Ümmühan Ocak

Synthesis and metal ion binding properties of thiaaza crown macrocycles

Two new macrocyclic ligands (3) and (4), containing nitrogen-sulfur donor atoms, were designed and synthesized in a multi-step reaction sequence. The macrocycles (3) and (4) were used in solvent extraction of metal picrates such as Ag(+), Hg(2+), Cd(2+), Zn(2+), Cu(2+), Ni(2+), Mn(2+), Co(2+), and Pb(2+) from aqueous phase to the organic phase. The metal picrate extractions were investigated at 25+/-0.1 degrees C by using UV-visible spectrometry. The extractability and selectivity of the mentioned metal picrates were evaluated according to the organic solvents. The values of the extraction constants (logK(ex)) and the complex compositions were determined for the extracted complexes.

New Heavy Metal Ion‐Selective Macrocyclic Ligands with Nitrogen and Sulfur Donor Atoms and their Extractant Properties

Abstract Two new macrocyclic ligands, containing nitrogen and sulfur donor atoms were designed and synthesized in a multi‐step reaction sequence. The macrocycles with amide group were used in solvent extraction of picrates of metals such as Ag+, Hg2+, Cd2+, Zn2+, Cu2+, Ni2+, Mn2+, Co2+ and Pb2+ from aqueous phase to the organic phase. The metal picrate extractions were investigated at 25±0.1°C by using UV‐visible spectrometry. The extractability and selectivity of the mentioned metal picrates were evaluated according to the organic solvents. The values of the extraction constants (log Kex) and the complex compositions were determined for the extracted complexes.

Simple time-saving method for iron determination based on fluorescence quenching of an azaflavanon-3-ol compound.

A simple and time-saving spectrofluorometric method developed using an azaflavanon-3-ol compound was used for the determination of iron in various food samples. Nitric acid and hydrogen peroxide were used for digestion of samples in a closed microwave system. The method was validated by analyzing two certified reference materials (CRM-SA-C Sandy Soil C and Mixed Polish Herbs INCT-MPH-2). Measurements were carried out using a modified standard addition method. The standard addition graph was linear until 21.6 mg/L in the determination of iron(III). Detection and quantification limits were 0.81 and 2.4 mg/L, respectively. Satisfactory accuracy was obtained for spinach, dill, mint, purslane, rocket, red lentils, dry beans, and two iron medicinal tablets. High recoveries were found for streamwater samples fortified at three different concentrations. The method is simple, time-saving, cost-effective, and suitable for the determination of the iron content of foods.

Evaluation of Mononuclear Ni(II) Complex of a Tetra-cryptanded Vic-dioxime and its Model Compound 14-Membered N2O2S2-Macrobicyclic Ligand as Pb2+, Cd2+, and Hg2+ Extractants

Abstract A macrobicyclic ligand and its mononuclear Ni(II) complex were studied as extractants for Pb2+, Cd2+, and Hg2+. The metal picrates were used for extraction experiments. The solutions of the ligands in chloroform and dichloromethane were used as organic phases. The most effective transport was observed for Cd2+ picrate among the tested metal picrates with dichloromethane. The effect of pH on the extraction efficiency was evaluated for both organic solvents. The cations were stripped from the organic phase with 0.75 M nitric acid and the ligands were determined spectrophotometrically in the proper wavelength. The recovery% values of the ligands were calculated at pH 3.5.

Effect of Pendant Group Length Upon Metal Ion Complexation in Acetonitrile by Di-Ionized Calix[4]Arenes Bearing Two Dansyl Fluorophores

