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      Volume 131, Issue 8

      August 2019

    • Table of Contents

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    • Stannous chloride catalyzed synthesis of Schiff bases from hydroxybenzaldehydes and determination of their antioxidant activity by ABTS and DPPH assay

      GYANASHREE BORA DIPANKOJ GOGOI SUBHASMITA SAIKIA ARCHANA PAREEK JYOTIREKHA G HANDIQUE

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      Phenolic compounds play a very important role in human life because of their antioxidant activity which can prevent harmful diseases caused by free radicals. In the present work, we have synthesized some Schiff bases by the reaction of different hydroxybenzaldehydes and primary aromatic diamines using StannousChloride (SnCl2·2H2O) as the catalyst. The products were characterized by FT-IR spectroscopy, GCMS and NMR spectroscopy. Furthermore, the antioxidant activity of the Schiff bases were determined by using DPPH assay and ABTS assay and the results were compared with a standard compound, trolox as well as with the parent aldehydes. The synthesized compounds were found to have better antioxidant activity than their corresponding parent aldehydes.

    • Cytotoxic effects of coumarin substituted benzimidazolium salts against human prostate and ovarian cancer cells

      MERT OLGUN KARATAS SUAT TEKIN BÜLENT ALICI SÜLEYMAN SANDAL

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      Coumarin and benzimidazole derivatives have individual biological activities including anticancer. In this study, we aimed to synthesize coumarin-benzimidazole hybrids in order to investigate their anticancer properties. For this purpose, six 6-substituted-4-chloromethylene coumarin derivatives were synthesized. Sixteen coumarin substituted benzimidazolium chlorides were synthesized by the reaction of 4-chloromethylene coumarin and N-benzylbenzimidazole derivatives. All of the synthesized compounds were characterized by 1H and 13C NMR, IR spectroscopic techniques and elemental analyses. Cytotoxicities of all compounds were testedby [3-(4,5-dimethylthiazole)-2-yl]-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay against human prostate (PC-3) and ovarian (A2780) cancer cells. All compounds performed significant cytotoxicities at 100 μMagainst both cancer cell lines. Moreover, some compounds performed significant activities at 1μM against both cancer cell lines and the obtained results suggest that this type of compounds are promising candidates for the treatment of human prostate and ovarian cancers.

    • Recent developments in synthetic chemistry and biological activities of pyrazole derivatives

      MUHAMMAD FAISAL AAMER SAEED SARWAT HUSSAIN PARSA DAR FAYAZ ALI LARIK

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      Pyrazole, a five-membered heterocycle containing two nitrogen atoms, is extensively found as a core framework in a huge library of heterocyclic compounds that envelops promising agro-chemical, fluorescent and biological potencies. Attributed to its several potential applications, there is a rise in the significance of designing novel pyrazoles, disclosing innovative routes for synthesizing pyrazoles, examining different potencies of pyrazoles, and seeking for potential applications of pyrazoles. This review consists of two parts. The firstpart provides an overview on the recent developments in synthetic approaches to pyrazoles, which is related to the new or advanced catalysts and other ‘environment-friendly’ procedures, including heterogeneous catalytic systems, ligand-free systems, ultrasound and microwave-assisted reactions. The second part focuses on the recently reported novel biological affinities of pyrazoles. This systematic review covers the published studies from 1990 to date. It is expected that this review will be helpful in future research and for new thoughts in thequest for rational designs for developing more promising pyrazoles

    • Pd-catalyzed C–H bond activation of Indoles for Suzuki reaction

      ISITA BANERJEE KESHAB CH GHOSH SURAJIT SINHA

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      We present a practical method for Suzuki coupling by which unprotected or N-protected indoles may be selectively arylated in the C2-position through direct C–H bond activation by electrophilic Pd(TFA)2 catalyst. The protocol is operationally simple as it is carried out in dioxane/water mixture, and air as the sole oxidant at room temperature. Various 2-arylated indoles were obtained in good yields. The protocol works for benzofuran, pyrrole and thiophene also.

