Low-temperature synthesis of phthalocyanine and its metal complexes

Conditions for synthesizing unsubstituted phthalocyanine and its metal complexes from phthalonitrile at low temperatures (0–50°C) are optimized. Phthalocyanine and phthalocyaninates are produced under these conditions using activated Rieke metals, metals on inert substrate, sources of “soluble” metals in the form of unstable metal complexes, zeolites, solid-phase electrosynthesis of phthalonitrile, and UV irradiation. The use of pyrophoric metals is found to be the most efficient due to a large number of defects in their structure favoring the initial stage of phthalonitrile cyclization on a metal matrix. The suggested mechanism of formation of phthalocyanine macrocycle assumes participation of metal agglomerates occurring in activated metals.     

Rigid ferrocenophane and its metal complexes with transition and alkaline-earth metal ions

The rigid [6]ferrocenophane, L¹, was synthesised by condensation of 1,1′-ferrocene dicarbaldehyde with trans-1,2-diaminocyclohexane in high dilution at r.t. followed by reduction. When other experimental conditions were employed, the [6,6,6]ferrocenephane (L²) was also obtained. Both compounds were characterised by single crystal X-ray crystallography. The protonation of L¹ and its metal complexation were evaluated by the effect on the electron-transfer process of the ferrocene (fc) unit of L¹ using cyclic voltammetry (CV) and square wave voltammetry (SWV) in anhydrous CH₃CN solution and in 0.1 M ⁿBu₄NPF₆ as the supporting electrolyte. The electrochemical process of L¹ between −300 and 900 mV is complicated by amine oxidation. On the other hand, an anodic shift from the fc/fc⁺ wave of L¹ of 249, 225, 81 and 61 mV was observed by formation of Zn²⁺, Ni²⁺, Pd²⁺ and Cu²⁺ complexes, respectively. Whereas Mg²⁺ and Ca²⁺ only have with L¹ weak interactions and they promote the acid-base equilibrium of L¹. This reveals that L¹ is an interesting molecular redox sensor for detection of Zn²⁺ and Ni²⁺, although the kinetics of the Zn²⁺ complex formation is much faster than that of the Ni²⁺ one. The X-ray crystal structure of [PdL¹Cl₂] was determined and showed a square–planar environment with Pd(II) and Fe(II) centres separated by 3.781(1) Å. The experimental anodic shifts were elucidated by DFT calculations on the [ML¹Cl₂] series and they are related to the nature of the HOMO of these complexes and a four-electron, two-orbital interaction.     

Synthesis of tetra-2,3-quinolinoporphyrazine and its metal complexes

Tetra-2,3-quinolinoporphyrazine and its complexes with a number of metals were synthesized. The electronic and IR spectra of the compounds obtained, which have typical phthalocyanine character, were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1068–1071, August, 1992.     

Aromatic properties of 8-hydroxyquinoline and its metal complexes

Chelatoaromaticity (aromaticity of chelate complexes) has been recently recognized as an important property influencing the stability of chelate compounds. In this paper, aromaticity of various forms of 8-hydroxyquinoline (anion, neutral molecule, zwitterion and cation) as well as its chelate complexes with magnesium and aluminium ions are investigated. Aromatic properties of these compounds are analyzed using several aromaticity indices based on energetic, geometric, magnetic and electronic physical manifestations of this phenomenon. Results of performed calculations have shown different aromatic properties for the two rings (pyridine and benzene) occurring in the studied ligand. Aromaticity of these rings in metal complexes of 8-hydroxyquinoline is significantly higher than that in corresponding ligand anion. This means that during complexation the aromaticity of the ligand increases and the chelatoaromatic effect stabilizes the studied metal complexes. In contrast, metallocyclic rings of studied metal complexes have non-aromatic properties, and, consequently, the metallocyclic ring is not stabilized by chelatoaromaticity. We conclude that, in the complex, every 8-hydroxyquinoline unit and the metal ion are separated p-electronic systems.      

