Design and synthesis of new chiral calix[4]arenes as liquid phase extraction agents for alpha-amino acid methylesters and chiral alpha-amines

The article describes the synthesis and extraction properties of new (S)(-)-1-phenylethylamine substituted p-tert-butylcalix[4]arene/calix[4]arene. These compounds have been synthesized via nucleophilic substitution reactions involving 5,11,17,2 3-tetra-tert-butyl-25,26,27,28-tetra(2-hydroxyethoxy)calix[4]arene (4a), or 5,11,17,23-tetra-H-25,26,27,28-tetra(2-hydroxyethoxy)calix[4]arene (4b) with (S)(-)-1-phenylethylamine in dry THF. The extraction properties of ligands 5a and 5b towards the some selected alpha-amino acid methylesters and chiral alpha-amines are also reported. It has been observed that receptor 5a was an excellent ionophore for alpha-amino acid methylesters/alpha-amines and good extractant than 5b. However, both of the ligands did not display any selectivity towards the configurations of this species

Synthesis and evaluation of extraction ability of calix[4]-crown-6 cone conformer and its oligomeric analogue

The synthesis of the cone conformers of 5,11,17,23-tetra-tert-butyl-25,27-bis[(4-nitrobenzyloxy)-26,28-dihydroxy]calix[4]-arene (2), 5,11,17,23-tetra-tert-butyl-25,27-bis[(4-nitrobenzyloxy)]calix[4]arene-crown-6 (3) and 5,11,17,23-tetra-tert-butyl-25,27-bis[(4-aminobenzyloxy)]calix[4]arene-crown-6 (4) containing polymerizable side arms, along with their oligomeric analogue 5, is reported. Extraction studies with monomers 3 and 4 and the oligomer 5 show no difference in their extraction behavior and selectivity, whereas, ionophore 2 is a poor extractant for alkali metal cations. These observations suggest that, substitution of side arms on the lower rim of calix moiety can enhance the calix[4]crown-6 cone conformers function to extract alkali metal cations in two phase extraction systems. (C) 2003 Elsevier B.V. All rights reserved

A useful approach toward the synthesis and metal extractions with polymer appended thioalkyl calix[4]arenes

This article describes a convenient method for the synthesis of two new polymeric resins via nucleophilic substitution reactions involving 5,11,17,23-tetrakis[(propylthio)methyl]-25,26,27,28-tetrahydroxycalix[4]arene 4, and 5,11,17,23-tetrakis[(methylthio)methyl]-25,26,27,28-tetrahydroxycalix[4]arene 6, as precursors with Merrifield's resin. The extraction studies were made using both liquid-liquid extraction and solid-liquid batchwise sorption procedures. The calix[4]arene based polymeric resins have high extraction ability toward metal cations and Na2Cr2O7 as compared to their monomeric precursors. (C) 2004 Elsevier Ltd. All rights reserved

A calix[4]arene derived dibenzonitrile receptor modified at its "lower rim" by a polymerizable group

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

The relationship between coagulation factor XI levels and cardiac syndrome X in patients with diabetes mellitus

Cardiac syndrome X (CSX) is a characterized with normal epicardial coronary arteries and exertional angina pectoris. The aim of this study was to measure the levels of coagulation factor XI (F XI) and XII (F XII) to compare the intrinsic coagulation pathway activities in DM patients with and without CSX. A total of 50 Type 2 DM patients with CSX diagnosed by non-invasive tests accompanied with coronary angiography, and control group of 51 Type 2 DM patients matching with the CSX group in terms of age and sex were included in the study. F XII levels were tended to be higher in patient group than controls [107 ± 26 vs 99 ± 21 IU/dL; p = 0.124, respectively]. Moreover F XI levels were found to be significantly higher in CSX patient group compared to the controls [130 ± 23 IU/dL vs 118 ± 17 IU/dL; p = 0.005, respectively]. This study demonstrates that intrinsic coagulation pathway of DM patients with CSX is more active than those without CSX. It is also suggested that hypercoagulability may play an important role in the pathogenesis of CSX

Removal of Chromium Anions with Nanofiltration-Complexation by Using p-Sulfonated Calix[4]arene

This article describes the removal of chromium anions from aqueous solutions by using nanofiltration-complexation consisting of pilot-scale nanofiltration equipment (Osmonics Sepa CF Membrane Cell) and water-soluble p-sulfonated calix[4]arene ligand. For the determination of optimum removal conditions of the chromium anions, the effect of pH, ligand cavity size, and foreign anions on the retention of the chromium anions in nanofiltration-complexation system was also evaluated. The results showed that water-soluble p-sulfonated calix[4]arene was an effective and selective ligand for the chromium anions over Cl(-), SO(4)(2-) and NO(3)(-) anions in nanofiltration-complexation system at pH 9.4.Scientific Research Projects Foundation of Selcuk UniversitySelcuk University [2003-187]We thank the Scientific Research Projects Foundation of Selcuk University (SUBAP-Grant Number 2003-187) for financial support of this work produced from a part of M. Tabakci's PhD Thesis