An insight into the morphology of DNA compaction induced by homobinuclear Ru(II) polypyridyl complexes.

Binuclear Ru(II) polypyridyl complexes [Ru(NN)(BIPMB)] (1-4), where N-N = 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), dipyrido [3,2-d:2',3'-f] quinoxaline (dpq), and dipyrido[3,2-a:2',3'-c]phenazine (dppz), have been synthesized using suitable precursors and bridging ligand (BIPMB), where BIPMB = 3,3'-bis-{(imidazol-1-yl)-[4,5-f]-1,10-phenanthroline) methyl}-1,1'-biphenyl. The binding mode and affinity of complexes 1-4 with Calf Thymus DNA (CT-DNA) were determined by absorption and steady-state fluorescence spectroscopy. The decrease in viscosity of CT-DNA on sequential addition of these complexes indicated DNA condensation and the result was corroborated by circular dichroism (CD).

Heterostructural CuO-ZnO Nanocomposites: A Highly Selective Chemical and Electrochemical NO Sensor.

A simple one-step chemical method is employed for the successful synthesis of CuO(50%)-ZnO(50%) nanocomposites (NCs) and investigation of their gas sensing properties. The X-ray diffraction studies revealed that these CuO-ZnO NCs display a hexagonal wurtzite-type crystal structure. The average width of 50-100 nm and length of 200-600 nm of the NCs were confirmed by transmission electron microscopic images, and the 1:1 proportion of Cu and Zn composition was confirmed by energy-dispersive spectra, i.

Tris-heteroleptic ruthenium(II) polypyridyl complexes: Synthesis, structural characterization, photophysical, electrochemistry and biological properties.

Three water-soluble tris-heteroleptic ruthenium(II) polypyridyl complexes [Ru(bpy)(phen)(bpg)] (1), [Ru(bpy)(dppz)(bpg)] (2), and [Ru(phen)(dppz)(bpg)] (3) (where bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, dppz = dipyrido[3,2-a:2',3'-c] phenazine, bpg = 4b,5,7,7a-tetrahydro-4b,7a-epiminomethanoimino-6H-imidazo[4,5-f] [1,10] phenanthroline-6,13-dione) have been synthesized and characterized. Molecular structures of complexes 1 and 3 are confirmed by single crystal X-ray structure determination. Interaction of complexes 1-3 with DNA is explored by various spectroscopic techniques.

Photochemical hydrogen evolution from water by a 1D-network of octahedral NiL cages.

A self-assembled M6L8 type cage-connected 1D-coordination network of formula {[Ni6(MeSi(3py)3)8Cl9(H2O)2]Cl3·16H2O}∞ (1) was obtained from a 3-pyridyl substituted silane ligand MeSi(3py)3. This complex shows significantly high performance for the electrocatalytic and photocatalytic hydrogen evolution reaction (HER) in water. A maximum turnover number (TON) of 2824 has been observed for photocatalytic HER after 69 h.

Coordination polymers of Cd and Pb derived from bipyridine-glycoluril: influence of metal-ion size and counter-ions.

Two new one-dimensional (1D) coordination polymers (CPs), namely catena-poly[[[aquacadmium(II)]-bis(μ-4b,5,7,7a-tetrahydro-4b,7a-epiminomethanoimino-6H-imidazo[4,5-f][1,10]phenanthroline-6,13-dione)] bis(perchlorate) dihydrate], {[Cd(CHNO)(HO)](ClO)·2HO} or {[Cd(BPG)(HO)](ClO)·2HO}, 1, and catena-poly[[lead(II)-bis(μ-4b,5,7,7a-tetrahydro-4b,7a-epiminomethanoimino-6H-imidazo[4,5-f][1,10]phenanthroline-6,13-dione)] bis(perchlorate) dihydrate], {[Pb(CHNO)](ClO)·2HO} or {[Pb(BPG)](ClO)·2HO}, 2, have been synthesized using bipyridine-glycoluril (BPG; systematic name: 4b,5,7,7a-tetrahydro-4b,7a-epiminomethanoimino-6H-imidazo[4,5-f][1,10]phenanthroline-6,13-dione), a urea-fused tecton, in a mixed-solvent system. The Cd ion in 1 is heptacoordinated and the Pb ion in 2 is hexacoordinated, with the Cd ion adopting a pentagonal bipyramidal geometry and the Pb ion adopting a distorted octahedral geometry. Both CPs form infinite linear chain structures which are hydrogen bonded to each other leading to the formation of three-dimensional supramolecular network structures.

A copper(ii)-coordination polymer based on a sulfonic-carboxylic ligand exhibits high water-facilitated proton conductivity.

