IISER Bhopal

Bhopal, India

IISER Bhopal

Bhopal, India
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Parshamoni S.,IISER Bhopal | Sanda S.,IISER Bhopal | Jena H.S.,IISER Bhopal | Konar S.,IISER Bhopal
Dalton Transactions | Year: 2014

A new 2D pillared-bilayer flexible open metal organic framework {[Cu(tdc)(bpe)]n·2n(H2O)·n(MeOH)} (compound 1) [H2tdc = 2,5 thiophenedicarboxylic acid; bpe = 1,2-bis(4-pyridyl)ethane] has been synthesized through a solvent diffusion technique and structurally characterized. The structure analysis reveals that the tdc ligands formed bilayers with the Cu(ii) ions along the b-direction and the layers are further pillared by bpe linkers and resulted in a 2D pillared-bilayer porous framework with a four connected uninodal sq1/Shubnikob tetragonal plane net with the Schälfli symbol {44·6 2}. The framework is enclosed with large square shaped channels (13.7 × 8.35 Å2) along the bc-plane and the channels are occupied by guest solvent molecules. The adsorption studies reveal that compound 1 shows selective adsorption for CO2 over CH4 at room temperature and it also shows hysteretic sorption for a few protic solvents (H2O and EtOH) and a Type-1 isotherm for an aprotic solvent (CH 3CN). The catalytic performance of compound 1 for Glaser type homo-coupling reactions has also been reported. © 2014 the Partner Organisations.

Biswas S.,IISER Bhopal | Adhikary A.,IISER Bhopal | Goswami S.,IISER Bhopal | Konar S.,IISER Bhopal
Dalton Transactions | Year: 2013

A new 2D Gd(iii)-based coordination polymer has close to the highest cryogenic magnetocaloric effect of any MOF reported so far. The experimental results reveal its structural features and magnetic properties. © 2013 The Royal Society of Chemistry.

Sanda S.,IISER Bhopal | Parshamoni S.,IISER Bhopal | Adhikary A.,IISER Bhopal | Konar S.,IISER Bhopal
Crystal Growth and Design | Year: 2013

Four new two-dimensional/three-dimensional (2D/3D) bpmh-based metal organic frameworks, namely, {[Zn(1,3-adaa)(bpmh)]}n (1), {[Cd(1,3-adaa)(bpmh)]}n (2), {[Zn(1,4-pdaa)(bpmh)]}n (3), and {[Co(1,4-pdaa)(bpmh)]}n (4) (bpmh = N,N-bis-pyridin-4- ylmethylene-hydrazine, 1,3-adaa = 1,3-adamantane diacetic acid, 1,4-pdaa = 1,4-phenylene diacetic acid) have been synthesized through the slow diffusion technique. Structural determination reveals that compounds 1 and 2 have 2D layered architectures with similar framework topology, whereas 3 and 4 are isostuctural 3D frameworks. Both 1 and 2 perceives a common secondary building unit (SBU) [M2(adaa)4(bpmh)4] [M = Zn(1) and Cd(2)]. In compound 1, 1,3-adaa exhibits both μ- 1,1 and μ- 1,2 bridging modes, whereas in 2 it shows both μ-1,1 and μ-1,1,2 bridging modes. The difference in the bridging mode of 1,3-adaa in 1 (Zn) and 2 (Cd) is responsible for the shorter M⋯M contacts in 2 (3.872 Å) than in 1 (4.13 Å) in the SBU. The 1,3-adaa ligands are sandwiched between the bpmh linkers in compounds 1 and 2. In compounds 3 and 4, 1,4-pdaa exhibits both μ-1 and μ-1,1 bridging modes and are isostructural in nature. The metal centers are arranged in a helical fashion around 21 screw axis in 3 and 4. In compounds 1-4, the used dicarboxylic acids act as pillars between the metal-bpmh layers. Solid-state photoluminescent properties of compounds 1-3 show ligand (n → π* and π → π*)-based florescence. The magnetic studies of compound 4 show presence of the antiferromagnetic exchange between the metal centers. © 2013 American Chemical Society.

