• Volume 132, All articles

      Continuous Article Publishing mode

    • Two efficient ligand-assisted systems of two different ionic Schiff base ligands for palladium chloride catalyzed in Suzuki-Miyaura reaction

      FARZANEH NEHZAT GHOLAMHOSSEIN GRIVANI

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      The bis- methyl imidazolium chloride-salophen Schiff base ligand as cationic Schiff base ligand (L1) was synthesized by the reaction of methyl imidazoliumsalicylaldehyde chloride (S1) and phenylendiamine.The phenylendiamine was also reacted by monosodium 5-sulfonatosalycilaldehyde (S2) to give the bis-sodium sulfonate-salophen Schiff base ligand (L2) as the anionic ligand. These two ligands were characterized by the 1H-NMR, 13C-NMR, IR, UV–visible and mass spectroscopy, as well as elemental analysis.The ligand assisted PdCl2 catalyst was investigated in the Suzuki-Miyaura reaction by using the L1 and L2 as cationic and anionic Schiff base ligands and different reaction conditions such as temperature, solvent and mol% of PdCl2 were optimized. The results revealed that the anionic ligand assistance had a better activity forthe catalytic system of PdCl2 in Suzuki-Miyaura reaction

    • A facile route to synthesize N-(Boc-Aminoethylglycin)thymine Ethyl Ester, application to the synthesis of PNA-oligonucleotide conjugates

      ANURADHA DAS BISWARANJAN PRADHAN

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      Peptide nucleic acid oligonucleotide conjugates are attracting immense interest currently because of their use in the biomedical and diagnostic field as antigene and molecular sensors. The efficient PNA synthesis methods can reduce their cost and may increase availability for their wider use. Here we described afacile synthesis of the peptide nucleic acid monomer N-(Boc-Aminoethylglycin)thymine Ethyl Ester [Ethyl2-(N-(2-((tert-butoxycarbonyl)amino)ethyl)-2-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamido) acetate]. The monomer N-(Boc-Aeg)thymine Ethyl Ester has been prepared in a good yield (96%) by highly efficient procedure involving direct coupling of nucleobase thymine with the backbone Ethyl N-(Bocaminoethyl)-N-(chloroacetyl)glycinate, which was prepared from the reaction of Ethyl N-[(2-Boc-amino)-ethyl]glycinate with chlroacetylchloride. The key intermediate Ethyl N-[(2-Boc-amino)-ethyl]glycinate involved in the synthesis has been prepared via a scalable and cost-effective route with a yield of (98%). The thyminyl PNA monomer was reported to be used in various synthetic applications, and our cost-effective, highly scalable method of synthesis will expand its wider use.

    • Squaric acid: an impressive organocatalyst for the synthesis of biologically relevant 2,3-dihydro-1H-perimidines in water

      SUSHIL KHOPKAR GANAPATI SHANKARLING

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      Squaric acid, a green, metal-free and eco-friendly organocatalyst, has been exploited for the synthesis of biologically interesting 2,3-dihydro-1H-perimidines. The reaction was performed using water as a green reaction medium and the organocatalyst can be easily recovered and reused up to four consecutivecycles without much decrease in catalytic activity. Several advantages of the present methodology are low catalyst loading, excellent catalytic performance, easy catalyst handling, mild reaction conditions, operational simplicity, ease of product isolation, avoidance of column chromatographic separation, a higher yield of the desired product in short reaction time, high atom economy and synthesis of benzophenone based perimidine

    • Diphenyl phosphate creatine immobilized on magnetite nanoparticles: an efficient and recyclable catalyst for Aza-Michael reaction

      FARZANE PAZOKI FAHIMEH MOHAMMADPANAH AREFE SALAMAT MANESH JAMSHID AZARNIA MEHRABAN AKBAR HEYDARI

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      In this paper, diphenyl phosphate creatine was successfully immobilized on Fe3O4 nanoparticles and used as the highly efficient catalyst for the aza-Michael reaction of 5-substituted tetrazole and a,bunsaturated carbonyl. The prepared nanocatalyst was fully analyzed by various techniques such as FouriertransformInfrared Spectroscopy (FT-IR), Field Emission Scanning electron microscope (FE-SEM), Vibrating Sample Magnetometer (VSM), Thermal Gravimetric Analysis (TGA) and X-ray Diffraction (XRD). This procedure possesses numerous advantages such as simple work-up, high yield and short reaction times.