Proton conduction ability has been investigated in a new Cu(ii) based coordination polymer (CP), {[Cu(sba)(bpg)(HO)]·5HO} (1), synthesized using the combination of 4-sulfobenzoic acid (4-Hsba) and bipyridine-glycoluril (BPG) ligands. Single crystal X-ray structure determination revealed that 1 features 1D porous channels encapsulating a continuous array of water molecules. Proton conductivity measurements reveal a high conductivity value of 0.

Acetylcholinesterase and Aβ Aggregation Inhibition by Heterometallic Ruthenium(II)-Platinum(II) Polypyridyl Complexes.

Two heteronuclear ruthenium(II)-platinum(II) complexes [Ru(bpy)(BPIMBp)PtCl] (3) and [Ru(phen)(BPIMBp)PtCl] (4), where bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, and BPIMBp = 1,4'-bis[(2-pyridin-2-yl)-1H-imidazol-1-ylmethyl]-1,1'-biphenyl, have been designed and synthesized from their mononuclear precursors [Ru(bpy)(BPIMBp)] (1) and [Ru(phen)(BPIMBp)] (2) as multitarget molecules for Alzheimer's disease (AD). The inclusion of the cis-PtCl moiety facilitates the covalent interaction of Ru(II) polypyridyl complexes with amyloid β (Aβ) peptide. These multifunctional complexes act as inhibitors of acetylcholinesterase (AChE), Aβ aggregation, and Cu-induced oxidative stress and protect neuronal cells against Aβ-toxicity.

Excited State Interaction of Ruthenium (II) Imidazole Phenanthroline Complex [Ru(bpy) ipH] with 1,4-Benzoquinone: Simple Electron Transfer or Proton-Coupled Electron Transfer?

The unidirectional proton coupled electron transfer (PCET) from the excited state of Ru(II) imidazole phenanthroline complex [Ru(bpy) ipH] to 1,4-benzoquinone, was studied by steady-state (SS) and time-resolved (TR) fluorescence and transient absorption (TA) measurements. The pK (9.7) and pK * (8.

Light-driven Hydrogen Evolution from Water by a Tripodal Silane Based CoL Octahedral Cage.

The octahedral cage assembly [CoLCl(HO)]Cl has been synthesized in a single-step reaction by using a polypyridyl-functionalized tripodal silane ligand. The electrochemical behavior of the cage in water exhibits the pH dependence of potential as well as catalytic current indicating the possible involvement of proton-coupled electron transfer in H evolution. Electrocatalytic hydrogen evolution from an aqueous buffered solution gave a turnover frequency of 16 h.

Proton conduction in a hydrogen-bonded complex of copper(ii)-bipyridine glycoluril nitrate.

Bipyridine glycoluril (BPG), a urea-fused bipyridine tecton, forms a square-pyramidal secondary building unit with copper(ii) which further self-assembles to give a porous hydrogen-bonded complex. This complex displays a high proton conductivity of 4.45 × 10 S cm at 90 °C and 95% relative humidity (RH).

Honeycomb-like Ordered Assembly of DNA Induced by Flexible Binuclear Ruthenium(II)-Polypyridyl Complexes.

A series of binuclear ruthenium(II)-polypyridyl complexes of the type [Ru (N-N) (BPIMBp)] , in which N-N is 2,2'-bipyridine (bpy; 1), 1,10-phenanthroline (phen; 2), dipyrido[3,2-d:2',3-f] quinoxaline (dpq; 3), dipyrido[3,2-a:2',3'-c] phenanzine (dppz; 4), and 1,4'-bis[(2-pyridin-2-yl)-1H-imidazol-1-yl)methyl]-1,1'-biphenyl (BPIMBp) is a bridging ligand, have been synthesized and characterized. These complexes are charged (4+) cations and flexible due to the -CH group of the bridging ligand and possess terminal ligands with variable intercalative abilities. The interaction of complexes 1-4 with calf thymus DNA (CT-DNA) was explored by using UV/Vis absorption spectroscopy, steady-state emission, emission quenching with K [Fe(CN) ], ethidium bromide displacement assay, Hoechst displacement assay, and viscosity measurements and revealed a groove-binding mode for all the complexes through a spacer and an intercalative mode for complexes 3 and 4.

Ruthenium(II) polypyridyl complexes with hydrophobic ancillary ligand as Aβ aggregation inhibitors.

The synthesis, spectral and electrochemical characterization of the complexes of the type [Ru(NN)2(txbg)](2+) where NN is 2,2'-bipyridine (bpy) (1), 1,10-phenanthroline (phen) (2), dipyrido [3,2-d:2',3f] quinoxaline (dpq) (3), and dipyrido[3,2-a:2',3'-c]phenazine (dppz) (4) which incorporate the tetra-xylene bipyridine glycoluril (txbg) as the ancillary ligand are described in detail. Crystal structures of ligand txbg and complex 2 were solved by single crystal X-ray diffraction. Thioflavin T (ThT) fluorescence and Transmission Electron Microscopy (TEM) results indicated that at micromolar concentration all complexes exhibit significant potential of Aβ aggregation inhibition, while the ligand txbg displayed weak activity towards Aβ aggregation.

