure with an average size of 20−30 nm. The EXAFS results further confirmed that the spinel NiCo 2 O 4 nanoparticles exist in a pure phase. The catalytic activity of the synthesized spinel NiCo 2 O 4 octahedron nanoparticles was evaluated for the conversion of styrene to styrene oxide by the oxidation reaction. It was found that the conversion of styrene was 78% with 67% of styrene oxide selectivity in the presence of hydrogen peroxide as an oxidant. The catalyst has also proven to be truly heterogeneous as it does not lose its phase and catalytic activity even after five consecutive cycles.

Sensitive and rapid monitoring of cholesterol levels in the human body are highly desirable as they are directly related to the diagnosis of cardiovascular diseases. By using the nanoarchitectonic approach, a novel fluorescent conjugated oligofluorene (OFP-CD) functionalized with β-cyclodextrin (β-CD) was assembled for “Turn-On” fluorescence sensing of cholesterol. The appended β-CD units in OFP-CD enabled the forming of host-guest complexes with dabsyl chloride moieties in water, resulting in fluorescence quenching of the oligofluorene through intermolecular energy transfer. In the presence of cholesterol molecules, a more favorable host-guest complex with stoichiometry 1 cholesterol: 2 β-CD units was formed, replacing dabsyl chloride in β-CD’s cavities. This process resulted in fluorescence recovery of OFP-CD, owing to disruption of energy transfer. The potential of this nanoarchitectonic system for “Turn-On” sensing of cholesterol was extensively studied by fluorescence spectroscopy. The high selectivity of the sensor for cholesterol was demonstrated using biologically relevant interfering compounds, such as carbohydrates, amino acids, metal ions, and anions. The detection limit (LOD value) was as low as 68 nM, affirming the high sensitivity of the current system.