    • Facile crystallization of 2-phenyl benzimidazole-5-sulfonic acid: Characterization of lattice water dependent zwitterionic supramolecular forms, with modulation in proton conductivities

      D SARAVANABHARATHI M OBULICHETTY M KUMARAVEL

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      A facile aqueous medium crystallization strategy has been found for this water insoluble title compound. Two crystalline forms, differing in the number of lattice water molecules (mono hydrated; form I & di-hydrated; form II), have been obtained, depending on the duration of crystallization. X-ray structural studies reveal that the compound crystallizes in the zwitterionic state in both the forms, due to the protonation of one imidazole nitrogen by –SO3H group, are engaged in hydrogen bonded interactions, involving lattice water molecule(s), and thus the supramolecular arrangements of the forms are influenced by lattice waters. Additional water molecules in the form II make it more hydrophilic, as confirmed using contact angle measurements. Procedures were optimized for better crystalline yields, and the bulk purity were ascertained by TGA, elementaland PXRD analysis. AC impedance measurements prove that both the crystalline forms are indeed proton conducting electrolytes, with magnitudes of 1×10-5 S cm-1 and 5×10-5 S cm-1 for form I & II, respectively under humidified conditions at 25°C. Proton conducting performance of II has been found to be greater than Iand could be correlated with its higher hydrophilicity and enriched hydrogen bonds for Grotthuss mechanism

    • Silicon-containing diorganotin complexes with salicylaldehyde thiosemicarbazone and their anticancer activity

      QIAN LIU BO XIE SEN LIN QIHUA LIAO RUIHONG DENG YAN ZHAOHUA

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      Eight novel silicon-containing diorganotin complexes with salicylaldehyde thiosemicarbazone were synthesized. They were characterized by 1H NMR, 13C NMR, IR spectra, elemental analysis and X-ray singlecrystal diffraction. Spectroscopic and X-rays studies indicated that the thiosemicarbazone Schiff base and tin atom were coordinated as a parallel five- and six-membered heterocyclic structure. In addition, the bioassay of the synthesized complexeswas performed and the results showthat the silicon-containing diorganotin complexeswith salicylaldehyde thiosemicarbazone have good anticancer activity on human breast cancer cells.

    • Novel protocol for synthesis of 1,4-diiminocurcumin stabilized silver nanoparticles and application as heterogenous recyclable catalyst and antibacterial agent

      NISHI GANDHA GOGOI JYOTIREKHA G HANDIQUE

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      Curcumin [(1E, 6E)-1,7-bis(4-hydroxy-3-methoxy-phenyl)-1,6-heptadiene-3,5-dione] is a low molecular weight yellow-orange polyphenolic pigment extracted from the powdered rhizome of Curcumalonga. Curcumin has wide medicinal applications as an antioxidant, anti-inflammatory, cancer chemopreventive,and potentially chemotherapeutic agents as well as stabilizer/reducing agent in silver nanoparticles (AgNPs) synthesis. However, the low solubility of curcumin in aqueous solutions limits its applications and also, many of AgNP synthetic processes lack a greener synthetic route. In the present work, a Schiff base ofcurcumin is synthesized condensing curcumin and 1,4-diaminobutane in 2:1 ratio. The resulting product shows improvement in solubility in water and favours the synthesis of AgNPs in aqueous medium at room temperature,acting as a self-reducing/stabilizing agent. This proposed synthetic route is simple, feasible and green. The size and morphology of AgNPs are analyzed by TEM, SEM, EDS and XRD techniques. The recyclable AgNPs as a heterogeneous catalyst in the reduction of nitroaromatics to amino compounds is environmentally benign andcan be re-used up to 5th cycle without considerable loss of its catalytic activity. Moreover, both Cur-1,4 and AgNPs show bactericidal properties against bacterial strains (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) which find medicinal importance in future

    • An investigation of the molecular mechanism, chemoselectivity and regioselectivity of cycloaddition reaction between acetonitrile N-Oxide and 2,5-dimethyl-2H-[1,2,3]diazaphosphole: a MEDT study

      ABDELLAH ZEROUAL MAR RIOS-GUTIERREZ MOHAMMED SALAH HABIB EL ALAOUI EL ABDALLAOUI LUIS RAMON DOMINGO

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      The [3?2] cycloaddition (32CA) reactions of acetonitrile N-oxide with 2,5-dimethyl-2H-[1,2,3]diazaphosphole has been studied using the Molecular Electron Density Theory (MEDT) through DFT calculations at the B3LYP/6-31G(d,p) computational level. Analysis of the relative free energies associated with the competitive ortho and meta reaction paths shows high chemo- and regioselectivity for this 32CA reaction in clear agreement with the experimental outcomes. The topological analysis of the electron localization function (ELF) of the selected points of the IRC associated with the formation of the P-C and C-O single bonds indicates a zwitterionic type structure. The 32CA reaction takes place through a two-stage one-step mechanism initialized with the formation of the P-C single bond.