    • Silver(I)-selective PVC membrane potentiometric sensor based on 5,10,15,20-tetra(4-pyridyl)-21H, 23H-porphine and potentiometric applications

      OMER ISILDAK OGUZ OZBEK

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      In this study, all-solid-state contact PVC membrane silver(I)-selective sensor has been prepared and 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine used as ionophore. Optimum membrane composition; 3.5% ionophore, 59.6% Bis(2-ethylhexyl) sebacate (BEHS), 1.0% potassium tetrakis (p-chlorophenyl) borate(KTpClPB) and 35.9% polyvinyl chloride (PVC). The developed silver(I)-selective sensor exhibited a linear response (E = -51,57 (-log[Ag+]) + 1690,6 and R2 = 0,9986) in the varying concentration range of 1.0 x 10-1 to 1.0 x 10-5 mol L-1 silver ions. The limit of detection of the sensor was calculated as 1.9 x 10-6 mol L-1. The silver(I)-selective sensor exhibited good selectivity towards some alkali, alkali earth and heavy metal ions. The sensor can be used in thepHrange from 4.0 to 10.0. The sensor has been shown to have good reusability and response time less than 8 s. The sensor was used as an indicator electrode in titrations of silver nitrate with sodium chloride solution and was successfully applied for the determination of the different water samples.

    • The one-pot four-component eco-friendly synthesis of spirooxindoles in deep eutectic solvent

      THOKCHOM JEETA DEVI THOKCHOM PRASANTA SINGH OKRAM MUKHERJEE SINGH

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      An efficient and facile synthesis of spirooxindole derivatives bearing pyrano[2,3-c]pyrazole moiety has been achieved using deep eutectic solvent (DES) promoting a four-component reaction. The protocol avoids the use of costly and toxic catalysts and organic solvents which encounters many side effects on the environment and human beings. The simplicity and versatility of this eco-friendly green method isdescribed.

    • Influence of pH on the structures of two Cd phosphonate compounds

      LING YAN ZHAO XIAO CHEN DENG GANG LIANG XI BAO ZHENG XI YUE LI

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      Two novel Cd-based coordination polymers Cd(H2BCP)2(phen)2 1 and {[Cd6(BCP)4(phen)3]-2H2O}n 2 (Phen=1,10-phenanthroline) have been hydrothermally synthesized from a combination of 4-(phosphonomethyl) benzoic acid 4-HOOCC6H4CH2PO3H2 (H3BCP) and 1,10-phenanthroline. The X-raycrystal structure analyses revealed that 1 is a 0D mononuclear molecular structure and 2 is a 3D structure existing the novel Cd6 cluster unit. It is worth mentioning that 1 and 2 have the same constitutional units, namely the Cd ion, H3BCP ligand and second ligand- Phen. However, their structures are different and it results from the different solution pH value. In order to explore the structural characteristics, FTIR, photoluminescent and solid UV-Vis spectra are employed.

    • Preparation of Ni2P on twinned Zn0.5Cd0.5S nanocrystals for highefficient photocatalytic hydrogen production

      XIAOPENG ZHOU LINXIN YIN KAIQING DAI XIANGYANG GAO YANAN FENG YAFEI ZHAO BING ZHANG

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      Developing efficient non-precious metal semiconductor photocatalysts is highly desirable for photocatalytically splitting water. In this work, the composite of the nanocrystal twinned Zn0.5Cd0.5S (ZCS) solid solution decorated with highly dispersed Ni2P nanoparticles was successfully formed by in situ growthmethod, and it exhibited remarkable photocatalytic hydrogen production activity of visible light. A high rate of hydrogen production of 30473 lmol h-1 g-1 was achieved, and the apparent quantum yield (AQY) was as high as 83.5% at 420 nm. Moreover, the sample could maintain outstanding photocatalytic hydrogenation activity after 4-cycle continuous catalytic process. The unique nano-twinned structure of ZCS and synergistic effects between the Ni2P and the twinned ZCS are responsible for the dramatically improved catalytic activities of photocatalysts composite.

