Rigid tetracatenar liquid crystals derived from 1,10-phenanthroline

Tetracatenar liquid crystals were obtained by substituting the 1,10-phenanthroline central core unit at the 3- and 8-positions by extended, rigid acetylene moieties, equipped at the termini with two alkoxy chains of various lengths (n = 6, 8, 10, 12, 14). The liquid crystals exhibit a rich mesomorphism including smectic C, cubic, hexagonal and rectangular columnar phases, depending on the alkoxy chain length. The corresponding rhenium(I) complexes containing the bulky [ReBr(CO)₃] fragment are not liquid-crystalline. The ligands and rhenium(I) complexes were investigated by scanning tunneling microscopy (STM). Both the ligands and the rhenium(I) complexes can be self-assembled into monolayers at the TCB–graphite and octanoic acid–graphite interfaces. The ligands and rhenium(I) complexes are luminescent.

Study of the luminescence of tris(2-thenoyltrifluoroacetonato)lanthanide(III) complexes covalently linked to 1,10-phenanthroline-functionalized hybrid sol-gel glasses

The solubility and uniform distribution of lanthanide complexes in sol-get glasses can be improved by covalently linking the complexes to the sol-gel matrix. In this study, several lanthanide beta-diketonate complexes (Ln = Nd, Sm, Eu, Tb, Er, Yb) were immobilized on a 1,10-phenanthroline functionalized sol-gel glass. For the europium(Ill) complex, a sol-gel material of diethoxydimethylsilane (DEDMS) with polymer-like properties was derived. For the other lanthanide complexes, the sol-gel glass was prepared by using a matrix of tetramethoxysilane (TMOS) and DEDMS. Both systems were prepared under neutral reaction conditions. High-resolution emission and excitation spectra were recorded. The luminescence lifetimes were measured. (c) 2004 Elsevier B.V. All rights reserved.

L'Action universitaire – vol. 10, no 5, janv. 1944

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Origin of electronic absorption spectra of MLCT-excited and one-electron reduced 2,2′-bipyridine and 1,10-phenanthroline complexes

UV–Vis absorption spectra of one-electron reduction products and 3MLCT excited states of [ReICl(CO)3- (N,N)] (N,N = 2,20-bipyridine, bpy; 1,10-phenanthroline, phen) have been measured by low-temperature spectroelectrochemistry and UV–Vis transient absorption spectroscopy, respectively, and assigned by open-shell TD-DFT calculations. The characters of the electronic transitions are visualized and analyzed using electron density redistribution maps. It follows that reduced and excited states can be approximately formulated as [ReICl(CO)3(N,Nÿ)]ÿ and ⁄[ReIICl(CO)3(N,Nÿ)], respectively. UV–Vis spectra of the reduced complexes are dominated by IL transitions, plus weaker MLCT contributions. Excited-state spectra show an intense band in the UV region of 50% IL origin mixed with LMCT (bpy, 373 nm) or MLCT (phen, 307 nm) excitations. Because of the significant IL contribution, this spectral feature is akin to the principal IL band of the anions. In contrast, the excited-state visible spectral pattern arises from predominantly LMCT transitions, any resemblance with the reduced-state visible spectra being coincidental. The Re complexes studied herein are representatives of a broad class of metal a-diimines, for which similar spectroscopic behavior can be expected.

Copper(II) complexes of benzene-1,2-dioxyacetic acid (bdoaH2): X-ray crystal structure of [Cu2(bdoa)(phen)4]bdoa·13H2O (phen = 1,10-phenanthroline)

Copper(II) acetate reacts with benzene-1,2-dioxyacetic acid (bdoaH2) in aqueous media to give [Cu(bdoa)(H2O)2] (1). Complex 1 reacts with the N-donor ligands pyridine (py), ammonia and 1,10-phenanthroline (phen) to give [Cu(bdoa)(NH3)2]·H2O (2), [Cu(bdoa)(py)2]·H2O (3) and [Cu2(bdoa)(phen)4]bdoa·13H2O (4), respectively. The X-ray crystal structure of the dicopper(II,II) complex 4 shows each copper atom at the centre of a distorted trigonal bipyramid comprising four nitrogen atoms from two chelating phen ligands and a single oxygen atom from one of the carboxylate moieties of the bridging bdoa2− ligand. The cyclic voltammogram of 4 shows a single reversible wave for the Cu2+/Cu+ couple at E = + 115 mV (vs Ag/AgCl). Spectroscopic and magnetic data for the complexes are given.