    • Synthesis, characterization and biological studies of cobalt(II), nickel(II), copper(II) and zinc(II) complexes of vanillin-4-methyl-4- phenyl-3-thiosemicarbazone

      LEKSHMI V KUMAR G RATHIKA NATH

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      Complexes of vanillin-4-methyl-4-phenyl-3-thiosemicarbazone with cobalt(II), nickel((II), copper(II) and zinc(II) metal ions were synthesized and characterized by elemental analysis, molar conductance, magnetic moment, infrared spectra, electronic spectra, 1H and 13C NMR, mass spectrum and thermal analysis.The low molar conductance values indicate that all the complexes are non-electrolytes. Spectral studies indicate that the ligand act in a tridentate manner coordinating with the metal ion through sulphur, oxygen and nitrogen atoms. Based on magnetic moment measurements, spectral studies and thermal analysis, suitable geometry was proposed for the metal complexes. Thermal stability of the complexes was ascertained on the basis of thermo gravimetric analysis and the lattice parameters, space group and grain size of the ligandand complexes were determined by using powder XRD measurements. Surface morphology of ligand and complexes were studied using SEM analysis. Antimicrobial studies were carried out against gram-positive, gram-negative bacteria and two fungal pathogens

    • Synthesis and characterization of hierarchical titanium-containing silicas using different size templates

      ALEKSEY FEDOSOV MARINA FEDOSOVA IRINA POSTNIKOVA SERGEY OREKHOV ALEKSEY GUSHCHIN DENIS RYABININ ILYA CHUZHAYKIN

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      The development of hierarchical catalytic heterogeneous catalytic systems with a controlled micro/mesopore ratio is an important issue in catalysis. The main purpose of the paper is to the establish influence of the size of the template molecule on the main characteristics of hierarchical titanium-containing silicas (H-TS). The H-TS were successfully synthesized by a bi-template method using tetrapropylammonium hydroxide (TPAG) as permanent template of MFI topology and tetramethylammonium bromide (TMAB), tetraethylammonium bromide (TEAB), tetrabutylammonium hydroxide (TBAG), dodecyltrimethylammoniumbromide (DTMAB), cetyltrimethylammonium bromide (CTAB), didecyldimethylammonium chloride (DDAC), tetradecylbenzyldimethylammonium bromide (TBDAB) as variable structure-directing agent (SDA) of a different size. The structure and morphology were characterized by X-ray diffraction, a Fourier transform infrared spectroscopy, a Raman spectroscopy, a scanning electron microscopy and low-temperature nitrogen adsorption-desorption. The catalytic properties of the prepared titanium-containing micro-mesoporous silicasfor hydroxylation of phenol with H2O2 have been evaluated, and their activities have been compared with those of TS-1 with only micropores. The findings of the research illustrate that with an increase in the molecule volume of the structure-directing agent, there is a decrease in the proportion of the crystallinephase and in the degree of the inclusion of Ti4+ atoms in the structure of the zeolite material. Increase in the volume of the structure-directing agent leads to the decrease of the crystallinity of the samples and decrease in the specific surface area of the material and in the specific volume of micropores. The result of this research will be used to create a theoretical model of controlled micro-/mesoporous ratio in silicas and it may open new perspectives for their potential application in selective oxidation reactions involving large molecules.

    • Novel 2-hydroxyethyl substituted N-coordinate-Pd(II)(NHC) and bis(NHC)Pd(II) complexes: Synthesis, characterization and the catalytic activity in the direct arylation reaction

      AYDıN AKTAS DUYGU BARUT CELEPCI YETKIN GOK

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      The direct arylation reaction has attracted attention in recent years especially because of its environment-friendly properties. In this study, we researched the synthesis of 2-hydroxyethyl substituted bis(NHC)Pd(II) complexes and also the synthesis of N-coordinate-Pd(II)(NHC) complexes containing Nbound benzimidazolium from palladium acetate ([Pd(CH3COO)2]) with 1,3-disubstituted benzimidazolium halides in DMSO. All the complexes have been characterized by using 1H NMR, 13C NMR, FTIR spectroscopy and elemental analysis techniques. The molecular and crystal structure of one of the complexes is confirmed by using single-crystal X-ray diffraction. These complexes have been examined as the catalyst in the direct arylation reaction with 2-n-butylfuran and 2-n-butylthiophene and have demonstrated excellent activity in this reaction.

