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      Volume 130, Issue 1

      January 2018

    • Table of Contents

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    • Editorial

      N Periasamy

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    • Picric acid sensing and CO2 capture by a sterically encumbered azo-linked fluorescent triphenylbenzene based covalent organic polymer

      Dhananjayan Kaleeswaran Ramaswamy Murugavel

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      A sterically encumbered isopropyl group substituted fluorescent triphenylbenzene based azo-linkedcovalent organic polymer, iPrTAPB-Azo-COP, has been synthesized by Cu(I) catalysed homo coupling (amineamine)reaction of 1,3,5-tris(4'-amino-3'

      5'-isopropylphenyl)benzene (iPrTAPB) under aerobic conditions. TheBrunauer-Emmett-Teller (BET) and Langmuir surface areas of iPrTAPB-Azo-COP have been estimated to be395 and 697 m2 g-1 with a pore diameter of 11.6 Å. Due to the presence of fluorescent triphenylbenzeneplatform iPrTAPB-Azo-COP exhibits broad emission band centred at 428 nm, when excited at 300 nm, as aresult of extended conjugation. The inherent fluorescent nature of iPrTAPB-Azo-COP has been utilized for sensing electron-deficient polynitroaromatic compounds (PNACs) such as a picric acid (PA), dinitrotoluene (DNT), p-dinitrobenzene (p-DNB) and m-dinitrobenzene (m-DNB). Further, iPrTAPB-Azo-COP has also been utilized for capture of carbon dioxide as the azo-COP is enriched with CO2-philic nitrogen atoms apart from its microporosity. Since the azo (–N=N-) linkages are masked by the bulky isopropyl groups, iPrTAPB-Azo-COP exhibits a CO2 uptake of 6.5 and 19.4 wt% at 1 bar and 30 bar, respectively, at 273 K.

    • Density functional theory study of structure, electronic and magnetic properties of non-metal (Group 13) doped stable Rhn(n = 2−8) clusters and their catalytic activities towards methanol activation


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      Rhodium clusters are very important finite size materials because of their unique electronic, magneticand catalytic properties. Tuning the physical and chemical properties of rhodium clusters by incorporatingdifferent metal and non-metal atoms have found a great research interest in recent years. In this study, nonmetalatoms of group 13, viz., B, Al or Ga were incorporated into the stable rhodium clusters to evaluate thestructure, stability, electronic, magnetic as well as catalytic properties using density functional theory (DFT).Stability function, dissociation energy and LUMO-HOMO gap analysis reveal the higher stability of Rh5B,Rh4Al and Rh4Ga clusters. Boron-doped on even-atomic rhodium clusters are more stable than odd-atomicrhodium clusters whereas both odd and even-atomic clusters were found to be stable for Al and Ga-dopedrhodium clusters. Deformed electron density was found to be higher in the case of Rh5B, Rh4Al, Rh7Al and Rh4Ga clusters along all the bonds as well as at the atoms, which indicates higher stability of these non-metaldoped rhodium clusters. LUMO and HOMO orbital analysis suggests that electronic redistribution occurs from HOMO (Rh) to LUMO (non-metal). DOS and COOP studies reveal the higher contribution of d electrons in the bonding region rather than s and p electrons. Spin density and magnetic moment analysis indicate zero magnetic moment for even-atomic B, Al or Ga-doped rhodium clusters due to the cancellation of spin up and spin down densities, whereas for the odd ones the magnetic moment is non-zero. Greater catalytic activity for the activation of methanol is noticed with Rh4Al and Rh4Ga in comparison to Rh5, while the activity with Rh5B is lower.

    • Nonpolar solvation dynamics for a nonpolar solute in room temperature ionic liquid: a nonequilibrium molecular dynamics simulation study


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      Nonpolar solvation dynamics of a nonpolar diatomic solute in a roomtemperature ionic liquid (RTIL) has been followed via nonequilibrium molecular dynamics (MD) simulation. Frank-Condon type excitation of the solute, previously in equilibrium inRTIL solvent, has been modelled by abruptly changing the Lennard-Jones(LJ) diameter of the solute atoms and thereby disrupting the equilibrium situation. The rearrangement of the RTIL solvent molecules,which has been seen to be mostly contributed by the solute’s first solvation shell, around the excited solute results overall spectral narrowing and biphasic decay of the solvation energy; a dominant and very rapid process having sub-100 fs relaxation time, followed by a slower one relaxing at a timescale of ∼5 ps. A mode-coupling theory based calculation is also used to obtain the nonpolar solvation relaxation function fora model nonpolar solute dissolved in model RTIL solvent. The theoretical relaxation decay is not in very good agreement with the simulated nonequilibrium solvation response function; the theory predicts the short timerelaxation component slower and the longtime component faster than those of the simulated nonequilibrium relaxation. We have also checked the validity of the linear response theory (LRT) for nonpolar solvation in RTIL by looking at the equilibrium solvation energy correlation in the RTIL solvent in presence of the ground state (GS) and the excited state (ES) solute. Apparent breakdown of the LRT in the present case elucidates the probable disagreement between the theoretical and simulated nonequilibrium nonpolar solvation responsefunctions

