Aydan Yilmaz

Synthesis and study of allosteric effects on extraction behavior of novel calixarene-based dichromate anion receptors

Abstract In this study the selective derivatization of p-tert-butylcalix[4]arene was carried out and two new calix[4]arene-based azacrown ionophores, 5,17-di-tert-butyl-11, 23-di-(methyl-3,5-dioxaoctane-1,8-diimine)-25,26,27,28-tetrahydroxycalix[4]arene ( 6 ), and 5,17-di-tert-butyl-11,23-di-(methyl-3,5-dioxaoctane-1,8-diimine)-25,27-diethoxyformyl-methoxy-26,28-dihydroxycalix[4]arene ( 7 ) have been synthesized. Treatment of 5,17-di-tert-butyl-11,23-diformylcalix[4]arene-25,26,27,28-tetrol ( 5 ) with 1,8-diamino-3,6-dioxaoctane gave the ionophore 6 which was converted to its diester derivative 7 by reaction with ethylbromoacetate in the presence of potassium carbonate. In the synthesis, the upper and lower rims of p-tert-butylcalix[4]arene were modified in order to acquire binding sites for the recognition of metal cations and dichromate anions. It was observed that receptor 7 is a better extractant for Cr2O72− anions than receptor 6 . The protonated alkylinium form of 7 is an effective extractant for transferring the Cr2O72− anions from aqueous into a dichloromethane layer and failed in transferring Na+ cations due to the allosteric effect produced by the crown part of the calix moiety present at the p-position.

Synthesis of Polymeric Calix[4]arene Dinitrile and Diamino‐Derivatives: Exploration of Their Extraction Properties Towards Dichromate Anion

Abstract The article describes the syntheses and extraction properties of new alkylnitrile and alkylamino substituted calix[4]arene based copolymers. These compounds have been synthesized via nucleophilic substitution reactions involving 5,11,17,23‐tetra‐tert‐butyl‐25,27‐bis(cyanomethoxy)‐26,28‐dihydroxycalix[4]arene (3), or 25,27‐bis(cyanomethoxy)‐26,28‐dihydroxycalix[4]arene (4) with 1,5‐dibromopentane and bisphenol‐A, followed by their reduction with sodium borohydride in the presence of CoCl2 · 6H2O. In addition an oligomer containing pendant calix[4]arene units with nitrile functionalities on its lower rim has been synthesized via nucleophilic reaction involving 5,11,17,23‐tetra‐tert‐butyl‐25,27‐bis(cyanomethoxy)‐26,28‐dihydroxycalix[4]arene 3 with p‐dibromoxylene. The extraction properties of polymers 5–9 toward the HCr2O7 − anion are also reported. Due to the higher oxidative stability of nitrile groups, polymers 5–7 have been developed as good extractants for transferring the HCr2O7 − anion from an aqueous into a dichloromethane phase.

Evaluation of the performance of calix(8)arene derivatives as liquid phase extraction material for the removal of azo dyes

This paper presents a study on the removal of azo dyes (Reactive Black 5, Trapaeolin 000, Methyl Orange and Direct Violet 51) with calix[n]arene derivatives from aqueous solution into the organic phase in order to explore the potential use of calixarenes as low-cost efficient extractants for wastewater dye removal. The carboxylic acid derivative of calix[8]arene shows highest affinity towards the azo dyes. The influence of NaCl (present in the solution) on extraction process was also studied. The extent of the dye removal increased with the addition of NaCl. The proposed extraction mechanism involves several kinds of interactions: electrostatic repulsion between carboxylic acid groups of calix[8]arenes and sulfonate groups of azo dyes, hydrogen bonding and formation of an inclusion complex due to three dimensional cavity type calix[n]arene molecules through host-guest interactions.

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.

