Parnajyoti Karmakar
@ggdck.ac.in
Assistant Professor in Chemistry
GOVERNMENT GENERAL DEGREE COLLEGE, KALNA-I
RESEARCH, TEACHING, or OTHER INTERESTS
Chemistry, Inorganic Chemistry
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Parnajyoti Karmakar
Springer Science and Business Media LLC
Debjani Ghosh and Parnajyoti Karmakar
Elsevier BV
Debabrata Nandi, Sumon Ray, Parnajyoti Karmakar, Animesh Chattopadhyay, Anwesha Dey, Roshni Sarkar(Sain), and Alak K Ghosh
Springer Science and Business Media LLC
Debabrata Nandi, Parnajyoti Karmakar, Sumon Ray, Animesh Chattopadhyay, Roshni Sarkar(Sain), and Alak K. Ghosh
Informa UK Limited
ABSTRACT A brief overview of mechanistic studies on the reactions of cis-[Pt(dap)(H2O)2]2+ (1) and cis-[Pt(pipen)(H2O)2]2+ (2) (where dap and pipen are 1,3-diaminopropane and 2-aminomethylpiperidine respectively) with 2-thiouracil (LH), a nitrogen and sulfur-donor bio molecule, is presented. All the substitution reactions have been monitored at 327(for 1) and 326 (for 2) nm respectively where the differences in abosorbances between the reactants and products are maximum. At pH 4.0, the kinetics shows two consecutive processes, i.e., they show a non linear dependence on the concentration of ligand: first process is [ligand] dependent but the second step is [ligand] independent. The activation parameters and the thermodynamic parameters were also calculated, which supports the spontaneous formation of an outer sphere association complex. The product of this reaction has been characterized with the help of Job's method, IR and ESI-MS spectroscopic analysis. The purpose of this work is to improve the understanding of the mechanism of action of Pt(II) complexes as potential anti-tumour drugs in the human body.
Animesh Chattopadhyay, Anwesha Dey, Parnajyoti Karmakar, Sumon Ray, Debabrata Nandi, Roshni Sarkar(Sain), and Alak K Ghosh
SAGE Publications
The synthesis and interactions of the cis-diaqua-chloro-tris(dimethyl sulfoxide)ruthenium(II) complex with selected sulfur-containing ligands such as 2-thiouracil, glutathione and L-cysteine have been studied by UV-Vis spectrophotometry in aqueous medium at pH 4.5. From experimental data it is clear that all three reactions proceed via two steps: the first one being a rate-limiting ligand-dependent replacement of one water molecule, followed by a ligand-independent ring closure step with the expulsion of the second water molecule. The substituted products have been characterised by Job's method, FTIR spectroscopy and electrospray ionisation mass spectrometry. Activation parameters (Δ H≠ and Δ S≠) and thermodynamic parameters (Δ H0 and Δ S0, from the temperature dependence of the outer-sphere association equilibrium constant) are presented. Consistent with the experimental findings, an associative interchange mechanism is proposed.
SUMON RAY, PARNAJYOTI KARMAKAR, ANIMESH CHATTOPADHYAY, DEBABRATA NANDI, SUSHOBHAN UKIL, ROSHNI SARKAR (SAIN), and ALAK K GHOSH
Springer Science and Business Media LLC
Sumon Ray, Parnajyoti Karmakar, Animesh Chattopadhyay, Debabrata Nandi, Roshni Sarkar (Sain), and Alak K Ghosh
Wiley
ABSTRACTThe substitution of the chelating oxalate group by a group of nucleophiles, viz. thiourea (L1), 2‐thiouracil (L2), diethyldithiocarbamate (L3), dl‐penicillamine (L4), and thiosemicarbazide (L5) was studied under pseudo–first‐order conditions as a function of concentration and temperature using UV–vis spectrophotometry and stopped‐flow technique. π‐Accepting effects are often used to account for the unusual high lability of Pt(bipy) complexes. The complexes [Pt(dach)(oxalate)] (1) (dach = cis‐1,2‐diaminocyclohexane) and [Pt(bipy)(oxalate)] (2) (bipy = 2,2'‐bipyridine) and substituted products were isolated and characterized by FTIR and ESI‐MS spectroscopic analysis. The negative entropies of activation support a strong contribution from bond making in the transition state of the substitution processes.
