D. Girija

Novel complexes of Co(III) and Ni(II) containing peptide ligands: Synthesis, DNA binding and photonuclease activity

The new cobalt(III) and nickel(II) complexes of the type [M(L)2(H2O)2](n)(+) (where M = Co(III) or Ni(II) ion, n = 3 for Co and 2 for Ni, L = peptides Fmoc. Ala-val-OH (F-AVOH), Fmoc-Phe-Leu-Ome (F-PLOMe) and Z-Ala-Phe-CONH2 (Z-APCONH2)) were synthesized and structurally characterized by FTIR, (1)H NMR, elemental analysis and electronic spectral data. An octahedral geometry has been proposed for all the synthesized Co(III) and Ni(II) metal complexes. The binding property of the complexes with CT-DNA was studied by absorption spectral analysis, followed by viscosity measurement and thermal denaturation studies. Detailed analysis revealed that the metal complexes intercalates into the DNA base stack as intercalator. The photo induced cleavage studies shows that the complexes possess photonuclease property against pUC19 DNA under UV-Visible irradiation.

Synthesis, DNA binding, and cleavage studies of Co(III) complexes with fused aromatic NO/NN-containing ligands.

Four new Co(III) complexes, namely [Co(cq)3](PF6)3, [Co(phen)2(cq)](PF6)3, [Co(bnp)3] (PF6)3, and [Co(phen)2(bnp)](PF6)3 (where cq = chromeno[2,3-b]quinoline, phen = 1,10-phenanthroline and bnp = dibenzo[b,g][1,8]naphthyridine), were synthesized and structurally characterized. Spectroscopic data suggested an octahedral geometry for all the complexes. Binding studies of these complexes with double-stranded (ds)DNA were analyzed by absorption spectra, viscosity, and thermal denaturation studies. The results revealed that the metal complex intercalates into the DNA base stack as intercalator. The oxidative cleavage activities of the complexes were studied with supercoiled pUC19 DNA using gel electrophoresis and the results show that the complexes have potent nuclease activity.

Metal Complexes of New Tetraazamacrocyclic Constrained Oxadiazole Ring as Subunits: Synthesis, DNA Binding and Photonuclease Activity

A new tetraazamacrocyclic ligand, L (C24H16N12O6) and its complexes of type, [MLCl2] and [CuL]Cl2 (Where M = Co(II), Fe(II); L = N,N′-(benzene-1,3-diyldi-1,3,4-oxadiazole-5,2-diyl)bis{2-[(5-benzene-1,3-diyl-1,3,4-oxadiazol-2-yl)amino]acetamide}) were synthesized and characterized by elemental analysis including IR, 1H NMR, 13C NMR, mass and electronic spectral data. An octahedral geometry has been proposed for Fe(II) and Co(II) complexes except the Cu(II) complex which have a square planar environment. The binding property of the complexes with CT-DNA was studied by absorption spectra, viscosity measurement and thermal denaturation studies. The absorption spectral results indicate that the complexes binds with the base pairs of DNA with an intrinsic binding constant Kb of Cu(II), Co(II) and Fe(II) complexes were found to be 4.5 × 104 M−1, 5.7 × 104 M−1 and 2.6 × 104 M−1, respectively in 5 mM Tris-HCl/50 mM NaCl buffer at pH 7.2. The photo induced cleavage studies revealed that the complexes show photonuclease property against pUC19 DNA under UV-visible irradiation.

