Erdal Kocabas

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 and dichromate anion sorption of silica gel-immobilized calix[4]arenes

Three new silica gel-immobilized calix[4]arene polymers 9-11 have been prepared via modification of calix[4]arene mono amido derivatives 3-5 with 3-aminopropyl triethoxysilane (APTES) and activated silica gel, respectively. The polymers were characterized by Fourier transform infrared spectroscopy, elemental analysis and thermal gravimetric analysis. The solid-liquid extraction properties of ligands 3-5 along with their immobilized derivatives 9-11 towards dichromate (HCr(2)O(7)(-)/Cr(2)O(7)(2-)) anions were reported. It was found that these calix[4]arene-based polymers have high extraction abilities towards dichromate anions as compared to their monomeric precursors.

Synthesis and Metal Ion Recognition Properties of a Novel Chiral Calix[4](azoxa)crown-7

A novel chiral calix[4](azoxa)crown-7 (9) has been synthesized and its metal ion recognition properties investigated. The starting reagents, chiral diamine 5 and calix[4]arene diacid chloride derivative 8, were prepared according to literature methods. 1H and 13C NMR data show that 9 exists in a cone conformation. In liquid–liquid extraction experiments, 9 exhibits selectivity for Li+ among the other alkali metals and a good extraction ability for transition metal cations, suggesting its potential use in different fields, such as a sensor for ions as well as for chiral molecules.

Polymer supported calix[4]arene schiff bases : A novel chelating resin for Hg2+ and dichromate anions

This article describes the synthesis and characterization of two new calix[4]arene Schiff bases and their polymeric resins. The extraction properties of these “proton switchable extractants” with alkali, transition, post transition metal cations and for dichromate anions are reported. The two new calix[4]arene based Schiff bases (5 and 6) have been synthesized from 5,17‐diformyl‐25,27‐dipropoxy‐26,28‐dihydroxycalix[4]arene (4) by treatment with 3‐amino‐methylpyridine and 1,8‐diaminooctane in two separate reaction flasks following the same procedure. Compounds 5 and 6 have been appended to a polymeric resin by treatment with Merrifield resin through a nucleophilic substitution reaction. The receptor compounds (3 and 5–8) do not extract alkali metal cations, but show some selectivity toward transition metal cations, and a particularly high selectivity to Hg2+ and Pb2+. The protonated forms of all of the calixarene‐based receptors are good extractants for transferring Cr2O7 2−/HCr2O7 − anions from an aqueous into a dichloromethane layer.

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.