Chains, ladders and sheets of d metal–organic polymers generated from the flexible bipyridyl ligands

By use of the three-layer diffusion method, reactions of flexible bipyridyl ligands (4,4′-bpp or 3,3′-bpp) with M(II) salts (M = Zn, Cd) and multi-carboxylate ligands resulted in the formation of four interesting d¹⁰ metal–organic coordination polymers: [Zn(μ-4,4′-bpp)Br₂]_n (1), [Zn(μ-4,4′-bpp)(1,2-bdc)]_n · nH₂O (2), [Zn(μ-3,3′-bpp)(1,3-bdc)]_n · nCH₃OH · 2nH₂O (3) and [Cd(μ-3,3′-bpp)(C₄H₂O₄)]_n · 3nH₂O (4) (4,4′-bpp = 2,2′-bis(4-pyridylmethyleneoxy)-1,1′-biphenylene; 3,3′-bpp = 2,2 ′-bis(3-pyridylmethyleneoxy)-1,1′-biphenylene; bdc=benzenedicarboxylate, C₄H₄O₄ = fumaric acid). Complex 1 has a 2D sheet structure consisting of two unusual zigzag Zn(II) chains which are nearly perpendicular to each other. Complex 2 is comprised of two-leg ladders, in which [Zn(4,4′-bpp)] chains serve as the side rails and 1,2-bdc ligands serve as the cross rungs. In complex 3, every two 1,3-bdc ligands connect the neighbouring Zn(II)-3,3′-bpp dimetallic rings in η¹ coordination modes into an interesting chain structure. Complex 4 consists of an anionic macrocycle-containing cadmium dicarboxylate sheets that are separated by 3,3′-bpp. These d¹⁰ metal complexes exhibit high thermal stabilities and strong luminescence efficiencies.     

Synthesis, structure and nuclease activity of copper complexes of disubstituted 2,2′-bipyridine ligands bearing ammonium groups

A series of Cu(II) complexes of disubstituted 2,2′-bipyridine bearing ammonium groups [Cu(L¹⁻⁴)₂Br]⁵⁺ (1–4, L¹ = [5,5′-(Me₂NHCH₂)₂-bpy]²⁺, L² = [5,5′-(Me₃NCH₂)₂-bpy]²⁺, L³ = [4,4′-(Me₂NHCH₂)₂-bpy]²⁺, L⁴ = [4,4′-(Me₃NCH₂)₂-bpy]²⁺ and bpy = 2,2′-bipyridyl) were synthesized, of which complexes 1 and 4 were structurally characterized. Both coordination configurations of Cu(II) ions can be described as distorted trigonal bipyramid. The interaction between all complexes and CT-DNA was evaluated by thermal-denaturation experiments and CD spectroscopy. Results show that the complexes interact with CT-DNA via outside electrostatic interactions and their binding ability follows the order: 1 > 2 > 3 > 4. In the absence of any reducing agents, the cleavage of plasmid pBR322 DNA by these complexes was investigated and the hydrolysis kinetics of DNA was studied in Tris buffer (pH 7.5) at 37 °C. Obtained pseudo-Michaelis–Menten kinetic parameters: 15.0, 13.6, 2.01 and 1.69 h⁻¹ for 1, 2, 3 and 4, respectively, indicate that complexes 1 and 2 exhibit very high DNA cleavage activities. According to their crystal data, the high nuclease activity may be attributed to the strong interaction of the metal moiety and two ammonium groups with phosphate groups of DNA.     

Synthesis, spectra and crystal structures of two Ru complexes with polypyridyl ligands: cis-[Ru(bpy)2(4,4′-bpy)Cl](PF6)·H2O and cis-[Ru(phen)2(CH3CN)2](PF6)2

Two mononuclear Ru^II complexes of polypyridyl ligands, cis-[Ru(bpy)₂(4,4′-bpy)Cl](PF₆)·H₂O (1) and cis-[Ru(phen)₂(CH₃CN)₂](PF₆)₂ (2) (bpy=2,2′-bipyridyl, 4,4′-bpy=4,4′-bipyridyl, and PHEN=1,10-phenanthroline), have been synthesized and characterized by elemental analyses, IR and UV–vis spectra. The crystal structures of both complexes have been determined by X-ray diffraction, indicating that each Ru^II center is hexa-coordinated (RuN₅Cl for 1 and RuN₆ for 2) and takes a distorted octahedral geometry. The favored feature of both complexes is that they are quite useful complex precursors for further constructing new functional architectures.     

