Mixed-ligand copper(ii)-diimine complexes of 3-formylchromone- -phenyl thiosemicarbazone: 5,6-dmp co-ligand confers enhanced cytotoxicity.

The promising biological applications of thiosemicarbazone derivatives have inspired the design, synthesis, and study of their Cu(ii) complexes for anticancer therapeutic applications. Herein, we have evaluated the DNA/protein binding, DNA cleaving, and cytotoxic properties of four mixed-ligand Cu(ii) complexes of the type [Cu(L)(diimine)](NO) 1-4, where HL is 4-oxo-4-chromene-3-carbaldehyde-4()-phenylthiosemicarbazone and diimine is 2,2'-bipyridine (bpy, 1) 1,10-phenanthroline (phen, 2), 5,6-dimethyl-1,10-phenanthroline (5,6-dmp, 3), or dipyrido-[3,2-:2',3'-]-quinoxaline (dpq, 4). Interestingly, complex 3 with higher lipophilicity shows stronger DNA binding and oxidative DNA cleavage, higher ROS production, and more reversible redox behaviour, resulting in its remarkable cytotoxicity (IC, 1.

Mononuclear nickel(ii)-flavonolate complexes of tetradentate tripodal 4N ligands as structural and functional models for quercetin 2,4-dioxygenase: structures, spectra, redox and dioxygenase activity.

Three new nickel(ii)-flavonolate complexes of the type [Ni(L)(fla)](ClO) 1-3, where L is the tripodal 4N ligand tris(pyrid-2-ylmethyl)amine (tpa, L1) or (pyrid-2-ylmethyl)bis(6-methylpyrid-2-ylmethyl)amine (6-Me-tpa, L2) or tris(-Et-benzimidazol-2-ylmethyl)amine (Et-ntb, L3), have been isolated as functional models for Ni(ii)-containing quercetin 2,4-dioxygenase. Single crystal X-ray structures of 1 and 3 reveal that Ni(ii) is involved in π-back bonding with flavonolate (fla), as evident from enhancement in C[double bond, length as m-dash]O bond length upon coordination [H(fla), 1.232(3); 1, 1.

Mixed ligand copper(II)-diimine complexes of 2-formylpyridine--phenylthiosemicarbazone: diimine co-ligands tune the nanomolar cytotoxicity.

Recently, mixed-ligand copper(II) complexes have received much attention in searching for alternative metallodrugs to cisplatin. A series of mixed ligand Cu(II) complexes of the type [Cu(L)(diimine)](ClO) 1-6, where the HL is 2-formylpyridine--phenylthiosemicarbazone and the diimine is 2,2'-bipyridine (1), 4,4'-dimethyl-2,2'-bipyridine (2), 1,10-phenanthroline (3), 5,6-dimethyl-1,10-phenanathroline (4), 3,4,7,8-tetramethyl-1,10-phenanthroline (5) and dipyrido-[3,2-:2',3'-]quinoxaline (6), has been synthesized and their cytotoxicity in HeLa cervical cancer cells examined. In the molecular structures of 2 and 4, as determined by single-crystal X-ray studies, Cu(II) assumes a trigonal bipyramidal distorted square-based pyramidal (TBDSBP) coordination geometry.

Rapid atmospheric carbon dioxide fixation by nickel(II) complexes: meridionally coordinated diazepane-based 3N ligands facilitate fixation.

Octahedral complexes of the type [Ni(L)(H2O)3](ClO4)2 (1 and 2), where L is the tridentate 3N ligand 4-methyl-1-(pyrid-2-ylmethyl)-1,4-diazacycloheptane (L1, 1), or 4-methyl-1-(N-methylimidazolyl)-1,4-diazacycloheptane (L2, 2), have been isolated and characterized using elemental analysis, ESI-MS and electronic absorption spectroscopy. The DFT optimized structures of 1 and 2 reveal that the tridentate 3N ligands are coordinated meridionally constituting a distorted octahedral coordination geometry around nickel(ii). In methanol solution, the complexes, upon treatment with triethylamine, generate the reactive red colored low-spin square planar Ni-OH intermediate [Ni(L1/L2)(OH)]+ (1a and 2a), as characterized by ESI-MS and electronic absorption spectroscopy, and energy minimized structures.

Octahedral copper(ii)-diimine complexes of triethylenetetramine: effect of stereochemical fluxionality and ligand hydrophobicity on Cu/Cu redox, DNA binding and cleavage, cytotoxicity and apoptosis-inducing ability.

Octahedral copper(ii) complexes of the type [Cu(trien)(diimine)](ClO4)2 (1-4), where trien is triethylenetetramine and diimine is 2,2'-bipyridine (1), 1,10-phenanthroline (2), 5,6-dimethyl-1,10-phenanthroline (3), and 3,4,7,8-tetramethyl-1,10-phenanthroline (4), have been isolated. Single crystal X-ray structures of 1 and 2 reveal that the coordination geometry around Cu(ii) is tetragonally distorted octahedral. The stereochemical fluxionality of the complexes illustrates the observed trend in CuII/CuI redox potentials and DNA binding affinity (Kb: 1, 0.