    • Gold nanodots self-assembled polyelectrolyte film as reusable catalyst for reduction of nitroaromatics


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      Separation of homogeneous catalyst from the reaction mixture is a crucial and difficult process in any catalytic process. To address this issue, a new class of multifunctional catalyst in the form of film was developed using a facile approach to enjoy the advantages of homogeneous catalyst with the versatility of heterogeneous catalyst. To achieve the same, methionine-capped gold nanodots (AuNDs) were self-assembled on a cationic polyelectrolyte modified glass plate for the catalytic reduction of nitro functional groups in the presence ofolefinic double bond at mild conditions. Separation of this reusable catalytic film from the reactionmixture is very simple and advantageous when compared to the currently available and conventional catalytic systems. Kinetics of nitro reduction was monitored using absorption spectroscopy and the product formation was confirmed by 1H and 13CNMR analyses. Prepared AuNDs catalyst was characterized using UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), high-resolution transmission electron microscopy(HRTEM), cyclic voltammetry and atomic force microscopy (AFM) techniques.

    • Effect of three aromatic polycarboxylates on the structural diversities and properties of three new cadmium(II) coordination compounds


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      Three newcadmium(II) coordination compounds [Cd2(L)2(btec)(H2O)2]·3H2O(1), [Cd(HL)(btb)] (2) and [Cd(L)(pda)] · 2H2O (3) were prepared by hydrothermal reactions of cadmium(II) chloride with ligands L (L = N,N'-bis(3-pyridyl)octandiamide) in the presence of different aromatic polycarboxylates(H2btec = 1,2,4,5-benzenetetracarboxylic acid, H2btb = 1,3,5-tri(4-carboxylphenyl)benzene, H2pda = 1,4-phenylenediacetic acid). The structures of compounds 1–3 have been determined by X-ray single crystal diffraction analyses and further characterized by infrared spectroscopy (IR), powder X-ray diffraction (PXRD) and thermogravimetric (TG) analyses. Compound 1 displays a 3D metal-organic framework with (4,4,4)-connected {62.84}{63.83}{64.82} topology constructed from 2D [Cd2(btec)]n layers and μ2-bridging L ligands.Compound 2 is a 3D (3,3)-connected {103} topological network based on the 3D [Cd(btb)]n−n framework and the protonated monodentate HL ligand. Compound 3 shows a 2D layer with (3,5)-connected (42 · 67 · 8)(42 · 6) topological structure, which are further linked by hydrogen bonding interactions to form a 3D supramolecular network. The influences of three aromatic polycarboxylates on the structures of title compounds are investigated. Further, the fluorescent properties of three cadmium(II) compounds and their fluorescent sensing properties towards small solvent molecules and metal cations have been studied.

    • Efficient click reaction towards novel sulfonamide hybrids by molecular hybridization strategy as antiproliferative agents


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      Twelve novel sulfonamide hybrids were designed by molecular hybridization strategy. The target sulfonamide hybridswere obtained in the click reaction of azide derivatives and commerciallly available alkynes. All sulfonamide hybrids were evaluated for their antiproliferative activity against three selected cancer cell lines (MGC-803, EC-109 and PC-3). Most of the synthesized compounds exhibited moderate to good activity against all the cancer cell lines selected. Particularly, compound 8c showed the potent antiproliferative activity withan IC50 value of 0.7μmol against MGC-803 cancer cells. These sulfonamide hybrids might be promising lead compounds to develop antitumor agents in the clinical practice

    • Electrochemical study of two structurally related compounds FeVMoO7 and CrVMoO7 synthesized by sol–gel method