Temperature-dependent reduction pathways of complexes fac-[Re(CO)3(N-R-imidazole)(1,10-phenanthroline)]+ (R = H, CH3)

Peculiar reduction pathways of the complexes fac-[Re(imH)(CO)3(phen)]+ and fac-[Re(imCH3)(CO)3(phen)]+ (imH = imidazole, imCH3 = N-methylimidazole and phen = 1,10-phenanthroline) have been unravelled by performing combined cyclic voltammetric and in situ IR spectroelectrochemical experiments. In the temperature range of 293–233 K, the initial reduction of the phen ligand in [Re(imH)(CO)3(phen)]+ results in irreversible conversion of the imidazole ligand to 3-imidazolate by a rapid phen•−→ imH intramolecular electron transfer coupled with N H bond cleavage. This process is followed by second phen-localized 1e− reduction producing [ReI(3-im−)(CO)3(phen•−)]−, similar to the analogous 2,2'-bipyridine complex. In contrast to the bpy analogue, the stability of the phen•−-containing complexes is significantly affected by lowering the temperature. At 233 K, a secondary reaction occurs in both [Re(3-im−)(CO)3(phen•−)]− and [Re(imCH3)(CO)3(phen•−)]. The resulting products exhibit v(CO) wavenumbers indistinguishable from those of the parent phen•− complexes; however, their oxidation occurs at a considerably more positive electrode potential. It is proposed that these species are produced by a new C C bond formation between the C(2) site of 3-im− or imCH3 and the C(2) site of the phen•−ligand.

On the synthesis and structures of the complexes [RuCl(L)(dppb)(N-N)]PF(6) (L = CO, py or 4-NH(2)py; dppb=1,4-bis(diphenylphosphino)butane; N-N=2,2 `-bipyridine or 1,10-phenanthroline) and [(dppb)(CO)Cl(2)-Ru-pz-RuCl(2)(CO)(dppb)] (pz = pyrazine)

The ""Ru(P-P)"" unit (P-P = diphosphine) is recognized to be an important core in catalytic species for hydrogenation of unsaturated organic substrates. Thus, in this study we synthesized six new complexes containing this core, including the binuclear complex [(dppb)(CO)Cl(2)Ru-pz-RuCl(2)(CO)(dPPb)] (pz = pyrazine) which can be used as a precursor for the synthesis of cationic carbonyl species of general formula [RuCl(CO)(dppb)(N-N)]PF(6) (N-N = diimine). Complexes with the formula (RuCl(py)(dppb)(N-N)]PF(6) were synthesized by exhaustive electrolysis of these carbonyl compounds or from the precursors [RuCl(2)(dppb)(N-N)]. The new complexes were characterized by microanalysis, conductivity measurements, IR and (31)P{(1)H)} NMR spectroscopy, cyclic voltammetry and X-ray crystallography. (C) 2010 Elsevier Ltd. All rights reserved.

Solvatochromic and lonochromic Effects of Iron(II)bis-(1,10-phenanthroline)dicyano: a Theoretical Study

Solvatochromic and ionochromic effects of the iron(II)bis(1,10-phenanthroline)dicyano (Fe(phen)(2)(CN)(2)) complex were investigated by means of combined DFT/TDDFT calculations using the PBE and B3LYP functionals. Extended solvation models of Fe(phen)(2)(CN)(2) in acetonitrile and aqueous solution, as well as including interaction with Mg(2+), were constructed. The calculated vertical excitation energies reproduce well the observed solvatochromism in acetonitrile and aqueous solutions, the ionochromism in acetonitrile in the presence of Mg(2+), and the absence of ionochromic effect in aqueous solution. The vertical excitation energies and the nature of the transitions were reliably predicted after inclusion of geometry relaxation upon aqueous micro- and global solvation and solvent polarization effect in the TDDFT calculations. The two intense UV-vis absorption bands occurring for all systems studied are interpreted as transitions from a hybrid Fe(II)(d)/cyano N(p) orbital to a phenanthroline pi* orbital rather than a pure metal-to-ligand-charge transfer (MLCT). The solvatochromic and ionochromic blue band shifts of Fe(phen)(2)(CN)(2) were explained with preferential stabilization of the highest occupied Fe(II)(d)/cyano N(p) orbitals as a result of specific interactions with water solvent molecules or Mg(2+) ions in solution. Such interactions occur through the CN(-) groups in the complex, and they have a decisive role for the observed blue shifts of UV-vis absorption bands.

