G Rajagopal

Madras Medical College, Chennai, Tamil Nādu, India

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Publications (49)41.03 Total impact

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    A Sundar, S Ranjith, G Rajagopal
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    ABSTRACT: In the title compound, C12H8BrClN2O3, the furan ring makes a dihedral angle of 17.2 (2)° with the six-membered ring. An intra-molecular O-H⋯N hydrogen bond stabilizes the mol-ecular conformation. In the crystal, N-H⋯O hydrogen bonds connect the mol-ecules into chains running along the c-axis direction. The crystal packing is additionally stabilized by C-H⋯O inter-actions into a three-dimensional supramolecular architecture.
    Acta Crystallographica Section E Structure Reports Online 06/2014; 70(Pt 6):o670. · 0.35 Impact Factor
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    ABSTRACT: New colorimetric chemosensor, N'-[(E)-3-Bromo-5-Chloro-2-hydroxybenzidene]-4-hydroxybenzohydrazide, containing OH and NH groups as binding sites have been synthesized and characterized by spectral UV, IR, NMR and ESR. The molecular structure of ligand is determined by X-ray crystallography and it has the monoclinic space group P21/c with cell parameters a=15.1058(6), b=14.3433(6), c=17.5800(8)Å and Z=8. The electronic spectral measurements show that Co(2+), Ni(2+) and Zn(2+) complexes have tetrahedral geometry, while Cu(2+) complex has square planar geometry. Magnetic measurements show that Cu(2+), Co(2+) and Ni(2+) complexes have paramagnetic behavior and Zn(2+) complex has diamagnetic behavior. Anion binding studies carried out using (1)H NMR and UV-visible spectrophotometric titrations revealed that these receptors exhibit selective recognition towards F(-) over other halide anions. The selectivity for F(-) among the halides is attributed mainly to the hydrogen-bond interaction of the receptor with F(-). Receptor (5×10(-5)M) shows color change from colorless to yellow in the presence of tetrabutylammonium fluoride (TBAF, 1.5×10(-3)M). Moreover, F(-)-induced color changes remain the same even in the presence of large excess of Cl(-), Br(-) and I(-). The binding constant is found to be higher towards F(-) ion and this may be due to presence of OH group, which offers extra binding site. Chromogenic receptor undergoes distinct color changes from colorless to green on gradual addition of Cu(2+) can be used as colorimetric probes for spectrophotometric and visual analysis of Cu(2+) in the presence of other transition metal ions such as Co(2+), Ni(2+) and Zn(2+).
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 04/2014; 129C:509-518. · 1.98 Impact Factor
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    ABSTRACT: h i g h l i g h t s Synthesis of novel morpholinoaniline based Schiff bases. Reporting structurally solved morpholinoaniline for the first time. Complexes having potential antibacterial and antifungal activity. Good to moderate anticancer activity against HepG2. Zinc complex exhibits a good inhibitory activity against the human gastric cancer cells. g r a p h i c a l a b s t r a c t a b s t r a c t Metal(II) chelates of Schiff bases derived from the condensation of 4-morpholinoaniline with substituted salicylaldehyde have been prepared and characterized by 1 H NMR, IR, electronic, EPR, and magnetic mea-surement studies. The complexes are of the type M(X-MPMP)2 [where M = Cu(II), Co(II)), Zn(II), or VO(IV); MPMP = 2-[(4 morpholinophenyl imino) methyl] 4-X-phenol, X = Cl, (L 1 H), X = Br (L 2 H)]. Single crystal X-ray crystallography studies confirm the structure of newly synthesized Schiff bases. The Schiff bases act as bidentate monobasic ligands, coordinating through deprotonated phenolic oxygen and azo-methine nitrogen atoms. The free ligands and metal complexes are screened for their biopotency. Metal complexes exhibit better activity than ligands. Anticancer activity of ligands and their metal complexes are evaluated in human heptocarcinoma(HepG2) cells. The preliminary bioassay indicates that the Schiff base and its zinc complex exhibit inhibitory activity against the human gastric cancer cell lines.
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    ABSTRACT: High-quality single crystals of 1-[(E)-{[4-(Morpholin-4-yl)phenyl]imino}methyl]naphthalen-2-ol were grown by slow evaporation method using ethylacetate solution at room temperature and the sample is characterized by FTIR, UV–visible, NMR and single crystal X-ray diffraction studies. The crystal structure was solved by direct methods and refined by full-matrix least-squares procedure to a final reliability value of 0.047. The asymmetric unit contains two crystallographically independent molecules in different orientations. The weak O- -H⋯N and C- -H⋯π interactions are responsible for the stability of the molecules in the unit cell. The antimicrobial activity of the compound was screened using different species of bacteria and for their ability to inhibit the heat shock protein 90(Hsp90). Molecular docking studies also supported the work.