    • Cobalt (II) complex catalyzed polymerization of lactide and coupling of CO2 and styrene oxide into cyclic styrene carbonate

      HARISH CHANDRA PRADHAN SOMANATH MANTRI ANITA ROUTARAY TUNGABIDYA MAHARANA ALEKHA KUMAR SUTAR

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      In the present study, the cobalt (II) complex [Co-HMBED] has been prepared and characterized by spectrochemical techniques, which confirmed its square planar structure. The catalytic activity of the cobalt complex was evaluated towards solvent-free conversion of CO2 and styrene oxide into cyclic styrene carbonate and polymerization of lactide

    • Correction to: Syntheses and structures of chalcogen-bridged binuclear group 5 and 6 metal complexes

      MOULIKA BHATTACHARYYA RINI PRAKASH CHANDAN NANDI MONOJIT GHOSAL CHOWDHURY BEESAM RAGHAVENDRA THIERRY ROISNEL SUNDARGOPAL GHOSH

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    • Half-sandwich iron complexes bearing vinyl-selenocarboxylato ligands

      TAGHREED AL-JAZZAZI MOHAMMAD EL-KHATEEB LAMA QURAAN HASSAN ABUL-FUTOUH HELMAR GORLS WOLFGANG WEIGAND

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      Vinyl selenocarboxylato iron complexes of the formula CpFe(CO)2SeCOCH=C(R1)(R2) {R1 = H, R2 = Me, R1 = R2 = Me, R1 = H, R2 = CH=CHMe} are synthesized by the reaction of (l-Se)[CpFe(CO)2]2 with the corresponding vinyl acid chlorides ClCOCH=C(R1)(R2). Photolytic substitutionsof CpFe(CO)2SeCOCH=CMe2 with EPh3 gave the monosubstituted complexes CpFe(CO)(EPh3)-SeCOCH=CMe2 (E = P, As, Sb) in good yields. The new complexes have been characterized by UV-Vis, IR,1H-NMR, 13C{1H}-NMR, 77Se{1H}-NMR, 31P{1H}-NMR spectroscopy and elemental analysis. The solidstate structures of CpFe(CO)2SeCOCH=CMe2 and CpFe(CO) AsPh3)SeCOCH=CMe2 were determined by X-ray crystallography. The cyclic voltammetric measurements of CpFe(CO)2SeCOCH=CMe2 were recorded.

    • Detection of hydrogen sulfide using BODIPY based colorimetric and fluorescent on-off chemosensor

      NAVENDU PAUL RUDRA SARKAR RIPON SARKAR ANANYA BARUI SABYASACHI SARKAR

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      A colorimetric and fluorescence turn-off probe 10-(4-azido phenyl)-5,5-difluoro-5h-dipyrrolo[1,2-c:1¢,2¢-f][1,3,2] diazaborinin-4-ium-5-uide, 1, for selective detection of H2S is reported. The probe displayed a robust decrease in fluorescence intensity with high sensitivity, specificity and least toxicity to detect exogenous H2S and also in live normal human oral fibroblast cells loaded with probe 1. The detectionlimit of probe 1 being 0.17 lm for H2S.

    • Rational design of novel N-doped polyaromatic hydrocarbons as donors for the perylene based dye-sensitized solar cells

      MASIYAPPAN KARUPPUSAMY VENKATA SURYA KUMAR CHOUTIPALLI DOLLY VIJAY VENKATESAN SUBRAMANIAN

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      This paper reports designing a series of new D-p-A topology-based metal-free organic dye molecules using ullazine and perylene by DFT methods. This work emphasizes the combination of ullazine analogs as donors and perylene dicarboxylic anhydride as an acceptor along with acetylene linker as p-bridgefor DSSC applications. The structural and optoelectronic properties of dyes before and after adsorption on to TiO2 semiconductor have been investigated. The screening of the designed dyes is carried out based on the energy gap (Eg), maximum absorption wavelength (kmax), light-harvesting efficiency (LHE), excited-state lifetime (s), the free energy of electron injection (DGinj) and regeneration (DGreg). DFT results reveal that the presence of ullazine analogs as a donor reduces the energy gap (Eg) and leads to red-shift in absorptionmaximum. Further, two different binding modes of dye molecules with (TiO2)38 cluster have been investigated to unravel the binding associated changes in the electronic structure. The results show that the completely dissociated bidentate bridging (CBB2) mode is more favorable, which contains two carboxylic groups.Findings emphasize the remarkable charge transfer characteristics which favors the fast electron injection from excited dye to the conduction band of TiO2. For the first time, this study provides comprehensive structural and electronic information combined with the Dye-TiO2 interactions for the development of perylene based dyes for DSSC applications