3D H-bonding networks self-assembly from pyridinium derivatives and bis(maleonitriledithiolato)zincate(II)

The two ion-pair complexes, [pyH]₂[Zn(mnt)₂] (1) and [4,4′-bipyH₂]-[Zn(mnt)₂] (2), were synthesized, where mnt²⁻ denotes maleonitriledithiolate, and [pyH]⁺, [4,4′-bipyH₂]²⁺ represent pyridinium and diprotonated 4,4′-bipyridinium, respectively. Their single crystal structures show that there are strong bifurcated H-bonding interactions between the cations of the pyridinium derivative and the [Zn(mnt)₂]²⁻ anions in both 1 and 2. The bifurcated H-bonding interactions between the N–H of the pyridiniums and the CN groups of the mnt²⁻ ligands give rise to a 2D layered H-bonding network, the adjacent layers come together in such way as mutual embrace to give a tight pack, thus 2D hydrogen-bonding sheets further develop into 3D H-bonding networks through weak C–HS and ππ stacking interactions in 1. As for 2, the cations and anions connect into several types of H-bonding macrorings ([2+2], [3+3] and [4+4]), these H-bonding macrorings fuse to extend into 2D layered structure, the interpenetration between [3+3] and [4+4] type H-bonding macrorings in the adjacent layers give further rise to novel 3D extended H-bonding networks, in which there are clearly parallel stacks of cations and the chelate rings of anions.     

Synthesis and crystal structure of a complex bearing interesting structural motifs: [Cu (C4H7N3) H2O (4,4′-Hbpy)]·SO4·NO3

A new complex [Cu (C₄H₇N₃) H₂O (4,4′-Hbpy)]·SO₄·NO₃ was synthesized and X-ray characterized. Elemental analysis, X-ray diffraction and infrared spectroscopy of the complex were performed. The crystal system is orthorhombic. Crystal data: Fw=498.98, spacegroup: P212121. Z=4, a=14.952(3), b=20.491(4), c=6.713 Å. V=2056.7(9) Å. λ(Mo-K)=0.71070 Å. μ=12.18 cm⁻¹, D_calc=1.66 g/cm³, F₀₀₀=1032.00, R=0.062, Rw=0.087. X-ray analysis illustrated that 4,4′-bpy is mono-protonated and that there are two kinds of anions in one molecule, which give rise to the hydrogen interaction between the molecules in the crystal. Then an extended three-dimensional network is formed along the hydrogen bonds and π–π bonds between the pyridine rings.     

A new three-dimensional supramolecular network, [Cd(Hbic)2(H2O)]·(4,4′-bpy)·H2O (H2bic = 1-H-benzimidazole-5-carboxylic acid; 4,4′-bpy = 4,4′-bipyridine): Synthesis, crystal structure and luminescence property

A photoluminescent supramolecular compound [Cd(Hbic)₂(H₂O)]·(4,4′-bpy)·H₂O, H₂bic = 1-H-benzimidazole-5-carboxylic acid, has been synthesized and structurally characterized. With CH–π stacking and hydrogen bond, the 4,4′-bipyridine is used as template to construct the neighboring layers into a three-dimensional supramolecular architecture. Solid-state emission spectrum of compound 1 shows luminescence with emission peak at 565 nm.     

Synthesis, characterization and crystal structure determination of zinc (II) and mercury (II) complexes with 2,2′-dimethyl-4,4′-bithiazole

The 2,2′-dimethyl-4,4′-bithiazole ligand (1), (dm4bt), and its Zn and Hg complexes have been prepared. A conformational property calculation at the DFT level for the ligand shows the anti conformation is energetically more stable by about 22.83 kJ/mol and the rotational barrier is about 32.01 kJ/mol for the anti → syn conversion, a phenomena happening during complex formation. The complexes [Zn(dm4bt)Cl₂] (2) and [Hg(dm4bt)Cl₂] (3) have spectral properties typical for d¹⁰ metal diimine systems. The structures of the ligand and the two complexes have been determined by the single crystal diffraction method. The X-ray structure determinations show that both complexes are four coordinated by two chloride atoms and one bidentate dm4bt. In the Hg complex one of the two chlorides is set at a semi-bridging position.     

