Phenanthroline Metal Complexes Research Articles

The Interaction of DNA with Phenanthroline and New Phenanthrocyanine Complexes of Zn(II)

The interaction of DNA with complexes of Zn(II) and 1,10-phenanthroline derivatives in aqueous salt solutions has been studied by the optical spectroscopy, fluorescence, and DNA melting methods. Bis-(1,10-phenanthroline)-(1,10-phenanthrocyanine)-dizinc (II) acetate (diZn) and its precursor, bis-(1,10-phenanthroline)-zinc (II) acetate (monoZn) have been used. The interaction of DNA with phenanthroline significantly differs from that with phenanthroline metal complexes. MonoZn and diZn form complexes with DNA. Depending on the molar ratio of the components, ligands may interact with DNA in several ways; one of these is presumably intercalation. No saturation binding was detected at 0.1 ≤ r ≤ 20 and 0.1 ≤ r ≤ 1.67 for monoZn and diZn, respectively. The formation of secondary complexes of monoZn and diZn with DNA is possible. The interaction with DNA leads to quenching the fluorescence of the metal complexes.

Influence of Rotator Design on the Speed of Self-Assembled Four-Component Nanorotors: Coordinative Versus Dispersive Interactions.

Four-component nanorotors are prepared by the self-assembly of stator [Cu4(4)]4+ with its four copper(I)-loaded phenanthroline stations and various rotators carrying one, two, or three pyridine terminals. The fourth component, 1,4-diazabicyclo[2.2.2]octane, serves as a connecting axle between rotator and stator. Capitalizing on the heteroleptic pyridyl and phenanthroline metal complexes concept, the rotator's pyridine terminals are connected to the copper(I)-loaded phenanthroline stations (Npy → [Cu(phen)]+) in the STOP state and disconnected in the transition state of rotation. As the barrier of the thermally activated rotation, measured by variable-temperature 1H NMR, is mainly governed by attractive forces between stator stations and rotator terminals, it increases along the series Ea (monopyridine rotator) < Ea (dipyridine rotator) < Ea (tripyridine rotator). However, there are even distinct differences in rate between rotors with equal number of rotator terminals. The change from the 5,10-dipyridyl (cis) to 5,15-dipyridyl (trans) zinc porphyrin rotator enhances the rotational frequency by almost 1000-fold. Density functional theory computational results suggest that not only coordinative Npy → [Cu(phen)]+ interactions but also dispersive attraction influence the barrier of rotation.

Three phenanthroline-metal complexes with topologically similar but geometrically different conformations.

The structures of three related complexes of general formula M(pds)(nab)2 [pds is the peroxodi-sulfate anion and nab is an nitro-gen-containing aromatic base], viz. bis(2,9-dimethyl-1,10-phenanthroline-κ2N,N')(peroxodi-sulfato-κ2O,O')cadmium, [Cd(S2O8)(C14H12N2)2], (V), bis-(3,4,7,8-tetra-methy-1,10-phenanthroline-κ2N,N')(peroxodi-sulfato-κ2O,O')zinc, [Zn(S2O8)(C16H16N2)2], (VI), and bis-(3,4,7,8-tetra-methy-1,10-phenanthroline-κ2N,N')(peroxodi-sulfato-κ2O,O')cadmium, [Cd(S2O8)(C16H16N2)2], (VII), present the same topological coordination, with three chelating ligands in an MN4O2 polyhedron. The main difference resides in the fact that the first two complexes are bis-ected by a crystallographic twofold axis, thus providing a symmetrical environment to the cation, while in the third one this symmetry is disrupted into a clearly unsymmetrical disposition, probably by way of an unusually strong intra-molecular C-H⋯O hydrogen bond. The situation is compared with similar inter-actions in the literature. The structure of (V) is based on a redetermination in the correct space group C2/c of the structure originally described in the Cc space group [Harvey et al. (2001). Aust. J. Chem.54, 307-311; Marsh (2004 ▸). Acta Cryst. B60, 252-253].