    • Quantitative investigation on the intermolecular interactions present in 8-(4-ethoxyphenyl)-1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione with insight from interaction energies, energy framework, electrostatic potential map and fingerprint analysis

      RAHUL SHUKLA PRABAL BANDOPADHYAY MANISHA SATHE DEEPAK CHOPRA

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      In this study, we have performed a detailed quantitative analysis of the different intermolecular interactions present in 8-(4-ethoxyphenyl)-1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione (I). The molecule crystallizes in the P-1 space group with one molecule in the asymmetric unit. The molecule had a layeredcrystal packing wherein the molecular sheets are primarily formed by hydrogen bonds and the stabilization is dominated via the electrostatic energy contribution. This molecular sheet is then interconnected to other similar sheets via different stacking motifs with significant contribution from dispersion energy components

    • Substituent effects on the halogen and pnictogen bonds characteristics in ternary complexes 4-YPhNH2...PH2F...ClX (Y = H, F, CN, CHO, NH2, CH3, NO2 and OCH3, and X = F, OH, CN, NC, FCC and NO2): A theoretical study

      TAHEREH TONDRO HOSSEIN ROOHI

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      The synergistic relationship between pnictogen and halogen non-covalent interactions in 4-YPhNH2...PH2F...ClX (Y = H, F, CN, CHO, NH2, CH3, NO2 and OCH3; X = F, OH, CN, NC, FCC and NO2) complexes were explored using Aug-ccpVDZ basis set and M06-2X and M06-2X-GD3, B2PLYP-GD3and mPW2PLYP-GD2 functionals. The effects of the substituents included at pnictogen bond and halogen bond segments on the correlation between BEs and pnictogen as well as halogen bond distances, electron density at both non-covalent interactions, charge transfer energies between components and the NMR properties were evaluated. The energy analysis indicates that the pnictogen bond interaction has a much greater stabilizing effect than the halogen bond one. In addition, the auxiliary effect of a pnictogen bond on a halogen bond is more pronounced than that of a halogen bond on a pnictogen bond

    • Autocatalyzed oxidation of amino acid, L-Citrulline by diperiodatocuprate(III) complex in aqueous alkaline medium: a kinetics and mechanistic approach

      SANTOSH B KONNUR SHARANAPPA T NANDIBEWOOR

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      Autocatalysed oxidation of important amino acid, L-Citrulline(L-Cit) by coordination complex, diperiodatocuprate(III) in aqueous alkaline medium at a constant ionic strength of 0.05 mol dm-3 wasstudied spectrophotometrically. Autocatalysis was observed by one of the products formed, i.e., Cu (II). 1:4 stoichiometry (L-Cit:DPC) exhibited between the reaction of L-Cit and DPC in aqueous alkaline medium. The path is of first-order in [DPC], less than unit order in [L-Cit] and independent in [OH-]. Periodate has aretarding effect on the rate of reaction. Ionic strength has a negligible effect on the reaction rate. The main reaction products were identified by spot tests and spectroscopic analysis. A composite mechanism involving uncatalysed and an autocatalysed reaction path (via free radical) was proposed. The activation parameters for the slow step of the mechanism and also the thermodynamic quantities for different steps of the mechanism were determined and discussed.

