Sankaralingam Arunachalam

Bharathidasan University, Tiruchchināppalli, Tamil Nādu, India

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Publications (48)101.57 Total impact

  • Journal of Luminescence 12/2014; · 2.14 Impact Factor
  • Karuppiah Nagaraj, Subramanian Sakthinathan, Sankaralingam Arunachalam
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    ABSTRACT: Abstract The binding interaction between tRNA and surfactant copper(II) complexes with imidazo[4,5-f][1, 10]phenanthroline, 6,7,8,9-tetrahydrodipyrido[3,2-a:2′,4′-c]phenazine, and benzo[1]dipyrido[3,2-a′:2′,3′-c]phenazine ligands has been studied using various physicochemical techniques. In the presence of tRNA, UV–Vis spectrum of surfactant complexes showed red shift of the absorption band along with significant hypochromicity indicating intercalation of surfactant complexes with tRNA. Competitive binding study with ethidium bromide shows that complexes exhibit the ability to displace the tRNA-bound EB indicating that these complexes bind to tRNA in strong competition with EB for the intercalative binding site. Observed changes in the circular dichroic spectra of tRNA in the presence of surfactant complexes support the strong binding of complexes with tRNA. CV and viscosity results also affirm this mode of binding. The results reveal that the extent of tRNA binding of the benzo[1]dipyrido[3,2-a′:2′,3′-c]phenazine complex was greater than that of the other complexes. Binding to tRNA appears to be mainly intercalative in nature. Graphical abstract
    Monatshefte fuer Chemie/Chemical Monthly 12/2014; 145(12). · 1.63 Impact Factor
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    ABSTRACT: The molecular interaction of polymer-anchored cobalt(III) complex, cis-[Co(bpy)2(BPEI)Cl]Cl2·4H2O (bpy = 2,2'-bipyridine, BPEI = branched polyethyleneimine) with two plasma proteins, human serum albumin (HSA) and bovine serum albumin (BSA) using various spectrophotomeric techniques has been investigated. The steady-state and time-resolved fluorescence spectra clearly demonstrated the static quenching mechanism. The calculated thermodynamic parameters revealed that the interaction between polymer-cobalt(III) complex and HSA/BSA was driven mainly by van der Waals force and hydrogen bonds. The resuts observed from three dimentional fluorescence and Cirucular dichorism (CD) spectral studies manifested the conformational changes of HSA/BSA upon addition of the polymer-cobalt(III) complex. Furthermore, the antimicrobial result showed that the polymer-cobalt(III) complex exhibits good antibacterial and antifungal activities against certain human pathogenic microorganisms. In addition, the antiproliferative property of the polymer-cobalt(III) complex on HEp-2 human larynx cancer cells was determined using MTT assay. The mode of cell death induced by the complex following treatment was analyzed adopting specific staining techniques. MTT assay revealed that the viability of the cells thus treated was significantly decreased and the cells succumbed to apoptosis as well as necrosis as reflected in changes in the nuclear morphology and cytoplasmic features by AO & EB and Hoechst staining methods.
    RSC Advances 10/2014; · 3.71 Impact Factor
  • Karuppiah Nagaraj, Subramanian sakthinathan, Sankaralingam Arunachalam
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    ABSTRACT: The kinetics of reductions of surfactant cobalt(III) complexes, cis-[Co(ip)2(C12H25NH2)2](ClO4)3, cis-[Co(dpq)2(C12H25NH2)2]3+ and cis-[Co(dpqc)2(C12H25NH2)2](ClO4)3 (ip = imidazo[4,5-f][1,10]phenanthroline, dpq = dipyrido[3,2-d:2’-3’-f]quinoxaline, dpqc = dipyrido[3,2-a:2’,4’-c](6,7,8,9-tetrahydro)phenazine, C12H25NH2=dodecylamine) by Fe2+ ion in liposome vesicles (DPPC) and ionic liquids ((BMIM)Br) were studied at different temperatures by UV-Vis absorption spectroscopy method under pseudo first order conditions using an excess of the reductant. The reactions were found to be second order and the electron transfer is postulated as outer-sphere. Below the phase transition temperature of DPPC, the rate decreased with increasing concentration of DPPC, while above the phase transition temperature the rate increased with increasing concentration of DPPC. It is concluded that below the phase transition temperature, there is an accumulation of surfactant cobalt(III) complexes at the interior of the vesicle membrane through hydrophobic effects, and above the phase transition temperature the surfactant cobalt(III) complexes is released from the interior to the exterior surface of the vesicle. The effects of amphiphilicity of the long aliphatic double chains of these surfactant complex ions into ionicliquids on these reactions have also been studied. The second order rate constant for the electron transfer reactions were found to increase with increasing concentrations of ionic liquids. The results have been interpreted in terms of the hydrophobic effect.