Synthesis of diferrocenylglyoxime and some of its transition metal complexes

Diferrocenylglyoxime has been prepared by the reaction of monolithioferrocene or dilithioferrocene with anti-dichloroglyoxime. Characterization of this novel vic-dioxime and some of its transition metal complexes are described.     

Structural elucidation of o-vanillin isonicotinoyl hydrazone and its metal complexes

Summary A new series of complexes with the tridentate dibasic Schiff base ligand o-vanillin isonicotinoyl hydrazone (o-VINH) were prepared and characterized by i.r., ¹H n.m.r. and electronic spectral studies, magnetic susceptibility measurements and t.g.a. The disappearance of low field signals due to OH, NH protons at 10.23 and 9.31 p.p.m. and downfield shift of the –CH=N proton signal at 8.17 p.p.m. in the n.m.r. spectrum confirms the involvement of these groups in coordination. Both t.g.a. and i.r. spectral data show evidence for one molecule of coordinated H₂O. These results taken in conjunction with electronic spectral data allow assignation of tetrahedral geometry for manganese(II), nickel(II) and palladium(II) complexes but a square planar configuration to cobalt(II), copper(II) amd zinc(II) complexes.     

Novel modified pectin for heavy metal adsorption

Modified pectin cross-linked with adipic acid, was synthesized and used for heavy metal removal from wastewater. SEM and FTIR were used to investigate its structure and morphology. The modified pectin had a rough, porous phase covered with carboxy groups, resulting a high adsorption capacity. And at the room temperature, the saturated loading capacity for Pb^2＋, Cu^2＋ and Zn^2＋ reached 1.82 retool/g, 1.794 mmol/g and 0.964 retool/g, respectively. The results proved its potential application to remove of the heavy metal.     

Acetylferrocenyl-3-hydroxyl-2-naphthoylhydrazone and its transition metal complexes

Summary Acetylferrocenyl-3-hydroxyl-2-naphthoylhydrazone and its transition metal coordination compounds were prepared. The composition and properties of the ligand and the nature of metal to ligand bonding in its coordination compounds were characterized by elemental analyses, i.r. spectra, n.m.r. spectra, u.v.-vis. spectra, thermal analyses and molar conductivities.     

Formylferrocenyl-3-hydroxyl-2-naphthoylhydrazone and its transition metal complexes

Summary Formylferrocenyl-3-hydroxyl-2-naphthoylhydrazone and its transition metal coordination compounds have been synthesized and characterized by elemental analyses, i.r., ¹H-n.m.r., u.v.-vis., t.g.-d.t.a. and molar conductivities. The results show that the ligand coordinates to transition metal ions in the enolic form, accompanied by the release of acetate or nitrate.     

DFT characterization of 1-acetylpiperazinyl-dithiocarbamate ligand and its transition metal complexes

Employing DFT and handling the solvent effects with the PCM model, the 1-acetylpiperazinyldithiocarbamate acpdtc ligand and its M(acpdtc)₂ complexes, where M is Mn(II), Fe(II), Co(II), Ni(II) and Cu(II), are characterized computationally. The obtained results suggest that the piperazine ring adopts chair conformation in all the studied species. In the gas and solution phases, the chair form of the ligand is dominant. For the Mn, Fe and Co complexes the tetrahedral structure is more stable than the square form in the gas and solution phases. However, the Ni and Cu complexes adopt the square form, in which the complex has the inversion center. The calculated vibrational frequencies are in agreement with the experimental ones, confirming the suitability of the optimized geometries of the compounds. Atomic charges, electron distribution of the frontier orbitals, and stabilizing electron transfers are determined by the NBO analysis.     

Determination of thiosemicarbazide alone and in its metal complexes with arylhalosulfonamides

The behavior of 10 arylhalosulfonamides as oxidimetric analytical reagents toward thiosemicarbazide (TSC) alone or in its metal complexes has been critically examined and general procedures for its estimation have been developed. The proposed analytical techniques are simple and reproducible. These procedures are also useful for computing the number of TSC ligands present in the complexes. The oxidation involves twelve-electron change per TSC molecule with all the oxidants. The complexes have been prepared and characterized by elemental analyses and IR spectra.     

