Murshidābād, India
Murshidābād, India

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Sinha R.,Kandi Raj College | Saha I.,Indian Institute of Science | Kumar G.S.,Indian Institute of Science
Chemistry and Biodiversity | Year: 2011

The interaction of bioactive protoberberine alkaloids berberine, palmatine, and coralyne with the DNA triplex poly(dT)·(poly(dA)·poly(dT)) was studied using biophysical and calorimetric techniques. All three alkaloids bound the triplex cooperatively. Berberine and palmatine predominantly stabilized the triplex structure, while coralyne stabilized both triplex and duplex structures as inferred from optical thermal melting profiles. Fluorescence quenching, polarization, and viscometric studies hinted at an intercalative mode of binding for the alkaloids to the triplex, coralyne being more strongly intercalated compared to partial intercalation of berberine and palmatine. The overall affinity of coralyne was two order higher (2.29× 10 7 M -1) than that of berberine (3.43× 10 5 M -1) and palmatine (2.34× 10 5 M -1). Isothermal titration calorimetric studies revealed that the binding to the triplex was favored by negative enthalpy change (ΔH=-3.34 kcal/mol) with favorable entropy contribution (TΔS = 4.07 kcal/mol) for berberine, favored by almost equal negative enthalpy (ΔH =-3.88 kcal/mol) and entropy changes (TΔS = 3.37 kcal/mol) for palmatine, but driven by large enthalpy contributions (ΔH =-25.62 kcal/mol and TΔS =-15.21 kcal/mol) for coralyne. These results provide new insights on the binding of isoquinoline alkaloids to the DNA triplex structure. Copyright © 2011 Verlag Helvetica Chimica Acta AG, Zürich.


Pattanayak P.,Kalyani University | Pratihar J.L.,Kandi Raj College | Patra D.,East Calcutta Girls College | Lin C.-H.,Chung Yuan Christian University | And 3 more authors.
Journal of Coordination Chemistry | Year: 2013

The reactions of HL1 [2-((2-(benzylthio)phenylimino)methyl) phenol] and HL2 [3-((2-(benzylthio)phenylimino)methyl)-2-hydroxy-5- methylbenzaldehyde] separately with Cu(OAc)2·H2O afforded new Cu(II) complexes [Cu(L1)(OAc)] (1) and [Cu(L 2)2] (2), respectively. These are characterized by microanalytical data and spectroscopic studies. UV-vis spectra of the complexes show intense low-energy transitions ∼ 420 nm which are ligand to metal charge transfer (LMCT) transitions. The single-crystal X-ray structures were determined for 1 and 2. Reactions of [Cu(L1)(OAc)] (1) with, SCN - and show the replacement of weakly coordinated acetate yielding [Cu(L1)(N3)], [Cu(L1)(SCN)] and [Cu(L 1)(NO2)], respectively. Unequivocal characterization of the substituted products has been done by single-crystal X-ray study of [Cu(L1)(N3)]. HL2 and its Cu(II) complex exhibited low-intensity emission bands at ∼575 nm upon excitation at 375 nm and at 420 nm, respectively. Redox properties of the complexes were determined electrochemically. Density functional theory (DFT) computations have been carried out to explain the spectroscopic and redox properties of the complexes. © 2013 Taylor & Francis.


Pattanayak P.,Kalyani University | Pratihar J.L.,Kandi Raj College | Patra D.,East Calcutta Girls College | Lin C.-H.,Chung Yuan Christian University | And 2 more authors.
Polyhedron | Year: 2013

Ligand, HL, 2-((2-(benzylthio)phenylimino)methyl)phenol, upon reaction with Co(NO3)3·6H2O, Ni(OAc) 2·4H2O and PdCl2 separately afforded complexes [(L)2Co]NO3 (1), [(L)2Ni] (2) and [(L)PdCl] (3) respectively. The new complexes were characterized by usual spectroscopic studies like UV-Vis, IR and NMR and authenticated by X-ray structure determination on [(L)2Co]NO3, [(L) 2Ni]. The analysis of crystal structures revealed that in all the complexes the ligand HL binds the metal center as uni-negative anion; L - dissociating phenolic proton and offers (O, N, S) tridentate binding mode to the metal. The compound [Co(L)2]NO3 is tested for in vitro antibacterial activity. Complex 3, acts as a catalyst in Heck reaction for a number of substrates. Complexes 1 and 2 exhibited a quasi reversible oxidative responses at 0.97 and 0.85 V, respectively, versus SCE. The electronic spectra and redox properties of the complexes have been explained with DFT computation. © 2013 Elsevier Ltd. All rights reserved.