    RSC Advances 10/2014; · 3.71 Impact Factor
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    ABSTRACT: A new class of surfactant cobalt(III) complexes, cis-[Co(ip)2(C12H25NH2)2](ClO4)3 (1) and cis-[Co(dpq)2(C12H25NH2)2](ClO4)3 (2) (ip = imidazo[4,5-f][1,10]phenanthroline, dpq = dipyrido[3,2-d:2’-3’-f]quinoxaline), have been synthesized and characterized by various spectroscopic and physico-chemical techniques. The critical micelle concentration (CMC) values of these complexes in aqueous solution were obtained from conductance measurements. The specific conductivity data (at 303, 308, 313, 318 and 323K) served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔG0m, ΔH0 m and ΔS0 m). The trend in DNA-binding affinities and the spectral properties of a series of complexes, cis-[Co(ip)2(C12H25NH2)2](ClO4)3 (1) and cis-[Co(dpq)2(C12H25NH2)2](ClO4)3 (2), have been experimentally and theoretically investigated. The experimental results indicate that the size and shape of the intercalated ligand and hydrophobicity of the complexes have a marked effect on the binding affinity of complexes to CT DNA in intercalation mode, and the order of their intrinsic DNA-binding constants Kb is Kb(1) < Kb(2). In addition, the influence of the extended aromatic ring and optical properties of the complexes can be reasonably explained by applying the DFT calculations. The energy gap between HOMO and LUMO indicates that these complexes are prone to interact with CT DNA. Further, molecular docking calculations have also been performed to understand the nature of binding of the complexes and the result confirms that the complexes interact with CT DNA through the alkyl chain. The cytotoxic activity of these complexes on human liver carcinoma cancer cells were determined adopting MTT assay and specific staining techniques, which revealed that the viability of the cells, thus treated was significantly decreased and the cells succumbed to apoptosis as seen in the changes in the nuclear morphology and cytoplasmic features.
    Dalton Transactions 10/2014; · 4.10 Impact Factor
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    Dataset: c4nj00460d1
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    ABSTRACT: The novel surfactant copper(II) complexes, [Cu(ip)2DA](ClO4)21, [Cu(dpqc)2DA](ClO4)22, [Cu(dppn)2DA](ClO4)23, where ip=imidazo[4,5-f][1,10]phenanthroline, dpqc=dipyrido[3,2-a:2',4'-c](6,7,8,9-tetrahydro)phenazine, dppn=benzo[1]dipyrido[3,2-a':2',3'-c]phenazine and DA-dodecylamine, were synthesized and characterized by physico-chemical and spectroscopic methods. In these complexes 1-3, the geometry of copper metal ions was described as square pyramidal. The critical micelle concentration (CMC) value of these surfactant copper(II) complexes in aqueous solution was found out from conductance measurements. Specific conductivity data at different temperatures served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔGm°, ΔHm° and ΔSm°). The binding interaction of these complexes with DNA (calf thymus DNA) in Tris buffer was studied by physico-chemical techniques. In the presence of the DNA UV-vis spectrum of complexes showed red shift of the absorption band along with significant hypochromicity indicating intercalation of our complexes with nucleic acids. Competitive binding study with ethidium bromide (EB) shows that the complexes exhibit the ability to displace the nucleic acid-bound EB indicating that the complexes bind to nucleic acids in strong competition with EB for the intercalative binding site. Observed changes in the circular dichoric spectra of DNA in the presence of surfactant complexes support the strong binding of complexes with DNA. CV results also confirm this mode of binding. Some significant thermodynamic parameters of the binding of the titled complexes to DNA have also been determined. The results reveal that the extent of DNA binding of 3 was greater than that of 1 and 2. The antibacterial and antifungal screening tests of these complexes have shown good results compared to its precursor chloride complexes.
