Metal Complexation Properties of Schiff Bases Containing 1,3,5-Triazine Derived from 2-Hydroxy-1-Naphthaldehyde in Solution. A Simple Spectrofluorimetric Method to Determine Mercury (II)

Four new Schiff base ligands carrying naphthalene groups were prepared from the reaction of 2,4-diamino-6-methyl-1,3,5-triazine and 2,4-diamino-6-undecyl-1,3,5-triazine with 2-hydroxy-1-naphthaldehyde. The influence of a series of metal ions including Cu²⁺, Co²⁺, Hg²⁺, Al³⁺, Cr³⁺, Fe³⁺, Pb²⁺, Ni²⁺, Cd²⁺, Zn²⁺, Mn²⁺, Ag⁺, Ba²⁺, Ca²⁺ and Mg²⁺ on the spectroscopic properties of the ligands was investigated by means of absorption and emission spectrometry. The results of spectrophotometric and spectrofluorimetric titrations disclosed the complexation stoichiometry and complex stability constant of the ligands with metal ions. A simple spectrofluorimetric method was developed using the Schiff base derived from 2,4-diamino-6-undecyl-1,3,5-triazine to determine Hg²⁺ ion. No cleanup or enrichment of the tap water sample was required. A modified standard addition method was used to eliminate matrix effect. The standard addition graph was linear between 0.2 and 2.6 mg/L in determination of Hg²⁺. Detection and quantification limits were 0.08 and 0.23 mg/L, respectively. The simple and cost-effective method can be applied to water samples.     

Axial-ligation and macrocyclization of novel (E,E)-dioximes of nickel(II) palladium(II), platinum(II) and cobalt(III)

Summary The synthesis and characterization of new Ni^II, Pd^II, Pt^II and Co^III complexes, with the BF _inf2 ^sup+ -bridged,bis(-di-oximato) ligands are described. The initially formed six-coordinate hydrogen-bonded macrocycles, were used as metal templates to prepare the corresponding BF _inf2 ^sup+ - capped macrocycles. The complexes were characterized by¹H-n.m.r. and i.r. spectroscopy, and by elemental analysis.     

The Synthesis and Characterization of a Novel vic-Dioxime and its Mononuclear Complexes Bearing an 18-Membered 2 O 2 S 2 Macro-Cycle and Their Characteristics as Extractants for Transition Metal Ions

A new (E, E)-dioxime (H ₂ L) containing a diazadioxadithia macrocyclic moieties has been synthesized by reaction of an aromatic primary amine with cyanogendi-N-dioxide. The BF₂ ⁺-capped Ni²⁺ mononuclear complex of this new oxime has been synthesized using a precursor hydrogen-bridged mononuclear Ni²⁺ complex. The solvent extraction of transition metal cations by (3) and (6) with picrate anion into chloroform has been studied at 25 °C and UV-visible spectroscopy. The extractability and selectivity of transition metal picrates, (Pb²⁺, Ni²⁺, Co²⁺, Cd²⁺, Zn²⁺, Cu²⁺, Ag⁺) has been evaluated. The structures of new compounds are identified by using elemental analysis, ¹H and ¹³C-NMR, IR and MS spectral data.     

Complexation of metal ions with the novel diazadithia crown ethers carrying two pyrene pendants in acetonitrile-tetrahydrofuran

Two crown ethers carrying pyrene side arms with nitrogen-sulfur donor atom were designed and synthesized by the reaction of the corresponding macrocyclic compounds and 1-bromomethyl-pyrene. The influence of metal cations such as Al³⁺, Zn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Mn²⁺, Cu²⁺, Cd²⁺, Hg²⁺ and Pb²⁺ on the spectroscopic properties of the ligands was investigated in acetonitrile-tetrahydrofuran (1:1) by means of absorption and emission spectrometry. Absorption spectra show isosbestic points in the spectrophotometric titration of Al³⁺, Zn²⁺, Fe²⁺, Ni²⁺, Cu²⁺, and Pb²⁺ with 16-membered crown ether. Similar results were obtained for Al³⁺, Fe²⁺, Hg²⁺, Cu²⁺ and Pb²⁺ with 14-membered crown ether. The results of spectrophotometric titration experiments disclosed the complexation stoichiometry and complex stability constants of the novel ligands with these cations. According to spectrofluorimetric titration measurements the 14-membered diazadithia crown ether showed sensitivity for Pb²⁺ with linear range and detection limit of 1.3 × 10^?6 to 5.2 × 10^?5 M and 5.2 × 10^?7 M, respectively. The 16-membered diazadithia crown ether showed sensitivity for Ni²⁺ with linear range and detection limit of 1.3 × 10^?7 to 5.2 × 10^?6 M and 4.1 × 10^?8 M, respectively.     

