Synthesis and characterization of bis(di-2-pyridylmethanamine)ruthenium(II)

The complex Ru(dipa)(2)(2+) (dipa = di-2-pyridylmethanamine) has been prepared, yielding approximately a statistical ratio of the meso and rac isomers. The electronic spectra of both isomers show pyridyl pi --> pi transitions in the UV region and MLCT bands in the visible region. The solvent dependence of the spectra provides evidence of hydrogen bond formation between the solvent and the NH(2) site on the ligand. The electrochemical properties of the two isomers are identical; each undergoes a reversible one-electron oxidation in acetonitrile (E(1/2) = 0.933 V vs Ag/AgCl) and in aqueous solution below pH 3 (E(1/2) = 0.786 V vs Ag/AgCl). In aqueous solution above pH 3, one-electron oxidation of the ruthenium center is followed by deprotonation of the ligand NH(2) site yielding a reactive amidoruthenium(III) species. The ruthenium-bound dipa ligand possesses structural constraints that prevent the usual oxidative dehydrogenation reaction, which would yield exclusively the corresponding imine. Instead the amidoruthenium(III) intermediate finds alternative reaction routes leading to multiple products.     

A trinuclear copper(II) complex of 2,4,6-tris(di-2-pyridylamine)-1,3,5-triazine shows prominent DNA cleavage activity

A highly water soluble 3:2 complex of copper(II) and 2,4,6-tris(di-2-pyridylamine)-1,3,5-triazine (TDAT) has been synthesized and structurally characterized. The complex crystallized in a triclinic P1 space group with a molecular formula of [Cu3(TDAT)2Cl3]Cl3.2H2O (1), where each copper ion is coordinated by four pyridine nitrogen atoms and an apical chloride. The trinuclear complex is stable at physiological relevant conditions. It can bind to DNA through electrostatic attraction and cleave efficiently the supercoiled pBR322 DNA into its nicked and linear forms at micromolar concentrations. Active oxygen intermediates such as hydroxyl radicals and singlet oxygen generated in the presence of 1 may act as active species for the DNA scission.     

Coordination geometry in bis(di-2-pyridylamine)copper(II) complexes. Crystal structures and spectroscopic properties of [Cu(L)2(NCS)2][Cu(L)2(NCS)]X,X= , I−

The crystal structures of [Cu(dpyam)₂(NCS)₂][Cu(dpyam)₂(NCS)](BF₄) (1) and [Cu(dpyam)₂(NCS)_1.14I_0.86][Cu(dpyam)₂(NCS)_0.77I_0.23]I (2) (dpyam?=?di-2-pyridylamine) have been determined by single-crystal X-ray methods. Species 1 and 2 consist of two crystallographically independent Cu-bearing complexes, one being centrosymmetric and octahedrally elongated, and the other close to square pyramidal. The structures of both complexes and their EPR and electronic reflectance spectra are discussed and compared with those of related complexes.     

Synthesis and X-ray crystal structures of three copper(II) complexes of 1,4- bis (di-2-pyridylmethyl)phthalazine

The synthesis and X-ray crystal structures of three discrete copper(II) complexes of 1,4-bis(di-2-pyridylmethyl)phthalazine (L) are reported. The complexes 1–3 have Cu₂L, Cu₃L and Cu₂L₂ composition and display interesting relationships to previously reported complexes of this ligand.