Syntheses and structural characterization of transition metal(II) coordination polymers containing 4,4′-dipyridyldisulfide

The reactions of Zn(NO₃)₂ · 6H₂O and FeSO₄ · 7H₂O with 4-PDS (4-PDS = 4,4′-dipyridyldisulfide) and NH₄SCN in CH₃OH afforded the complexes [Zn(NCS)₂(4-PDS)]_n (1) and [Fe(NCS)₂(4-PDS)₂ · 4H₂O]_n (2), respectively, while the reaction of CoCl₂ · 6H₂O with 4-PDS in CH₃OH gave the complex {[Co(4-PDS)₂][Cl]₂ · 2CH₃OH}_n, (3). These complexes have been characterized by spectroscopic methods and their structures determined by X-ray crystallography. The 4-PDS ligands in 1 are coordinated to the metal centers through the nitrogen atoms to form 1-D zigzag-chains, and the distorted tetrahedral coordination geometry at each zinc center is completed by a pair of N-bonded thiocyanate ligands. Compound 2 has a 1-D channel-chain structure and each octahedral Fe(II) metal center is coordinated by four 4-PDS ligands and two trans N-bonded thiocyanate ligands. Weak SS interactions in complex 1 link the 1-D chains into 2-D molecular sheets. In complex 2, the channel chains are interlinked through SS interactions to form molecular sheets, which interpenetrate through the SS interactions to form 3-D structures with large cavities that are occupied by the water molecules. Compound 3 also has a 1-D channel-chain structure with each square-planar Co(II) metal center coordinated by four 4-PDS ligands. Multiple C–HCl hydrogen bonds and SO interactions in 3 link the 1-D chains into 2-D structures.     

Ternary complexes of 5′-cytidine monophosphate and cytosine with some biologically important secondary ligands

Potentiometric equilibrium measurements have been made at 35°C for the interaction of 5′-cytidine monophosphate and Cu(II), Ni(II), Zn(II), Co(II), Mn(II), Mg(II) and Ca(II) with biologically important secondary ligands (glycine, oxalic cid, histidine and histamine) in a 1:1:1 ratio. Similar studies with cytosine were carried out for comparison. For the above systems, the ternary complexes are found to be more stable than the corresponding binary complexes. The Δ log K values for 1 : 1 : 1 complexes of metal-5′-cytidine monophosphate (or cytosine) with aromatic ligands are more positive compared to the corresponding complexes with aliphatic ligands. This is explained in terms of “stacking phenomenon” that occur between the two aromatic moieties of the primary and secondary ligands in solution.     

Synthesis, structure and spectroscopic study of Rh polypyridine complexes with phenylcyanamide derivative ligands

Several new Rh^III complexes, [Rh(tpy)(bpy)L](PF₆)₂ (tpy=2,2′:6′,2″-terpyridine, bpy=2,2′-bipyridine, and L=monoanions of phenylcyanamide(pcyd)), 4-methylphenylcyanamide (4-MePcyd), 2,4-dimethylphenylcyanamide (2,4-Me₂pcyd), 4-methoxyphenylcyanamide (4-MeOPcyd), 2-chlorophenylcyanamide (2-Clpcyd) and 2,5-dichlorophenylcyanamide (2,5-Cl₂pcyd) have been synthesized and characterized by elemental analysis, IR, ¹H NMR and electronic absorption spectroscopies. ORTEP drawing of [Rh(tpy)(bpy)(2,5-Cl₂pcyd)](PF₆)₂·1/2CH₃CN shows three pyridyl rings of the tpy ligand that are nearly coplanar, as are the two rings of bpy. The anionic cyanamide group is coordinated end-on by the nitrile nitrogen to the Rh^III. The Rh^III–NCN bond is bent, having an angle of 125.4°. This bent bond is largely determined by the σ-bonding interaction of a cyanamide non-bonding electron pair in a sp² hybrid orbital.     

Synthesis and electrical properties of novel supramolecular octa-phthalocyaninato-dicobalt(II)-hexazinc(II) and dicobalt(II)-dimeric-phthalocyanine with six ferrocenylimin pendant groups

In this study supramolecular octakis phthalocyaninato-diCo(II)hexakis-Zn(II) has been synthesized in two steps. Starting with tetracyanodibenzo(1,4,7,10-tetrathia-(12-crown)) (1) and 4-nitro-1,2-dicyanobenzene (2), nitro-substituted dimeric phthalocyanine (3) was synthesized. Compound 3 reacted with unsymmetric Zn(II) phthalocyanine (4) to furnish a supramolecular assemble of a Co(II) dimer with six Zn(II) phthalocyanines through azo bridges (5). Co(II) dimeric phthalocyanine with six ferrocenyl groups (7) was obtained by the condensation of 6 with ferrocenylaldehyde. Compounds 3, 5, 6 and 7 were characterized by elemental analysis, ICP-MS, IR, UV–Vis and ¹H NMR spectroscopy. The electronic properties of a thin film of the compounds were investigated by impedance spectroscopy and d.c. conductivity measurements as a function of temperature. The a.c. conductivity is found to vary with frequency, ω, as ω^s with index s  1, suggesting a hopping conduction mechanism for 3 and 6. Whereas a frequency independent conductivity was observed for 5. It was found that reducing the nitro group to amines and azo coupling by the asymmetric nitro groups increases the electrical conductivity. The higher conductivity of 5 can be attributed to the increase in the mobility of charge carriers due to overlap of the π electron systems along the stacking direction of the molecules.     