Parnajyoti Karmakar
Springer Science and Business Media LLC
Sumon Ray, Debabrata Nandi, Animesh Chattopadhyay, Roshni Sarkar, Parnajyoti Karmakar, and Alak K. Ghosh
Springer Science and Business Media LLC
Arup Mandal, Sumon Ray, Animesh Chattopadhyay, Parnajyoti Karmakar, Debabrata Nandi, and Alak K. Ghosh
Springer Science and Business Media LLC
Arup Mandal, Parnajyoti Karmakar, Biplab K. Bera, Sumon Ray, Subala Mondal, and Alak K. Ghosh
SAGE Publications
The interaction of the cis-diaqua-chloro-tris(dimethyl sulfoxide)ruthenium(II) complex with selected nucleosides such as adenosine (L1H) and cytidine (L2H) has been studied spectrophotometrically in aqueous medium as a function of [substrate complex], [ligand] and temperature. The reaction has been monitored at 295 nm where the difference in spectra between the reactant and product is a maximum. At pH 5.0, the interaction with the two nucleosides shows two distinct consecutive steps, i.e., it shows a non-linear dependence on the concentration of the nucleosides: both steps are [ligand] dependent. The rate constants for the processes are: k1∼ 10–3s–1and k2∼ 10–5s–1. The activation parameters were calculated from Eyring plots. Based on the kinetic and activation parameters, an associative interchange mechanism is proposed for the interaction processes. From the temperature dependence of the outer sphere association equilibrium constant, the thermodynamic parameters were also calculated, which gives a negative Δ G° value for both the steps at all temperatures studied, supporting the spontaneous formation of an outer sphere association complex. The product of the reaction has been characterised by IR and ESI-mass spectroscopic analysis.
Parnajyoti Karmakar, Sumon Ray, Arup Mandal, Subala Mondal, Subhasis Mallick, Biplab K. Bera, and Alak K. Ghosh
Informa UK Limited
The kinetics of interaction of cis-[Pt(cis-dach)(H2O)2]2+ (where dach is cis-1,2-diaminocyclohexane) with three different amino acids, namely L-Asparagine (L1H), L-Arginine (L2H), and L-Gluatmic acid (L3H) have been studied spectrophotometrically in the 40–60°C temperature range. The substitution was found to occur in two subsequent reaction steps: the first step is the ligand-assisted anation and the second one is the chelation step. The kinetic study has been substantiated by product isolation, IR, NMR, and ESI-MS spectroscopic analysis.
Biplab K. Bera, Sumon Ray, Subala Mondal, Parnajyoti Karmakar, Arup Mandal, Subhasis Mallick, and Alak K. Ghosh
Hindawi Limited
The kinetics of the interaction of three glycine-containing dipeptides, namely, glycyl-L-alanine (L1-L′H), glycyl-L-asparagine (L2-L′H), and glycyl-L-tyrosine (L3-L′H) with has been studied spectrophotometrically in aqueous medium as a function of the molar concentration of , [dipeptide], pH, and temperature at constant ionic strength. Reactions were studied at pH 4.3, where the substrate complex exists predominantly as the hydroxopentaaqua species and dipeptides as the zwitterion. The reaction has been found to proceed via two parallel paths: both processes are ligand dependent. The rate constant for the processes are and . The activation parameters for both the steps were evaluated using Eyring’s equation. The low and large negative value of as well as and indicate an associative mode of activation for both the aqua ligand substitution processes for both the parallel paths. The product of the reaction has been characterized by IR and ESI-mass spectroscopic analyses.
