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      Volume 131, Issue 3

      March 2019

    • Table of Contents

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    • A novel 1,2,3-benzotriazolium based ionic liquid monomer for preparation of MMT/poly ionic liquid (PIL) pH-sensitive positive charge nanocomposites

      FATEMEH SOGHRA JAHED MOHAMMAD GALEHASSADI SOODABEH DAVARAN

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      In this work, a new ionic liquid (IL) with two acidic and vinylic functional groups based on 1,2,3-benzotriazolium cation was synthesized. This IL monomer was intercalated into the montmorillonite (MMT) layers by the ion exchange reaction and subsequently copolymerized with the IL monomer and methacrylic acid in order to obtain positive charge pH-sensitive nanocomposites. The structure of the IL monomer was characterized by FT-IR and 1H-NMR spectroscopy, and the structure of the nanocomposites was studied and confirmed by the FT-IR, XRD, TGA, SEM, and EDX data. These pH-sensitive nanocarriers were used to loadand in vitro release of the anticancer drug, methotrexate (MTX) in pH = 4 and pH = 7.4. The results showed that the release is pH dependent and more effective in acidic pH; therefore, these nanocarriers have potential to be used for cancer therapy.

    • Transition metal complexes obtained from an ionic liquid-supported Schiff base: synthesis, physicochemical characterization and exploration of antimicrobial activities

      BISWAJIT SINHA MALAY BHATTACHARYA SANJOY SAHA

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      An ionic liquid-supported Schiff base 1-{2-(2-hydroxy-5-chlorobenzylamine) ethyl}-3-methy limidazolium tetrafluoroborate and its Co(II), Ni(II), Cu(II), Mn(III), Fe(III) and Cr(III) complexes were synthesized and characterized by various analytical (elemental analysis, molar conductance and magnetic susceptibility measurements) and spectroscopic (PXRD, SEM, ESI-MS, UV-Visible, FT-IR, 1H NMR and 13C-NMR) methods. Based on these spectral data and spectra, tetra coordinated and hexacoordinated geometries were assigned for the synthesized metal complexes. Molar conductance of the complexes showed their (1:2) electrolytic nature. The Schiff base ligand and its complexes were screened for in vitro antimicrobial activities against some naturally available gram positive and gram negative bacteria to assess their inhibition potentials. Maximum inhibition zone was produced by the Cu(II) complex (5a) in plates of Klebsiella pneumoniae while the minimum inhibition zone was produced by in plates of Bacillus cereus.

    • Recyclable Pd ionic catalyst coated on cordierite monolith for high TOF Heck coupling reaction

      SHRIKANTH K BHAT JAGADEESH D PRASAD M S HEGDE

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      Pd2+ ionic catalyst, Ti0.97Pd0.03O1.97 was coated over cordierite monolith by solution combustion method. The catalyst coated on the cordierite is nano-crystalline as seen from XRD studies. Coated catalyst was used for Heck coupling reactions with different substrates of aryl halides and olefins. Thus handling nanocrystalline catalyst powder is avoided by fixing it on a solid catalyst cartridge. Heck coupled products were characterized using 1H NMR, 13C NMR, Mass and FTIR spectroscopy. This catalyst showed high selectivity towards Heck coupling reaction. Turnover frequencies (TOF) for each of the reactions were found to be very high. The catalyst was recycled up to 7 times with total TOF 3017 h -1, which is found to be a new green technique in the Heck coupling reaction

    • Electrochemical sensors based on functionalized carbon nanotubes modified with platinum nanoparticles for the detection of sulfide ions in aqueous media