    Colloids and surfaces B: Biointerfaces 06/2014; 122C:151-157. · 4.28 Impact Factor
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    ABSTRACT: A series of surfactant-copper(II) Schiff base complexes (1-6) of the general formula, [Cu(sal-R2)2] and [Cu(5-OMe-sal-R2)2], {where, sal = salicylaldehyde, 5-OMe-sal = 5-methoxy- salicylaldehyde, and R2 = dodecylamine (DA), tetradecylamine (TA), or cetylamine (CA)} have been synthesized and characterized by spectroscopic, ESI-MS, and elemental analysis methods. For a special reason, the structure of one of the complexes (2) was resolved by single crystal X-ray diffraction analysis and it indicates the presence of a distorted square-planar geometry in the complex. Analysis of the binding of these complexes with DNA has been carried out adapting UV-visible-, fluorescence-, as well as circular dichroism spectroscopic methods and viscosity experiments. The results indicate that the complexes bind via minor groove mode involving the hydrophobic surfactant chain. Increase in the length of the aliphatic chain of the ligands facilitates the binding. Further, molecular docking calculations have been performed to understand the nature as well as order of binding of these complexes with DNA. This docking analysis also suggested that the complexes interact with DNA through the alkyl chain present in the Schiff base ligands via the minor groove. In addition, the cytotoxic property of the surfactant-copper(II) Schiff base complexes have been studied against a breast cancer cell line. All six complexes reduced the visibility of the cells but complexes 2, 3, 5, and 6 brought about this effect at fairly low concentrations. Analyzed further, but a small percentage of cells succumbed to necrosis. Of these complexes (6) proved to be the most efficient aptotoxic agent.
    Journal of biomolecular Structure & Dynamics 05/2014; · 2.98 Impact Factor
  • Karuppiah Nagaraj, Subramanian Ambika, Sankaralingam Arunachalam
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    ABSTRACT: A surfactant-copper(II) complex, [Cu(dpq)2DA](ClO4)2 (dpq = dipyrido[3,2-d:2'-3'-f]quinoxaline; DA-dodecylamine), was synthesized and characterized on the basis of elemental analyses, UV-vis, IR, and EPR spectra. The critical micelle concentration (CMC) value of this surfactant-copper(II) complex in aqueous solution was found out from conductance measurements. Specific conductivity data at different temperature served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization ([Formula: see text], [Formula: see text], and [Formula: see text]). In addition, the complex has been examined by its ability to bind to nucleic acids (DNA and RNA) in tris-HCl buffer by UV-vis absorption, emission spectroscopy techniques, and viscosity measurements. The complex has been found to bind strongly to nucleic acids with apparent binding constants at DNA and RNA is 4.3 × 10(5), 9.0 × 10(5) M(-1), respectively. UV-vis studies of the interaction of the complex with DNA/RNA have revealed that the complex can bind to both DNA and RNA by the intercalative binding mode via ligand dpq into the base pairs of DNA and RNA which has been verified by viscosity measurements. The presence of long aliphatic chain in the surfactant complex increases this hydrophobic interaction. The binding constants have been calculated. The cytotoxic activity of this complex on human liver carcinoma cancer cells was determined by adopting 3-(4, 5-dimethylthiazol-2-yl)-2, 5- diphenyl tetrazolium bromide assay and specific staining techniques. The antimicrobial and antifungal screening tests of this complex have shown good results.