Goswami S.,IISER Bhopal | Jena H.S.,IISER Bhopal | Konar S.,IISER Bhopal
Inorganic Chemistry | Year: 2014

We present here a simple, milder, and environmentally benign heterogeneous catalytic method for the transformation of tetrazines to oxadiazole derivatives at room temperature (25 °C) using our earlier synthesized iron-squarate based 3D metal organic framework, [Fe3(OH)3(C 4O4)(C4O4)0.5] n (FeSq-MOF). © 2014 American Chemical Society.

Biswas S.,IISER Bhopal | Jena H.S.,IISER Bhopal | Adhikary A.,IISER Bhopal | Konar S.,IISER Bhopal
Inorganic Chemistry | Year: 2014

Two isostructural lanthanide-based 3D coordination networks [Ln = Gd 3+ (1), Dy3+(2)] with densely packed distorted cuboid nanoscopic cages are reported for the first time. Magnetic characterization reveals that complex 1 shows a significant cryogenic magnetocaloric effect (-ΔSm = 44 J kg-1 K-1), whereas 2 shows slow relaxation of magnetization. © 2014 American Chemical Society.

Dutta P.,IISER Bhopal
Monthly Notices of the Royal Astronomical Society: Letters | Year: 2016

Here we introduce moments of visibility function and discuss howthose can be used to estimate the power spectrum of the turbulent velocity of external spiral galaxies. We perform numerical simulation to confirm the credibility of this method and found that for galaxies with lower inclination angles it works fine. The estimator outlined here is unbiased and has the potential to recover the turbulent velocity spectrum completely from radio interferometric observations. © 2015 The Authors.

Sanda S.,IISER Bhopal | Parshamoni S.,IISER Bhopal | Konar S.,IISER Bhopal
Inorganic Chemistry | Year: 2013

A new 2D interdigitated and highly flexible, breathing metal-organic framework has been synthesized through a diffusion technique by using the aldrithiol linker and pyromellitate ligand. The compound shows selective, stepwise, reversible, and hysteretic adsorption properties for CO2 gas and H2O, MeOH, and CH3CN vapors. © 2013 American Chemical Society.

Dutta K.,Saha Institute of Nuclear Physics | Panda S.,IISER Bhopal | Patel A.,IISER Bhopal
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Although f(R) modification of late-time cosmology is successful in explaining the present cosmic acceleration, it is difficult to simultaneously satisfy the fifth-force constraint. Even when the fifth-force constraint is satisfied, the effective scalar degree of freedom may move to a point, close to its potential minimum, in the field space where the Ricci scalar diverges. We elucidate this point further with a specific example of f(R) gravity that incorporates several viable f(R) gravity models from the literature. In particular, we show that the nonlinear evolution of the scalar field in pressureless contracting dust can easily lead to the curvature singularity, making this theory unviable. © 2015 American Physical Society.

Dutta P.,IISER Bhopal
Monthly Notices of the Royal Astronomical Society | Year: 2015

We use numerical simulations to investigate effect of turbulent velocity on the power spectrum of HI intensity from external galaxies when (a) all emission is considered, (b) emission with velocity range smaller than the turbulent velocity dispersion is considered. We found that for case (a) the intensity fluctuation depends directly only on the power spectrum of the column density, whereas for case (b) it depends only on the turbulent velocity fluctuation. We discuss the implications of this result in real observations of HI fluctuations. © 2015 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society.

A three-dimensional (3D) porous metal organic framework namely, {[Cu 3(N3)2(4-ptz)4(DMF) 2]·2DMF}n, has been synthesized using Cu(CH 3COO)2·H2O and ligand 4-ptz [5-(4-pyridyl)-tetrazolate] which was formed in situ from 4-cyanopyridine and sodium azide in presence of water and CuII ions. Crystal structure analysis showed that the complex crystallizes in the monoclinic space group P21/c and has a decorated body centred cubic (bcu) topological net with 8-connected Cu3 cluster as node. Magnetic studies exhibit prominent antiferromagnetic interactions influenced by EO (end on) azide and μ2,η2-tetrazolato bridge among the metal centres. Gas adsorption studies reveal moderate carbon dioxide uptake, which is also reflected in the isosteric heat of adsorption (Qst) value of -28 kJ mol-1. This journal is © The Royal Society of Chemistry.

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