Bithiazole-bridged polysilsesquioxane and its metal complexes: synthesis and magnetic properties

A novel alkoxysilylated derivative based on 2,2′-diamino-4,4′-bithiazole (DABTH) was firstly synthesized. The corresponding polysilsesquioxane (PBSIBTH) and its metal complexes (PBSIBTH-Eu³⁺, PBSIBTH-Tb³⁺ and PBSIBTH-Ni²⁺) were also obtained via sol–gel method, respectively. The morphology of their xerogels was investigated by scanning electron microscopy means. The magnetic measurements of these polymer complexes show all obtained solid materials feature soft ferromagnet properties at low temperature. The metal ions in polymer complexes have a significant influence on both microstructure and magnetic properties.     

Nanostructures of polyelectrolyte gel–surfactant complexes

Small‐angle X‐ray scattering was used to investigate the nanostructures of complexes formed by slightly crosslinked anionic copolymer gels of poly(sodium methacrylate‐co‐N‐isopropylacrylamide) [P(MAA/NIPAM)] with cetyltrimethylammonium bromide (CTAB), and didodecyldimethylammonium bromide (DDAB), respectively, at room temperature (∼ 23°C). Several highly ordered supramolecular structures were observed in the polyelectrolyte gel–surfactant complexes. In P(MAA/NIPAM)–CTA systems, in sequence with decreasing charge density of the P(MAA/NIPAM) copolymer chains, structures of the Pm3n space group cubic, face‐centered cubic close packing of spheres, and hexagonal close packing of spheres were determined at a charge content of ≥ 75, 67, and 50%, respectively. The spheres and rods in these structures were the spherical and cylindrical micelles formed by the self‐assembly of CTA cations with their paraffin chains inside. Both the aggregation number and the size of the micelles decreased with a decreasing charge density of the copolymer chains. In the P(MAA/NIPAM)–DDA systems, the bilayer lamellar structures formed at charge contents ≥ 75% transferred to bicontinuous cubic structures of the Ia3d space group at charge contents of 50–67%. The rods in the Ia3d cubic structures were formed by the self‐assembly of double‐tailed DDA cations with polar moieties inside. The formation of these highly ordered structures were driven by both electrostatic and hydrophobic interactions of the charged copolymer chains/surfactants and the surfactants/surfactants inside the charged gels. The structures became less ordered by further decreasing the charge content of the P(MAA/NIPAM) chains. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2165–2172, 1999     

A novel tetraoxime and its dinuclear and tetranuclear transition metal complexes

A new bis(dioxime) ligand (H₄L) containing the diphenyl ether moiety has been prepared by reacting 3,3,4,4-tetraaminodiphenyl ether (1) with 2,3-butanedione monoxime (2). Dinuclear copper(II) and cobalt(III) complexes of H₄L exhibit a metal–ligand ratio of 2:1 and the ligand coordinates through the 4 nitrogen atoms, as do most bis(dioximes). The [Cu₂(H₂L)](ClO₄)₂ molecule coordinates to the other two copper(II) ions through the deprotonated oximate oxygens to yield a tetranuclear structure, doubly-bridged by the oximate groups in a cis arrangement. The structure of bis(dioxime) and its complexes were identified by elemental analyses, ¹H-, ¹³C-n.m.r, i.r and m.s. spectral data.     

Synthesis and physicochemical properties of the pectin complexes with Xymedon

Russian Chemical Bulletin - The formation of stable complexes of pectin polysaccharides with 1-(2-hydroxyethyl)-4,6- dimethyl-1,2-dihydropyrimidin-2-one (Xymedon drug) was shown by UV and IR...     