    • Clean synthesis of benzylidenemalononitrile by Knoevenagel condensation of benzaldehyde and malononitrile: effect of combustion fuel on activity and selectivity of Ti-hydrotalcite and Zn-hydrotalcite catalysts

      AMARSINH L JADHAV GANAPATI D YADAV

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      Benzylidene malononitrile find applications in pharmaceutical industries, pharmacology, biotech,specialty chemicals, perfumery, and for fluorescence-based assay to determine methane and is produced by polluting routes. Hydrotalcites (HT) have been very effective as solid bases in different reactions and their properties can be changed by using different synthetic methods. In this work, the effect of additional metal in the synthesis of Al-Mg hydrotalcite was systematically studied to prepare Ti-Al-Mg (Ti modified hydrotalcite) and Zn-Al-Mg HT (Zn modified hydrotalcite) using combustion method with glycine as well as glycerol as a fuel. All synthesized catalysts were evaluated in Knoevenagel condensation of benzaldehyde with malononitrile to give benzylidene malononitrile. The catalysts were completely characterized by SEM, EDXS, N2 Adsorption, CO2-TPD and NH3-TPD and XRD techniques. Ti-Al-Mg hydrotalcite using glycine as a fuel was found to be the most active, selective and reusable catalyst. Langmuir-Hinshelwood-Hougen-Watson (LHHW) model was used to establish the reaction mechanism and kinetics. All species were weakly adsorbed leading to the second order power law model. Using mole ratio of 1:3 of benzaldehyde to malononitrile with ethyl acetate as a solvent and 2.5×10-4 g/cm3 catalyst loading, 67.1% conversion of benzaldehyde and 97.6% selectivity to benzylidene malononitrile were achieved in 4 h at 60°C. The apparent activation energy was 10.01 kcal/mol. The process is green.

    • Transition metal containing ionic liquid-assisted one-pot synthesis of pyrazoles at room temperature

      MANASHJYOTI KONWAR HANAN M F ELNAGDY PRAVEEN SINGH GEHLOT NAGESHWAR D KHUPSE ARVIND KUMAR DIGANTA SARMA

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      The feasible and one of the green ways to synthesize organic compounds especially pyrazole and its derivatives are systematically presented. The one-pot synthesis of pyrazole was achieved by condensation of various hydrazines and 1,3-diketone derivatives at room temperature using transition metal-based ionicliquids. Herein, the unique combination of Fe(III) with ionic liquid is explored and utilized as an efficient homogeneous catalyst for the synthesis of pyrazole and its derivatives. The homogenous catalyst thus synthesised was re-used up to the fourth cycle (with 90%, 88%, 84%, 78% yields respectively).

    • One-pot synthesis of new water-soluble binuclear octahedral Ni(II) and mononuclear Ru(II) carbonyl complexes containing 2,6 pyridine dicarboxylic acid

      P KALAIVANI H PUSCHMANN M V KAVERI T SURESH R PRABHAKARAN

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      An attempt to synthesize mixed geometrical hetero binuclear complexes has been made by reacting 2,6 pyridinedicarboxylic acid with [NiCl2(PPh3)2] and [RuHCl(CO)(PPh3)3]. However, the reaction afforded a mononuclear complex [Ru(dipic)(CO)(PPh3)2].DMF (1) and homo binuclear complex [Ni2(-dipic)2(H2O)5].2H2O (2) [dipic = 2,6-pyridinedicarboxylate] respectively. The new complexes (1 and 2) were characterized by elemental analyses, IR, UV-Vis, 1H-NMR and single-crystal X-ray diffraction studies. The complexes 1 and 2 crystallized in the monoclinic P21/c and triclinic P-1 space groups, respectively. Complex 2 displayed a three-dimensional (3D) network with lattice water molecules. The redox behaviour of the complexes was studied by cyclic voltammetry. The DNA and albumin binding studies of the complexes weredone by taking CT-DNA and BSA as models. The new complexes exhibited significant binding efficiency with DNA and albumin.

    • Synthesis and performance evaluation of silica-supported copper chromite catalyst for glycerol dehydration to acetol

      S BASU A K SEN M MUKHERJEE

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      Sol-gel technique was used to prepare silica-supported copper chromite catalyst from acid hydrolysis of sodium silicate. The catalyst was characterized by BET surface area, FESEM, XRD, H2-TPR and pyridine adsorption by FTIR. The catalyst was activated in a hydrogen atmosphere based on H2-TPR result. The surface acidity of the catalyst was evaluated by NH3-TPD and pyridine adsorption. XRD result of reduced catalyst showed the presence of Cu0, Cu1+ and Cr2O3 in the catalyst. Glycerol dehydration was carried out at different temperature (180°C to 240°C) from aqueous glycerol solution with the reduced catalyst in a batch reactor. The glycerol conversion was reached 100% with maximum acetol selectivity of 70% for highest Copper chromite loaded (40 wt%) on silica at 220°C in atmospheric pressure. The distilled liquid product was analyzed by high-performance liquid chromatography. Oxidized catalyst and spent catalyst showed lower glycerol conversion with low acetol selectivity than the reduced form of the catalyst. This is due to the cuprous ion in the reduced form of the catalyst, which acts as Lewis acid sites in glycerol dehydration.

