Tris(1H-benzimidazol-3-ium-2-ylmeth-yl)amine tris-(2,4,6-trinitro-phenolate) acetonitrile disolvate.

In the cation of the title salt, C(24)H(24)N(7) (3+)·3C(6)H(2)N(3)O(7) (-)·2C(2)H(3)N, the three benzimidazolium ring systems are oriented to each other at dihedral angles of 10.42 (7), 23.98 (7) and 22.17 (7)°. In the crystal, the cation links to the adjacent picrate anions via N-H⋯O hydrogen bonds; one of independent acetonitrile solvent mol-ecules is also linked to the cation via an N-H⋯N hydrogen bond.

Study on synthesis, crystal structure, antioxidant and DNA-binding of mono-, di- and poly-nuclear lanthanides complexes with bis(N-salicylidene)-3-oxapentane-1,5-diamine.

A Schiff base ligand bis(N-salicylidene)-3-oxapentane-1,5-diamine H2L have been prepared. Reaction of the shape-specific designed ligand with Ln(NO3)3⋅6H2O afforded three novel complexes, namely, Sm(L)(NO3)(DMF)(H2O) 1, [Eu(H2L)2(NO3)3]n2 and Tb2(L)2(NO3)23. The ligand and complexes were characterized by elemental analysis, UV-Vis, IR, NMR spectroscopy and X-ray crystallography. It is noteworthy that the complexes demonstrate three different types of the structure which changed according to the charge density and acidity of the lanthanide. Complex 1 is a discrete mononuclear species that Sm(III) ion is nine-coordinated in the structure and forming a distorted tricapped trigonal prism geometry. Complex 2 is possessed a 1-D ribbon framework constructed from an extended array of ten-coordinated Eu(3+) centers and the Schiff base ligands. Complex 3 is revealed as a centrosymmetric binuclear neutral entity, in which Tb(III) ion is eight-coordinated with the coordination surround of distorted square antiprism geometry. In order to explore the relationship between the structure and biological properties, the DNA-binding properties have been investigated by electronic absorption, fluorescence, and viscosity measurements. The results suggest that the ligand and complexes bind to DNA via groove modes. The intrinsic binding constants Kb of the complexes 1-3 are (1.19±0.112)×10(5), (4.22±0.086)×10(4) and (3.89±0.104)×10(4) M(-)(1) respectively. Moreover, the antioxidant activity experiments show that these compounds also exhibit good antioxidant activities against OH· and O2(-·) in vitro studies.

The V-shaped ligand bis(N-allylbenzimidazol-2-ylmethyl)benzylamine and its Ag(I) complex: synthesis, crystal structure, DNA-binding properties and antioxidation.

A novel dinuclear Ag(I) complex of the type, [Ag2L2](pic)2, was synthesized by the reaction of the V-shaped ligand bis(N-allylbenzimidazol-2-ylmethyl)benzylamine (L) with Ag(pic) (pic=picrate). Ligand L and Ag(I) complex were characterized on the basis of elemental analysis, UV-vis, IR, NMR spectroscopy and X-ray crystallography. Single-crystal X-ray revealed that two L coordinated to a central silver(I) cation in a near-linear fashion through their benzimidazol-1-yl nitrogen atoms, and a centrosymmetric dinuclear pore canal structure was constructed in the discrete [Ag2L(2)2](2+) cation. The DNA-binding properties of the free ligand L and Ag(I) complex have been carried out by using electronic absorption, fluorescence, and viscosity measurements. The results support that ligand L and Ag(I) complex both bind to DNA via an intercalative binding mode, and the affinity for DNA is more strongly in case of Ag(I) complex when compared with ligand L. Moreover, Ag(I) complex also exhibited potential antioxidant properties in vitro studies.

A seven-coordinated manganese(II) complex with V-shaped ligand bis(N-benzylbenzimidazol-2-ylmethyl)benzylamine: synthesis, structure, DNA-binding properties and antioxidant activities.

