Ahmet Coskun

A novel benzothiazole based azocalix[4]arene as a highly selective chromogenic chemosensor for Hg2+ ion: A rapid test application in aqueous environment

A novel calix[4]arene derivative containing benzothiazole azo groups at the upper rim was synthesized as chromogenic chemosensor, and its binding and sensing properties with heavy metal ions (Pb(2+), Hg(2+), Ni(2+), Cd(2+), Cu(2+), Zn(2+), Co(2+), Fe(2+), Mn(2+), Cr(3+), Ag(+)) were investigated by UV-vis spectroscopy and voltammetric techniques. The results of spectroscopic and voltammetric experiments showed that the chromogenic chemosensor has high selectivity towards Hg(2+) ion over the other heavy metal ions. Moreover, it was shown that the interaction between Hg(2+) and the chromogenic chemosensor occurs by means of the benzothiazole azo groups at the upper rim by using differential pulse voltammetry. The stoichiometric ratio and the association constant were determined as 1:1 and (6.1+/-0.3)x10(5) L mol(-1) for the complex between Hg(2+) and the ionophore. Furthermore, we prepared a rapid test kit for early detection of Hg(2+) in aqueous environment in the concentration range of 1 x 10(-4) to 1 x 10(-2)M.

Synthesis of novel tripodal-benzimidazole from 2,4,6-tris(p-formylphenoxy)-1,3,5-triazine: Structural, electrochemical and antimicrobial studies

Four new tripodal-benzimidazole derivatives were synthesized by Schiff base reaction between 2,4,6-tris(p-formylphenoxy)-1,3,5-triazine (TRIPOD) and different diamine derivatives. The structures of the obtained compounds were identified by FT-IR, (1)H NMR, (13)C NMR and UV-vis spectral data, thermal analysis and elemental analysis. Electrochemical behaviors of the compounds were studied by cyclic voltammetry in DMF including 0.1 M [NBu(4)] [PF(6)]. The voltammograms showed peaks having similar characteristics except tripodal-benzimidazole including -NO(2) derivative. In addition, their antimicrobial activities were evaluated by using the standard disk diffusion method in dimethylformamide media. The activities were determined against 4 bacteria cultures by comparing to those of gentamycin.

Synthesis and Characterization of a New Dioxime and Its Heterotrinuclear BF2 + Capped Complexes

ω‐Isonitrosoacetophenone 1, phenylglyoxime 2, chlorophenylglyoxime 1, dopaminophenylglyoxime 3 and [(salen/saloph)Fe]2O 4 have been synthesized as described in the literature procedure. [Fe(III)(salen/saloph)dopaminophenylglyoxime)] (starting complexes) have been synthesized from dopaminophenylglyoxime and tetradentate schiff bases which contain dinuclear Fe(III) oxygen‐bridges N,N′‐bis(salicylidene)ethylenediamine (salenH2) and bis(salicylidene)‐o‐phenylenediamine (salophH2). The new heterotrinuclear complexes have been obtained from starting complexes and Co(II), Ni(II), Cu(II) salts. Then, heterotrinuclear vic‐dioxime complexes containing BF2 + capped have been synthesized. The complexes have been characterized as low‐spin distorted octahedral Fe(III) bridged by o‐hydroxyphenolic groups. The o‐hydroxyphenolic groups play a role as bridges for weak antiferromagnetic intramolecular exchange. The structure of dioxime and its complexes were identified by using elemental analysis, ICP‐AES, 1H‐NMR and IR spectral data.

A newly synthesized thiazole derivative as a fluoride ion chemosensor: naked-eye, spectroscopic, electrochemical and NMR studies.

2,3-Indoledione 3-thiosemicarbazone (TSCI) and a novel compound 3-(2-(4-(4-phenoxyphenyl)thiazol-2-yl)hydrazono)indolin-2-one (FTHI) were synthesized with high yield and characterized by spectroscopic techniques. The complexation behaviors of TSCI and FTHI for various anionic species (F(-), Cl(-), Br(-), I(-), NO2(-), NO3(-), BzO(-), HSO4(-), ClO4(-)) in CH3CN were investigated and compared by UV-vis spectroscopy, cyclic voltammetry and (1)H NMR titration techniques. FTHI showed high degree of selectivity for fluoride over other anions. This selectivity could be easily observed by the naked eye, indicating that FTHI is potential colorimetric sensor for fluoride anion.

A RAPID AND HIGH-YIELDING SYNTHESIS OF THIAZOLES AND AMINOTHIAZOLES USING TETRABUTYLAMMONIUM SALTS

A convenient method for the synthesis of thiazoles and aminothiazoles by treatment of phenacyl bromides with thioamides/thiourea in the presence of tetrabutylammonium hexafluorophosphate (Bu 4 NPF 6 ) at room temperature was developed. The products having high yields were formed rapidly (within 15 min). The method is simple, rapid and practical, generating thiazole derivatives in excellent isolated yields. The structures of the newly synthesized products were identified by FT-IR, 1 H NMR, 13 C NMR spectroscopy and elemental analysis data.