Synthesis,electrochemical, in situ spectroelectrochemical and in situ electrocolorimetric characterization of new phthalocyanines peripherally fused to four flexible crown ether moieties

Novel Ni(II), Zn(II), Co(II) and Cu(II) phthalocyanines with four peripheral 4-[methyleneoxy(18-crown-6)] groups have been synthesized via the cyclic tetramerization of 4-[{(18-crown-6)-yl}methyleneoxy]phthalonitrile and the corresponding metal salts (NiCl₂, Zn(CH₃COO)₂, CoCl₂ and CuCl₂). The thermal stabilities of the metal-free and metallophthalocyanine compounds were determined by thermogravimetric analysis. The structures of the target compounds were confirmed using elemental analysis, IR, ¹H-NMR, ¹³C-NMR, UV–Vis and MS spectral data. Voltammetric and in situ spectroelectrochemical measurements show that while the cobalt phthalocyanine complex gives both metal-based and ring-based redox processes, the metal-free, nickel, zinc and copper phthalocyanines show only ring-based reduction and oxidation processes. An in situ electrocolorimetric method has been applied to investigate the color of the electro-generated anionic and cationic forms of the complexes.     

Synthesis and characterization of metal-free and metallophthalocyanines containing N2S2-type macrocyclic moieties linked ferrocenyl groups

The new metal-free (4) and metallophthalocyanines (5) carrying macrocyclic moieties linked ferrocenyl groups have been synthesized by direct cyclotetramerization of the pre-cursor, 12,13-dicyano-4,7-bis(ferrocenylmethyl)-2,3,4,5,6,7,8,9-octahydrocyclobenzo[k]-4,7-diaza-1,10-dithiacyclododecine (3) which has been prepared by the macrocyclization reaction of 1,2-bis(2-iodoethylmercapto)-4,5-dicyanobenzene (1) with N,N′-ethylenebis-(ferroceneylmethyl)amine (2), in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a strong organic base. Nickel (II) phthalocyanine (5) was synthesized by the reaction of metal-free phthalocyanine with anhydrous NiCl₂ in dry quinoline. The target compound and its intermediates have been characterized by a combination of elemental analysis and ¹H, ¹³C NMR, IR, UV-Vis and MS spectral data.     

Synthesis,electrochemical, in situ spectroelectrochemical and in situ electrocolorimetric characterization of new metal-free and metallophthalocyanines substituted with 4-{2-[2-(1-naphthyloxy)ethoxy]ethoxy} groups

The synthesis of novel metal-free and metallophthalocyanines [Ni(II), Zn(II), Co(II), Cu(II)] were prepared by cyclotetramerization of a novel 4-{2-[2-(1-naphthyloxy)ethoxy]ethoxy}phthalonitrile and the corresponding metal salts (NiCl₂, Zn(CH₃COO)₂, CoCl₂ and CuCl₂). The structures of the target compounds were confirmed using elemental analysis, IR, ¹H NMR, ¹³C NMR, UV–Vis and MS spectral data. Voltammetric and in situ spectroelectrochemical measurements show that while cobalt phthalocyanine complex gives both metal-based and ring-based redox processes, metal-free, and zinc phthalocyanines show only ring-based reduction and oxidation processes. All complexes decomposed and coated on the electrode as nonconductive film at positive potential window of the electrolyte. An in situ electrocolorimetric method has been applied to investigate color of the electro-generated anionic and cationic forms of the complexes.     

Synthesis and characterization of a new organo-soluble metal-free and metallophthalocyanines bearing flexible moieties

This paper describes a new symmetric metal-free phthalocyanine and its transition metal complexes which were prepared by a condensation of 1,2-dihydroacenaphthylen-1-ol 1 and 4-nitro phthalonitrile 2 with Co(II), Ni(II), Cu(II), and Zn(II) salts in 2-(dimethylamino)ethanol, respectively. The novel phthalocyanines bearing oxygen donor atoms on peripheral position have been characterized by IR, UV-Vis, ¹H NMR, ¹³C NMR, Mass spectra and elemental analysis. The thermal behaviours of 4-8 were investigated by TG/DTA.     

Electrochemistry of Novel Phthalocyanines Bearing 1,2,4 Triazole Groups

The phthalonitrile (3) and triazole substituted metallo phthalocyanines (MPc) (4–7) were prepared. The novel compounds were characterized with spectroscopic data. Electrochemical analyses of metallophthalocyanines (4–7) bearing triazole substituents were performed to investigate redox activity of phthalocyanines (Pcs) ring. While incorporation of Ni²⁺ and Cu²⁺ cations in the Pc core only influenced peak positions of Pc ring processes, Co²⁺ and Cl^1?Fe³⁺ cations of CoPc and FePc gave extra redox couples to the Pc based ones. Releasing the axial Cl^1? anion on Fe³⁺ cation of FePc during the reduction reactions complicated the redox responses. Redox reactions of Co²⁺ and Fe³⁺ metal centers also considerable influenced spectral and color responses of these complexes.