    Journal of biomolecular Structure & Dynamics 01/2014; · 2.98 Impact Factor
  • Karuppiah Nagaraj, Sankaralingam Arunachalam
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    ABSTRACT: The kinetics of reduction of the surfactant complex ions cis-[Co(phen)2(C12H25NH2)2]3+ and cis-[Co(bpy)2(C12H25NH2)2]3+ (phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine, C12H25NH2 = dodecylamine) in solutions of unilamellar vesicles of dipalmitoylphosphatidylcholine (DPPC) were studied at different temperatures by a spectrophotometric method under pseudo-first-order conditions using an excess of the reductant. Experimentally the reaction was found to be second order and the electron transfer postulated as outer sphere. Below the phase temperature of DPPC the second-order rate constant for this electron-transfer reaction of both the complexes was found to decrease with increasing concentration of the liposome. Above the phase transition temperature the reaction rate was found to increase with increasing concentration of DPPC. Below the phase transfer temperature the results have been explained on the basis of electrostatic double layer repulsion which prevents the vesicles from accumulation of surfactant–cobalt(III) complexes in the interior of the vesicle membrane. Above the phase transfer temperature the release of the surfactant–cobalt(III) complex molecules from the interior core to the exterior surface of the vesicle through the strong hydrophobic effect increases the reaction rate. The main driving force for this phenomenon is considered to be the intervesicular hydrophobic interaction between the surfactant complexes and vesicles surface. We could observe isokinetic relationships for both the complexes of the present study at the phase transfer temperature of DPPC.
    Monatshefte fuer Chemie/Chemical Monthly 01/2014; 145(3). · 1.63 Impact Factor
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    ABSTRACT: Polymer conjugates containing copper(ii) phenanthroline complex units and ferrocenyl methylene units bound to the same polymer backbone were synthesized and characterized by spectroscopic and analytical techniques. We could observe both the EPR spectrum for the paramagnetic copper(ii) units and the proton NMR spectrum due to the diamagnetic ferrocenyl methylene units. Binding interaction of this complex with calf thymus DNA (CT-DNA) has been investigated by absorption, emission, cyclic voltammetry, and circular dichroism studies. The complex displays significant binding properties to the CT-DNA. In fluorimetric studies, the binding mode of the complex with CT-DNA was investigated using ethidium bromide (EB) as a fluorescence probe. The binding of copper(ii) complex units to DNA was facilitated by the presence of ferrocenyl methylene units in the same polymer molecule. These polymer conjugates show good anticancer activity against HepG2 cells and antimicrobial studies have shown better activity.
    New Journal of Chemistry 01/2014; · 3.16 Impact Factor
  • Karuppiah Nagaraj, Sankaralingam Arunachalam
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    ABSTRACT: The surfactant–cobalt(III) complex, cis-[Co(trien)(4CNP)(DA)](ClO4)3 (trien = triethylenetetramine, 4CNP = 4-cyanopyridine and DA = dodecylamine) was synthesized and characterized by various spectroscopic and physicochemical techniques. The critical micelle concentration (CMC) value of this surfactant–cobalt(III) complex in aqueous solution was obtained from conductance measurements. The conductivity data (at 303, 308, 313, 318 and 323 K) were used for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔG0m, ΔH0m and ΔS0m). Absorption, fluorescence, cyclic voltammetry, circular dichroism and viscosity experiments have been carried out to study the interaction of the surfactant–cobalt(III) complex with DNA and RNA. The results suggest that the complex can bind to nucleic acids by intercalation via the long aliphatic chain of the complex into the base pairs of DNA/RNA. In the presence of an ionic liquid additive, the binding strength of the surfactant–cobalt(III) complex to the nucleic acids increased. The complex was tested in vitro on HepG2 (human hepatocellular liver carcinoma) tumor cell lines and found to be active.
