title: Synthesis, crystal structure, magnetic property and oxidative DNA cleavage activity of an octanuclear copper(II) complex showing water-perchlorate helical network.
abstract: A new octanuclear copper(II) complex has been synthesized and structurally characterized by X-ray crystallography: [Cu(8)(HL)(4)(OH)(4)(H(2)O)(2)(ClO(4))(2)].(ClO(4))(2).2H(2)O (1) (H(3)L=2,6-bis(hydroxyethyliminoethyl)-4-methyl phenol). The complex is formed by the linkage of two terminal bimetallic cationic units and a tetranuclear mu(3)-hydroxo bridged dicubane core by a very short intramolecular hydrogen bond (O-H...O, 1.48(3)A and the angle 175 degrees). The coordination sphere of the terminal copper atoms is square pyramidal, the apical positions being occupied by water and a perchlorate ion. Complex 1 self-assembles to form a new type of water-perchlorate helical network [(H(2)O)(2)(ClO(4))](infinity) involving oxygen atoms of coordinated perchlorate ion and the two lattice water molecules through hydrogen-bonding interaction. The variable temperature-dependent susceptibility measurement (2-300K) of 1 reveals a strong antiferromagnetic coupling, J(1)=-220cm(-1) and J(2)=-98cm(-1) (J(1) and J(2) representing the exchange constant within [Cu(2+)](4) and [Cu(2+)](2) units, respectively). The complex binds to double-stranded supercoiled plasmid DNA giving a K(app) value of 1.2x10(7)M(-1) and displays efficient oxidative cleavage of supercoiled DNA in the presence of H(2)O(2) following a hydroxyl radical pathway.
authors.affiliation: Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, 2A, 2B Raja Subodh Mullick Road, Jadavpur, Kolkata, West Bengal 700 032, India.
authors.forename: Koushik
authors.initials: K
authors.lastname: Dhara
authors.forename: Jagnyeswar
authors.initials: J
authors.lastname: Ratha
authors.forename: Mario
authors.initials: M
authors.lastname: Manassero
authors.forename: Xin-Yi
authors.initials: XY
authors.lastname: Wang
authors.forename: Song
authors.initials: S
authors.lastname: Gao
authors.forename: Pradyot
authors.initials: P
authors.lastname: Banerjee
mesh_terms: D003300:Copper / Q000737:chemistry* / Q000494:pharmacology*; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry*; D006860:Hydrogen Bonding; D006868:Hydrolysis; D008280:Magnetics; D008958:Models, Molecular; D015394:Molecular Structure; D010472:Perchlorates / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D010472:Perchlorates; D014867:Water; D003300:Copper; D004247:DNA; C494474:perchlorate