Synthesis and characterization of novel 4-nitro-2-(octyloxy)phenoxy substituted symmetrical and unsymmetrical Zn(II), Co(II) and Lu(III) phthalocyanines

Compounds 3 and 4 have been prepared by the reaction of 4-nitrocatechol 1 and 4-nitrophthalonitrile 2 by a common method, aromatic nucleophilic subtitution of the nitro group in 4-nitrophthalonitrile. Starting from 4 and 1-bromooctane, their alkylation reaction gave compound 5. Zn(II) 8, Co(II) 9 and Lu(III) 10 complexes were synthesized from the corresponding metal salts by the tetramerization of compound 5. Compound 7 was prepared by the statistical condensation of 5 and 4,5-bis(hexylthio)phthalonitrile 6 with CoCl₂ · 6H₂O in dry dimethylformamide. The new compounds were characterized by FT-IR, UV/Vis, NMR and mass spectra. The electrochemical properties of the complexes were also investigated by cyclic voltammetry in non-aqueous medium. The effect of temperature on the dc conductivity and the impedance spectra of spin coated film of the compounds was investigated at temperatures between 295 and 433 K and in the frequency range 40–10⁵ Hz. Thermally activated conductivity dependence on temperature was observed for all compounds.     

Synthesis, characterization and magnetic properties of novel μ-isophthalato oxovanadium(IV) binuclear complexes

Four novel oxovanadium(IV) binuclear complexes have been synthesized, namely [(VO)₂(IPHTA) (L)₂SO₄ (L denotes 2,2′-bipyridine (bpy); 1,10-phenanthroline (phen); 4,4′-dimethyl-2,2′-bipyridine (Me₂bpy) and 5-nitro-1,10-phenanthroline (NO₂-phen)), where IPHTA is the isophthalate dianon. Based on elemental analyses, molar conductivity measurements, IR and electronic spectra studies, it is proposed that these complexes have IPHTA-bridged structures and consist of two vanadium(IV) atoms in a square-pyramidal environment. The complexes [(VO)₂(IPHTA)(Me₂bpy)₂]SO₄ (1) and [(VO)₂(IPHTA)(bpy)₂]SO₄ (2) were characterized by variable temperature magnetic susceptibility (4–300 K) and the data could be well fitted by the least-squares method to a susceptibility equation derived from the spin Hamiltonian operator, . The exchange integral, J, was found to be −26.8 cm⁻¹ for (1) and −31.0 cm⁻¹ for (2). These results are commensurate with antifferomagnetic interactions between two oxovanadium(IV) ions within each molecule. The influence of different terminal ligands on magnetic interactions between the metals of this kind of complexes is also discussed.     

Synthesis and physico-chemical studies on complexes of 1,2-diaminophenyl-N,N′-bis-(2-pyridinecarboxaldimine), (L): A spectroscopic approach on binding studies of DNA with the copper complex

The Schiff base ligand, 1,2-diaminophenyl-N,N′-bis-(2-pyridinecarboxaldimine), (L) has been synthesized by the reaction of o-phenylenediamine and 2-pyridinecarboxaldehyde, and a series of mononuclear complexes of the type [ML(NO₃)₂] [M = Co(II), Ni(II), Cu(II) and Zn(II)] has also been synthesized. The formation of the Schiff base ligand (L) and its complexes have been envisaged from IR, ¹H and ¹³C NMR studies. The absorption band observed in the electronic spectra and magnetic moment values confirm an octahedral environment around the metal ion. The molar conductivity measurements confirm the non-ionic character of these complexes. Fluorescence and UV–Vis absorption studies performed on the Cu(II) complex revealed a significant binding ability to DNA.     