    New Journal of Chemistry 12/2013; 38(1). · 3.16 Impact Factor
  • Karuppiah Nagaraj, Subramanian Sakthinathan, Sankaralingam Arunachalam
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    ABSTRACT: A new water-soluble surfactant copper(II) complex [Cu(sal-ala)(phen)(DA)] (sal-ala = salicylalanine, phen = 1,10-phenanthroline, DA = dodecylamine), has been synthesized and characterized by physico-chemical and spectroscopic methods. The critical micelle concentration (CMC) values of this surfactant-copper(II) complex in aqueous solution were obtained from conductance measurements. Specific conductivity data (at 303, 308, 313. 318 and 323 K) served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔG(0)m, ΔH(0)m and ΔS(0)m). The interaction of this complex with nucleic acids (DNA and RNA) has been explored by using electronic absorption spectral titration, competitive binding experiment, cyclic voltammetry, circular dichroism (CD) spectra, and viscosity measurements. Electronic absorption studies have revealed that the complex can bind to nucleic acids by the intercalative binding mode which has been verified by viscosity measurements. The DNA binding constants have also been calculated (Kb = 1.2 × 10(5) M(-1) for DNA and Kb = 1.6 × 10(5) M(-1) for RNA). Competitive binding study with ethidium bromide (EB) showed that the complex exhibits the ability to displace the DNA-bound-EB indicating that the complex binds to DNA in strong competition with EB for the intercalative binding site. The presence of hydrophobic ligands, alanine Schiff-base, phenanthroline and long aliphatic chain amine in the complex were responsible for this strong intercalative binding. The surfactant-copper (II) complex was screened for its antibacterial and antifungal activities against various microorganisms. The results were compared with the standard drugs, amikacin(antibacterial) and ketokonazole(antifungal).
    Journal of Fluorescence 12/2013; · 1.79 Impact Factor
  • Karuppiah Nagaraj, Sankaralingam Arunachalam
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    ABSTRACT: The surfactant–cobalt(III) complex, cis-[Co(trien)(4CNP)(DA)](ClO 4) 3 (trien = triethylenetetramine, 4CNP = 4-cyanopyridine and DA = dodecylamine) was synthesized and characterized by various spectroscopic and physicochemical techniques. The critical micelle concentration (CMC) value of this surfactant– cobalt(III) complex in aqueous solution was obtained from conductance measurements. The conductivity data (at 303, 308, 313, 318 and 323 K) were used for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (DG 0 m , DH 0 m and DS 0 m). Absorption, fluorescence, cyclic voltammetry, circular dichroism and viscosity experiments have been carried out to study the interaction of the surfactant–cobalt(III) complex with DNA and RNA. The results suggest that the complex can bind to nucleic acids by intercalation via the long aliphatic chain of the complex into the base pairs of DNA/RNA. In the presence of an ionic liquid additive, the binding strength of the surfactant–cobalt(III) complex to the nucleic acids increased. The complex was tested in vitro on HepG2 (human hepatocellular liver carcinoma) tumor cell lines and found to be active.
    New Journal of Chemistry 10/2013; · 3.16 Impact Factor
  • Karuppiah Nagaraj, Sankaralingam Arunachalam
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    ABSTRACT: The surfactant–cobalt(III) complex, cis-[Co(trien)(4AMP)(DA)](ClO4)3, trien = triethylenetetramine, 4AMP = 4-aminopyridine, DA = dodecylamine was synthesized and characterized by various spectroscopic and physico-chemical techniques. The critical micelle concentration (CMC) value of this surfactant–cobalt(III) complex in aqueous solution was found out from conductance measurements. The conductivity data (at 303, 308, 313, 318 and 323 K) were used for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔG m°, ΔHm and ΔS m°). Also the kinetics of reduction of this surfactant–cobalt(III) complex by hexacyanoferrate(II) ion in micelles, β-cyclodextrin, ionic liquids (ILs) and in liposome vesicles (DPPC) media were studied at different temperature. The rate constant for the electron transfer reaction in micelles was found to increase with increase in the initial concentration of the surfactant–cobalt(III) complex. This peculiar behaviour of dependence of second-order rate constant on the initial concentration of one of the reactants has been attributed to the presence of various concentration of micelles under different initial concentration of the surfactant–cobalt(III) complex in the reaction medium. Inclusion of the long aliphatic chain of the surfactant complex ion into β-cyclodextrin leads to decrease in the rate constant. Below the phase transition temperature of DPPC, the rate decreased with increasing concentration of DPPC, while above the phase transition temperature the rate increased with increasing concentration of DPPC. It is concluded that below the phase transition temperature, there is an accumulation of surfactant–cobalt(III) complex at the interior of the vesicle membrane through hydrophobic effects, and above the phase transition temperature the surfactant–cobalt(III) complex is released from the interior to the exterior surface of the vesicle. In the presence of ionic liquid medium the second order rate constant for this electron transfer reaction for the same complex was found to increase with increasing concentration of ILs has also been studied. An outer-sphere mechanism is proposed for all these reactions and the results have been explained based on the hydrophobicity of the ligand and the reactants with opposite charges.