    Journal of Molecular Structure. 01/2014; s 1065–1066:21–28.
  • Journal of Molecular Structure. 01/2014; 1075:227–233.
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    ABSTRACT: A series of new hexa coordinated ruthenium(III) complexes of the type [RuY2(EPh3)2(X-DPMP)] (where Y = Br or Cl; E = P or As; DPMP = 2-[(2,6-Diisopropyl-phenylimino)-methyl]-phenol, X = H, Br, Cl, I and Ph) have been synthesized by equimolar [RuY3(EPh3)3] and the Schiff base ligands in benzene. The bidentate Schiff base ligands (X-DPMP) have been derived from condensation of 2,6-diisopropylaniline with mono and multisubstituted salicylaldehyde derivatives. The complexes have been characterized by elemental analysis, magnetic susceptibility, UV–Vis., IR and EPR spectral and electrochemical measurements. All the ruthenium(III) complexes are found to be stable, paramagnetic, low spin, redox active and display either quasi reversible or irreversible redox couples based on metal centre. They have exhibited catalytic activity for the oxidation of wide range of primary and secondary alcohols to corresponding aldehydes or ketones with moderate to high conversion in the presence of N-methylmorpholine-N-oxide (NMO) as co-oxidant.
    Journal of Molecular Structure. 01/2014; 1060:49–57.
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    ABSTRACT: Several new lanthanide complexes of Pr(III), Sm(III), Gd(III), Tb(III), Er(III) and Yb(III) with the sodium salt of the Schiff base, 2-[(5-bromo-2-hydroxy-benzylidene)-amino]-5-methyl-pentanoic acid, derived from leucine and 5-bromosalicylaldehyde have been synthesized. These complexes having general formula [Ln(HL)(NO3)2(H2O)]·NO3 were characterized by elemental analysis, UV–vis., FT-IR, EPR, Mass spectrometry and Thermal analysis. The FT-IR spectral data suggested that the ligand behaves as a tridentate ligand with one nitrogen and two oxygen donor atoms, sequence towards central metal ion. From the analytical data, the stoichiometry of the complexes was found to be 1:1 (metal:ligand). The physico-chemical data suggested eight coordination number for Ln(III) Schiff base complexes. Thermal behaviour (TGA/DTA) and fluorescence nature of the complexes were also studied. The Gd(III) Schiff base complex was found to be an efficient catalyst for the oxidation of aniline and substituted anilines under mild conditions.
    Journal of Organometallic Chemistry 01/2014; 753:72–80. · 2.00 Impact Factor
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    ABSTRACT: A series of six Ln(III) Schiff base complexes, Pr(III), Sm(III), Gd(III), Tb(III), Er(III) and Yb(III), were synthesized using sodium salt of Schiff base, 2-[(5-bromo-2-hydroxy-benzylidene)-amino]-3-hydroxy-propionic acid, derived from L-serine and 5-bromosalicylaldehyde. These complexes having general formula [Ln(L)(NO3)2(H2O)]·NO3 were characterized by elemental analysis, conductivity measurements, UV-Vis, FT-IR, mass spectrometry and fluorescence studies. Elemental analysis and conductivity measurements suggest the complexes have a 1:1 stoichiometry. From the spectral studies it has been concluded that Ln(III) complexes display eight coordination. The Schiff base and its Ln(III) metal complexes have also been screened for their antibacterial activities by Agar diffusion method.
    Journal of Molecular Structure 01/2014; · 1.40 Impact Factor
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    ABSTRACT: Metal(II) chelates of Schiff bases derived from the condensation of 4-morpholinoaniline with substituted salicylaldehyde have been prepared and characterized by (1)H NMR, IR, electronic, EPR, and magnetic measurement studies. The complexes are of the type M(X-MPMP)2 [where M=Cu(II), Co(II)), Zn(II), or VO(IV); MPMP=2-[(4 morpholinophenyl imino) methyl] 4-X-phenol, X=Cl, (L1H), X=Br (L2H)]. Single crystal X-ray crystallography studies confirm the structure of newly synthesized Schiff bases. The Schiff bases act as bidentate monobasic ligands, coordinating through deprotonated phenolic oxygen and azomethine nitrogen atoms. The free ligands and metal complexes are screened for their biopotency. Metal complexes exhibit better activity than ligands. Anticancer activity of ligands and their metal complexes are evaluated in human heptocarcinoma(HepG2) cells. The preliminary bioassay indicates that the Schiff base and its zinc complex exhibit inhibitory activity against the human gastric cancer cell lines.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 08/2013; 117C:87-94. · 1.98 Impact Factor