A manganese(II) complex of the type, [MnL(pic)(2)]·H(2)O, was obtained by the reaction of the V-shaped ligand bis(N-benzylbenzimidazol-2-ylmethyl)benzylamine (L) with Mn(pic)(2) (pic=picrate). The ligand L and Mn(II) complex were confirmed on the basis of elemental analysis, molarconductivities, (1)H NMR, IR, UV-vis spectra and X-ray crystallography. Single-crystal X-ray revealed that central Mn(II) atom is seven-coordinate with a MnN(3)O(4) environment, in which ligand L acts as a tridentate N-donor. The remaining coordination sites were occupied by four O atoms afforded by two picrate anion. Interaction of the free ligand L and Mn(II) complex with DNA were investigated by spectrophotometric methods and viscosity measurements. The results suggested that both ligand L and Mn(II) complex bind to DNA in an intercalative binding mode, and DNA-binding affinity of the Mn(II) complex is stronger than that of ligand L. Moreover, antioxidant assay in vitro shows the Mn(II) complex possesses significant antioxidant activities.

Synthesis, structure, DNA-binding properties and antioxidant activity of a nickel(II) complex with bis(N-allylbenzimidazol-2-ylmethyl)benzylamine.

A V-shape ligand bis(N-allylbenzimidazol-2-ylmethyl)benzylamine (babb) and its nickel complex, [Ni(babb)(2)](pic)(2) (pic=picrate), have been synthesized and characterized by physico-chemical and spectroscopic methods. Single-crystal X-ray revealed that the coordination sphere around Ni(II) is distorted octahedral with a N(6) ligand set, in which six nitrogen atoms were afforded by two tridentate ligand babb. The DNA-binding properties of the free ligand babb and Ni(II) complex have been investigated by electronic absorption, fluorescence, and viscosity measurements. The results suggest that babb and Ni(II) complex both bind to DNA via an intercalative binding mode, and the affinity for DNA is more strong in case of Ni(II) complex when compared with babb. The intrinsic binding constants (K(b)) of the Ni(II) complex and ligand with DNA were 3.65×10(4) M(-1) and 2.26×10(3) M(-1), respectively. Additionally, Ni(II) complex also exhibited potential antioxidant properties in vitro studies.

Synthesis, structure, DNA-binding properties and antioxidant activity of silver(I) complexes containing V-shaped bis-benzimidazole ligands.

A V-shaped ligand bis(2-benzimidazol-2-ylmethyl)benzylamine L(1) with its two derivatives bis(N-methylbenzimidazol-2-ylmethyl)benzylamine L(2) and bis(N-benzylbenzimidazol-2-ylmethyl)benzylamine L(3) have been prepared. Reaction of these shape-specific designed ligands with Ag(pic) (pic = picrate) afforded three novel complexes, namely, [Ag(2)L(1)(2)](pic)(2)1, [Ag(2)L(2)(2)](pic)(2)·2DMF 2 and [AgL(3)(pic)] 3. The ligands and complexes were characterized on the basis of elemental analysis, UV-Vis, IR, NMR spectroscopy and X-ray crystallography. Complex 1 is a dinuclear metallacycle with a 2-fold rotational symmetry in which two syn-conformational L(1) ligands are connected by two linearly coordinated Ag(I) atoms. Due to the strong interaction between two adjacent Ag(I) atoms, the coordination mode of the central Ag(I) atom can be described as T-shaped. Complex 2 consists of a centrosymmetric dinuclear pore canal structure assembled from two nearly linearly coordinated Ag(I) atoms and two L(2) ligands. The structure of complex 3 adopts a four-coordinate environment for AgN(2)O(2), with the counterion participating in an eight-shaped geometry. In order to explore the relationship between the structure and biological properties, the DNA-binding properties have been investigated by viscosity measurements, electronic absorption, and fluorescence. The results suggest that the ligands and complexes bind to DNA in an intercalation mode, and their binding affinities for DNA are also different. Moreover, the three Ag(I) complexes also exhibited potential antioxidant properties in vitro studies.