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      FeVMoO7 and CrVMoO7 phases were synthesized by sol–gel method for the first time and used as promising cathode materials for Lithium ion batteries. Effortless and flexible procedure for the preparation of FeVMoO7 and CrVMoO7 via a facile sol–gel method was developed. The structure, morphology and the electrochemical properties have been studied by X-ray diffraction (XRD),scanning electronic microscope (SEM) and galvanostatic charge-discharge test measurements. Study of these compounds as electrode materials was motivated by the three-dimensional structure and the redox couples of Fe, V and Mo. The first cycle discharge capacity values for FeVMoO7 and CrVMoO7 phases were 284 mAhg-1 and 264 mAhg-1, respectively, in the voltage range of 3.2–1.5V. The discharge capacity of FeVMoO7 was 160 mAhg-1 after 20 cycles

    • A combined electrochemical and theoretical study of pyridine-based Schiff bases as novel corrosion inhibitors for mild steel in hydrochloric acid medium


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      Three pyridine-based Schiff bases namely N2,N6-bis(4-methylbenzylidene)pyridine-2,6-diamine (DAP-1), N2,N6-dibenzylidenepyridine-2,6-diamine (DAP-2) and N2,N6-bis(4-nitrobenzylidene)pyridine-2,6-diamine (DAP-3) were synthesized, characterized, and their corrosion inhibition performance was studied on mild steel (MS) in 1 M hydrochloric acid solution using electrochemical experiments and theoretical study.The results showed that all the three DAPs act as mixed type corrosion inhibitors, and are adsorbed on MS surface by following Langmuir adsorption isotherm. The methyl-substitutedDAP-1 showed maximum inhibition effiency of 98.5% at 40 mgL-1. The formation of inhibitor film on MS surface was confirmed by SEM andAFM. Quantum chemical calculations and Monte Carlo simulations were used to understand metal-inhibitor interaction and orientation of adsorption ofDAP molecules.Agood correlationwas observed between theoretical and experimental results.

    • Physico-chemical characterization and biological studies of newly synthesized metal complexes of an Ionic liquid-supported Schiff base: 1-{2-[(2-hydroxy-5-bromobenzylidene)amino]ethyl}-3- ethylimidazolium tetrafluoroborate


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      Co(II), Ni(II) and Cu(II) complexes of an ionic liquid-supported Schiff base 1-{2-[(2-hydroxy-5-bromobenzylidene)amino]ethyl}-3-ethylimidazolium tetrafluoroborate were synthesized and characterized by various analytical and spectroscopic methods such as elemental analysis, UV-Visible, FT-IR,1H NMR, ESI MS,molar conductance and magnetic susceptibility measurements. Based on the spectral studies, tetra coordinated geometry was proposed for the complexes and molar conductance of the complexes revealed their electrolyticnature. The synthesized Schiff base and its complexes were evaluated for in vitro antibacterial activities against Gram positive and Gram negative bacteria. The complexes along with the Schiff base showed very significant biological activity against the tested bacteria

    • Sodium dichloroiodate promoted C-C bond cleavage: An efficient synthesis of 1,3-Benzazoles via condensation of o-amino/mercaptan/hydroxyanilines with β-diketones


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      An efficient aqueous sodium dichloroiodate (NaICl2) mediated protocol is developed for the synthesis of benzofused azoles by the cyclization of 2-amino anilines/thiophenols/phenols with β-diketone compounds. The reactions gave moderate to good yield of the corresponding 2-substituted benzimidazoles/benzothiazoles/benzoxazoles under mild conditions. This tandem process involved a C-C bond cleavage and C-N bond formation.

    • Preparation and evaluation of mesoporous nickel and manganese bimetallic nanocatalysts in methane dry reforming process for syngas production


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      In this paper, Ni-Mn catalysts supported on mesoporous nanocrystalline γ -Al2O3 were prepared and employed in carbon dioxide reforming of methane for the production of synthesis gas. The physicochemical properties of the catalysts were determined by XRD, BET, TPO and SEM techniques. The obtained resultsrevealed that the Mn-promoted catalysts exhibited higher activity and stability and lower degree of carbon formation compared to unpromoted nickel catalyst. The catalytic results showed that the 10 (wt%) Ni-3 (wt%) Mn/Al2O3 catalyst possessed the highest catalytic activity. The XRD results confirmed that the addition of Mn improves the dispersion of the active metal species on the catalyst or incorporates into the support due to a decrease in the crystallite size of Ni and consequently causes an increase in Ni dispersion. The 10 (wt%) Ni-3(wt%) Mn/Al2O3 catalyst was stable during 20 hour on stream without any decrease in methane conversion

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