Novel carbazole-based main chain polymeric metal complexes containing complexes of phenanthroline with Zn(II) or Cd(II): Synthesis, characterization and photovoltaic application in DSSCs

In this work, four main chain polymeric complexes(P1–P4), with fluorene or phenylethyl linked with carbazole as electron donor, phenanthroline metal complexes as a electron withdrawing unit, were synthesized through simple synthetic procedures and with low cost. They were characterized by FT-IR, Elemental analysis, GPC. The UV–vis absorption spectroscopy, photoluminescence spectroscopy, cyclic voltammetry are also determined and studied. Dye-sensitized solar cells (DSSCs) based on P1–P4 as the dye sensitizers exhibit some conversion efficiencies. It was found that the incorporation of 2,7-divinyl-9,9-dioctylfluorene unit instead of 1,4-divinyl-2-methoxyl-5-octyloxybenzene unit results in a negative shift of the lowest unoccupied molecular orbital(LUMO) levels for P3 and P4, in comparison to P1and P2, which induces a remarkable enhancement of the electron injection driving force from the excited polymer sensitizers to the TiO2 semiconductor. Moreover, when the coordinated ion of the polymer complexes changed from zinc ion to cadmium ion, a bathochromically shifted maximum absorption band can be realized, which consequently results in an increased light harvesting efficiency and photogenerated current. All of these dyes performed as sensitizers for the DSSCs test under AM 1.5 similar experimental conditions, and a maximum solar-to-electric power-conversion efficiency (PCE) is up to 1.15% (Jsc=2.71mAcm−2, Voc=0.649eV, FF=0.653).

Heteroleptic Metallosupramolecular Racks, Rectangles, and Trigonal Prisms: Stoichiometry-Controlled Reversible Interconversion

A simple approach toward preparation of heteroleptic two-dimensional (2D) rectangles and three-dimensional (3D) triangular prisms is described utilizing the HETPYP (HETeroleptic PYridyl and Phenanthroline metal complexes) concept. By mixing metal-loaded linear bisphenanthrolines of varying lengths with diverse (multi)pyridine (py) ligands in a proper ratio, six different self-assembled architectures arise cleanly and spontaneously in the absence of any template. They are characterized by (1)H and DOSY NMR, ESI-FT-ICR mass spectrometry as well as by Job plots and UV-vis titrations. Density functional theory (DFT) computations provide information about each structure. A stoichiometry-controlled supramolecule-to-supramolecule interconversion based on the relative amounts of metal bisphenanthroline and bipyridine forces the rectangular assembly to reorganize to a rack architecture and back to the rectangle, as clearly supported by variable temperature and DOSY NMR as well as dynamic light scattering data. The highly dynamic nature of the assemblies represents a promising starting point for constitutional dynamic materials.

Implications of Stoichiometry-Controlled Structural Changeover Between Heteroleptic Trigonal [Cu(phenAr2)(py)]+ and Tetragonal [Cu(phenAr2)(py)2]+ Motifs for Solution and Solid-State Supramolecular Self-Assembly

A stoichiometric variant of the HETPYP concept (HETeroleptic PYridine and Phenanthroline metal complexes) opens the venue to heteroleptic metallosupramolecular HETPYP-I assemblies both in solution and the solid state, involving the trigonal [Cu(phenAr(2))(py)](+) coordination motif (phenAr(2) = 2,9-diarylphenanthroline; py = various oligopyridines). Combining the same building blocks at another stoichiometric ratio furnished metallosupramolecular HETPYP-II aggregates in the solid state, now based on the tetrahedral [Cu(phenAr(2))(py)(2)](+) coordination motif. Thus, a stoichiometry-controlled structural changeover based on the relative amounts of oligopyridines leads from a discrete assembly with trigonally coordinated copper(I) centers to a coordination polymer with tetrahedrally coordinated copper(I) ions, as shown by solid state studies. In solution, the analysis of both stoichiometric variants indicates that the HETPYP-I structure is congruent with that in the solid state, while the HETPYP-II assembly, as established through DOSY NMR and dynamic light scattering measurements, is only oligomeric at low temperature. At room temperature, i.e. due to entropic costs, the latter assembly prefers to keep "unsaturated" coordination sites that are in rapid exchange, making it an interesting system as a dynamic protecting group and for constitutional dynamic materials through the exchange and reshuffling of components.