    • The investigation of cooperative binding between psulfonatocalix[ 6]arene and fluorescein with transition metal ions by spectrometrically

      SHARADCHANDRA GAWHALE NILESH RATHOD SANHITA PATIL RUPALI THORAVE VRASHALI KALYANI RAJESH SAPKAL VILAS SAPKAL GAJANAN CHAUDHARI DIPALEE MALKHEDE

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      The ternary complexes are formed by self-assembly through cooperative hydrogen bonding between p-SCX6-FL and M2+ through water molecule which is reinforced by columbic and electrostatic interactions. The binding efficiency of Cu2+ and Zn2+ is observed at a greater extent than Co2+ and Ni2+. Furthermore, the kinetic study of p-SCX6-FL-Cu2+ and Zn2+ reveals that the process of complexation isslower than the binary system (FL+p-SCX6).

    • A hydrogel based on dialdehyde carboxymethyl cellulose–gelatin and its utilization as a bio adsorbent

      SAPNA SETHI BALBIR SINGH KAITH MANDEEP KAUR NEERAJ SHARMA SADHIKA KHULLAR

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      In the present study, the dialdehyde carboxymethyl cellulose (DCMC) was cross-linked covalently to gelatin via the Schiff base reaction to form a three-dimensional hydrogel (DCMC-cl-G). The crosslinking degree of DCMC and gelatin was estimated to be 50.31 ± 2.65. The maximum swelling capacityof the hydrogel in aqueous medium was around 74 g/g at pH 10.0 and 37°C with equilibrium swelling attained in three hours and the compressive strength of the hydrogel was found to be 55 ± 0.76 kPa at 60% strain. The biodegradation studies confirmed 82.67% degradation of the hydrogel sample within a period oftwelve weeks. Further, the hydrogel was evaluated as a bio adsorbent for the removal of hazardous dyes, namely Rhodamine B (RhB) and Methyl Violet (MV) from water due to its decent swelling capacity and good mechanical strength. The maximum percentage of RhB and MV removed from the respective dye solutionsusing DCMC-cl-G hydrogel was 96.5% and 90% at pH 6.0, respectively. Both dyes followed Langmuir adsorption isotherm, which considers monolayer adsorption of adsorbate over adsorbent, with a pseudosecond-order kinetic model.

    • An equation of motion approach for the vibrational transition energies in the effective harmonic oscillator formalism: the Random phase approximation

      T DINESH LALITHA RAVICHANDRAN M DURGA PRASAD

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      A theory for calculating vibrational energy levels and infrared intensities is developed in the equation of motion framework at the random phase approximation level. The vibrational Hamiltonian is expanded in the harmonic oscillator ladder operators making a Hamiltonian a bosonic Hamiltonian. Theexcitation operator is expanded to include at most two creations and two annihilation operators making it equivalent to the random phase approximation. The method is applied for the calculation of vibrational spectral properties of two molecules. The results are found to be satisfactory, making this approach a viable option for large molecular systems.

    • Synergistic cobalt–nickel co-catalyst for enhanced visible light-induced photocatalytic water oxidation

      PEGAH NAZARI OMID NOURI SHAHRBANOO RAHMAN SETAYESH

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      The loading of co-catalyst is an efficient way to increase the activity of synthesized carbon-based photocatalysts in the energy and environmental applications. Herein, Co and Ni decorated on g-C3N4 was synthesized as a visible light active photocatalyst and characterized with XRD, FT-IR, BET, DRS, TGA, FESEM, EDX, and EIS techniques. From the characterization results, it was demonstrated that cobalt and nickel which were present in the structure of the nanocatalyst, were in the metallic form. The decoration of Ni and Co reduced bandgap energy of g-C3N4 and made the synthesized nanocomposite active under visible light. The operating condition of O2 photocatalytic generation was optimized (193.75 lmol L-1 O2 productions using 0.2 g Co2Ni1/g-C3N4/rGO at 7 h without sacrificial reagents). The effect of sacrificial reagents (Fe(NO3)3, AgNO3, and methanol) was investigated and Fe(NO3)3 showed the best results during water oxidation. The kinetics study indicates that the presence of cocatalysts could be helpful in reducing the apparent activation energy about 3.5 times. The photocatalyst represented acceptable stability (2% Ni and 3%Co leaching) and reusability up to six cycles. According to the obtained results, we can introduce Co2Ni1/g- C3N4/rGO as a potential powerful photocatalyst for water oxidation reaction under visible light.