      SOHA MOHAJERI ABOLGHASSEM DOLATI SALVA SALMANI REZAIE

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      Vertically aligned carbon nanotube (CNT) arrays were synthesized by thermal chemical vapor deposition (CVD) on stainless steel substrates coated by cobalt nanoparticles as catalyst. Morphological and elemental analyses conducted by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy(EDX) revealed that bamboo-like CNTs were blocked by Co nanoparticles at the tips. The fabricated nanotubes underwent functionalization by electrochemical oxidation in sulfuric acid, and the subsequent structural studies, as well as Fourier transform infrared (FTIR) spectroscopy confirmed that the tips of functionalized CNTs were opened while oxygenated functional groups were generated at the sidewalls and tube endings. In order to enhance the catalytic performance of the functionalized CNT-based electrodes, platinum nanoparticles were deposited on nanotubes by the potentiostatic and pulse potential lectrodeposition processes, and the optimum operating parameters in both techniques were determined. The catalytic activities of these two electrodes towards methanol oxidation were determined by cyclic voltammetry (CV) testing, and a superior electrocatalytic activity and poisoning tolerance were detected for the electrode prepared by pulse deposition. The sensing performance of the pulse plated Pt/CNT electrode for the electrochemical detection and oxidation of dissolved sulfide ions was investigated. A sensitivity of 0.632 μA μM -1cm -2and a detection limit of 0.26 μM were obtained, indicating the enhanced capabilities of the developed sensor as a promising candidate for various industrial and environmental applications.

    • Synthesis of novel phase transfer catalysts derived from proline-mandelic acid/tartaric acid: their evaluation in enantioselective epoxidation and Darzen condensation

      DEEPAK P MAHAJAN HIMANSHU M GODBOLE GIRIJ P SINGH GAUTHAM G SHENOY

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      Herein, we have described the synthesis of novel chiral cyclic phase transfer catalysts (PTCs). These catalysts are synthesized from proline, mandelic acid and tartaric acid by using simple synthetic methods with competitive yields. These chiral cyclic phase transfer catalysts have been characterized by 1H NMR and 13C NMR spectroscopy, IR spectroscopy and elemental analysis. The effectiveness of these novel chiral cyclic phase transfer catalysts was evaluated by applying them in the enantioselective epoxide synthesis from α, β unsaturated ketone (chalcone) and Darzens condensation. The obtained results show that the synthesized derivatives of proline, mandelic acid and tartaric acid are effectual as PTCs.

    • Effect of anharmonicity on energy relaxation of a dissipative quantum oscillator

      RAMESH KUMAR PRADEEP KUMAR

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      The effect of anharmonicity on the energy relaxation of excited state has been studied by means of a dissipative oscillator. The present study also sheds light on the recent femtosecond stimulated Raman spectroscopy results of Kovalenko et al. (J. Chem. Phys. 139 011101 2013) on optical cooling of trans-stilbene.It has been shown that anharmonicity plays a crucial role in explaining the time-dependent frequency shift as well as the time evolution of bandwidth of νC=C mode of trans-stilbene in excited state, found in experiment.

    • Rhodium(III) complex with pyrene-pyridyl-hydrazone: synthesis, structure, ligand redox, spectral characterization and DFT calculation

      SOUMITRA DINDA SARAT CHANDRA PATRA SANJIB GANGULY

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      The pyridylhydrazone ligand incorporating a pendant pyrene moiety HL has been synthesized starting from 2-hydrazinopyridine and its coordinating behaviour towards rhodium(III) have been scrutinized. The complex of type [RhL(PPh3)2Cl2], incorporating five-membered chelate ring has been isolated and the structure has been authenticated by single-crystal X-ray diffraction study. The ligand exhibits an oxidative response at ~1.2 V upon coordination with rhodium(III) and the optoelectronic properties as well as theoretical exploration have been performed by the density functional theory (DFT) as well as time-dependent density functional theory (TD-DFT) analyses.

    • Formal total synthesis of mandelalide A

      V YAMINI K MAHENDER REDDY A SHIVA KRISHNA J K LAKSHMI SUBHASH GHOSH

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      In this article the formal total synthesis of mandelalide A has been described in details. The highly convergent and flexible strategy developed for mandelalide A involved the construction of key building blocks ent-9 and 7, and their assembly to the target compound. For the synthesis and coupling of these buildingblocks, the Brown’s crotylation, Sharpless asymmetric dihydroxylation followed by in situ Williamson type etherification, modified Prins cyclization, Masamune-Roush olefination and Heck cyclization were employed, the latter being crucial for the highly stereoselective formation of the macrocycle of mandelalide A. Initially,Julia Kocienski olefination, ring-closing metathesis reaction were investigated for the synthesis of the aglycone of the proposed structure of the mandelalide A, and found to be unsuccessful.

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