Iron (III) derivatives of 4,7-dihydroxy-1,10-phenanthroline

The chemistry of the iron (III) derivatives of 4,7-dihydroxy-l,10-phenanthroline has been studied in detail. Oxidation of the intensely red tris(4,7-dihydroxy-l,10-phenanthroline) iron (II) ion results in a grey compound, tris(4,7-dihydroxy-l,10-phenanthroline)iron(III), which is stable below pH 10. Above pH 10 the grey compound is partially converted into an amber compound in which the ratio of phenanthroline to iron is 2:1. The amber compound is the conjugate base of a purple 2:1 compound with pK(a) = 9.77. The visible absorption spectra of the three species at various pH values are reported. For 4,7-dihydroxy-1,10-phenanthroline pK(3), as determined by ultraviolet absorptometry, is 12.62 +/- 0.2.     

Diporphyrinyl derivatives of 1,10-phenanthroline and 2,2′-bipyridyl

The title derivatives were synthesized containing two meso-tri-p-tolylpheneleneporphyrin units attached via amide bridges to 4, 7- and 4,4′ positions of the respective heteroaromatic spacers.     

Protonation of 2,2′-bipyridyl and 1,10-phenanthroline in chlorosulphuric acid

Summary Conductivity techniques have been used to monitor the behaviour of the two title ligands in chlorosulphuric acid at 25.0° using 2-methylimidazole as a reference base. In this totally anhydrous medium two protons (1.995 ± 0.045) are involved in the protonation of 1,10-phenanthroline.     

Spectrophotometric determination of copper in plutonium metal with 2,9-dimethyl-1,10-phenanthroline

A spectrophotometric method for the determination of copper plutonium has been developed. The copper is complexed with neocuproine, extracted into chloroform, and the absorbance read at 457 mmu. The average relative error of the method is -1.4% with an average relative standard deviation of 4%.     

Inftared study of the interaction between proton donors and 1,10-phenanthroline derivatives

The hydrogen bond complexes between 1,10-phenanthroline derivatives (bathocuproine, neo-cuproine and bathophenanthroline) and phenols have been investigated by i.r. spectrometry. The presence of two adjacent nitrogen atoms influences the thermodynamic and spectroscopic properties to a great extent. Comparison with recent results suggests that the 1,10-phenanthroline derivatives cannot be considered as “proton sponges”.     

Chelation-assisted electrocyclic reactions of 3-alkenyl-2,2'-bipyridines: an efficient method for the synthesis of 5,6-dihydro-1,10-phenanthroline and 1,10-phenanthroline derivatives

An efficient method for the synthesis of substituted 5,6-dihydro-1,10-phenanthrolines and 1,10-phenanthrolines has been developed by means of the chelation-assisted photochemical electrocyclic reactions of 3-alkenyl-2,2'-bipyridines.     

Synthesis and biological activity of novel heavy metal complexes of 5-amino-1, 10-phenanthroline and 1,10-phenanthroline

Novel heavy metal complexes: Sr(5-NH₂-phen)₄(NO₃)(OH)(H₂O)₂ (1) (synthesized via a static self-assembly process) and Sn(phen)(NO₃)(OH)(H₂O) (2), Sn(5-NH₂-phen)(OH)(Cl)(H₂O) (3), Pb(5-NH₂-phen)(NO₃)₂(H₂O) (4) (obtained via metal competitive reactions under mild conditions) were reported. The coordination compounds were characterized by elemental analysis, FTIR-spectroscopy and FAB-mass spectrometry. Their cytotoxicity was measured by MTS-test towards human tumour (MDA-MB-231, HT-29, HeLa, HepG2) and non-tumour diploid (Lep-3) cell lines. The most pronounced cytotoxic effect on all cancer lines showed 1 and 4 at their high concentrations as well as 1 at its lower ones (≤ 4×10⁻² mg). Therefore, strontium complex of 5-amino-o-phenanthroline (1) exhibited the widest antitumour spectrum activity, having no toxicity to non-tumour cells at quantities ≤ 4×10⁻² mg. The computed EC₅₀ values of 1–4 against MDA-MB-231, HT-29, HeLa, HepG2 varied from 1.40×10⁻³ to 6.31×10⁻⁶ M. Towards Lep-3 substances 2–4 showed IC₅₀ 7.52×10⁻⁴ − 0.44 M. Substance 1 possess EC₅₀=1.26×10⁻⁷ M to the non-tumour cells.      