Synthesis,characterization and electrochemistry of a new organosoluble metal-free and metallophthalocyanines

4-[2-(Phenylthio)ethoxy]phthalonitrile 3 was synthesized by nucleophilic displacement of nitro group in 4-nitrophthalonitrile with 2-(phenylthio)ethanol 1. The metal-free phthalocyanine 4 was prepared by the reaction of a dinitrile monomer with 2-(dimethylamino)ethanol. Ni(II), Co(II), Cu(I) phthalocyanines 5, 7, 8 were prepared by reaction of the dinitrile compound with the chlorides of Ni(II), Co(II), Cu(I) in DMAE. Zn(II) phthalocyanine 6, was prepared by reaction of the dinitrile compound with the acetates of Zn(II) in DMAE. Electrochemical behaviours of novel metal-free, Co(II) and Zn(II) phthalocyanines were investigated by cyclic voltammetry, potential differential pulse voltammetry techniques. The new compounds were characterized by a combination of IR, ¹H NMR, ¹³C NMR, UV–Vis, elemental analysis and MS spectral data.     

Intervalence electron transfer through a thiolate bridge ligand: a Fe–S–R–Fe mixed valence complex

The reaction of Cp(dppe)FeI with the ligands 2,2′- and 4,4′-dithiobispyridine (S₂(Py)₂) give the mononuclear or binuclear complexes of the type [Cp(dppe)Fe-S₂(Py)₂]PF₆, [Cp(dppe)Fe---SPy]PF₆ or [{Cp(dppe)Fe}₂-μ-SPy](PF₆)₂ depending on the reaction condition. Reaction of Cp(dppe)FeI with dithiobispyridines in presence of TlPF₆ as halide abstractor and using CH₂Cl₂ as a solvent gives the complexes [Cp(dppe)Fe-4,4′-S₂(Py)₂)₂]PF₆ (1) and [CpFe(dppe)-2,2′-S₂(Py)₂]PF₆ (2) whereas the same reaction using CH₃OH as a solvent and NH₄PF₆ as the halide abstractor leads to the formation of the Fe^III–thiolate complex [Cp(dppe)Fe-2,2′-SPy]PF₆ (3) and the mixed-valence complex [Cp(dppe)Fe^III-μSPy-Fe^II(dppe)Cp](PF₆)₂ (4). Magnetic and ESR measurements are in agreement with one unpaired electron delocalized between them. Mössbauer data indicate clearly the presence of two different iron sites, each one of the N-bonded and S-bonded iron atoms, with intermediate oxidation state Fe^II---Fe^III. An electron transfer intervalence absorption was observed for this complex at 780 nm (in CH₂Cl₂). By applying the Hush theory the intervalence parameters were obtained; =0.028, H_ab=361 cm⁻¹ which indicate Class II Robin–Day. Estimation of the rate electron transfer affords a value k_th=6.5×10⁶ s⁻¹. Solvent effect on the intervalence transition follow the Hush prediction for high dielectric constants solvents which permit the evaluation of the outer and inner-sphere reorganizational parameters, which were analyzed and discussed. The electronic interaction parameters compare well with those found for electron transfer in metalloproteins.     

Nuclear magnetic resonance of Zn(II) complexes with 2,2′-bipyridine

The complexes Zn(bipy)Cl₂ and Zn(bipy)₂Cl₂ as well as 2,2′-bipyridyl in aqueous solution (D₂O) have been examined by the NMR method. The presence of the monocationic bipy D⁺ form in aqueous bipyridyl solution has been found. The changes of chemical shifts of bipyridyl protons for complexes Zn(bipy)₃Cl₂ and Zn(bipy)Cl₂ have confirmed explicitly the essential influence of diamagnetic currents on the NMR spectrum of Zn(bipy)₃Cl₂. The comparison of the spectra of 2,2′-bipyridyl (in CH₃OH) and of Zn(bipy)Cl₂ may also suggest the presence of the nonbonding metal-proton 6 interaction.     

Photophysical, electrochemical and electrochromic properties of copper-bis(4,4′-dimethyl-6,6′-diphenyl-2,2′-bipyridine) complexes