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    ABSTRACT: The asymmetric unit of the title compound, C(19)H(22)ClNO, contains two independent mol-ecules in which the dihedral angles between the aromatic rings are 76.45 (9) and 74.69 (9)°. An intra-molecular O-H⋯N hydrogen bond occurs in each mol-ecule. The crystal structure features weak C-H⋯π inter-actions.
    Acta Crystallographica Section E Structure Reports Online 06/2012; 68(Pt 6):o1721. · 0.35 Impact Factor
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    ABSTRACT: The asymmetric unit of title compound, C(19)H(22)INO, contains two independent mol-ecules. Classical intra-molecular O-H⋯N hydrogen bonds stabilize the mol-ecular structures. The crystal structure is stabilized by weak inter-molecular C-H⋯π and π-π [centroid-centroid = 3.8622 (18) Å] inter-actions. In both mol-ecules, the aromatic rings are nearly perpendicular to each other [dihedral angles = 84.26 (17) and 86.69 (15)°].
    Acta Crystallographica Section E Structure Reports Online 06/2012; 68(Pt 6):o1915. · 0.35 Impact Factor
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    ABSTRACT: In the title compound, C(19)H(22)BrNO, the dihedral angle between the benzene rings is 76.17 (14)° and an intra-molecular O-H⋯N hydrogen bond with an S(6) graph-set motif is present. One methyl group is disordered over two sets of sites with site occupancies of 0.66 (3) and 0.34 (3). A weak inter-molecular C-H⋯π inter-action is observed in the crystal structure.
    Acta Crystallographica Section E Structure Reports Online 06/2012; 68(Pt 6):o1782. · 0.35 Impact Factor
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    ABSTRACT: DNA interaction studies of two mononuclear [1:1(1); 1:2(2)] copper(II) complexes of curcumin have been studied. The interaction of these complexes with CT-DNA has been explored by physical methods to propose modes of DNA binding of the complexes. Absorption spectral titrations of complex 1 with CT-DNA shows a red-shift of 3nm with the DNA binding affinity of K(b), 5.21×10(4)M(-1) that are higher than that obtained for 2 (red-shift, 2nm; K(b), 1.73×10(4)M(-1)) reveal that the binding occurs in grooves as a result of the interaction is via exterior phosphates. The CD spectra of these Cu(II) complexes show a red shift of 3-10nm in the positive band with increase in intensities. This spectral change of induced CD due to the hydrophobic interaction of copper complexes with DNA is the characteristic of B to A conformational change. The EB displacement assay also reveals the same trend as observed in UV-Vis spectral titration. The addition of complexes 1 and 2 to the DNA bound ethidium bromide (EB) solutions causes an obvious reduction in emission intensities indicating that these complexes competitively bind to DNA with EB. The positive shift of both the E(pc) and E(0)' accompanied by reduction of peak currents in differential pulse voltammogram (DPV), upon adding different concentrations of DNA to the metal complexes, are obviously in favor of strong binding to DNA. The super coiled plasmid pUC18 DNA cleavage ability of Cu(II) complexes in the presence of reducing agent reveals the single strand DNA cleavage (ssDNA) is observed. The hydroxyl radical (HO()) and the singlet oxygen are believed to be the reactive species responsible for the cleavage.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 05/2012; 97:223-30. · 1.98 Impact Factor
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    ABSTRACT: A series of mononuclear transition metal(II) complexes of type [M(LL)]2+ (LL = the template condensate of orthophenylene diamine and benzilidene diacetyl curcumin (ben-diacecur) and M = Cu(II) (1) or Co(II) (2) or Ni(II) (3) or Mn(II) (4)), have been isolated and the spectral behaviors are discussed. The ligand and complexes have also been characterized by the analytical and spectral methods like UV–Visible, FT-IR, NMR and EPR. Further, the interaction of the transition metal complexes with Calf thymus (CT) DNA have also been studied by the use of physical methods like UV–Visible, emission and CD spectroscopic techniques. The electrochemical responses of these metal complexes both in presence and absence of DNA have also been demonstrated. All these findings support the hypothesis of DNA interactions of all these metal complexes through the grooves with a higher degree of interaction by complex 1 (Kb = 1.4 × 105) possibly through the interposition of the aromatic rings of the ligand compared to complexes, 2–4. The complex 1 display significant oxidative cleavage of circular plasmid pUC18 DNA in the presence of H2O2 using the singlet oxygen as a reactive species. The spectral and electrochemical response of these complexes designate that the square-planar Cu(II), Ni(II) and Co(II) complexes interact much better than the axially coordinated octahedral Mn(II) complex.
