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Anju K.S.,Indian National Institute for Interdisciplinary Science and Technology | Ramakrishnan S.,Indian National Institute for Interdisciplinary Science and Technology | Srinivasan A.,National Institute of Science Education and Research NISER
Organic Letters | Year: 2011

Chemical equations presented. Synthesis, spectral, and single-crystal X-ray structural analysis of meso-aryl triphyrin(2.1.1) featuring three pyrrole rings and four meso-aryl rings are described. The title compound represents the first example of a ring-contractedmeso-aryl β-unsubstituted free-base triphyrin containing only pyrrole rings reported to date and generates 2-D supramolecular assembly in the solid state. © 2011 American Chemical Society.


Chatterjee B.,National Institute of Science Education and Research NISER | Gunanathan C.,National Institute of Science Education and Research NISER
Chemical Communications | Year: 2014

A chemoselective hydrosilylation method for aldehydes is developed using a ruthenium catalyst [(Ru(p-cymene)Cl2)2] and triethylsilane; a mono hydride bridged dinuclear complex [{(η6-p- cymene)RuCl}2(μ-H-μ-Cl)] and a Ru(iv) mononuclear dihydride complex [(η6-p-cymene)Ru(H)2(SiEt3) 2] are identified as potential intermediates in the reaction and the proposed catalytic cycle involves a 1,3-hydride migration. This journal is © The Royal Society of Chemistry.


Bairathi V.,National Institute of Science Education and Research NISER
Journal of Physics: Conference Series | Year: 2016

The measurements of the azimuthal anisotropy of φ meson in the U+U and Au+Au collisions at the Relativistic Heavy-Ion Collider (RHIC) are reported. The centrality dependence of the Fourier coefficients v2, v3, v4 and v5 is presented for φ meson at midrapidity (|| < 1.0), in U+U and Au+Au collisions at -√8NN = 193 and 200 GeV, respectively. The -sub event plane method is used with a n gap of 0.1 to suppress the non-flow effects. A strong centrality dependence is observed for the φ meson elliptic flow (v2), whereas no clear centrality dependence is observed for v3, v4 and v5. Ratios of the Fourier coefficients, v3/v2 and v4/v2 2 as a function of transverse momentum (pT) are also presented. A systematic comparison of the Fourier coefficients for the two systems U+U and Au+Au is discussed.


Gunanathan C.,National Institute of Science Education and Research NISER | Milstein D.,Weizmann Institute of Science
Chemical Reviews | Year: 2014

Activation of inert chemical bonds by transition metal complexes is an area of utmost importance. Efficient bond activation can provide a leading entry to successful catalytic design with the potential of providing greener synthetic methods for useful products. These coordinatively saturated and unsaturated ruthenium pincer complexes with heteroaromatic and aliphatic backbones developed in recent years exhibit new reactivities, activate strong chemical bonds, and act as efficient catalysts for several synthetic methods including unprecedented green transformations, the pivotal interest of this Review. One of the characteristic properties of pincer complexes is the ability to stabilize low valent metal complexes with uncommon geometries.


Nasim M.,National Institute of Science Education and Research NISER
Journal of Physics: Conference Series | Year: 2014

We present measurements of φ-meson production and elliptic flow (v 2) at mid-rapidity in Au + Au collisions at 7.7-200 GeV. Energy dependence of nuclear modification factor (RcP) of φ meson is presented. The φ-meson RcP has a value ≥ 1.0 for ≤ 39 GeV. The Ω/φ ratios are also presented and show a different trend at the intermediate transverse momentum (pT) for 11.5 GeV compared to higher beam energies. The number-of-constituent quark (NCQ) scaling of v2 has been studied at various beam energies. The NCQ scaling holds for particles and anti-particles separately including the φ meson for ≥ 19.6 GeV, which can be considered as an evidence of partonic collectivity. We observe that φ-meson v2 falls off the trend from the other hadrons at highest measured pT values by 1.8σ and 2.3σ at 7.7 and 11.5 GeV, respectively.


Parhi N.,National Institute of Science Education and Research NISER
Computers and Mathematics with Applications | Year: 2011

In this paper, sufficient conditions in terms of coefficient functions are obtained for non-oscillation of all solutions of a class of linear homogeneous third order difference equations of the form y(n+3)+α(n)y(n+2)+β(n) y(n+1)+γ(n)y(n)=0,n<0,Δ3y(n-1)+a(n) Δ2y(n-1)+b(n)Δy(n)+c(n)y(n)=0,n<1, and Δ(p(n-1)Δ2y(n-1))+q(n)Δy(n)+r(n)y(n)=0,n<1, where γ(n)≠0 and p(n)>0. The technique developed depends on non-oscillation of certain linear homogeneous second order difference equations. © 2011 Elsevier Ltd. All rights reserved.


