Publications

This study presents the synthesis of metal oxides composite nanosheets (oxides of cobalt, zinc and iron) and their pressure sensing properties. A transducer has been fabricated to directly measure the resistance—pressure and impedance—pressure relationships of pristine nanopowder. At the initial stage, a nanopowder sample of 10 mm diameter and 1 mm height was placed in the transducer and by applying pressure of up to 8.15 kN/m2; the DC resistance and the impedance are reduced by 44% on average. It can be explained by the densification of the samples and a decrease in porosity due to the effect of pressure. It was also observed that the DC resistance increases with time and saturated within 8 min. It is considered that this phenomenon is based on the effect of displacement currents of bound charges. The dependences of the impedance phase (θ) on frequency and pressure have also been investigated.

2-Substituted benzothiazoles were synthesized in excellent yields by a benzotriazole methodology, with the conditions being efficient, green, economical, and suitable for broad applications in medicinal chemistry and the synthesis of specialty chemicals.

In this work, Cu nanoparticles (Cu NPs, 2-20 nm) supported on Hydrotalcite catalysts exhibit enhanced selectivity for γ-valerolactone (GVL) during hydrogenolysis of levulinic acid (LA). At 260 °C, over 3 wt% Cu achieved 87.5% of LA conversion with a maximum GVL selectivity (95%). In contrast, LA hydrogenolysis over 3Cu/Hydrotalcite catalyst is highly active and stable toward the production of GVL due to balanced acido-basicity and higher Cu dispersion with ultrasmall particle sizes, which are investigated through the temperature programmed desorption (TPD) of ammonia, N₂O titration, and transmission electron microscopy (TEM) analysis. Hydrotalcite in combination with inexpensive Cu catalyst is found to be an efficient and environmentally benign for LA hydrogenolysis.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A series of novel 4-{5-[(2-benzylidenehydrazine)carbonyl]phenyl}-3-(trifluoromethyl)-1 H-pyrazol-1-yl]benzenesulfonamides was synthesised from 4-[1-(4-aminosulfonylphenyl)-3-(trifluoromethyl)-1 H-pyrazol-5-yl]benzoic acid (celecoxib). Initially, celecoxib was selectively oxidised. The product was then esterified and this was followed by hydrazinolysis to get the carbohydrazide. The carbohydrazide was subsequently reacted with a number of benzaldehyde derivatives to give the title compounds. These compounds were characterised by spectral and elemental analyses along with the single crystal X-ray crystallography of a representative compound. All the synthesised compounds were found active for their anti-inflammatory activity in the carrageenan-induced rat paw oedema model. A few of them possessed even greater in vivo anti-inflammatory activities when compared to the reference drug celecoxib and showed minimal or no ulcerogenic effect.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

C-dots obtained in the homogeneous phase may exhibit a broad particle size distribution. The formation of C-dots within nanometric reaction cavities could be a methodology to gain control on their size distribution. Among the various possibilities, in the present work, the cavities of small pore size zeolites have been used to confine C-dots generated by the pyrolysis of the organic structure directing agent present in the synthesis of these crystalline aluminosilicates. To explore this methodology, ITQ-29 zeolite having a Linde type A (LTA) structure was prepared as pure silica with 4-methyl-2,3,6,7-tetrahydro-1H,5H-pyrido[3.2.1-ij]quinolinium as the organic structure directing agent. Pyrolysis under an inert atmosphere at 550 °C of a pure-silica ITQ-29 sample (cubic particles of 4 μm edge) renders a highly fluorescent zeolite containing about 15 wt% of the carbonised residue. While another small pore zeolite, ITQ-12 (ITW), also renders photoluminescent C-dots under similar conditions, medium or large pore zeolites, such as silicalite (MFI) or pure silica Beta (BEA), failed to produce fluorescent powders under analogous thermal treatment and only decomposition and complete removal of the corresponding quaternary ammonium ion templates was observed for these zeolites. The dissolution of the pyrolysed ITQ-29 zeolite framework and the extraction of the carbon residue with ethyl acetate have allowed the characterisation of C-dots with particle sizes between 5 and 12 nm and a photoluminescence quantum yield of 0.4 upon excitation at 350 nm that is among the highest reported for non-surface functionalized C-dots. Photoluminescence varies with the excitation wavelength and is quenched by oxygen. Pyrolysed ITQ-29 powders can act as fluorescent oxygen sensors.

Complex hierarchical structures are closely associated with their performance in catalysts and protein adsorbents. However, it still remains a great challenge to develop a facile strategy to engineer their structural traits. Herein, we describe a facile strategy combining a hydrothermal reaction and mussel chemistry with a subsequent thermal treatment process for the controllable synthesis of three dimensional hierarchical nickel based composites, which are constructed from MnO nanowire (NW) cores and thin Al2O3@C shells anchored with ultrasmall metallic Ni nanoparticles (NPs). During the processing, MnO₂ NWs were utilized as templates for the cores, while the two dimensional NiAl nanosheets were directly adopted as the shell to form three dimensional hierarchical MnO₂@NiAl nanowires. After coating with polydopamine-Ni²⁺ (PDA-Ni²⁺) and subsequent carbonization under a nitrogen atmosphere, high coverage of metallic Ni NPs and the transformation from MnO₂ to MnO cores were all observed in the final product. The size of outer Ni NPs and the morphology of the carbonized product can be tailored by varying the temperature of carbonization, which is also in close association with the performance of catalysis and protein adsorption. Notably, the N-doped carbon layer from polydopamine can act as an electron conductor and facilitate the prevention of the migration and aggregation of the Ni nanoparticles, while the ultrafine Ni nanoparticles can achieve maximum material utilization for catalysis and protein adsorption. In addition, the unique structures can expose more active catalytic or adsorption sites while enabling free diffusion of mass/electron transfer. As a result, the MnO@Al₂O₃@C/Ni composite exhibited excellent performance in catalysis and protein adsorption.

Abstract The 4-NPHyd (4-nitrophenylhydrazine) electrochemical sensor assembled using wet-chemically prepared ZnO/SnO 2 nanoparticle (NPs) decorated a glassy carbon electrode (GCE) with conductive Nafion binder. The synthesized NPs characterized by XPS, ESEM, EDS, and XRD analysis. The calibration of the proposed sensor obtained from current versus concentration of 4-NPHyd found linear over a concentration (0.1nM~0.01mM) of 4-NPHyd, which denoted as the dynamic range (LDR) for detection of 4-NPHyd. The 4-NPHyd sensor sensitivity calculated using the LDR slope considering the active surface of GCE (0.0316 cm2), which is equal to be 7.6930 µAµM-1cm-2, an appreciable value. The detection limit (LOD) at signal/noise (S/N=3) estimated, and outstanding lower value at 94.63±4.73 pM perceived. The analytical parameters such as reproducibility, long-term performing ability and response time are found as appreciable. Finally, the projected sensor shows exceptional performances in the detection of 4-NPHyd in environmental samples.