Patra D.,Kalyani University | Patra D.,East Calcutta Girls College | Pattanayak P.,Kalyani University | Pratihar J.L.,Kalyani University | And 2 more authors.
Polyhedron | Year: 2013

The reactions of 1-{[2-(arylazo)phenyl]iminomethyl}-2-naphthol, H 2Lnap [where H represents the dissociable proton upon complexation and aryl groups of H2Lnap are phenyl for H2L1 nap; p-methyl phenyl for H 2L2 nap and p-chloro phenyl for H 2L3 nap] with nickel acetate tetra hydrate or disodium tetrachloropalladate in methanol afforded M-C(aryl) bonded species of composition [M(Lnap)] (M = Ni(II) and Pd (II)). The dinegative (Lnap)2- ligands bind the Ni(II) or Pd(II) in tetradentate (C, N, N, O) fashion in distorted square planar geometry. Ligands and complexes were characterized by spectroscopic methods. The X-ray structures of H 2L1 nap, [Ni(L1 nap)] and [Pd(L1 nap)] were determined to authenticate the characterization. Reactions with metachloroperbenzoic acid (mCPBA), TBHP and hydrogen peroxide leading to oxygen insertion into the M-C bond have been examined. Luminescent properties of ligands and complexes have been reported. © 2012 Elsevier Ltd. All rights reserved.


Pattanayak P.,Kalyani University | Pratihar J.L.,Kandi Raj College | Patra D.,East Calcutta Girls College | Brandao P.,University of Aveiro | And 2 more authors.
Polyhedron | Year: 2013

The newly designed multidentate ligand HL, derived from 2-(benzylthio)aniline and 2-hydroxy-5-methylbenzene-1,3-dialdehyde, upon reaction with Cu(II) perchlorate in methanol yielded the binuclear Cu(II) complex [Cu2(L)(μ-OH)](ClO4)2 (1), which was authenticated by single crystal X-ray diffraction. The diffraction analysis revealed that the ligand binds each of the two Cu(II) centers in an (O, N, S) fashion in a distorted square pyramidal geometry where the two copper centers are bridged by μ-phenoxo and μ-hydroxo oxygen atoms. The apical position of one copper center is coordinated by one perchlorate ion and the other center by a water molecule. The packing of the molecule is stabilized through OH 2â̄O hydrogen bonds, mediated through solvent water and perchlorate anions. The emission and redox properties of both the ligand and the complex were examined. The electronic spectra and redox properties of the complex have been explained with DFT computations. The complex [Cu 2(L)(μ-OH)](ClO4)2 shows very good catalytic activities towards the oxidation of benzyl alcohol to benzaldehyde and organic thioethers to the corresponding sulfoxide and sulfones using H2O 2 as the oxidant. © 2013 Elsevier Ltd. All rights reserved.


Pratihar J.L.,Kalyani University | Pratihar J.L.,Kandi Raj College | Pattanayak P.,Kalyani University | Patra D.,Kalyani University | And 2 more authors.
Polyhedron | Year: 2012

The 1N-(N,N-diethylaminoethyl)-2-arylazoaniline, HL [where HL = ArN = NC 6H 4N(H){C 2H 4N(C 2H 5) 2}; Ar = C 6H 5 (for HL 1), p-MeC 6H 4 (for HL 2) or p-ClC 6H 4 (for HL 3)], ligands were prepared by treating the appropriate 2-(arylazo)aniline with 2-bromo-N,N-diethylethanamine. Reactions of Na 2PdCl 4 with HL afforded the [(L)PdCl] complexes. HL binds palladium(II) in a tridentate fashion (N,N,N), forming a new diazoketiminato chelate. The X-ray structure of [(L 3)PdCl] was determined to confirm the characterization. The newly synthesized complex [(L 1)PdCl] was utilized to carry out Suzuki and Heck reactions for a variety of substrates. © 2011 Elsevier Ltd. All rights reserved.