Synthesis and characterization of new vic-dioximes and their metal complexes with Cu(II), Ni(II), and Co(II) salts

Abstract4-Acetyldiphenyl sulfide and 4,4′-diacetyldiphenyl sulfide were synthesized from diphenyl sulfide and acetyl chloride in the presence of AlCl3 as catalyst in the Friedel-Crafts reaction. Subsequently, the ketooxime and glyoxime derivatives were also prepared. The metal complexes of the glyoximes, such as copper, nickel, and cobalt complexes were prepared. The BF2+ capped Ni(II) mononuclear complex of 4-thiophenoxyphenylglyoxime was prepared. The structures of these ligands were identified by FT-IR, 1H NMR, and 13C NMR spectral data and elemental analysis. The structures of the complexes were identified by FT-IR, elemental analysis, and magnetic measurements.

Synthesis, Characterization and Extraction Properties of Four Unsymmetricall vic‐Dioximes and their Complexes with Nickel (II), Cobalt (II) and Copper (II)

Four new unsymmetrical vic‐dioximes: [L 1 H 2 ] N‐(4‐acetanilidyl)amino‐amphi‐glyoxime, [L 2 H 2 ] N‐(4‐acetanilidyl)amino‐anti‐glyoxime, [L 3 H 2 ] N‐(2‐thiazolyl)amino‐amphi‐glyoxime and [L 4 H 2 ] N‐(2‐thiazolyl)amino‐anti‐glyoxime were prepared by the reaction of amphi‐chloroglyoxime and anti‐chloroglyoxime with 4‐aminoacetanilide and 2‐aminothiazol in absolute ethanol. The preparation Ni(II), Co(II), and Cu(II) complexes of the amphi‐and anti‐isomers of these ligands are described.The ligands and their complexes were characterized by elemental analyses, IR, mass, H1 and 13C NMR spectra and magnetic susceptibility measurements. Ligands complexing properties were studied by the liquid‐liquid extraction of selected alkali (Li+, Na+, K+, Cs+) and transition metals (Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+). It has been observed that all ligands show a high affinity to Cu2+ and Hg2+ ions, where as almost no affinity to alkali metals. The extraction equilibrium constants (K ex) for complexes of ligands with Cu2+ and Hg2+ metal picrates between dichloromethane and water have been determined at 25°C.

Synthesis and Characterization of Some vic-Dioxime and its Mononuclear Complexes

In this study, acetophenone is used as a basis substance. ω-Isonitrosoacetophenone has been synthesized from nitrosyl with amyl nitrite of acetophenone in the presence of sodium ethoxide. Subsequently, anti-phenylglyoxime has been prepared by reacting ω-isonitrosoacetophenone with hydroxylamine and sodium acetate in a ethanolic media. Chlorophenylglyoxime has been obtained from reaction with chlorine gases. Then, three aminophenylglyoxime (ligands) have been prepared by the reaction of chlorophenylglyoxime and the corresponding amines. The Ni(II), Co(II), and Cu(II) complexes with BF2+-bridge of anilinophenylglyoxime and 2,4-dimethylanilinophenylglyoxime were prepared. Then polymeric metal complexes with BF2+-bridge of dopamiophenylglyoxime were prepared. Their structures were identified by FT-IR, 1H NMR, and ICP-AES spectral data, elemental analysis and magnetic measurements.

Synthesis and electrochemical properties of a novel calix[4]arene derivative for facilitated transfer of alkali metal ions across water/1,2-dichloroethane micro-interface

The alkali metal ion transfers facilitated by a novel calix[4]arene derivative (OPEC) across the water/1,2-dichloroethane (1,2-DCE) micro-interface supported at the tip of a micropipette were presented. The well-defined voltammetric behaviours except Cs+ was obtained by cyclic voltammetry and differential pulse voltammetry. The bulk concentration of metal ions was much higher than that of OPEC in the performed measurements. The diffusion coefficient of OPEC in the 1,2-DCE phase was calculated as 5.18 ± 0.70 × 10− 6 cm2 s− 1. On the basis of the changes of the half-wave transfer potentials, the logarithms of the association constants having 1:1 ionophore–ion complex stoichiometry for Li+, Na+, K+ and Rb+ in 1,2-DCE were determined as 4.80, 4.62, 4.98 and 5.32, respectively. The facilitated ion transfers were also evaluated by the Randles equivalent circuit used for ac-impedance data analysis.