Non-enolisable Knoevenagel condensate appended Schiff bases-metal (II) complexes: Spectral characteristics, DNA-binding and nuclease activities.
New Schiff base complexes [Cu(L1)Cl] (1), [Ni(L1)Cl] (2), [Zn(L1)Cl] (3), and [Fe(L2)H2OCl] (4) {L1=(4E)-3-(2-hydroxybenzylidene)-4-(2-hydroxyphenylimino)pentan-2-one, L2=2,2'-(1E,1'E)-(3-(2-hydroxybenzylidene)-pentane-2,4-diylidene)bis(azan-1-yl-1 idene)diphenol} have been synthesized and characterized by elemental analysis, UV-Vis, IR, FAB-mass, EPR, spectral studies and electrochemical studies, the ligands L1&L2were characterized by1H and13C NMR spectra. Complex 1 show a visible spectral d-d band near 600nm and display cyclic voltammetric quasireversible response for the Cu(II)/Cu(I) couple vs Ag/AgCl in DMSO. The EPR spectrum of 1 show g‖>g⊥suggesting a square planar geometry around copper with dx2-y2as the ground state. The mass spectral results have confirmed the proposed structure for complexes 1-4. DNA binding properties of these complexes 1-4 have been investigated by absorption titrations, cyclic voltammetric studies and circular dichroism studies. On titration with DNA, the complexes 1-4 show hypochromism at the MLCT band (13-31%) with a red shift of 1-8nm in the electronic spectrum and positive shift of voltammetric E1/2in the CV studies are in favour of intercalative binding. CD spectra of 1 showed an increase in molar ellipticity (θ278) of the positive band with a minor red shift indicating the transition of B-form of DNA to A like form. DNA cleavage studies of complexes 1 and 4 with pUC18 DNA were studied by gel electrophoresis and complex 4 cleaves supercoiled pUC18 DNA in an oxidative manner in the presence of H2O2and on photo irradiation at 312nm.
Department of Inorganic Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai 625 021, India; Department of Chemistry, Saraswathi Narayanan College, Madurai 625 022, India.
Ammavasi
A
Gubendran
Chemistry Research Centre, Mohamed Sathak Engineering College, Kilakarai 623 806, Tamilnadu, India.
Mookkandi Palsamy
MP
Kesavan
Chemistry Research Centre, Mohamed Sathak Engineering College, Kilakarai 623 806, Tamilnadu, India.
Srinivasan
S
Ayyanaar
Department of Physics and Chemistry, University of Pitesti, Pitesti 110040, Romania.
Liviu
L
Mitu
Department of Inorganic Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai 625 021, India.
Periyakaruppan
P
Athappan
Department of Inorganic Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai 625 021, India; Chemistry Research Centre, Mohamed Sathak Engineering College, Kilakarai 623 806, Tamilnadu, India. Electronic address: mkuraji@gmail.com.
Jegathalaprathaban
J
Rajesh
D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D053837:DNA Cleavage; D003851:Deoxyribonucleases / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D012545:Schiff Bases / Q000737:chemistry / Q000378:metabolism
D012545:Schiff Bases; D004247:DNA; D003851:Deoxyribonucleases
CD spectra; DNA cleavage; DNA interaction; Non-enolisable Knoevenagel condensate; Schiff base complexes