Study on the Transport Kinetics of Hg2+ Through Calix‐Oligomer Bulk Liquid Membrane

In this article, a calix‐oligomer derivative is used (1) as a carrier to transport Hg2+ ions from an aqueous solution into an aqueuos receiving solution. The kinetic parameters were analyzed in the formation of two consecutive, irreversible first order reactions. The influence of temperature and solvent and stirring rate on the kinetic parameters (k1, k2, Rm max, tmax, Jd max, Ja max) have also been investigated. The membrane entrance rate, k1, and the membrane exit rate, k2, constants were increased with temperature and stirring rate. The membrane entrance and exit rate constants depend on the solvent type and are found to be in the order CH2Cl2>CHCl3>CCl4. For the maximum membrane exit flux, Ja max, the activation energy was found from the slope of the linear Arrhenius relationship to be 7.06 kcal/mol, which indicates that the process is controlled by species diffusion.

Facilitated Transport of Cr(VI) Through a Bulk Liquid Membrane Containing p-tert-Butylcalix[4]arene Amine Derivative as a Carrier

The facilitated transport of Cr(VI) through a bulk liquid membrane (BLM) is investigated, using the by p-tert-butylcalix[4]arene amine derivative as mobile carrier. The transport efficiency of Cr(VI) by p-tert-butylcalix[4]arene amine derivative was investigated under various experimental conditions such as the influence of pH on the donor and the acceptor phase, effect of Cr(VI) and carrier concentration, the type of solvent, the stirring speed, and the temperature. The kinetic parameters (k 1, k 2, , t max , , ) were calculated for the interface reactions assuming two consecutive, irreversible first order reactions. The activation energy values are calculated as 5.94 and 12.51 kJ mol−1 for extraction and reextraction, respectively. The values of the calculated activation energy indicate that the process is diffusionally controlled by species.

Novel copper(II) complexes of p-tert-butylcalix[4]arene diamide derivatives: synthesis, antimicrobial and DNA cleavage activities

In this study, two new Cu(II) complexes of p-tert-butylcalix[4]arene amide derivatives (8, 9) have been synthesised and investigated their DNA cleavage and antimicrobial activities. On the basis of spectral studies, a smaller distortion of square planar geometry has been proposed for both of the copper(II) complexes. The DNA cleavage studies show that the ligands are not efficacious, whereas the complexes have high activity. Futhermore, in order to determine the site of DNA cleavage, the DNA interactions of these compounds were investigated with some restriction enzymes. In addition, all synthesised compounds were screened for antimicrobial activities against some bacteria and for antifungal activities against yeast strains. The results showed that ethyl ester and furfuryl amide derivatives of the calixarenes are more efficient than other compounds against tested bacteria. However, complexes have not been effective. In case of DNA interaction studies, compounds were very effective against plasmid DNA.

Synthesis and properties of calix[4]arene polymers containing amide groups: Exploration of their extraction properties towards dichromate and nitrite anions

AbstractThe article describes the synthesis and extraction properties of three new diamide substituted calix[4] arene based polymers (3a, 4a, and 5a). The examination of their recognition abilities towards some selected oxyanions shows that the new calix[4]arene polymers are more effective receptors than their amide derivatives for dichromate anions and nitrite. It has been observed that receptor 4a is a better extractant for dichromate and nitrite anions at low pH.

Synthesis of a Calix[4]crown‐6 Cone Conformer‐Based Oligomer and its Metal Cation Extraction Abilities

A new calixcrown‐6 oligomer 5 was synthesized by reacting a 1,3‐distal di‐amino derivative of cone p‐tert‐butylcalix[4]crown‐6 with malonyl dichloride. Extraction studies with precursor monomers 2 and 3 and oligomer 5 showed differences in their metal cation extraction behavior and selectivity. Precursors monomers 2 and 3 were selective for Hg2+; whereas, oligomer 5 showed high affinity towards both alkali (Li+, Na+, K+, and Cs+) and heavy metal cations (Cu2+, Cd2+, Hg2+ and Pb2+).