Sadhukhan M.,National Institute of Science Education and Research NISER | Barman S.,National Institute of Science Education and Research NISER
Journal of Materials Chemistry A | Year: 2013

We report microwave assisted bottom-up fabrication of flat two-dimensional carbon nitride from formamide (HCONH2). Microwave irradiation of HCONH2 produces carbon nitride dots (CNDs) which are used as precursors for synthesis of carbon nitride (C3N4). The two-dimensional (2D) carbon nitride sheets are formed by evaporation induced self-assembly and condensation of CNDs on a solid substrate. The drying of CND solution generates different morphologies such as 0D carbon nitride quantum dots, 2D carbon nitride sheets and 3D carbon nitride, depending on the concentration of CNDs. The carbon nitrides are well characterized by TEM, AFM, SEM, XRD, XPS, FT-IR, FT-Raman Spectroscopy and TGA, CHN analysis. In addition, the C3N4 modified glassy carbon electrode can be used as a highly sensitive electrochemical sensor for mercuric ions in aqueous solution. The lower detection limit of Hg2+ is found to be 9.1 × 10 -11 M, which is far below the WHO guideline for drinking water (10-8 M). The simultaneous electrochemical detection of Pb 2+, Cu2+ and Hg2+ using a C3N 4 modified GC electrode is also described. This journal is © 2013 The Royal Society of Chemistry.


Barman S.,National Institute of Science Education and Research NISER | Sadhukhan M.,National Institute of Science Education and Research NISER
Journal of Materials Chemistry | Year: 2012

Highly blue fluorescent graphitic carbon nitride quantum dots (g-CNQDs) were synthesized by a simple microwave mediated method from formamide (HCONH 2). The fluorescence emission of g-CNQDs is found to be strongly dependent on solvent, pH as well as on excitation wavelengths; the life time of the emission decreases with increasing polarity of the solvent. These quantum dots are highly sensitive and selective florescent probes for mercuric ions in aqueous media due to the "superquenching" of fluorescence. The complex formation of Hg 2+ ions with the CN x sheet involving π delocalized electron moieties of the latter, in fact, is responsible for the quenching of fluorescence. The addition of iodide ions abstracts the bound Hg 2+ forming HgI 2 and gives back the fluorescence characteristic of g-CNQDs. Thus, g-CNQDs can play a dual role for selective and sensitive detection of mercuric ions as well as iodide ions in aqueous media via "ON-OFF-ON" fluorescence response. © 2012 The Royal Society of Chemistry.


Sharma N.K.,National Institute of Science Education and Research NISER | Ganesh K.N.,Indian Institute of Science
Organic and Biomolecular Chemistry | Year: 2011

Nucleic (DNA) acids having contiguous stretch of G sequence form quadruplex structure, which is very critical to control cell division. Recently the existence of G-quadruplex in RNA is also reported in presence of monovalent metal ion. PNA is a promising DNA analogue which binds strongly to DNA to form PNA:DNA duplex or PNA2:DNA triplex. PNA also forms quadruplexes such G-quadruplex and i-motif in G and C-rich sequences respectively. aep-PNA containing a prolyl ring is one of several PNA analogues that provide rigidity and chirality in backbone and has binding affinity to natural DNA which is higher than that of PNA. Here we examine the ability of aep-PNA-G to form a quadruplex by UV, CD and mass spectroscopic techniques. © 2011 The Royal Society of Chemistry.


Karthik G.,National Institute of Science Education and Research NISER | Srinivasan A.,National Institute of Science Education and Research NISER | Chandrashekar T.K.,National Institute of Science Education and Research NISER
Organic Letters | Year: 2014

Two new, fused core-modified expanded porphyrins, sapphyrins 3 and 4, were synthesized by a simple acid-catalyzed condensation of electron-rich and rigid precursor, dithienothiophene (DTT) diol, and core-modified tripyrrane. These sapphyrins exhibit structural diversity depending upon the heteroatom present in the macrocyclic framework, where the thiophene ring is inverted in 3, while the selenophene ring in 4 exists in normal and inverted form in the free base and addition of two protons shifts the equilibrium to inverted form. © 2014 American Chemical Society.

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