Mustafa Tabakci

Synthesis and Extraction Studies of a Versatile Calix[4]arene-Based “Proton-Switchable Extractant” for Toxic Metals and Dichromate Anions

The article describes the syntheses and extraction properties of a new calixarenebased extractant 5, which has been synthesized from5,11,17,23-tetra-tert-butyl-25,27-bis(chlorocarbonyl-methoxy)-26,28-dihydroxycalix[4]arene(4) by treatment with isoniazid (isonicotinic acid hydrazide) in the presence ofpyridine. The compound 5 was converted to its methyl iodide salt (6) by refluxing 5 with methyl iodide in acetonitrile. In this synthesis it was thought to explore the role of pyridinium sites in the extraction of HCr2O7-/Cr2O72- anions. The complexing properties of 5 toward selected alkali/transition metal cationsand HCr2O7-/Cr2O72- anions are reported. It has been observed that receptor 5 does not extract alkali metal cations but shows an excellent selectivity toward transition metals. The protonated pyridinium form of 5 is an effective formfor transferring the HCr2O7-/Cr2O72- anions from an aqueous into adichloromethane layer.

Polymer Supported Calix[4]Arene Derivatives for the Extraction of Metals and Dichromate Anions

Three newly synthesized polymer supported calix[4]arene ionophores (7–9) were synthesized, and their ion binding properties toward selected alkali (Li+, Na+, K+, Cs+) and transition metal (Hg2+, Ni2+, Cu2+, Co2+, Cd2+, and Pb2+) cations were investigated. It has been observed that these ionophores are not selective toward a particular metal cation but show better ion binding property as compared to monomeric calixarene derivatives (2 and 6). Ionophore 6 and its supported polymer were also employed in dichromate anion extraction experiments. The polymeric ionophore (9) was found an effective extractant for dichromate anion even at pH 7.

A Convenient Approach towards the Synthesis of a “Proton Switchable” Chromium(VI) Extractant Based on Calix[4]arene

A convenient synthesis and Cr(VI) extraction properties of a new calix[4]arene-based receptor (5), which has been synthesized from 5,17-diformyl-25,27-dimethoxycarbonylmethoxycalix[4]arene (4) by treatment with 3-aminomethylpyridine in one step, are described. The receptor 5 contains four pyridinyl groups, two on each rim. Two of them are joined by an amide linkage onto the lower rim, and other two are linked by an imine-type linkage onto the upper rim of the calix[4]arene moiety. Receptor 5 is very soluble in water at low pH (<2.5). Calixarene 5 also represents a good extractant for Thus, the partially protonated form of 5 is an effective extractant for transferring ions from an aqueous into a chloroform layer. Deprotonation of 5 results in a reversal, with migrating back into the aqueous layer.

A Calix[4]arene Derived Dibenzonitrile Receptor Modified at Its “Lower Rim” by a Polymerizable Group

Abstract The present work describes the synthesis of a new monomeric dibenzonitrile derivative of p‐tert‐butylcalix[4]arene containing a polymerizable group at its lower rim. This monomer with an acryl amide group has been copolymerized with styrene yielding a linear polymer with pendant calixarene groups. Extraction studies with this monomer and its copolymer show no selectivity for metal cations. Nevertheless, dibenzonitrile groups with calixarene moiety provide a suitable binding site for transferring metal salt (NaHCr2O7) as an ion‐pair.

Synthesis of a chitosan-linked calix[4]arene chelating polymer and its sorption ability toward heavy metals and dichromate anions

This communication describes preparation, characterization, and the evaluation of sorption properties of a calix[4]arene-based chitosan polymer (C[4]BCP). C[4]BCP was used to sorption studies of some heavy metal cations (Co(2+), Ni(2+), Cu(2+), Cd(2+)(,) Hg(2+) and Pb(2+)) and dichromate anions (Cr(2)O(7)(2-)/HCr(2)O(7)(-)) as sorbent material. Also the supporting material (chitosan) was used for comparison in these experiments. The results for heavy metal cations showed that C[4]BCP was excellent sorbent and the effect of chitosan was low. In the sorption studies of dichromate anions, C[4]BCP was highly effective sorbent at pH 1.5.