    • Graphene oxide: an efficient carbocatalyst for the solvent-free synthesis of 2-(substituted benzoyl)-3-(substituted phenyl)imidazo[1,2-a]pyridines

      DILPREET KOUR SONAKSHI SASAN KAMAL K KAPOOR

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      GO has been found as a remarkable heterogeneous carbocatalyst for the solvent-free synthesis of 2-(substituted benzoyl)-3-(substituted phenyl)imidazo[1,2-a]pyridines from chalcones and 2-aminopyridine. The present methodology offers a novel and eco-friendly approach with appreciable yields of the desired products.

    • Fluxional nature in cyclohexane and cyclopentane: spherical conformational landscape model revisited

      SAHAR SAKHAEE MOHAMMAD HOSSEIN SAKHAEE AHMAD TAKALLOU FATEMEH FOROUZANFAR NADER SAKHAEE

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      Spherical conformational landscape model was revisited to include yet another class of cyclic compounds; the derivatives of cyclohexane. The updated model is not only capable of explaining Raman spectral features in fluxional cyclopentane but is also capable of revealing similarities between cyclopentane and cyclohexane derivatives for the first time. At the heart of the model lies the aspect of B/T ring coordinates (B/T conformational platform) that represents different levels of puckering (q). DFT-wb97xd/6-311 + G* computations confirmed by MP2/aug cc-pVTZ computations were used to fully investigate 16 differentderivatives of both cyclohexane and cyclopentane. Intrinsic reaction coordinate, IRC, computations were performed to gain insight into patterned inter-platform pathways connecting ring coordinates. These pathways revealed the coupling strength between bent/boat, B, and twist, T, ring coordinates. The coupling is found to be stronger for cyclopentane compared to cyclohexane. Some spectral features in the overlap region near 1400 cm-1 show promising signs on spin–spin relaxation, T2, mechanism. The work opens up an avenue for conformational studies of medium-sized rings. Also, ongoing studies to unravel potential relationships between conformational flexibility and bioactivity of cyclic compounds are underway.

    • Two acetylenedicarboxylato-bridged 4-styrylpyridine appended 1D coordination polymers: synthesis, structural characterization and variable temperature magnetism

      BASUDEB DUTTA AKHTARUZZAMAN HIROKI SATO TAKASHIRO AKITSU ALEXANDRA M Z SLAWIN UDDALOK KAR CHITTARANJAN SINHA MOHAMMAD HEDAYETULLAH MIR

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      Two hitherto unknown one-dimensional coordination polymers (1D CPs) [M(adc)(4-spy)2 (H2O)2]n, (M = Mn(II) (1) and Co(II) (2); H2adc = acetylenedicarboxylic acid and 4-spy = 4-styrylpyridine) have been characterized by infrared spectra, elemental analysis, thermogravimetric analyses (TGA), powder X-ray diffraction (PXRD) patterns and single-crystal X-ray diffraction techniques. Both these compounds 1 and 2, are isostructural and construct 3D supramolecular networks by the combination of hydrogen bonding and C–H...p interactions. Interestingly, these two materials exhibit variable temperature magnetic moment

    • Effect of aggregation on hydration of HSA protein: Steady-state Terahertz absorption spectroscopic study

      BISWAJIT MANNA AMITABHA NANDI MASAHITO TANAKA HIROYUKI TOYOKAWA RYUNOSUKE KURODA DIPAK K PALIT

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      Terahertz (THz) absorption behaviour of HSA protein in aqueous buffer solutions has been investigated in the 0.1–2 THz frequency range using a highly intense THz source based on coherent transition radiation (CTR) generated using a femtosecond electron accelerator of 42 MeV energy (for 0.3–2 THz) and aklystron (at 0.1 THz). Like in the cases of other proteins reported earlier, THz absorbance of the protein solutions follow nonlinear behaviour with increasing concentration of HSA protein monitored through the entire frequency range. THz absorbance of the solution initially increases to follow an apparently linearbehaviour up to the concentration of ~6 9 10-4 mol dm-3 but decreases gradually with further increase in HSA concentration. The linear behaviour in low concentration regime could be explained considering the increase in concentration of the monomer HSA molecules in solution with a well-defined hydration layer of thickness of about 22 A° around it. However, the study of dynamic light scattering measurements suggest the presence of increasing number of protein aggregates in solution with increasing concentration of protein. THz absorbance of each of these samples could be calculated to show that absorbance decreases with increasing number of aggregates in solution and also the relative concentrations of the monomer and aggregated particles existing in solutions could be estimated. This work, for the first time, explains the nonlinear change in THz absorbance of protein solutions with increasing protein concentration considering the protein aggregation effect at very high concentration.