Spectrophotometric determination of iron in highly alkaline solution with 4-hydroxy-1,10-phenanthroline

4-Hydroxy-1,10-phenanthroline forms a stable tris-chelate with iron(II) in the range of alkalinity from pH 10 to 2M sodium hydroxide, with molar absorptivity 1.19 x 10(4) l.mole(-1).cm(-1) at 545 nm. The determination of iron is performed by adding the phenanthroline, stannous chloride, and iron-free sodium hydroxide to the sample to give pH > 13; stannite is the active reductant. Beer's law is obeyed over the iron concentration range from 1 x 10(-5) to 8 x 10(-5)M. Advantages over existing methods are the use of stannous chloride instead of sodium dithionite, which avoids the problem of turbidity, and the stability of the iron(II) chelate towards oxidation by air. The conditional reduction potential at pH 11 for the iron(III)/iron(II) complex couple is 0.39 V.     

Oxidative DNA cleavage by copper ternary complexes of 1,10-phenanthroline and ethylenediamine-sulfonamide derivatives

Ternary copper(II) complexes (1–3) of 1,10-phenanthroline and ethylenediamine-R-sulfonamide derivatives (R = benzene, toluene and naphthalene rings) have been synthesized and characterized with the aid of X-ray diffraction and spectroscopic and electrochemical techniques. The crystal structures of the complexes show that the coordination polyhedron around copper(II) is distorted square planar. Both 1,10-phenanthroline and ethylenediamine-R-sulfonamide act as bidentate ligands. The three structures are stabilized by π–π stacking interactions. The interaction of the complexes with calf thymus DNA has been investigated by thermal denaturation studies which indicated that DNA was stabilized in the presence of the compounds. The increase in DNA stability induced by the complexes follows the order: 3 > 2 > 1. All three complexes were found to be very efficient agents of plasmid DNA cleavage in the presence of ascorbate as reducing agent. Mechanistic studies of the DNA cleavage process performed with radical scavengers show that the reactive oxygen species involved in the DNA damage are the hydroxyl radical, singlet oxygen-like species, the superoxide* and hydrogen peroxide.     

Synthesis and luminescence of polymeric metal complexes based on 1,10-phenanthroline and 8-hydroxyquinoline

A ligand containing different coordination groups, 5-([1,10]phenanthroline-[4,5-f]imidazo-2-yl)-8-hydroxyquinoline (PhenI8Q) has been synthesized and two corresponding polymeric metal complexes Cu(II) (1) and Zn(II) (2) were prepared by coordination polymerization of the ligand with copper(II) and zinc(II) halides, respectively. The ligand was characterized by ¹H-NMR, ¹³C-NMR, and Fourier transform-infrared (FT-IR) and its corresponding polymeric metal complexes 1 and 2 were characterized by FT-IR, UV-Vis, elemental analysis, thermal gravimetric analysis, and conductivity measurements. The absorption spectra and luminescence of the ligand, 1, and 2 were investigated by UV-Vis and fluorescence spectroscopy at room temperature. Compared with the ligand, the fluorescence spectra of the polymeric metal complexes exhibit blue shifts in dimethyl sulfoxide (DMSO) solution and bathochromic shifts in the solid state. Complexes 1 and 2 emit blue light with emission maximum (λ _{f max}) at 449 and 431 nm in DMSO solution and at 485 and 484 nm in the solid state, respectively.     

Synthesis and characterization of a new bisphosphonic acid and several metal hybrids derivatives