Studies on the interaction of achiral cationic pseudoisocyanine with chiral metal complexes

The effect of chiral metal complexes ([Co(en)(3)]I(3)·H(2)O, cis-[CoBr(NH(3))(en)(2)]Br(2), K[Co(edta)]·2H(2)O and [Ru(phen)(3)](PF(6))(2)) on the polymer-bound J-aggregates in aqueous mixtures of pesudoisocyanine (PIC) iodine and poly(acrylic acid, sodium)(PAAS) have been studied by UV-vis absorption, circular dichroism (CD) and fluorescence spectra. At low concentration, the PIC monomers could self-assemble to form supermolecules by binding to each of the COO(-) groups on the polymer chains through electrostatic interactions. After the addition of chiral metal complexes to the formed PIC-PAAS J-aggregates, we found that only the chiral multiple π-conjugated phenanthroline metal complexes could transfer their metal-centered chiral information to the formed J-aggregates. The chiral J-aggregates showed a characteristic induced circular dichroism (ICD) in the visible region of J-band chromophore, and the ICD signals depend on the absolute configuration, concentration of the chiral multiple π-conjugated metal complexes, as well as temperature. More interestingly, the supramolecular chirality of the polymer supported PIC J-aggregates could be memorized even after the addition of an excess opposite chiral complex enantiomers. This is in sharp contrast to the behavior in the high concentrated NaCl induced PIC-J aggregates, in which the optical rotation of a mixture of two enantiomers varies linearly with their ratio.

Heterogenized Ru(II) phenanthroline complex for chemoselective hydrogenation of diketones under biphasic aqueous medium

The chemoselective hydrogenation of acetylacetone to 4-hydroxypentan-2-one over immobilized ruthenium phenanthroline metal complexes in amino functionalized MCM-41 in biphasic aqueous reaction medium was investigated. The catalyst was characterized by XRD, TEM, surface analysis, FT-IR and UV–vis to understand the morphology, complex geometry, and XPS such that the oxidation state of the metal complex inside the MCM-41 framework could be understood. The use of water as a solvent, not only gives high activity and selectivity for hydrogenation of acetylacetone, but also gives a path for an environmentally safer process. The optimizations of ligand, metal to ligand ratio, the choice of solvent and other reaction parameters were studied in detail. The heterogeneous catalytic system gave a higher degree of chemoselectivity (99%) towards 4-hydroxypentan-2-one as compared to homogeneous catalyst when hydrogenation was carried out using water as a solvent. The immobilized ruthenium–phenanthroline complex was easily separated and reused.

Cap for Copper(I) Ions! Metallosupramolecular Solid and Solution State Structures on the Basis of the Dynamic Tetrahedral [Cu(phenAr2)(py)2]+ Motif

The tetrahedral [Cu(phenAr(2))(py)(2)](+) coordination motif (phen = 1,10-phenanthroline; py = pyridine) conceived on the basis of the HETPYP concept (heteroleptic pyridyl and phenanthroline metal complexes) is a versatile dynamic unit for constructing various heteroleptic metallosupramolecular pseudo-1D, 2D, and 3D structures, both in solution and the solid state. The 2,9-diaryl substituted phenanthroline (phenAr(2)) serves as a capping ligand for copper(I) ions, as its bulky nature prevents formation of the homoleptic complex [Cu(phenAr(2))(2)](+). Combination of the dynamic and concave metal ligand building block [Cu(phenAr(2))](+) with various pyridine (py) ligands, such as bi-, tri-, and tetra-pyridines, opened the way to infinite 1D helicates, 2D networks, and discrete 3D hexanuclear cages, whereas spatial integration of both phenAr(2) and py units into a single ligand resulted in the formation of a Borromean-ring-type hexanuclear cage.

Chemical and photochemical probing of DNA complexes

An overview of the chemical and photochemical probes which over the past ten years have been used in studies of DNA/ligand complexes and of non-B-form DNA conformations is presented with emphasis on the chemical reactions of the probes with DNA and on their present 'use-profile'. The chemical probes include: dimethyl sulfate, ethyl nitroso urea, diethyl pyrocarbonate, osmium tetroxide, permanganate, aldehydes, methidiumpropyl-EDTA-Fell (MPE), phenanthroline metal complexes and EDTA/FeII. The photochemical probes that have been used include: psoralens, UVB, acridines and uranyl salts. The biological systems analysed by use of these probes are reviewed by tabulation.