Antiproliferative activity of ruthenium(ii) arene complexes with mono- and bidentate pyridine-based ligands.

A series of Ru(II) arene complexes of mono- and bidentate N-donor ligands with carboxyl or ester groups and chlorido ancillary ligands were synthesised and structurally characterised. The complexes have a distorted tetrahedral piano-stool geometry. The binding interaction was studied with calf thymus DNA (CT-DNA) by absorption titration, viscosity measurement, thermal melting, circular dichroism, ethidium bromide displacement assay and DNA cleavage of plasmid DNA (pBR322), investigated by gel electrophoresis.

Copper(ii) mixed-ligand polypyridyl complexes with doxycycline - structures and biological evaluation.

Mixed-ligand Cu(ii) complexes of the type [Cu(doxycycline)(L)(H2O)2](NO3)2, where doxycycline = [4-(dimethylamino)-3,5,10,12,12a-pentahydroxy-6-methyl-1,11-dioxo-1,4,4a,5,5a,6,11,12a-octahydrotetracene-2-carboxamide] and L = 2,2'-bipyridine (bpy, 1), 1,10-phenanthroline (phen, 2), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 3) and dipyrido[3,2-a:2',3'-c]phenazine (dppz, 4) have been synthesised and characterised by structural, analytical, and spectral methods. The single-crystal X-ray structures of 1 and 2 exhibited two different geometries, distorted square-pyramidal and octahedral respectively as well as different coordination modes of doxycycline. Complexes 2-4 exhibit prominent plasmid DNA cleavage at significantly low concentrations probably by an oxidative mechanism.

Ruthenium(II) polypyridyl complex as inhibitor of acetylcholinesterase and Aβ aggregation.

Two ruthenium(II) polypyridyl complexes [Ru(phen)3](2+) (1) and [Ru(phen)2(bxbg)](2+) (2) (where phen = 1,10 phenanthroline, bxbg = bis(o-xylene)bipyridine glycoluril) have been evaluated for acetylcholinesterase (AChE) and Amyloid-β peptide (Aβ) aggregation inhibition. Complex 2 exhibits higher potency of AChE inhibition and kinetics and molecular modeling studies indicate that ancillary ligand plays significant role in inhibitory potency exhibited by complex 2. The inhibitory effect of these complexes on Aβ (1-40) aggregation is investigated using Thioflavin T fluorescence and Transmission Electron Microscopy.

Efficient DNA condensation induced by ruthenium(II) complexes of a bipyridine-functionalized molecular clip ligand.

Complexes of the type [Ru(bxbg)(2) (N-N)](2+), where N-N denotes 2,2'-bipyridine (bpy) (1), 1,10-phenanthroline (phen) (2), dipyrido[3,2-d:2',3-f] quinoxaline (dpq) (3), and dipyrido[3,2-a:2',3'-c]phenazine (dppz) (4), incorporating bis(o-xylene)bipyridine-glycoluril (bxbg) as an ancillary "molecular clip" ligand, have been synthesized and characterized. These ruthenium(II) complexes of bis(o-xylene)bipyridine-glycoluril self-associate in water through specific molecular recognition processes to form polycationic arrays. These arrays containing electrostatic binders as well as intercalator ligands at micromolar doses rapidly condense free DNA into globular nanoparticles of various sizes.

Ruthenium(II) polypyridyl complexes as carriers for DNA delivery.

Two novel water soluble ruthenium(II) complexes [Ru(bpy)(2)(bqbg)](2+) and [Ru(phen)(2)(bqbg)](2+) have been structurally characterized and their DNA condensation activity, cytotoxicity, and cellular uptake studies of DNA condensates as potential non-viral DNA carriers were evaluated.

Mixed ligand cobalt(II) picolinate complexes: synthesis, characterization, DNA binding and photocleavage.

Complexes of the type [Co(pic)(2)(NN)], where pic = picolinate, NN = dipyrido[3,2-d:2',3'-f]quinoxaline (dpq) (4) and 4b,5,7,7a-tetrahydro-4b,7a-epiminomethanoimino-6H-imidazo[4,5-f][1,10]-phenanthroline-6,13-dione (bipyridyl-glycoluril) (bpg) (6) have been synthesized and characterized by elemental analysis, IR, UV-vis, NMR and ESI-MS spectroscopy and thermogravimetic analysis (TGA). Their physicochemical properties are compared with previously synthesized complexes, where NN = (H(2)O)(2) (1), 2,2'-bipyridine (bpy) (2), 1,10-phenanthroline (phen) (3) and dipyrido[3,2-a:2',3'-c]phenazine (dppz) (5). The crystal structures of the complexes 4-6 were solved by single-crystal X-ray diffraction.