    Journal of Molecular Structure 02/2012; 1010:169–178. · 1.40 Impact Factor
  • Acta Cryst. 01/2012; E68:o1915.
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    ABSTRACT: The asymmetric unit of title compound, C19H22INO, contains two independent mol­ecules. Classical intra­molecular O—H⋯N hydrogen bonds stabilize the mol­ecular structures. The crystal structure is stabilized by weak inter­molecular C—H⋯π and π–π [centroid–centroid = 3.8622 (18) Å] inter­actions. In both mol­ecules, the aromatic rings are nearly perpendicular to each other [dihedral angles = 84.26 (17) and 86.69 (15)°].
    Acta Crystallographica Section E Structure Reports Online 01/2012; · 0.35 Impact Factor
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    ABSTRACT: In the title compound, C(18)H(18)BrClN(2)O(2)·C(2)H(6)O, the hy-droxy group forms an intra-molecular O-H⋯N hydrogen bond, which influences the conformation of the Shiff base mol-ecule, where the two aromatic rings form a dihedral angle of 21.67 (8)°. Inter-molecular N-H⋯O and O-H⋯O hydrogen bonds link two Shiff base mol-ecules and two solvent mol-ecules into a centrosymmetric heterotetra-mer. Weak inter-molecular C-H⋯O inter-actions link further tetra-mers related by translation along the a axis into chains.
    Acta Crystallographica Section E Structure Reports Online 11/2011; 67(Pt 11):o2857. · 0.35 Impact Factor
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    ABSTRACT: In the title compound, C(22)H(26)N(4)O(2), the phenyl ring and hy-droxy-benzene group are twisted with respect to the central pyrazolone ring, making dihedral angles of 54.05 (5) and 21.80 (6)°, respectively. One of the ethyl groups is disordered over two positions with site occupancies of 0.872 (6) and 0.128 (6). The mol-ecular structure features short intra-molecular O-H⋯N and C-H⋯O contacts. The crystal packing exhibits weak inter-molecular C-H⋯O and C-H⋯π inter-actions.
    Acta Crystallographica Section E Structure Reports Online 10/2011; 67(Pt 10):o2692. · 0.35 Impact Factor
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    ABSTRACT: In the title compound, C(14)H(10)I(2)N(2)O(2), the two aromatic rings are inclined at a dihedral angle of 16.72 (33)°. The mol-ecular structure is stabilized by an intra-molecular O-H⋯N hydrogen bond. In the crystal, inter-molecular N-H⋯O inter-actions link the mol-ecules into chains running along the c axis. C-H⋯O inter-actions also occur. The crystal used for the structure determination was a non-merohedral twin with a domain ratio of 0.972 (2):0.028 (2).
    Acta Crystallographica Section E Structure Reports Online 10/2011; 67(Pt 10):o2620. · 0.35 Impact Factor
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    ABSTRACT: There are two independent mol-ecules in the asymmetric unit of the title compound, C(13)H(9)BrClN(3)O(2), in which the dihedral angles between the benzene and pyridine rings are 8.23 (9)° and 52.84 (12)°. Both the mol-ecules exist in an E configuration with respect to the C=N double bond. The two mol-ecules in the asymmetric unit are linked via weak C-H⋯O hydrogen bonds. In both the mol-ecules, an intra-molecular O-H⋯N hydrogen bond generate an S(6) graph-set motif. In the crystal, inter-molecular N-H⋯O and C-H⋯O hydrogen bonds generate bifurcated R(1) (2)(7) ring motifs. The crystal packing is further stabilized by weak inter-molecular N-H⋯O, N-H⋯N, C-H⋯O and π-π [centroid-centroid distance 3.615 (2) Å] inter-actions.
    Acta Crystallographica Section E Structure Reports Online 10/2011; 67(Pt 10):o2716. · 0.35 Impact Factor

Publication Stats

36 Citations
41.03 Total Impact Points

Institutions

  • 2014
    • Madras Medical College
      Chennai, Tamil Nādu, India
  • 2008–2014
    • Government Arts College for Men
      Chennai, Tamil Nādu, India
    • Govt. college for Women (Autonomous)
      Kumbakonam, Tamil Nādu, India
    • Sri Sairam Engineering college
      • Department of Chemistry
      Chennai, State of Tamil Nadu, India
  • 1995–2012
    • Madurai Kamaraj University
      • Department of Inorganic Chemistry
      Madurai, State of Tamil Nadu, India
  • 2010
    • Govt Arts College Melur
      Mailore, Tamil Nādu, India
  • 2001
    • B.S. ABDUR RAHMAN CRESCENT ENGINEERING COLLEGE
      Vandalūr, Tamil Nādu, India