• PAWAN KUMAR

      Articles written in Journal of Chemical Sciences

    • N′, N″, N‴-tris(2-pyridyloxymethyl) ethane as ionophore in potentiometric sensor for Pb(II) ions

      Pawan Kumar Ashok Kumar S K Susheel K Mittal

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      N′,N″,N‴ tris(2-pyridyloxymethyl) ethane (TPOME) has been used as an ionophore in a polyvinylchloride (PVC)-based membrane. Membrane electrode with a composition 30:5:62:3 (PVC:TPOME: o-NPOE:NaTPB) exhibits Nernstian response towards Pb(II) ions with a slope of 30mV/decade, over a concentration range of $1 \times 10^{−5}$ M to $1 \times 10^{−1}$ M. Potential response remains almost unchanged over pH range of 3.7-6.4. The electrode shows fast response time of $15 \pm 2$ s and a lifetime of four months. It shows good selectivity for Pb(II) ions over other mono-, di- and trivalent cations. Electrode response is satisfactory in mixed solvent media up to 30% (v/v) non-aqueous contents. Selectivity of the ionophore for Pb(II) ions was determined by spectrophotometric method. The electrode can also be used as an indicator electrode in potentiometric titration of Pb(II) ions with standard chromate solution and its determination in real-life samples. Surface morphology of membrane electrode at different stages of its development and use is also discussed.

    • Application of bisphosphomide-palladium(II) pincer complex in Suzuki-Miyaura cross-coupling reaction under microwave irradiation

      Maruthai Kumaravel Pawan Kumar Maravanji S Balakrishna

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      The bisphosphomide-based pincer complex [PdBr{2,6-{Ph2PC(O)}2(C6H3)}] (2) has shown very high catalytic activity in Suzuki-Miyaura cross coupling reaction under microwave irradiation for a variety of aryl bromides and aryl boronic acids. The complex showed the same efficiency for gram scale reactions.

    • Reactions of 4-diphenylphosphino benzoic acid with organotin oxides and -oxy-hydroxide

      RAMAKIRUSHNAN SURIYA NARAYANAN PAKKIRISAMY THILAGAR JOYDEV ACHARYA PAWAN KUMAR DODDAPUNENI KRISHNA RAO VADAPALLI CHANDRASEKHAR ANUKUL JANA

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      The reactions of p-diphenylphosphinobenzoic acid (LCOOH) with various organotin precursors have been carried out. Accordingly, the reaction of [n-BuSn(O)(OH]n with LCOOH afforded the hexameric compound, [n-BuSn(O)O2C–C6H4–p-PPh2]6(1). On the other hand, the reaction of LCOOH with [n-Bu2SnO]n gave the tetrameric compound [{n-Bu2SnO2C–C6H4–p-PPh2}2O]2 (2). The 1-D coordination polymers [R3SnO2C–C6H4–p-P(O) Ph2]n,[ R=n-Bu (3), R=Ph (4)] were prepared in the reaction of [n-Bu3Sn]2O or [Ph3Sn]2O with LCOOH. The compounds 1–4 were structurally characterized by multinuclear NMR spectroscopic and single crystal X-ray diffraction studies

    • Imine linked AntiBSA@NUS-15 for molecular sensing applications

      GAGANDEEP KAUR PAWAN KUMAR

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      1,3,5-tris-(4 formyl phenyl) benzene and p-Phenylenediamine based covalent organic framework(COF) i.e., National University of Singapore-15 (NUS-15) have been synthesized using the solvothermal method at room temperature. Importantly, synthesized NUS-15 has been analysed using powdered X-ray diffraction (PXRD), Field emission scanning electron microscopy (FE-SEM), Infrared and UV-Visible spectroscopy techniques. Afterward, the optical properties of NUS-15 (excitation wavelength = 298 nm,emission wavelength = 404 nm) were confirmed through a photoluminescence spectrophotometer. Later on,biofunctionalization of NUS-15 was performed with Anti-BSA using coordination chemistry and confirmed through various analysis techniques. Based on optical properties, NUS-15-based Bioconjugate i.e., Anti-BSA@ NUS-15, has been utilized for selective sensing applications and noted 0.366 ppm detection limit for BSA. Our results imply that NUS-15 might be applied in future biomedical applications.

      Synopsis. In this work, a covalent organic framework i.e., NUS-15 was synthesised and characterised for Anti-BSA tagged through simple coordination chemistry. Later, Anti BSA-tagged NUS-15 was explored for selective BSA sensing in a certain range using a photoluminescence spectrophotometer. Our results confirm 1.11 ppm (limit of quantification) and 0.366 ppm (limited of detection) during BSA detection.

    • Optical detection of nitroaromatic compounds using MAPbBr3 at room temperature

      RAJIT SIKKA PAWAN KUMAR

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      Methylammonium lead bromide, i.e., MAPbBr3, has been synthesized at room temperature through chemical stirring method. The structural characterization of synthesized MAPbBr3 has been confirmed through X-ray diffraction technique, Field emission scanning electron microscopy, Fourier transform infrared, thermo gravimetric analysis and UV-Vis spectroscopy. Afterward, the optical properties (excitation wavelength 415 nm; emission wavelength = 535 nm) of MAPbBr3 were confirmed through a photoluminescence spectrophotometer. To end, MAPbBr3 has been used for the optical detection of nitroaromatic compounds, i.e., nitrobenzene (NB), dinitrobenzene (DNB), dinitrotoluene (DNT), trinitrophenol (TNT) inhexane. Our research has confirmed the 7.1 ppb and 10 ppb detection limit (LOD) for nitrobenzene and dinitrobenzene only using MAPbBr3, respectively. Importantly, we found out the selectivity %, i.e., 1.3% and2.7% in the case of nitrobenzene and dinitrobenzene sensing using MAPbBr3 in hexane, respectively.

      SYNOPSIS * Synthesis and analysis of MAPbBr3, i.e., metal halide perovskite (MHPs), has been performed at room temperature through the chemical stirring method. * MAPbBr33 has been used for optical sensing of nitroaromatic compounds, i.e., nitrobenzene (NB), dinitrobenzene (DNB), dinitrotoluene (DNT), trinitrophenol (TNT) in hexane. * We have achieved 7.1 ppb and 10 ppb limit of detection (LOD) with selectivity %, i.e., 1.3% and 2.7% for nitrobenzene and di-nitrobenzene only using MAPbBr3, respectively.

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