DNA Interaction Studies of a New Platinum(II) Complex Containing Different Aromatic Dinitrogen Ligands

A new mononuclear Pt(II) complex, [Pt(DMP)(DIP)]Cl2.H2O, in which DMP is 4,4-dimethyl-2,2-bipyridine and DIP is 4,7-diphenyl-1,10-phenantroline, has been synthesized and characterized by physicochemical and spectroscopic methods. The binding interaction of this complex with calf thymus DNA (CT-DNA) was investigated using fluorimetry, spectrophotometry, circular dichroism, viscosimetry and cyclic voltametry (CV). UV-VIS spectrum showed 4 nm bathochromic shift of the absorption band at 280 nm along with significant hypochromicity for the absorption band of the complex. The intrnisic binding constant (Kb = 2 × 104 M−1) is more in keeping with intercalators and suggests this binding mode. The viscosity measurements showed that the complex-DNA interaction can be hydrophobic and confirm intercalation. Moreover, the complex induced detectable changes in the CD spectrum of CT-DNA. The fluorescence studies revealed that the probable quenching mechanism of fluorescence of the complex by CT-DNA is static quenching. The thermodynamic parameters (ΔH > 0 and ΔS > 0) showed that main interaction with hydrogenic forces occurred that is intercalation mode. Also, CV results confirm this mode because, with increasing the CT-DNA concentration, shift to higher potential was observed

(6,6′-Dimethyl-2,2′-bipyridine-κ2 N,N′)diiodidomercury(II)

In the title complex, [HgI2(C12H12N2)], the HgII atom has a distorted tetra­hedral coordination formed by two N atoms of the 6,6′-dimethyl-2,2′-bipyridine ligand and two terminal I atoms [N—Hg—N = 70.1 (2) and I—Hg—I = 130.59 (3)°]. The crystal packing features π–π contacts between the pyridine rings of adjacent mol­ecules [centroid–centroid distance = 3.773 (5) Å] and also between a pyridine ring of one mol­ecule and the five-membered chelate ring of an adjacent mol­ecule [centroid–centroid distance = 3.668 (4) Å]

(6,6′-Dimethyl-2,2′-bipyridine-κ2 N,N′)diiodidozinc(II)

The complete mol­ecule of the title compound, [ZnI2(C12H12N2)], is generated by crystallograpic twofold symmetry, with the ZnII atom lying on the rotation axis. The ZnII atom is coordinated by the N,N-bidentate 6,6′-dimethyl-2,2′-bipyridine ligand and two iodide ions, resulting in a distorted ZnN2I2 tetra­hedral geometry for the metal. In the crystal, there are weak π–π contacts between the pyridine rings [centroid–centroid distance = 3.978 (3) Å]

Dibromido(6,6′-dimethyl-2,2′-bipyridine-κ2 N,N′)zinc(II)

In the title compound, [ZnBr2(C12H12N2)], the ZnII atom is four-coordinated in a distorted tetra­hedral arrangement by an N,N′-bidentate 6,6′-dimethyl-2,2′-bipyridine ligand and two bromide ions. In the crystal, there are aromatic π–π contacts between the pyridine rings [centroid–centroid distances = 3.818 (3) and 3.728 (4) Å]

Tetra­kis(6-methyl-2,2′-bipyridine)-1κ2 N,N′;2κ2 N,N′;3κ2 N,N′;4κ2 N,N′-tetra-μ-nitrato-1:2κ2 O:O′;2:3κ3 O:O′,O′′;2:3κ3 O,O′:O′′;3:4κ2 O:O′-tetra­nitrato-1κ4 O,O′;4κ2 O,O′-tetra­lead(II)

In the tetranuclear centrosymmetric title compound, [Pb4(NO3)8(C11H10N2)4], irregular PbN2O5 and PbN2O4 coordination polyhedra occur. The hepta­coordinated lead(II) ion is bonded to two bidentate and one monodentate nitrate ion and one bidentate 6-methyl-2,2′-bipyridine (mbpy) ligand. The six-coordinate lead(II) ion is bonded to one bidentate and two monodentate nitrate anions and one mbpy ligand. In the crystal, bridging nitrate anions lead to infinite chains propagating in [111]. A number of C—H⋯O hydrogen bonds may stabilize the structure

Dichlorido(6,6′-dimethyl-2,2′-bipyridine-κ2 N,N′)zinc(II)

In the title compound, [ZnCl2(C12H12N2)], the complete mol­ecule is generated by crystallographic mirror symmetry, with the Zn atom and both chloride ions lying on the reflecting plane, yielding a distorted ZnN2Cl2 tetra­hedral coordination for the metal ion. In the crystal, there are π–π contacts between the pyridine rings [centroid–centroid distance = 3.7857 (17) Å]

(2,9-Dimethyl-4,7-diphenyl-1,10-phen­anthroline-κ2 N,N′)bis­(thio­cyanato-κS)mercury(II)

In the mol­ecule of the title compound, [Hg(NCS)2(C26H20N2)], the HgII atom is four-coordinated in a distorted tetra­hedral configuration by two N atoms from a chelating 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline ligand and by two S atoms from two thio­cyanate anions. The ligand ring system is not planar. The dihedral angle between the phenyl rings is 53.20 (3)° . In the crystal structure, π–π contacts between phenanthroline rings [centroid–centroid distance = 3.981 (1) Å] may stabilize the structure

5,5′-Dimethyl-2,2′-bipyridine

The asymmetric unit of the title compound, C12H12N2, contains two half-mol­ecules related by an inversion center, the planes of their pyridine rings being oriented at a dihedral angle of 69.62 (4)°. In the crystal structure, a π–π contact between the pyridine rings [centroid–centroid distance = 3.895 (3) Å] may stabilize the structure. A weak C—H⋯π inter­action is also found

Dichlorido(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline-κ2 N,N′)mercury(II) acetonitrile hemisolvate

The asymmetric unit of the title compound, [HgCl2(C26H20N2)]·0.5CH3CN, contains two crystallographic­ally independent [HgCl2(C26H20N2)] mol­ecules and one acetonitrile solvent mol­ecule. The HgII atoms are four-coordin­ated in distorted tetra­hedral configurations by two N atoms from 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline ligands and two Cl atoms. The ligand ring systems are not planar. The phenyl rings are oriented at dihedral angles of 74.61 (3) and 66.00 (3)° in the two molecules. In the crystal structure, π–π contacts between phenanthroline rings [centroid–centroid distances = 3.809 (1), 3.686 (1), 3.986 (1), 3.877 (1), 3.697 (1), 3.789 (1), 3.745 (1), 3.797 (1) and 3.638 (1) Å] may stabilize the structure

Dibromido(4,4′-dimethyl-2,2′-bipyridine-κ2 N,N′)zinc(II)

The asymmetric unit of the title compound, [ZnBr2(C12H12N2)], contains two half-mol­ecules; both are completed by crystallographic twofold axes running through the ZnII atoms which are coordinated by an N,N′-bidentate 4,4′-dimethyl-2,2′-bipyridine ligand and two Br− ions, resulting in distorted ZnN2Br2 tetra­hedral coordination geometries. In the crystal, C—H⋯Br inter­actions link the mol­ecules