Transition metal complexes of novel ligands derived from the cis,cis-1,3,5-triaminocyclohexane (TACH) framework: Structural and biological studies

Transition and Group IIB metal complexes of novel ligands derived from cis,cis-1,3,5-triaminocyclohexane (tach) were prepared for structural and biological activity study. Copper(II) complexes of N,N \u27,N″-trialkylated derivatives of tach [Cu(tach-R3)Cl2] (R = Me, Et, Pr, furanyl, and thiophenyl) were prepared from CuCl2 in MeOH or MeOH/Et2O solvent. The structures of [Cu(tach-R3)Cl2] in the solid and solution (aqueous and methanolic) states were extensively studied by UV-vis and EPR spectroscopies and were consistent to X-ray structure of [Cu(tach-Et 3)Br0.8Cl1.2] which reveals a slightly distorted square-based pyramidal geometry. Displacement of halide ions with water molecules in aqueous media was observed by the band shift to high-energy transition. Catalytic behavior of [Cu(tach-Me3)]2+ in the hydrolysis of activated phosphate diesters in aqueous medium is different from other labile metal complex. Hydrolysis is first-order in phosphate ester and second-order in [Cu(tach-Me3)]2+ suggesting a binuclear complex in which a substrate bridges two Cu(II) ions. Iron-mediated oxidative dehydrogenation of a coordinated ligand was observed in the reactions of Fe(II) and Fe(III) with tachpyr and (+/-)tach(C-Me)3pyr in the presence of O 2 resulting in the formation of a mixture of corresponding mono- and di-imino Fe(II) complexes characterized by 1H NMR, IR, and UV-vis spectroscopies. Further oxidation can be achieved by adding H 2O2 in the case of tachpyr, and by longer exposure of the complex to air, for (+/-)tach(C-Me)3pyr, affording the tris-imino complex. Tachpyr also reveals cytotoxicity toward cancer cells through an iron depletion mechanism. The abilities of tachpyr to complex iron, to reduce intracellular Fe(III) to Fe(II), and to produce hydroxyl radicals is believed to correlate to its cytotoxic effect. First-row transition and Group IIB metal complexes of tachpyr, N,N\u27, N″-tris(2-pyridylmethyl)-cis,cis-1,3,5-triaminocyclohexane, exhibit a metal radius effects on coordination geometry. The tachpyr ligand forms a nearly octahedral complex with the Zn(II) and Ni(II), a tetragonally distorted octahedral complex with Cu(II), an intermediate between octahedron and trigonal prismatic complex with Cd(II), while it forms a nearly trigonal prism complexes with Mn(II) and Hg(II). Tach-Me3pyr, N,N\u27,N″-trimethyl- N,N\u27,N″-tris(2-methylpyridyl)- cis,cis-1,3,5-triaminocyclohexane, forms a distorted octahedral complexes with Ni(II) and Zn(II) while it forms a Jahn-Teller distorted Cu(II) complex. The steric effects of methyl groups govern the coordination of metal complexes of tach-6-Mepyr, N,N\u27,N ″-tris(6-methyl-2-methylpyridyl)-cis,cis-1,3,5-triaminocyclohexane, affording a nearly octahedral geometry with the Zn(II) Ni(II) Co(II) and Mn(II) metal ions, while it forms a distorted trigonal bipyramidal complexes with Cu(II) as a consequence of a twisted pendent arm away from Cu(II) ion

Poly[bis­(N,N-dimethyl­formamide)tris­(μ4-trans-stilbene-4,4′-dicarboxyl­ato)­tricadmium(II)]: a two-dimensional network with an unusual 36 topology

