Using ancillary ligands to tune the DNA binding properties of self-assembled luminescent metallomacrocycles.

The optical response, binding parameters, and duplex DNA binding mode of water-soluble kinetically inert tetranuclear metallomacrocycles can all be controlled by judicious selection of ancillary ligands.

Kinetically locked luminescent metallomacrocycles as duplex DNA binding substrates.

A self-assembled, kinetically locked, tetranuclear metallomacrocycle interacts with duplex DNA with an affinity that is several orders of magnitude higher than its mononuclear building blocks, producing large-scale bending of the duplex structure.

Synthesis, structure, magnetism, and spectroscopic properties of heterobinuclear copper(II)-zinc(II) complexes and their copper(II)-copper(II) analogues in asymmetric ligand environments.

Heterobinuclear copper(II)-zinc(II) complexes and their homobinuclear dicopper(II) counterparts (1-4) of two asymmetric ligands (H2L1 and H2L2), based on 2-aminocyclopent-1-ene-1-dithiocarboxylate, are reported. The ligands are capable of providing both donor set and coordination number asymmetry in tandem. Metal centers in these complexes are connected by a micro-alkoxo and a bridging pyrazolate moiety, as confirmed by X-ray structure analyses of 1, 3, and 4.

Equilibrium studies in solution involving nickel(II) complexes of flexidentate Schiff base ligands: isolation and structural characterization of the planar red and octahedral green species involved in the equilibrium.

Three new flexidentate 5-substituted salicylaldimino Schiff base ligands (L1-OH-L3-OH) based on 1-(2-aminoethyl)piperazine (X=H, L1-OH; X=NO2, L2-OH; and X=Br, L3-OH) and their nickel(II) complexes (1a, 1b, 2, and 3) have been reported. The piperazinyl arm of these ligands can in principle have both boat and chair conformations that allow the ligands to bind the Ni(II) center in an ambidentate manner, forming square-planar and/or octahedral complexes. The nature of substitution in the salicylaldehyde aromatic ring and the type of associated anion in the complexes have profound influences on the coordination geometry of the isolated products.

Mixed-spin binuclear nickel(II) complexes in unsymmetrical ligand environments and related mononuclear compounds: electronic and molecular structures in solution and in the solid state.

Nickel(II) complexes of three new heterodonor ligands (HL(1), H(2)L(2), and H(3)L(3)) based on 2-aminocyclopent-1-ene-1-dithiocarboxylate have been synthesized, and their crystallographic characterizations are reported. With the pentacoordinating ligands HL(1) and H(3)L(3), the products obtained (1 and 2) are both mononuclear square planar compounds in which one of the pyrazolyl arms of ligand HL(1) and the bridgehead alkoxy oxygen of H(3)L(3) are staying away from coordination in 1 and 2, respectively. The saturated three carbon alkanyl chain in the ligand H(3)L(3) provides enough flexibility to generate tetrahedral distortion (dihedral angle, 22.

Oxovanadium(IV) and -(V) complexes of dithiocarbazate-based tridentate Schiff base ligands: syntheses, structure, and photochemical reactivity of compounds involving imidazole derivatives as coligands.

The tridentate dithiocarbazate-based Schiff base ligands H(2)L (S-methyl-3-((5-R-2-hydroxyphenyl)methyl)dithiocarbazate, R = NO(2), L = L(2); R = Br, L = L(3)) react with [VO(acac)(2)] in the presence of imidazole derivatives as coligands to form oxovanadium(IV) and cis-dioxovanadium(V) complexes. With benzimidazole and N-methylimidazole, the products are oxovanadium(IV) complexes, viz. [VOL(3)(BzIm)].

Oxovanadium(V) and cobalt(III) complexes of dithiocarbazate-based Schiff base ligands: formation of a thiadiazole ring by vanadium-induced cyclization of the coordinated ligand.

S-Methyl 3-((2-hydroxyphenyl)methyl)dithiocarbazate (H(2)L(1)) and its bromo derivative (H(2)L(2)), which are traditionally biprotic tridentate (ONS) ligands, behave in an unprecedented manner when allowed to react with [VO(acac)(2)] under an oxidative environment in acetonitrile-water medium containing a catalytic amount of alkali metal ion. The products obtained are oxovanadium(V) compounds [VOL(L(cyclic))] (L = L(1), 1a, and L(2), 1b) that contain one molecule of ligand which undergoes metal-induced cyclization to form a thiadiazole ring. Compound 1a crystallizes in the triclinic space group P(-)1 with a = 9.