Synthesis,characterization and biological activity of triaminoxime and its metal complexes

Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes of multifunctional triaminoxime have been synthesized and characterized by elemental analyses, IR, UV–Vis spectra, magnetic moments, ¹H- and ¹³C-NMR spectra for ligand and its Ni(II) complex, mass spectra, molar conductances, thermal analyses (DTA, DTG and TG) and ESR measurements. The IR spectral data show that the ligand is bi-basic or tri-basic tetradentate towards the metals. Molar conductances in DMF indicate that the complexes are non-electrolytes. The ESR spectra of solid copper(II) complexes [(HL)(Cu)₂(Cl)₂] · 2H₂O (2) and [(L)(Cu)₃(OH)₃(H₂O)₆] · 7H₂O (6) show axial symmetry of a d _{x²???y ²} ground state; however, [(HL)(Co)] (4) shows an axial type with d _Z ² ground state and manganese(II) complex [(L)(Mn)₃(OH)₃(H₂O)6] · 4H₂O (10) shows an isotropic type. The biological activity of the ligand and its metal complexes are discussed.     

High- and low-energy collisionally activated decompositions of octaethylporphyrin and its metal complexes

High-energy (HE) and low-energy (LE) collisionally activated decompositions of octaethylporphyrin (OEP) and its metal complexes (ZnOEP and CuOEP) depend on whether the precursor is produced by electrospray ionization as protonated molecules or by fast atom bombardment as radical cations or protonated molecules. LE activation leads to such simple product-ion spectra that a complete picture of fragmentation emerges only after nine stages of tandem mass spectrometry (MS⁹). HE activation, on the other hand, gives product-ion spectra that afford an integrated view of all the decomposition channels in a single MS/MS experiment. These results are the basis of a recommendation that OEP is an appropriate model compound for investigating energy effects in the collisional activation of organic and bioorganic molecule ions.     

Oxidimetric determination of methionine and its metal complexes with chloramine-B and dichloramine-B

Simple, rapid, and reproducible methods for the determination of methionine (HMt) and its metal complexes, [NiMt]ClO₄₊ and Na[AgMt₂], in aqueous solutions have been developed, based on their oxidation with chloramine-B and dichloramine-B at room temperature. The direct titration, with a visual or potentiometric endpoint, involves a two-electron change corresponding to the formation of methionine sulfoxide. Several amino acids and common anions and cations do not interfere under these conditions. In the back-titration procedure methionine and its complexes are oxidized by excess CAB in 0.1 N NaOH medium with a four-electron change corresponding to the formation of methionine sulfone. The amino acid and its complexes are, however, oxidized to the respective nitrile, with excess DCB with an eight-electron change.     

Synthesis and properties of a temperature-sensitive chelating hydrogel and its metal complexes

A temperature-sensitive chelating hydrogel was synthesized by the copolymerization of 1-(β-acrylamidoethyl)-3-hydroxy-2-methyl-4(1H)-pyridinone (AHMP) and N-isopropylacrylamide (NIPAA) in the presence of N,N' -ethylene-bis-acrylamide as a crosslinking agent. The AHMP-NIPAA hydrogel formed a red complex with iron(III) and a pale green complex with Cu(II), respectively. It was observed that the hydrogel and its metal complexes had a high swelling ratio below the temperature of 35°C, while above that temperature the swelling ratios were dramatically decreased. Furthermore, the swelling ratio of the metal complexes was much lower at the swelling temperature (below 35°C) than that of the hydrogel itself, which might be due to the lower flexibility of the complexes. The iron(III) chelating study showed that the hydrogel had a high chelating efficiency at its swelling temperature, while the chelating efficiency of the hydrogel was very low at its deswelling temperature (>35°C). It was found that the chelating efficiency depended on the swelling ratio of the hydrogel in water, which could be explained by the difference in contactable internal surfaces at different temperatures. The hydrogel and its metal complexes could be easily separated at their deswelling temperature. It was also convenient to regenerate the hydrogel with 1 M HCl for reuse.