Synthesis of p‐tert‐Butylcalix[4]arene Dinitrile Bonded Aminopropyl Silica and Investigating Its Usability as a Stationary Phase in HPLC

The chromatic separation of adenine, adenosine, cytosine, phenol, benzene, and toluene were investigated by using 5,11,17,23‐tert‐butyl‐25,27‐bis(cyanomethoxy)‐26‐(chloroformyl)‐28‐hydroxy‐calix[4]arene bonded aminopropyl silica (CDBAPS) as a stationary phase. The separation ability of the stationary phase was observed to be good for target species. The effect of non‐polar calix[n]arene network was observed in chromatographic processes, and it was thought that, thanks to the relatively polar nitrile groups, further selectivity would be obtained in various chromatographic separations.

A Calix[4]arene‐Containing Polysiloxane Resin for Removal of Heavy Metals and Dichromate Anion

A new calix[4]arene‐based polysiloxane resin (CBPSR) was prepared from 5,11,17,23‐tert‐butyl‐25,27‐bis(cyanomethoxy)‐26‐(chloroformyl)‐28‐hydroxy‐calix[4]arene via nucleophilic substitution reaction with 3‐aminopropyltriethoxysilane and followed by copolymerization with octyltriethoxysilane. Batchwise extraction studies have revealed a high adsorption ability of the calix[4]arene‐nitrile derivatives loaded resin toward heavy metals (Cu2+, Co2+, Cd2+, Ni2+, Hg2+ and Pb2+) and dichromate anion (Cr2O7 2−). Liquid–liquid extraction studies show that the monomeric analogs (2, 3 and 4) do not exhibit a good affinity toward these ions.

Synthesis and Extraction Study of Calix[4]arene Dinitrile Derivatives Incorporated in a Polymeric Backbone with Bisphenol-A

Two new copolymers containing pendant calix[4]arene units with nitrile functionalities at their lower rim have been synthesized via nucleophilic substitution reactions involving 5,11,17,23-tetra-tert-butyl-25,27-bis(cyanomethoxy)-26,28-dihydroxy-calix[4]arene (3) or 25,27-bis(cyanometh oxy)-26,28-dihydroxy-calix[4]arene (4) with 1,5-dibromopentane and bisphenol-A. The phase transfer studies were performed by using liquid–liquid extraction procedures. It has been deduced from the observations that both copolymers show a good phase transfer affinity toward selected alkali, alkaline earth, and transition metal cations, unlike their precursor (3).

New diamino derivatives of p-tert-butylcalix[4]arene for oxyanion recognition: synthesis and complexation studies

We have prepared new diamino derivatives of p-tert-butylcalix[4]arene from the reduction of corresponding amide derivatives. The examination of their recognition abilities towards some selected oxyanions shows that the new calix[4]arene amines are mostly more effective receptors than their amide derivatives for dichromate anions and nitrite, and capable of extracting these anions in yields as high as 95%. However, neither the calix[4]arene amines nor their corresponding amides were capable of extracting phosphate or nitrate at pH 1.5.

Calix[4]arene coated QCM sensors for detection of VOC emissions: Methylene chloride sensing studies.

This paper describes the sensing studies of QCM sensors with coated some calixarene derivatives bearing different functional groups for some selected Volatile Organic Compounds (VOCs) such as acetone, acetonitrile, carbon tetrachloride, chloroform, methylene chloride (MC), N,N-dimethylformamide, 1,4-dioxane, ethanol, ethyl acetate, xylene, methanol, n-hexane and toluene. The initial experiments have revealed that whole the calix[4]arene modified QCM sensors exhibited strongest sensing ability to MC emissions. Thus, the detailed studies were performed for only MC emissions after the determination of relatively more effective calix-coated QCM sensors for MC emissions in aqueous media. The results demonstrated that QCM sensor coated with calix-7 bearing both amino and imidazole groups was most useful sensor for MC emissions with 54.1ppm of detection limit. Moreover, it was understood that cyclic structures, H-bonding capabilities and also good preorganization properties of calixarene derivatives played an important role in VOC sensing processes.