A series of three di-ionizable calix[4]arenes with two pendant dansyl (1-dimethylaminonaphthalene-5-sulfonyl) groups linked to the lower rims was synthesized. Structures of the three ligands were identical except for the length of the spacers which connected the two dansyl groups to the calix[4]arene scaffold. Following conversion of the ligands into their di-ionized di(tetramethylammonium) salts, absorption and emission spectrophotometry were utilized to probe the influence of metal cation (Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+, Ag+, Cd2+, Co2+, Fe2+, Hg2+, Mn2+, Pb2+, Zn2+ and Fe3+) complexation in acetonitrile. Upon complexation with these metal cations, emission spectra underwent marked red shifts and quenching of the dansyl group fluorescence for the di-ionized ligand with the shortest spacer. A similar effect was noted for the di-ionized ligand with an intermediate spacer for all of the metal ions, except Ba2+. For the di-ionized ligand with the longest spacer, the metal cations showed different effects on the emission spectrum. Li+, Mg2+, Ca2+ and Ba2+ caused enhancement of emission intensity with a red shift. Other metal cations produce quenching with red shifts in the emission spectra. Transition metal cations interacted strongly with all three di-ionized ligands. In particular, Fe3+ and Hg2+ caused greater than 99% quenching of the dansyl fluorescence in the di-ionized ligands.

Evaluation of a (E,E)-Dioxime Containing Two 15-Membered Dioxatrithiamacrocycles and its Mononuclear Ni(II) Complex as Ag^+ Extractants

Abstract A macrocyclic vic‐dioxime (1) and its mononuclear Ni(II) complex (2) were studied as extractant. The aqueous solutions of Ag+, Mn2+, Pb2+, Ni2+, Cu2+, Cd2+, and Zn2+ picrates were used for extraction experiments. The solutions of the ligands in two different organic solvents were used as organic phases. The metal picrate extractions were carried out at 25±0.1°C by using UV‐visible spectrometry. The most effective transport was observed for Ag+ picrate among the tested metal picrates. The effect of pH on the extraction of Ag+ picrate was evaluated with the ligands. The ratio of extracted Ag‐complex to chloroform phase was 2:1 (L:M) for (2). In other cases the ratios were 1:1 for both (1) and (2). Molar ratio method was also used to demonstrate the composition. The values of the extraction constants (log Kex) were determined for the extracted Ag‐complexes.

Synthesis of metal-free and zinc phthalocyanines containing 2-pyridyl-methyl pendant arm linked with NS4-donor macrocyclic moiety and their selectivity towards Cu(II) cations

New phthalonitrile (L1), metal-free phthalocyanine (H2Pc) and zinc-phthalocyanine (ZnPc) substituted in peripheral positions with 2-pyridyl methyl pendant arm linked mixed donor macrocyclic ligands have been prepared in a multi-step reaction sequence. The novel compounds were characterized by a combination of elemental anlaysis, 1H NMR, 13C NMR, IR, UV-vis and MS spectral data. The influence of metal cations such as Cd2+, Zn2+, Hg2+, Al3+, Fe3+ and Cu2+ on the spectroscopic properties of dinitrile compound L1 and free phthalocyanine H2Pc was investigated by means of absorption spectrophotometry. Spectrophotometric titrations were carried out with these ligands for Cu2+ ion. The complex composition of Cu-L1 was found 1:1 by means of spectrophotometric titration data. The spectrophotometric method showed good sensitivity for Cu2+ with linear range of 2.6 × 10-6 to 1.3 × 10-4 M with dinitrile compound.

Synthesis, characterization and complexation properties of a novel Mg-porphyrazine with metal ions in acetonitrile-chloroform

The synthesis and characterization of a novel metal derivative of a peripherally symmetrically tetrasubstituted porphyrazine derived from 25,26-dioxa-6,7,9,10,15,16,18,19-octahydro-25H-1,24-methanodibenzo[q,t][1,4, 13,16,17,10]tetraoxadithiacyclohenicosine-12,13-dicarbonitrile was carried out. The influence of metal cations such as Zn2+, Fe2+, Mn2+, Ni2+, Co2+, Hg2+ and Cu2+ on the spectroscopic properties of the ligands, the starting material dinitrile and MgPz were investigated in acetonitrile-chloroform solution (1/1) by means of absorption spectrometry. Absorption spectra showed isosbestic points in the spectrophotometric titration of Cu2+ and Hg2+ with MgPz ligand. The results of spectrophotometric titration experiments disclosed the complex stability constant of the novel ligand, MgPz with Cu2+ and Hg2+ cations.