Commercial bis-(4-bromophenyl)-ether, [BrC(6)H(4)](2)-O, has been used to prepare 4-[4'-(diethoxyphosphoryl)phenoxy]phenyl-phosphonic acid diethyl ester, [(CH(3)CH(2))(2)O(3)P-C(6)H(4)](2)-O, (I) following a slight modification of the Michaelis-Arbuzov reaction. The acid hydrolysis of I gave 4-(4'-phosphonophenoxy)phenyl phosphonic acid, [H(2)O(3)P-C(6)H(4)](2)-O (II), and both compounds have been characterized by (1)H NMR and (13)C NMR. The crystal structure of II has been determined by single-crystal X-ray diffraction. II crystallizes in an orthorhombic unit cell, space group Pbcn, with a = 7.822(3) A, b = 5.821(2) A, c = 28.982(9) A, and V = 1319.7(7) A(3). The final R factor was R1 = 0.0614. The structure is layered, being held together through a hydrogen bonding network. II has been used as precursor in the syntheses of new metal (Mn, Fe, Co, Ni, Cu, and Zn) bisphosphonates. The syntheses were carried out using a fixed metal/bisphosphonic acid molar ratio of 2.1:1 and the influence of the pH in the reactions has been studied. Nine new compounds have been isolated: Mn(2)(O(3)PC(6)H(4)OC(6)H(4)PO(3)).1.5H(2)O (III), Mn(5)(OH)(2)(O(3)PC(6)H(4)OC(6)H(4)PO(3))(2).2H(2)O (IV), Fe(HO(3)PC(6)H(4)OC(6)H(4)PO(3)).0.5H(2)O (V), Co(2)(O(3)PC(6)H(4)OC(6)H(4)PO(3)).2H(2)O (VI), Ni(2)(O(3)PC(6)H(4)OC(6)H(4)PO(3)).3H(2)O (VII), Ni(2)(O(3)PC(6)H(4)OC(6)H(4)PO(3)).2H(2)O (VIII), Cu(2)(O(3)PC(6)H(4)OC(6)H(4)PO(3)) (IX), Zn(2)(O(3)PC(6)H(4)OC(6)H(4)PO(3)) (X), and Zn(HO(3)PC(6)H(4)OC(6)H(4)PO(3)H) (XI). Compound IX crystallizes in an orthorhombic unit cell, space group Pbcn, and unit cell parameters a = 8.1012(5) A, b = 5.3109(3) A, c = 29.2595(5) A, and V = 1258.8(1) A(3). Its structure has been solved by ab initio powder diffraction and refined by the Rietveld method to R(F) = 0.042. IX has a pillared layer framework with highly distorted CuO(5) groups sharing edges to give isolated dimers. XI was indexed in a monoclinic unit cell, space group P112(1), with parameters a = 9.4991(9) A, b = 5.0445(5) A, c = 29.131(2) A, gamma = 91.945(7) degrees, and V = 1395.1(3) A(3). Its structure has been refined by the Rietveld method, R(F) = 0.054, since it is isostructural with the known compound, Zn[HO(3)P(C(6)H(4))(2)PO(3)H]. All solids were also characterized by thermal analysis and IR and UV-Vis spectroscopies.     

Protonation thermodynamics of 1,10-phenanthroline in aqueous solution. Salt effects and weak complex formation

The protonation of 1,10-phenanthroline has been studied potentiometrically in different aqueous salt media (LiCl, NaCl, KCl, Me₄NCl, Et₄NI, MgCl₂, CaCl₂, SrCl₂, and BaCl₂) in the ionic strength range 0≤1≤1 M. This ligand forms two protonated species, [H(phen)]⁺ and [H(phen)₂]⁺; the monoligand species shows protonation constants strongly dependent on the medium. Medium effects were explained by the formation of some weak species: [H(phen)Cl]⁰, [M(phen)]²⁺ (M=alkaline earth metal cations). Formation thermodynamic parameters are reported.     

Determination of metal ions by capillary electrophoresis using pre-column complexation with 1,10-phenanthroline

The capillary electrophoretic separation of Fe(II), Cu(II) and Zn(II) ions in an acidic buffer solution (pH 2.5) by complexation with 1,10-phenanthroline is investigated. As 1,10-phenanthroline is a neutral ligand, the positively charged metal complexes formed migrate in the same direction as the EOF, providing a rapid separation of metal ions in acidic buffers. The method was applied to the determination of metal ions in vitamin tablets. Received: 5 January 1998 / Revised: 27 March 1998 / Accepted: 15 May 1998     

Displacement reactions of 2-chloro- and 2,9-dichloro-1,10-phenanthroline: synthesis of a sulfur-bridged bis-1,10-phenanthroline macrocycle and a 2,2′-amino-substituted-bis-1,10-phenanthroline

The synthesis and structural assignments of 9-chloro-1,1-phenanthroline-2(1H)-thione and 1,10-dihydro-1,10-phenanthroline-2,9-dithione have been accomplished. The sulfur-bridged bis-1,10-phenanthroline macrocycle was readily prepared by heating the thione or equimolar amounts of the dithione and 2,9-dichloro-1,10-phenanthroline in diphenyl ether. Displacements of 2-chloro- or 2,9-dichloro-1,10-phenanthroline with N,N-dimethylethylenediamine afforded the corresponding amine and diamino analogues. An amino-substituted-2,2′-bis-1,10-phenanthroline has been prepared.     

Aza-bridged bis-1,10-phenanthroline acyclic derivatives: synthesis, structure, and regioselective alkylation

A family of acyclic aza-bridged bis-1,10-phenanthroline compounds has been synthesized in a convenient way. The resulting compounds 2 and 2·HCl were fully characterized and their solid state structures and NMR spectroscopic properties were investigated to assess how the structural units affect the alkylation reactions. The results reveal the transoid structure for 2. The broadening NMR peak in 2 is shown to be due to an unusual intramolecular CH?N hydrogen bond. This unique conformation offers an efficient and regioselective method to prepare the amino-substituted bis-2,2′-1,10-phenanthroline derivatives and 1,10-phenanthrolino-N-alkylated compounds.