Imdadullah Qureshi

Estimation of chromium(VI) sorption efficiency of novel regenerable p-tert-butylcalix[8]areneoctamide impregnated Amberlite resin

The article describes a convenient synthesis and Cr(VI) extraction efficiency of a novel p-tert-butylcalix[8]areneoctamide impregnated Amberlite (XAD-4) resin. Using p-tert-butylcalix[8]arene macrocyclic building block, two strategies have been developed; i.e., derivatization of p-tert-butylcalix[8]arene framework with sophisticated ionophoric groups having efficiency to extract oxoanions from aqueous media and, impregnation of p-tert-butylcalix[8]arene derivative onto the polymeric support. Liquid-liquid and solid-liquid extraction experiments have been performed to evaluate the Cr(VI) extraction efficiency of both p-tert-butylcalix[8]arene derivative and the impregnated resin. From the results, it has been deduced that solid-phase extraction method is more convenient and efficient than liquid-liquid extraction process. The impregnated XAD-4 resin has been found regenerable with better extracting efficiency as compared to the simple p-tert-butylcalix[8]areneoctamide ionophore.

Hg(II) Selective Complexation by Chromoionophoric Calix[4]arene Derivative

The present article describes an exploration regarding Hg(II) selective complexation behavior of 5,11,17,23-tetrakis[(N,N-dimethylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (4). The binding affinity of 4 toward selected transition metal ions such as Cd(II), Co(II), Cu(II), Hg(II), Ni(II), Pb(II) and Zn(II) have been investigated by UV-visible and fluorescence spectroscopies. From the results it has been noticed that 4 confers a pronounced preference for Hg(II) in complexation phenomenon even in the presence of other metal ions. The results of Job’s plot analysis reveal 1:1 host-guest complex formation between Hg(II) and 4. The FT-IR spectroscopy also supports the complexation affinity of 4 for Hg(II).

A highly copper selective chromogenic calix[4]arene derivative

In this article, copper selective complexation behavior of 5,11,17,23-tetrakis[(N,N-dicyclohexylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (4) has been explored. Besides this, the binding ability of 4 toward different metal ions such as Cd2+, Co2+, Cu2+, Hg2+, Ni2+, Pb2+ and Zn2+ has been investigated by UV-visible and fluorescence spectroscopies. The chromoionophore 4 shows pronounced selectivity for Cu2+ even in the presence of other metal ions. The results reveal that Cu2+ forms 1 ∶ 1 host–guest complex with 4. The FT-IR spectroscopic method has also been applied for further confirmation of complex formation between 4 and Cu2+ and found to be satisfactory.

Analytical Evaluation of Cu2+ Selective Behavior of calix[4]arene Derivative

The present article describes the solvatochromic effect including solvent system selection, time study and a detailed complexation study along with exploration of extraction properties of 5,11,17,23-tetrakis[(diethylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (4) that bears nitrogen atom as a donor group available for chelating metal ions. Complexation properties of 4 toward selected transition metal ions have been investigated by UV-visible and fluorescence spectroscopies. The% efficiency of 4 toward selected transition metal ions was found in order Cu2+> Ni2+> Hg2+> Zn2+> Co2+> Cd2+> Pb2+. It has been noticed that 4 is not only proved to be an efficient Cu2+ selective chromoionophore but also possesses an effective extraction property for transferring Cu2+ ions from an aqueous to dichloromethane layer. The FT-IR spectroscopic method has also been applied for further confirmation of the complexation phenomenon of 4 with Cu2+ ion and found adequate.

Calix[4]arene Derivative as Copper(II) Carrier in a Bulk Liquid Membrane: A Kinetic Study

A bulk liquid membrane (BLM) experiment was carried out to check the Cu(II) transport efficiency of p-morpholinomethylcalix[4]arene (1) which was used as carrier. Liquid/liquid extraction experiments were also carried out to check the extraction and decomplexation efficiency of carrier 1. It has been observed that the maximum amount of Cu(II) was transported at pH = 12. The mass transfer of Cu(II) was analyzed on the basis of kinetic laws of two consecutive irreversible first order reactions. Thus, the kinetic parameters studied for the transport of Cu(II) were k1, k2, . BLM study revealed that Cu(II) transport increase with increase in concentration of carrier 1 from 1 × 10−5 to 1 × 10−4 M, rise in temperature from 298 to 308 K and at high stirring speed from 90 to 800 rpm. The effect of binary solvents on Cu(II) transport through BLM has also been studied. The values of k1, k2, decrease in the order of dichloromethane-hexane > dichloromethane-diethylether > dichloromethane > dichloromethane-ethylacetate > chloroform. However, dichloromethane was proved as a stable BLM solvent. The activation energy value for the extraction and re-extraction was found as 31.52 and 8.08 kJmol−1, respectively. These values demonstrate that Cu(II) transport is a diffusion controlled process. Thus, 1 was found to be an efficient carrier for Cu(II) transport through BLM.