    • A simple Schiff base platform: sensing of Al3+ ions in an aqueous medium

      RAJASEKARAN DHIVYA ASAITHAMBI GOMATHI PERIASAMY VISWANATHAMURTHI

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      A simple Schiff base probe PADP ((1,2-phenylenebis(azanylylidene)) bis(methanylylidene)) bis(3-(diethylamino)phenol) was synthesized from 4-(diethylamino)salicylaldehyde and o-phenylenediamine and has been characterized using analytical and spectral methods. The emission spectrum of PADP Schiff base shows notable enhancement in the emission intensity at 500 nm in the presence of Al3+ in MeOH-H2O (1:9 v/v). On the other hand, other relevant metal ions did not influence considerably the emission spectrum of PADP. The detection limit and binding constant (Kb) of PADP towards Al3+ were found to be 0.104 lM and 3.0 9 106 M-1 from the fluorescence titration experiments. The 1:1 binding stoichiometry was further determined by Job’s plot and ESI-MS spectroscopy. The MTT assay shows no or negligible toxicnature of probe and thus it was utilized in vitro cell imaging studies of Al3+ ions. The results show that the probe PADP could be useful to detect Al3+ in an aqueous medium

    • Synthesis, structure and solid-state electrical conductivity of bis(1,2-diphenylethylene-1,2-dithiolate)nickel(II)

      ARGHYA DUTTA ARNAB CHATTERJEE KISHALAY BHAR ANINDITA BANERJEE RAJARSHI GHOSH

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      One nickel(II)-dithiolene complex bis(1,2-diphenylethylene-1,2-dithiolate)nickel(II) has been synthesized and crystallographically characterized. The complex is square planar at its metal centre. The compound in its solid-state is found to conduct electricity at room temperature. Variation of conduction is also found on raising the temperature. Instead of a metal…metal orbital overlap, the electron density is expected here to pass through some other covalent and electrostatic bonds of the compound in solid-state resulting in electricity conduction.

    • Novel series of acridone-1,2,3-triazole derivatives: microwave-assisted synthesis, DFT study and antibacterial activities

      MOHAMMED AARJANE SIHAM SLASSI BOUCHRA TAZI MOHAMED MAOULOUA AMINA AMINE

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      A series of novel acridones bearing a 1,2,3-triazole unit have been synthesized and characterized. The copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) was performed using both a conventional method and amicrowave-assisted synthetic method. The in vitro antibacterial potencies of all the synthesized compounds were determined against five clinically isolated strains: Escherichia coli, Klebsiella pneumonia, Pseudomonas putida, Serratia marcescens and Staphyloccocus aureus. Furthermore, DFT quantum chemical calculationswere carried out to investigate geometry structures, frontier molecular orbital and gap energies, and molecular electrostatic potential maps (MEP). Lipophilicities of the studied compounds were also determined.

    • Coupling of CH3OH and CO2 with 2-cyanopyridine for enhanced yields of dimethyl carbonate over ZnO–CeO2 catalyst

      PRATHAP CHALLA VENKATA RAO M NAGAIAH P NAGU A DAVID RAJU B RAMA RAO K S

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      The present work is aimed to produce dimethyl carbonate by coupling of CH3OH and CO2 with 2-cyanopyridine over ZnO–CeO2 catalysts prepared by co-precipitation method. These catalysts were characterized by XRD, TEM, UV-Vis DRS, BET surface area, CO2 and NH3-TPD techniques and applied forthe titled reaction. Among the investigated catalysts 10ZnO–90CeO2 catalyst with CeO2 crystallite size 8.0nm exhibited 96% conversion of methanol with 99% selectivity to dimethyl carbonate. The superior catalytic activity is a unified effect of crystalline size of CeO2 and presence of an optimum number of acidic and basic sites. This protocol offers enhanced conversion of methanol with the simultaneous conversion of 2-cyanopyridine into 2-picolinamide by removing water molecules formed in the reaction.

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