    Journal of inclusion phenomena and macrocyclic chemistry 10/2013; · 1.17 Impact Factor
  • Selvan Nehru, Sankaralingam Arunachalam, Renganathan Arun, Kumpati Premkumar
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    ABSTRACT: A new series of pendant-type polymer-cobalt(III) complexes, [Co(LL)2(BPEI)Cl](2+), (where BPEI = branched polyethyleneimine, LL = dipyrido[3,2-a:2',3'-c](6,7,8,9-tetrahydro)phenazine (dpqc), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq) and imidazo[4,5-f]1,10-phenanthroline (ip)) each with three different degrees of coordination have been synthesized and characterized. Studies to know the mode and strength of interaction between these polymer-metal complexes and calf thymus DNA have been performed by UV-Visible absorption and emission techniques. Among these series, each polymer metal complex having higher binding strength with DNA has been selected to test against human cancer/normal cell lines. On the basis of these spectral studies, it is proposed that our polymer-metal complexes bind with DNA mainly through intercalation along with some electrostatic binding. The order of binding strength for the complexes with ligand, dpqc > dpq > ip. The analysis of the results suggests that polymer-cobalt(III) complexes with higher degree of coordination effectively binds with DNA due to the presence of large number of positively charged cobalt(III) chelates in the polymer chain which cooperatively act to increase the overall binding strength. These polymer-cobalt(III) complexes with hydrophobic ligands around the cobalt(III) metal centre favour the base stacking interactions via intercalation. All the complexes show very good anticancer activities and increasing of binding strength results in higher inhibition value. The polymer-cobalt(III) complex with dpqc ligand possess two fold increased anticancer activity when compared to complexes with other ligands against MCF-7 cells. Besides, the complexes were insensitive towards the growth of normal cells (HEK-293) at the IC50 concentration.
    Journal of biomolecular Structure & Dynamics 09/2013; · 2.98 Impact Factor
  • Karuppiah Nagaraj, Sankaralingam Arunachalam
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    ABSTRACT: The interaction of cis-[Co(phen)2(HA)2](ClO4)3, a cationic surfactant complex (phen=1,10- phenanthroline, HA= hexadecylamine), with calf thymus DNA has been studied by UV-Visible absorption, fluorescence spectroscopy, cyclic voltammetry, circular dichroism, and viscosity measurements. The spectroscopic studies together with cyclic voltammetry and viscosity experiments support that the surfactant-cobalt(III) complex binds to calf thymus DNA (CT DNA) by intercalation through the aliphatic chain present in the complex into the base pairs of DNA. The presence of phenanthroline ligand with larger π-frame work may also enhance intercalation. Besides the effect of binding of surfactant cobalt(III) complex to DNA in presence of β-cyclodextrin has also studied. In presence of β-cyclodextrin the binding occurs through surface and (or) groove binding. The complex was investigated as one of the potential selective anticancer prodrugs. The complex was tested also in vitro on human monolayer tumour cell lines: HepG2 (Human hepatocellular liver carcinoma).