The synthesis, solution and solid state structural characterization, photophysical and electrochemical properties of two redox forms of an electrochromic copper-bis(4,4′-dimethyl-6,6′-diphenyl-2,2′-bipyridine) complex, [Cu(3)₂]ⁿ (n=+1, +2), are presented. Both complexes were characterized in the solid state by X-ray diffraction methods on single-crystals showing that both forms exist in a pseudo-tetrahedral coordination, and a comparison with other structures was made. Like most copper(I) complexes, the red [Cu(3)₂]⁺ complex shows a rather weak emission (Φ_em=2.7×10⁻⁴, dichloromethane). The lifetime of the emitting MLCT state is 34±1 ns, as observed with time resolved emission, and transient absorption (in deoxygenated dichloromethane). Typical emission and transient absorption spectra are presented. The transient absorption spectra indicate that the MLCT state absorbs stronger than the ground state, which is relatively uncommon for metal bipyridine complexes, i.e. no ground state bleaching is observed. The green [(3)₂Cu]²⁺ complex does not show any observable emission or transient absorption, which is a common feature for Cu(II) complexes of this type. The electronic absorption spectra of the chemically and electrochemically produced copper(I/II) complexes are identical. The repeated electrochemical conversion of the Cu(I) center into Cu(II) and vice versa does not cause any decomposition. This is consistent with a fully reversible Cu(I)/Cu(II) redox couple in the corresponding cyclic voltammogram, (E_1/2 (Cu(I)/Cu(II))=+0.68 V vs. SCE=+0.23 V vs. Fc/Fc⁺). These observations indicate that no large structural reorganization occurs upon electrochemical timescales (sub second), and that the different ways of generating the complexes does not effect their final structure, apart from the small differences observed in the X-ray structures of both forms. These characteristics make these complexes rather well suited for their incorporation into an electrochromic display configuration.     

Thermodynamic, crystallographic and solvent extraction properties of cobalt(II), nickel(II) and copper(II) complexes of ethylenediamine- N,N,N′,N′-tetraacetanilide

Complexes of ethylenediamine-N,N,N′,N′-tetraacetanilide (edtan, C₃₄H₃₆N₆O₁₄) with cobalt(II), nickel(II) and copper(II) in the solid state and in solution are reported for the first time. Thermodynamic data (stability constant, and derived Gibbs energy, enthalpy and entropy changes)for the 1 : 1 complexation of edtan with the metal ions at 298.15 K in water-saturated butan-1-ol gave the selectivity sequence log₁₀K_s; Ni²⁺, 4.56±0.02; Cu²⁺, 4.41±0.01; Co²⁺, 4.18±0.04 as found from microcalorimetric titration studies. The entropies suggested that the structure of the 1 : 1 complex with copper(II) contains fewer chelate rings than those for nickel(II) and cobalt(II) (δ_cS⁰ : Cu-21.4, Co 5.7, Ni 3.9 J mol⁻¹K⁻¹). Solid complexes of the metal ions with edtan and perchlorate as the counter anion were prepared. For each, a complex with a 1 : 1 metal: edtan stoichiometry with non-coordinated perchlorate was isolated. The X-ray structure of [Cu(edtan)(H₂O)][ClO₄]₂·1.5H₂O (1) revealed a six-coordinate Cu centre with edtan acting as pentadentate ligand (2N, 3O) with the coordination sphere completed by an oxygen atom from water. In striking contrast to the Cu complex, the Co centre in [Co(edtan)(H₂O)][ClO₄]₂·H₂O·0.5C₂H₅OH (2) is seven-coordinate with hexadentate edtan (2N, 4O) and one coordinated water molecule. There is thus an excellent confirmation of the results obtained from the microcalometric study in that edtan forms four chelate rings to Cu but five to Co in the solid state. The ability of the ligand to extract metal ions from water to the water-saturated butan-1-ol phase was assessed from distribution data as a function of the aqueous phase hydrogen ion concentration and of the ligand concentration in the organic phase. The data showed that Cu²⁺ is selectively extracted over a wide range of aqeous phase hydrogen ion concentrations.     

Synthesis and electrochemical characterization of biphenyl-malonic ester substituted cobalt,copper, and palladium phthalocyanines

Phthalocyanines with four biphenyl-malonic ester groups on the periphery were synthesized by cyclotetramerization of 4-(1,1-dicarbethoxy-2-(4-biphenyl)-ethyl)-phthalonitrile. The new compounds were characterized by elemental analyses, FT-IR, ¹H NMR, ¹³C NMR, UV–Vis, and MASS spectral data. Electrochemical behaviors of novel Co(II), Cu(II), and Pd(II) phthalocyanines were investigated by cyclic voltammetry, potential differential pulse voltammetry, and applied potential chronocoulometry techniques. While Cu(II) and Pd(II) phthalocyanines give up to four common phthalocyanine ring reductions, Co(II) phthalocyanine gave two ligand-centered and two metal-centered redox processes. HOMO–LUMO gap of the complexes are comparable with the reported MPc papers.