Saha J.K.,Narula Institute of Technology | Bhattacharyya S.,Kandi Raj College | Mukherjee T.K.,Narula Institute of Technology | Mukherjee P.K.,Ramakrishna Mission Vivekananda University
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2010

Extensive non-relativistic variational calculations for estimating the energy values of 2 pnd(1, 3Do) states [n = 3 - 6] of two electron atoms (He, Li+, Be2 +) and 2 pnp(1Pe)[n = 3 - 8] and 2 pnp(3Pe) states [n = 2 - 7] of Be2 + under weakly coupled plasma screening have been performed using explicitly correlated Hylleraas type basis. The modified energy eigenvalues of 1, 3Pe states arising from two p electrons of Be2 + ion and 1, 3Do states due to 2 pnd configuration of Li+ and Be2 + ion in the Debye plasma environment are being reported for the first time. The effect of plasma has been incorporated through the Debye screening model. The system tends towards gradual instability and the number of bound states reduces with increasing plasma coupling strength. The wavelengths for 2 pn′ p (1Pe) [n′ = 3 - 8] → 2 pnd (1Do) [n = 3 - 6] and 2 pn′ p (3Pe) [n′ = 2 - 8] → 2 pnd (3Do) [n = 3 - 6] transitions in plasma embedded two electron atoms have also been reported. © 2009 Elsevier Ltd. All rights reserved.


Saha J.K.,Narula Institute of Technology | Bhattacharyya S.,Kandi Raj College | Mukherjee T.K.,Narula Institute of Technology
Journal of Chemical Physics | Year: 2010

The applicability of Ritz-variational principle for 3dnf (D 1,3 o) states lying between N=2 and N=3 ionization threshold of singly ionized helium is discussed in this communication. Probable existence of such a state for O6+ within the planetary atmosphere in the polar regions of Jupiter is discussed. © 2010 American Institute of Physics.


Nandi T.,Inter University Accelerator Center | Oswal M.,Panjab University | Kumar S.,Panjab University | Jhingan A.,Inter University Accelerator Center | And 2 more authors.
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2012

Evidence is provided for radiative resonant energy transfer (RRET) from bulk plasmons to discrete states for the first time. The difference of the excitation mechanisms of the 1s2s 3S 1 and 1s2p P2o3 states in He-like Ti ions on target nuclear charge have been studied by the beam-two-foil technique. We observed that the 1s2s 3S 1 states are mostly populated with an aluminum target where as the 1s2p P2o3 states with a carbon target. The 1s2s 3S 1 states produced with a carbon target are further excited to 1s2p P2o3 state, but this type of excitation does not occur with an aluminum target. This excitation mechanism is attributed to resonant energy transfer from bulk plasmons in the carbon target. Furthermore, the resonant process is confirmed by observation that the 1s2s 3S 1 states populate more than the 1s2p P2o3 states with He-like V, Fe and Ni ions even with carbon targets. © 2012 Elsevier Ltd.


Pal D.,Sn Bose National Center For Basic Science | Pal D.,Kandi Raj College | Ghosh A.,Sn Bose National Center For Basic Science | Mandal K.,Sn Bose National Center For Basic Science
Journal of Magnetism and Magnetic Materials | Year: 2014

Nickel rich Ni52Mn34Sn14 Heusler alloy was prepared by arc melting and subsequent homogenization by annealing. Existence of first order magneto-structural transition (FOMST) was confirmed by various measurements. In comparison to conventional Ni50-xMn 36+xSn14 alloys, a larger magnetic entropy change (â̂†SM≈8 J/kg K using Maxwellש2014 Elsevier B.V. All rights reserved.

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