    International journal of biological macromolecules 09/2013; · 2.37 Impact Factor
  • Karuppiah Nagaraj, Sankaralingam Arunachalam
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    ABSTRACT: A surfactant–cobalt(III) complex, cis-[Co(en)2(4AMP)(DA)](ClO4)3, (en = ethylenediamine, 4AMP = 4-aminopyridine, DA = dodecylamine), was synthesized and characterized by physicochemical and spectroscopic methods. The critical micelle concentration (CMC) value of this surfactant–cobalt(III) complex in aqueous solution was obtained from conductance measurements. Conductivity data were used for evaluation of the temperature-dependent CMC and the thermodynamics of micellization ( $ \Updelta {\text{G}}_{\text{m}}^{ 0} $ Δ G m 0 , $ \Updelta {\text{H}}_{\text{m}}^{0} $ Δ H m 0 , and $ \Updelta {\text{S}}_{\text{m}}^{0} $ Δ S m 0 ). The kinetics of reduction of this surfactant–cobalt(III) complex by ion(II) in micelles, β-cyclodextrin (β-CD), and ionic liquid (IL) were studied. The reaction was found to be second order, and the electron transfer is postulated as outer sphere. The second-order rate constant for the electron transfer reaction was found to increase with increasing concentration of IL, but inclusion of the long aliphatic chain of the surfactant complex into β-CD decreases the rate of the reaction. The results have been interpreted in terms of the amphiphilicity of the surfactant complex.
    Transition Metal Chemistry 09/2013; 38(6). · 1.40 Impact Factor
  • Karuppiah Nagaraj, Sankaralingam Arunachalam
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    ABSTRACT: Surfactant ] Complex Ion, cis-[Co(en) 2 (4CNP)(DA)] 31 with [Fe(CN) 6 ] 42 in Micelles, b-cyclodextrin, and Liposome (Dipalmidoylphosphotidylcholine) Vesicles The surfactant cobalt(III) complex, cis-[Co(en) 2 (4CNP)(DA)](ClO 4) 3 , en ¼ ethylenediamine, 4CNP ¼ 4-cyanopyridine, DA ¼ dodecylamine, was synthesized and characterized by physico-chemical and spectroscopic methods. The critical micelle concentration value of this complex was obtained from the conductivity measurements at different temperatures to evaluate, DG m 0 , DH m 0 , and DS m 0 . The kinetics of outer sphere electron transfer reaction of this complex with Fe(CN) 6 4À ion in micelles, b-cyclodextrin as well as in liposome vesicles media were studied. The rate constant increases with increase in the concentration of micelles but decreases in presence of b-cyclodextrin, which is a good structure breaker of micelles. In liposome vesicles media the rate constant is different at below and above phase transition temperature. The results have been explained based on the hydrophobic effect, the presence of pyridine ligand containing 4-cyano substituent and the reactants with opposite charge.
    Australian Journal of Chemistry 06/2013; 66:930-937. · 1.87 Impact Factor
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    ABSTRACT: The comparative binding effect of single and double aliphatic chain containing surfactant-cobalt(III) complexes cis-[Co(bpy)2(DA)2](ClO4)3⋅2H2O (1), cis-[Co(bpy)2(DA)Cl](ClO4)2⋅2H2O (2), cis-[Co(phen)2(CA)2](ClO4)3⋅2H2O (3), and cis-[Co(phen)2(CA)Cl](ClO4)2⋅2H2O (4) with bovine serum albumin (BSA) under physiological condition was analyzed by steady state, time resolved fluorescence, synchronous, three-dimensional fluorescence, UV-Visible absorption and circular dichroism spectroscopic techniques. The results show that these complexes cause the fluorescence quenching of BSA through a static mechanism. The binding constants (Kb) and the number of binding sites were calculated and binding constant values are found in the range of 10(4)-10(5)M(-1). The results indicate that compared to single chain complex, double chain surfactant-cobalt(III) complex interacts strongly with BSA. Also the sign of thermodynamic parameters (ΔG°, ΔH°, and ΔS°) indicate that all the complexes interact with BSA through hydrophobic force. The binding distance (r) between complexes and BSA was calculated using Förster non-radiation energy transfer theory and found to be less than 7nm. The results of synchronous, three dimensional fluorescence and circular dichroism spectroscopic methods indicate that the double chain surfactant-cobalt(III) complexes changed the conformation of the protein considerably than the respective single chain surfactant-cobalt(III) complexes. Antimicrobial studies of the complexes showed good activities against pathogenic microorganisms.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 05/2013; 113C:415-422. · 1.98 Impact Factor