    • Effect of nano-confinement on the structure and properties of water clusters: An ab initio study

      MANOJ K TRIPATHY DEVENDRA K MAHAWAR K R S CHANDRAKUMAR

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      An ab initio investigation on water clusters confined to armchair carbon nanotubes (CNT) with varying diameters has been performed using the density functional theory-based calculations. Different parameters have been investigated including structure, hydrogen bonding pattern and vibrational spectra of water-CNT complexes. Our results reveal that one-dimensional water chain parallel to CNT axis is formed in narrow nanotubes CNT(4,4) and CNT(5,5), whereas in CNT(6,6), zigzag structure is observed. An increase in the CNT diameter results in more symmetric structures similar to the gas phase. The vibrational analysis shows a redshift in stretching frequency of the hydrogen bond assisted O–H in CNT(6,6) due to the reduction in O—O separation whereas a significant blue shift in stretching frequency mode is observed in highlyconfined CNT(4,4) and CNT(5,5). It implies that the hydrogen bond strength between water molecules is strongest in CNT(6,6). It is also observed that water cluster tends to be near CNT wall due to H...p interaction between water molecule and the p-electron cloud of CNT. An inverse relation between the electronic charge transfer (from CNT to water) and the diameter is also established. This study demonstrates that the degree of confinement is extremely important in deciding the properties of confined water molecules.

    • Core–shell-structured MnO2@carbon spheres and nitrogen-doped activated carbon for asymmetric supercapacitors with enhanced energy density

      JIE WEN XIAOPING CHEN MAOLIN HUANG WEN YANG JIE DENG

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      Asymmetric supercapacitors have potential applications in renewable-energy technology owing to their remarkable electrochemical properties. A high-voltage asymmetric supercapacitor was developed based on a core–shell-structured MnO2@carbon sphere composite (MnO2@CS) as the cathode, nitrogendopedactivated carbon as the anode and a neutral aqueous Na2SO4 solution as the electrolyte. MnO2@CS was successfully fabricated by hydrothermally growing MnO2 on the surface of carbon spheres. A nitrogencontaining benzoxazine resin was adopted as a precursor to produce in situ nitrogen-doped activated carbon.Such an aqueous electrolyte-based asymmetric supercapacitor can be cycled reversibly in the high-voltage region of 0–1.9 V and exhibits a superior energy density of 8 Wh kg-1 at an ultrahigh power density of 9627 W kg-1 owing to the matching of MnO2@CS and porous nitrogen-doped activated carbon. Moreover,the asymmetric supercapacitor presents acceptable cycling performance, with 74.4% retention after 1000 cycles at 1 A g-1, and a charge–discharge efficiency of the electrode of almost 100%.

    • Profiling of LINS01 compounds at human dopamine D2 and D3 receptors

      MICHELLE F CORREA DAVID REINER GUSTAVO A B FERNANDES MARINA T VARELA CECILIA M S Q ARANHA HOLGER STARK JOAO PAULO S FERNANDES

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      Histamine and dopamine neuronal pathways display interesting overlapping in the CNS, especially in the limbic areas, making them very attractive to designing drugs with synergistic and/or additive effects. The roles of these systems to treat schizophrenia, drug addiction, Parkinson’s and Alzheimer’s diseases, among others are widely known. The LINS01 compounds were previously reported as histamine H3 receptor (H3R) antagonists and some of them are under evaluation in rodent memory models. Considering their pharmacological potential and similarities to literature dopamine D2 receptor (D2R) and dopamine D3 receptor (D3R) ligands, this work aimed to evaluate these compounds as ligands these receptors by using [3H]spiperone displacement assays. A set of 11 compounds containing the dihydrobenzofuranyl-piperazine core with substituents at 5-position of dihydrobenzofuran ring and at the piperazine nitrogen was examined. The compounds showed low to moderate affinities at both, D2R and D3R. N-Phenyl compounds LINS01005 (1d), LINS01011 (1h), LINS01012 (1i) and LINS01016 (1k) showed the highest affinities in the set to D3R (Ki 0.3–1.5 mM), indicating that N-phenylpiperazine moiety increases the affinity to this receptor subtype with some selectivity, since they showed lower affinities to D2R (Ki 1.3–5.5 mM). With the LINS01 compounds showing moderate binding affinity, new lead structures for optimization with regards to combined H3R and D2R/D3R-ligands are provided.