Two New Ternary Complexes of Copper(II) with Tetracycline or Doxycycline and 1,10-Phenanthroline and Their Potential as Antitumoral: Cytotoxicity and DNA Cleavage

This paper reports on the synthesis and characterization of two new ternary copper(II) complexes: [Cu(doxy-cycline)(1,10-phenanthroline)(H(2)O)(ClO(4))](ClO(4)) (1) and [Cu(tetracycline)(1,10-phenanthroline)(H(2)O)(ClO(4))](ClO(4)) (2). These compounds exhibit a distorted tetragonal geometry around copper, which is coordinated to two bidentate ligands, 1,10-phenanthroline and tetracycline or doxycyline, a water molecule, and a perchlorate ion weakly bonded in the axial positions. In both compounds, copper(II) binds to tetracyclines`. via the oxygen of the hydroxyl group and oxygen of the amide group at ring A and to 1,10-phenanthroline via its two heterocyclic nitrogens. We have evaluated the binding of the new complexes to DNA, their capacity to cleave it, their cytotoxic activity, and uptake in tumoral cells. The complexes bind to DNA preferentially by the major groove, and then cleave its strands by an oxidative mechanism involving the generation of ROS. The cleavage of DNA was inhibited by radical inhibitors and/or trappers such as superoxide dismutase, DMSO, and the copper(I) chelator bathocuproine. The enzyme T4 DNA ligase was not able to relegate the products of DNA cleavage, which indicates that the cleavage does not occur via a hydrolytic mechanism. Both complexes present an expressive plasmid DNA cleavage activity generating single- and double-strand breaks, under mild reaction conditions, and even in the absence of any additional oxidant or reducing agent. In the same experimental conditions, [Cu(phen)(2)](2+) is approximately 100-fold less active than our complexes. These complexes are among the most potent DNA cleavage agents reported so far. Both complexes inhibit the growth of K562 cells With the IC(50) values of 1.93 and 2.59 mu mol L(-1) for compounds I and 2, respectively. The complexes are more active than the free ligands, and their cytotoxic activity correlates with intracellular copper concentration and the number of Cu-DNA adducts formed inside cells.

Spectroscopic investigation and thermal behavior of new carbonyl complexes [M(CO)(4)(N-N)(CuX)], (M = W, Mo; N-N=2,2 '-bipyridine, 1,10-phenanthroline; X = Cl, SCN)

M(CO)(4)(N-N)] reacts with CuCl to give new heterobimetallic metal carbonyls of the type [M(CO)(4)(N-N)(CuCl)], M = W, Mo; N-N = 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen). Reactions of [M(CO)(4)(N-N)(CuCl)] with NaSCN produced the series of complexes of general formula [M(CO)(4)(N-N)(CuSCN)]. The i.r. spectral of all the bimetallic carbonyls exhibited the general four m ( CO) band patterns of the precursors. The u.v.-vis. spectral data for precursors and products showed bands associated with pi --> pi* (nitrogen ligands), d-->d (intrametal), as well as MLCT d-->pi* (nitrogen ligands) and MLCT d --> pi*(CO) transitions. The [M(CO)(4)(N-N)(CuX)] (X = Cl, SCN) emission spectra showed only one band associated with the MLCT transition. The t.g. curves revealed a stepwise loss of CO groups. The initial decomposition temperatures of the [M(CO)(4)(N-N)(CuX)] series suggest that the bimetallic compounds are indeed thermally less stable than their precursors, and the X- ray data showed the formation of MO3, CuMO4, Cu2O and CuO as final decomposition products, M = W, Mo. The spectroscopic data suggests that the heterobimetallic compounds are polymeric.

Treatment of 1,10-phenanthroline laboratory wastewater using the solar photo-Fenton process

The red Fe2+-phenanthroline complex is the basis of a classical spectrophotometric method for determination of iron. Due to the toxicity of this complexing agent, direct disposal of the wastewaters generated in analytical laboratories is not environmentally safe. This work evaluates the use of the solar photo-Fenton process for the treatment of laboratory wastewaters containing phenanthroline. Firstly, the degradation of phenanthroline in water was evaluated at two concentration levels (0.1 and 0.01%, w/v) and the efficiencies of degradation using ferrioxalate (FeOx) and ferric nitrate were compared. The 0.01% w/v solution presented much higher mineralization, achieving 82% after 30 min of solar irradiation with both iron sources. The solar photo-Fenton treatment of laboratory wastewater containing, in addition to phenanthroline, other organic compounds such as herbicides and 4-chlorophenol, equivalent to 4500 mg L-1 total organic carbon (TOC) resulted in total degradation of phenanthroline and 25% TOC removal after 150 min, in the presence of either FeOx or ferric nitrate. A ratio of 1: 10 dilution of the residue increased mineralization in the presence of ferrioxalate, achieving 38% TOC removal after 120 min, while use of ferric nitrate resulted in only 6% mineralization over the same period. (c) 2007 Elsevier B.V. All rights reserved.

Synthesis and structural studies of (1,10-phenanthroline)(thiocyanate-N)-(triphenylphosphine)copper(I)

The compound (1,10-phenanthroline)(thiocyanate-N)(triphenylphosphine)copper(I), was synthesized and studied by IR spectroscopy and X-ray diffraction techniques. It is monomeric with the thiocyanate acting as a N-donor ligand. The copper atom shows a distorted tetrahedral coordination geometry.