• HAQ NAWAZ SHEIKH

      Articles written in Journal of Chemical Sciences

    • Synthesis and characterization of bi-functional magneto-luminescent Fe₃O₄ @ SiO₂ @ NaLuF₄ :Eu³⁺ hybrid core / shell nanospheres

      JIGMET LADOL HEENA KHAJURIA HAQ NAWAZ SHEIKH YUGAL KHAJURIA

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      A step-wise synthetic method has been developed for the synthesis of multifunctional, magnetic luminescent nanocomposites with Fe₃O₄ nanospheres as the core encapsulated in silica and europium-doped sodium lutetium fluoride (NaLuF₄ :Eu³⁺) as the shell. X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL), kinetics of luminescence decay and magnetic studies were used to characterize the structural, optical and magnetic properties of these nanospheres. SEM and TEM images define their spherical morphology with average crystallite size in the range of 90–180 nm. Ultraviolet excited photoluminescent properties of Eu³⁺ doped Fe₃O₄ @ SiO₂ @ NaLuF₄ nanospheres were investigated and impact of doping has been explored. Eu³⁺ as dopant ion induces highly efficient luminescence with average lifetime value of 6.235 ns. Fe₃O₄ magnetic core exhibits super- paramagnetic behavior at room temperature.

    • Surfactant-assisted sacrificial template-mediated synthesis, characterization and photoluminescent properties of LaPO₄ : Eu³⁺ phosphor

      HEENA KHAJURIA JIGMET LADOL RAJINDER SINGH HAQ NAWAZ SHEIKH VINAY KUMAR

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      In this paper, we report a surfactant-assisted self-sacrificing route for synthesis of Eu³⁺ doped LaPO4 nanostructures under hydrothermal conditions using the La(OH)CO₃ : Eu³⁺ precursor as a template andNH₄H₂PO₄ as the phosphate source. The synthesis was carried out in the absence and presence of surfactant [cetyltrimethyl ammonium bromide (CTAB)] and two different solvents (water and ethylene glycol). The precursor and products were characterized by powder X-ray diffraction, fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopyand photoluminescence studies. Influence of surfactant and solvents on morphology and luminescence of the final product in sacrificial template-assisted method has been investigated in detail.

    • Axially coordinated tin porphyrins anchored graphene oxide hybrid composites as productive catalyst for catalytic conversion of 4-nitrophenol to 4-aminophenol

      REHANA YASMEEN RICHA SINGHAAL GAURI DEVI BAJJU HAQ NAWAZ SHEIKH

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      Axially ligated tin porphyrins were synthesized by proceeding through the preparation of freebase and metal incorporated porphyrins. Axially ligated tin porphyrins were anchored with graphene oxide via amide linkage among the carboxylic functional moieties of graphene oxide (GO) and an amino group ofaxial ligand (4-amino salicylic acid) coordinated to tin porphyrins. 1H NMR spectroscopy was used to detectthe successful formation of free-base porphyrins and their corresponding metal-linked and axially ligated tinporphyrins. In order to probe the interactions between GO and tin porphyrins, the nanohybrids were carefully characterized by using various analytical techniques like Powder X-Ray diffraction (P-XRD), Fourier transform infrared (FT-IR), UV–Visible spectroscopy (UV-Vis) and Fluorescence spectroscopy. These hybrid composites were also characterized by Powder-XRD analysis. The Ground-state absorption and steady-state luminescence measurement illustrated the presence of significant covalent interactions along with effective photoelectrons and excited energy exchange between the tin porphyrin and GO structure. The catalytic activity of resulting hybrids (GO-Sn-Porph 1) and (GO-Sn-Porph 2) were carefully investigated by using a UV-visible Spectrophotometer manifesting the effective reduction of 4-nitrophenol into 4-aminophenol. The mechanism for the catalytic activity of the synthesized nanocatalysts has been discussed.

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