Stabilization of acyclic water tetramer in a copper(II) malonate framework structure.

Copper(II) complex [Cu(dpq)(mal)(H(2)O)]·3H(2)O (1) (dpq = dipyrido-[3,2-d:2',3'-f]-quinoxaline, mal = malonato) was synthesized and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis and single-crystal X-ray crystallography. The single-crystal X-ray structure of 1 reveals a square pyramidal structure, with the dipyrido-[3,2-d:2',3'-f]-quinoxaline and malonato at the equatorial positions and a water molecule at the axial position. The molecule acts as a building block generating a supramolecular three-dimensional metal-organic framework (MOF) encapsulating metal linked acyclic water tetramer.

Bis(maltolato)vanadium(III)-polypyridyl complexes: synthesis, characterization, DNA cleavage, and insulin mimetic activity.

Four vanadium(III) complexes of the general formula [V(maltol)(2)(N-N)]ClO(4), where N-N is 2,2'-bipyridine (bpy) (1); 1,10-phenanthroline (phen) (2); dipyrido[3,2-d:2',3'-f]quinoxaline (dpq) (3), and dipyrido[3,2-a:2',3'-c]phenazine (dppz) (4), have been synthesized and characterized by IR, UV-visible, NMR spectroscopies, and electrospray ionization mass spectra (ESI-MS). The complexes exhibit the typical (1)H NMR spectra for paramagnetic V(III) species. The structures of complexes 1, 2, and 3 were characterized by single crystal X-ray diffraction.

Synthesis, characterization and pulse radiolysis of cobalt(II) complexes of 2-picolinate and polypyridyl ligands.

Complexes of the type [Co(pic)(2)(LL)], where pic = picolinate; LL = (H(2)O)(2) (1), 2,2'-bipyridine (bpy) (2), 1,10-phenanthroline (phen) (3) and dipyrido[3,2-a:2',3'-c]phenazine (dppz) (4) have been synthesized and characterized by elemental analysis, IR, UV-visible and (1)H-NMR spectroscopy. Complex 2 crystallized from a mixture of chloroform and methanol in orthorhombic crystal system, space group Iba2. Complex 3 crystallizes from chloroform in monoclinic crystal system, space group P12(1)/a1 and in a mixture of water and methanol in triclinic crystal system, space group P1.

Self-association of ruthenium(II) polypyridyl complexes and their interactions with calf thymus DNA.

Complexes of the type [Ru(N-N)(2)(bxbg)]Cl(2) where N-N is 2,2'-bipyridine (bpy) (1), 1,10-phenanthroline (phen) (2), dipyrido [3,2-d:2',3f] quinoxaline (dpq) (3), and dipyrido[3,2-a:2',3'-c]phenazine (dppz) (4) which incorporate the bis(o-xylene)bipyridine glycoluril (bxbg) as the ancillary ligand have been synthesized and characterized by IR, NMR, UV-visible, luminescence, ESI-MS, cyclic voltammetry, and spectroelectrochemistry. The bis(o-xylene)bipyridine glycoluril initiates a head to head association which act as the nucleation point for the further growth in two direction by head-to-head and tail-to-tail self-association resulting in formation of aggregates in water which have been investigated by (1)H NMR, NOESY, steady state luminescence dilution experiments, and electron microscopy studies. The self-association has been confirmed by single crystal X-ray analysis of complex 2.

Ruthenium(II) complexes of bipyridine-glycoluril and their interactions with DNA.

Nine complexes of the type [Ru(N-N)(2)(BPG)]Cl(2) 1-4, [Ru(N-N)(BPG)(2)]Cl(2) 5-8, and [Ru(BPG)(3)]Cl(2) 9 where N-N is 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq), dipyrido[3,2-a:2',3'-c]phenazine (dppz), which incorporates bipyridine-glycoluril (BPG-4b,5,7,7a-tetrahydro-4b,7a-epiminomethanoimino-6H-imidazo[4,5-f][1,10]phenanthroline-6,13-dione) as the ancillary ligand, have been synthesized and characterized. These complexes with the peripheral polypyridyl ligands have the ability to form conjugates with DNA. The DNA binding (absorption spectroscopy, steady-state and time-resolved emission measurements, steady-state emission quenching measurements) and cleavage (under dark and irradiated conditions) by these complexes has been studied to investigate the influence of the ancillary ligand.

An unexpected metal-promoted transformation yields an anthrylmethyl spiroanthracene.

The isolation and characterization of an unusual spiroanthracene, from the reaction of bisdichlororuthenium(II)bipyridine dihydrate with 3-(9-anthrylmethyl)pentane-2,4-dione (AMPD), is reported. This metal-promoted formation of spiroanthracene has been obtained for the first time during the synthesis of metal complexes.