    • Conceptual approach to the synthesis of symmetrical 1,3-diynes from b-bromo vinyl carboxylic acids

      RAJU SINGHA

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      A conceptual route has been developed for the synthesis of 1,3-diyne from b-bromo vinyl carboxylic acids. The reaction of the b-bromo vinyl carboxylic acid with palladium catalyst is conceptually similar to the decomposition of 2-diazoniumbenzoic acid to benzyne. In the presence of palladium catalyst,the b-bromo vinyl carboxylic acid undergoes a fragmentation to generate terminal alkyne. The terminal alkyne undergoes dimerisation in the presence of palladium catalysts to produce the product 1,3-diyne.

    • Lowest order perturbative approximation to vibrational coupled cluster method in bosonic representation

      T DINESH SUBRATA BANIK

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      We propose a perturbative approximation to the vibrational coupled cluster method in bosonic representation to reduce the cost of calculating the cluster matrix elements by considering only the first order of S and r for the construction of the effective Hamiltonian ese-SHeSes. With the systematic analysis of theresults of two molecules, H2O and 1,1-difluoroethylene, we find that the accuracy of the transition energies with such low order approximation is comparable to the fully converged VCCM

    • First principles investigation on the applicability of ruthenium as a potential ORR catalyst

      SURAJIT NANDI AKHIL S NAIR BISWARUP PATHAK

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      Exploration of new materials for oxygen reduction reaction has long been a major area of research in heterogeneous catalysis. As the currently available oxygen reduction catalysts have not achieved the optimal efficiency, search for alternative resources is a continuing effort. Realizing the wide acceptance ofruthenium as a promising catalyst for various catalytic reactions, we have investigated the plausibility of Ru to perform in the bulk as well as nanoparticle forms as an efficient oxygen reduction reaction catalyst. Two nanoclusters with face-centred and hexagonal symmetry were scrutinized for ORR activity along with Ru(111) and Ru(0001) surfaces as periodic counterparts and compared the activity with Pt(111) surface. We report here that Ru cannot be an alternative to the Pt-based catalysts owing to a high overpotential

    • Electrochemical aspects of restricted rhenium(I)-based supramolecular complexes with semi-rigid benzimidazolyl and rigid hydroxyquinone ligands

      SARITA YADAV MOOKAN NATARAJAN MALAICHAMY SATHIYENDIRAN SANDEEP KAUR-GHUMAAN

      More Details Abstract Fulltext PDF

      Supramolecular coordination complex [(Re(CO)3)2(dhnq)(L2)] (3) containing two fac-Re(CO)3 cores, rigid dianionic dhnq (H2-dhnq = 6,11-dihydroxy-5,12-naphthacenedione) motif and semi-rigid ditopic nitrogen donor 1,2-bis(2-nonylbenzimidazol-1-ylmethyl)benzene (o-Nbenzbix = L2) was synthesized.Compounds o-Nbenzbix and 3 were characterized using various analytical and spectroscopic methods. The electrochemical properties of 3 were studied using cyclic voltammetric measurements. SCCs [(Re(CO)3)2(-dhnq)(L1)] (1) and [(Re(CO)3)2(dhaq)(L1)] (2) possessing p-xylene spacer 1,4-bis(2-nonylbenzimidazol-1-ylmethyl)benzene (L1) and 1,4-dihydroxy-9,10-anthraquinone (H2-dhaq) were also synthesized as reported previously. SCCs 1–3 were investigated via electrochemical methods. A plot of the Randles-Sevcik equation yielded a straight line for complex 3 thus, establishing that the redox processes were diffusion-controlled.

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