In the title compound, [Cd3(C16H10O4)3(C3H7NO)2]n or [Cd3(SDA)3(DMF)2]n (H2SDA is trans-stilbene-4,4′-dicarboxylic acid and DMF is dimethyl­formamide), the linear dicarboxylate ligand forms a two-dimensionally layered metal–organic network with the relatively uncommon 36 topology. The structure reveals trinuclear secondary building units and has an octa­hedral geometry at a central metal ion (occupying a symmetry site) and tetra­hedral geometries at two surrounding symmetrically equivalent metal ions lying on a threefold axis. The six-connected planar trinuclear CdII centers, Cd3(O2CR)6, play a role as potential nodes in generation of the relatively uncommon 36 topology. The coordinated DMF unit is disordered around the threefold axis

1,3-Bis[(6-methyl-2-pyrid­yl)meth­yl]imidazolium bromide

The title compound, C17H19N4 +·Br−, is built up from 1,3-bis­[(6-methyl-2-pyridin­yl)meth­yl]imidazolium cations and bromide anions. Each of two 6-methyl-2-pyridyl rings is rotated out of the imidazole plane, making dihedral angles of 79.90 (9) and 86.40 (9)°. The packing is consolidated by aromatic π–π inter­actions between the pyridine rings of neighbouring mol­ecules [centroid–centroid distance = 3.554 (2) Å] and by weak C—H⋯N and C—H⋯Br hydrogen bonds

2-Hydr­oxy-3-nitro-N-phenyl­benzamide

The asymmetric unit of the title compound, C13H10N2O4, contains two crystallographically independent mol­ecules. The aromatic rings are oriented at dihedral angles of 24.39 (3) and 7.47 (3)° in the two mol­ecules and intra­molecular N—H⋯O and O—H⋯O hydrogen bonds result in the formation of two planar six-membered rings. In the crystal structure, inter­molecular O—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules into chains, forming R 2 2(10) ring motifs. Weak π–π contacts between the benzene and phenyl rings [centroid–centroid distance = 3.955 (3) Å] may further stabilize the structure

Mutagenicity of Ochratoxin A and Its Hydroquinone Metabolite in the SupF Gene of the Mutation Reporter Plasmid Ps189

Ochratoxin A (OTA) is a mycotoxin that enhances renal tumor formation in the outer medulla of male rat kidney. Direct DNA damage and subsequent mutagenicity may contribute to these processes. In this study we have determined whether OTA in the absence or presence of activated rat liver microsomes (RLM) or redox-active transition metals (Fe(III) or Cu(II)) causes promutagenic DNA damage in the supF gene of the mutation reporter plasmid pS189 replicating in human Ad293 cells. In addition, we have assessed the mutagenicity of the hydroquinone metabolite (OTHQ) of OTA in the absence or presence of cysteine without added cofactors. Our results show that oxidation of OTA, either by RLM or by transition metal ions, activates OTA to a directly genotoxic mutagen(s). The Fe(III)/OTA system was the most potent mutagen in our experimental system, causing a 32-fold increase in mutant fraction (MF) above the spontaneous control MF. The Cu(II)/OTA system caused a 9-fold increase in MF, while a 6–10-fold increase in MF was observed for OTA in the presence of RLM. The OTHQ metabolite is also mutagenic, especially in the presence of cysteine, in which a 6-fold increase in MF was observed. Our data provide further insight into OTA bioactivation that may account for its in vivo mutagenicity in male rat kidney

1,3-Bis(6-methylpyridin-2-yl)-1H-imidazol-3-ium hexafluorophosphate

In the title salt, C17H19N4+·PF6−, the two pyridine rings of the cation are inclined to one another by 15.89 (8)°, and inclined to the imidazole ring by 65.05 (10) and 64.07 (10)°. In the crystal, the cations and anions are linked via a series of C—H...N and C—H...F hydrogen bonds, forming two-dimensional networks lying parallel to (001)

N,N′-Dimethyl-N,N′-bis(pyridin-2-yl)methanediamine

The title compound, C13H16N4, consists of two pyridine rings which are linked by an N,N′-dimethylmethaneamine chain. The pyridine rings adopt a twist conformation and the dihedral angle between them is 60.85 (5)°. The crystal packing is stabilized by weak C—H...π interactions