Synthesis and Biological Evaluation of New Tetra-aza Macrocyclic Scaffold Constrained Oxadiazole, Thiadiazole and Triazole Rings

A new series of N,N′‐(benzene‐1,3‐diyldi‐1,3,4‐oxadiazole‐5,2‐diyl)bis{2‐[(5‐benzene‐1,3‐diyl‐1,3,4‐oxadiazol‐2‐yl)amino]acetamide}(macrocycle 1), N,N′‐(benzene‐1,3‐diyldi‐1,3,4‐thiadiazole‐5,2‐diyl)bis{2‐[(5‐benzene‐1,3‐diyl‐1,3,4‐thiadiazol‐2‐yl)amino]acetamide} (macrocycle 2) and S,S′‐[benzene‐1,3‐diylbis(4H‐1,2,4‐triazole‐5,3‐diyl)]bis{[(5‐benzene‐1,3‐diyl‐4H‐1,2,4‐triazol‐3‐yl)sulfanyl]ethanethioate}(macrocycle 3) was synthesized from isophthalic dihydrazide (4) through a multistep reaction sequence. All the synthesized compounds were screened for their inhibitory effect against four different bacterial strains: P. aeruginosa ATCC‐20852, K. pneumoniae MTCC‐618, S. aureus ATCC‐ 29737, S. typhi MTCC‐ 3214. The synthesized compounds showed a significant zone of inhibition and the results were comparable with that of the standard drug ciprofloxacin. The synthesized compounds were further studied for their possible in vitro antioxidant effects by DPPH scavenging, total antioxidant capacity, total reductive capacity and H2O2 scavenging activity. The results indicated that the in vitro antioxidant activity for all the three molecules was efficient when compared to the standards. The DNA interaction behavior of macrocycles 1–3 with CT‐DNA was investigated by the absorption spectra obtained (Kb constant for 1 is 4.53 × 104 M−1, for 2 is 5.75 × 104 M−1 and for 3 is 5.86 × 104 M−1). Based on the results it can be interpreted that the reducing power effect of the newly synthesized compounds demonstrates a direct effect on DNA binding and hence inhibiting the bacterial growth through their action on DNA by inhibiting DNA replication or DNA transcription.

Synthesis of Functionalized Iron Oxide Nanoparticle with Amino Pyridine Moiety and Studies on Their Catalytic Behavior

Aim: The main objective of this paper is to study the synthesis of functionalized iron oxide nanoparticle and its reactivity towards chromene synthesis Study design: Functionalized iron oxide nanoparticle study. Place and duration of study: Department of Studies and Research in Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta, between December 2009 and July 2010. Methodology: This paper describes synthesis of stable functionalized iron oxide nanoparticles through surface modification of magnetic iron oxide nanoparticles by amino pyridine. Iron oxide nanoparticles were synthesized by co-precipitation method and the surface modification process was achieved by treating the nanoparticles with (chloro propyl trimethoxy silane) CPTS and aminopyridine. The developed functionalized iron oxide nanoparticle was evaluated as the catalyst for synthesis of chromones under MW irradiation conditions. Results: The catalysts were magnetically recovered and reusable without significant loss of their catalytic efficiency. To receive morphological and structural information on the obtained functionalized nanoparticle, the samples were analyzed by X-ray diffraction (XRD) measurements, FTIR and scanning electron microscopy (SEM) imaging. All synthesized chromene derivatives were characterized using analytical techniques such as IR, H NMR, and mass spectroscopy. Also the identity of these compounds was easily established by comparison of their melting point with those of reported samples. Conclusion: In summary, we have developed a new magnetically recyclable and Research Article American Chemical Science Journal, 1(3): 97-108, 2011 98 efficient functionalized magnetic nano catalyst for the chromene synthesis. Magnetic nanoparticle catalyst achieves a simple separation of catalyst without filtration including high yield in product.

Synthesis, Characterization, DNA Binding, and Cleavage Activity of New Co(III) and Ru(II) Complexes of Substituted Quinolines

The cobalt(III) and ruthenium(II) complexes of the type [M(L)2]n+ (M = Co(III) or Ru(II) ion, n = 3 for Co and 2 for Ru, L = 2-thiol/seleno 4-methylquinoline) were synthesized and structurally characterized. The spectral and magnetic data suggested octahedral geometry for all the complexes. DNA binding behaviors of these complexes with calf thymus DNA (CT-DNA) have been investigated by absorption spectra, viscosity, and thermal denaturation methods. The metal complexes intercalates into the DNA base stack. The oxidative cleavage activities of the complexes shows that the complexes act as potent nucleases.