Parnajyoti Karmakar, Sumon Ray, Debabrata Nandi, Arup Mandal, Subala Mondal, Subhasis Mallick, Biplab K. Bera, and Alak K. Ghosh
Springer Science and Business Media LLC
Arup Mandal, Subala Mondal, Parnajyoti Karmakar, Subhasis Mallick, Biplab K. Bera, and Alak K. Ghosh
Wiley
AbstractThe interaction of the title complex with selected amino acids such as glycine (L1H), l‐valine (L2H), and l‐leucine (L3H) has been studied spectrophotometrically in aqueous medium as a function of [substrate complex], [ligand], and temperature. The reaction has been monitored at 600 nm, where the spectral difference between the reactant and product is maximum. At pH 7.4, the reaction has been found to proceed via two distinct consecutive steps, i.e., it shows a nonlinear dependence on the concentration of ligands: The first process is [ligand] dependent, but the second step is [ligand] independent. The rate constants for the processes are k1∼10−3 s−1 and k2∼10−4 s −1. The activation parameters were calculated from Eyring plots. Based on the kinetic and activation parameters, an associative interchange mechanism is proposed for the interaction processes. From the temperature dependence of the outer sphere association equilibrium constant, the thermodynamic parameters were also calculated, which gives a negative Δ Go value for both the steps at all temperatures studied, supporting the spontaneous formation of an outer sphere association complex. The product of the reaction has been characterized with the help of conductance measurement, IR, NMR, and ESI‐mass spectroscopic analysis. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 612–623, 2012
Biplab K. Bera, Subala Mondal, Subhasis Mallick, Arup Mandal, Parnajyoti Karmakar, and Alak K. Ghosh
Springer Science and Business Media LLC
BIPLAB K BERA, ARUP MANDAL, BISWARUP MAITY, SUMON RAY, PARNAJYOTI KARMAKAR, SUBALA MONDAL, SUBHASIS MALLICK, and ALAK K GHOSH
Springer Science and Business Media LLC
ARUP MANDAL, PARNAJYOTI KARMAKAR, SUBHASIS MALLICK, BIPLAB K BERA, SUBALA MONDAL, SUMON RAY, and ALAK K GHOSH
Springer Science and Business Media LLC
Subhasis Mallick, Arup Mandal, Biplab K. Bera, Pamajyoti Karmakar, Subala Mondal, and Alak K Ghosh
SAGE Publications
The interaction of diethyldithiocarbamate (Et2DTC) with diaquaethylenediamineplatinum(II) has been studied spectrophotometrically in aqueous medium as a function of [substrate complex], [ligand], temperature and pH at constant ionic strength. The reaction proceeds via rapid outer-sphere association complex formation followed by two consecutive steps: the first is ligand dependent and second is assigned to intramolecular ring closure. The low enthalpy and negative entropy of activation indicate an associative mode of activation for both steps.
Arup Mandal, Subhasis Mallick, Parnajyoti Karmakar, Biplab K. Bera, Subala Mondal, and Alak K. Ghosh
SAGE Publications
The interaction of glycyl-L-leucine (L-I/H) with [(H2O) (tap)2RuORu(tap)2(H2O)]2+ (tap=2-(m-tolylazo) pyridine) has been studied spectrophotometrically in aqueous medium as a function of [(H2O) (tap)2RuORu(tap)2(H2O)2+], [glycyl-L-leucine], pH and temperature. The reaction was monitored at 600 nm where the spectral difference between the reactant and product is a maximum. At pH 7.4, the interaction with glycyl-L-leucine shows two parallel steps, i.e. it shows a non-linear dependence on the concentration of glycyl-L-leucine; both processes are ligand dependent. The rate constants for the processes are: kl 10−3 s 1 and K2∼10−5 s−1. The activation parameters calculated from Eyring plots are: Δ H#1 = 15.8∓0.6kJ mol−1, A Sf = −232 + 2J K 1 mol−1, AH2# =31.7∓3.5kJmol−1, AS* = −216∓ 10J K−1 mol−1. Based on the kinetic and activation parameters, an associative interchange mechanism is proposed for the interaction processes. from the temperature dependence of the outer sphere association equilibrium constant, the thermodynamic parameters were also calculated, which gave a negative AG° value for both the steps at all temperatures studied, supporting the spontaneous formation of an outer sphere association complex. The product of the reaction has been characterized from IR and ESI-mass spectroscopic analysis.
ARUP MANDAL, SUBALA MONDAL, PARNAJYOTI KARMAKAR, BIPLAB K BERA, SUBHASIS MALLICK, and ALAK K GHOSH
Springer Science and Business Media LLC