Exploration of Pb2+ Selective Behavior of Calix[6]arene Ester Derivative

The selective behavior of calix[n]arene ester derivatives in two-phase extraction systems using polarographic technique has been investigated. Calix[4]arene tetraester derivative shows remarkable Na⁺ over Pb²⁺ selectivity; whereas calix[6]arene hexaester derivative shows Pb²⁺ over Na⁺ selectivity. The interference of some selected cations (Na⁺, K⁺, Cu²⁺ and Mg²⁺) were also examined and no significant effect on the selectivity behavior as well as extraction ability of these ionophores was found except Na⁺. The study reveals for the first time that the calix[6]arene hexaester derivative is highly Pb²⁺ selective ionophore and can be employed in the field of sensor as well as separation science and technology. The work also highlights the usefulness of polarographic technique in trace metal determination.     

Quantum simulation on donor and acceptor II calix[4]arene substrate and alkali metal ions: the driven inclusion

The energetic and structural optimized of a calix[4]arene with and without alkali-metal cations are presented with performance of various quantum chemical methods such as Hartree--Fock, second order Møller-Plesset perturbation theory, and density functional theory. The geometry optimizations have been carried out with the 3-21G (Li⁺--Cs⁺) and 3-21G(d,p) (Li⁺--K⁺) and the 3-21G basis sets for Cs⁺ and Rb⁺. Additional single-point energy ab initio calculations for Li⁺–K⁺ were carried out at HF/6--31G, HF/6-31G (d,p), HF/6--311G(d,p) for complexes of Li⁺ and Na⁺. The calculations were carried out to analyze the complexation of calix[4]arene with alkali metal cationic species (Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺). Assumption to isolate the effects of the aromatic core and cation-π interactions. Particular emphasis has been on conformational binding selectivity and the structural characterization of the complexes, the smaller cation as Li⁺ and Na⁺ has been placed in the lower rim's of the calix[4]arene's cavity. The large cations like K⁺, Rb⁺, and Cs⁺ take placed in upper rim and the endo (inclusive) complexation is driven by cation-π interactions, that reflect a superior interaction with two phenol rings. The endo complexation of Cs⁺ with calix[4]arene is in agreement with X-ray diffraction data. The binding modes of calixarene-cation systems are studied to involve cooperative effects between cation-π and electrostatic forces.     

Hydrophobically modified poly (acrylic acid) using calix[4]arene derivative. Ionophoric properties and extraction abilities toward alkali metal cations

p‐t‐Butyl calix[4]arene diol (distal cone) (1) was grafted with poly (acrylic acid) (PAA) to obtain hydrophobically modified PAA (PAA‐C) bearing calixarene moieties. The grafting method includes the direct esterification reaction of PAA with calixarene diol 1 which was carried out in a system of tosyl chloride (TsCl), pyridine (Py), and N,N‐dimethylformamide (DMF). The grafting yield was studied using different molar ratios of PAA to calix[4]arene diol 1, temperature, and reaction time. The chemical composition of the PAA‐C was studied by IR and ¹H NMR spectroscopy. Also, the morphology of PAA‐C was evaluated by scanning electron microscopy. The PAA‐C had different solubility and thermal properties. The extraction ability measurements of modified PAA toward alkali metal cations (Na⁺, K⁺, Cs⁺) and Ag⁺ showed a remarkable efficiency and selectivity of PAA‐C toward Na⁺. The main goal of this work was to design hydrophobically modified PAA with binding ability that is suitable for ion selective membranes and chemical sensor devices such as ion‐specific electrodes, semipermeable membranes, and quartz microbalances. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis of novel p-tert-butyl-calix[4]arene derivatives and their cation binding ability: chromogenic effect upon side arms binding

A series of novel double-armed calix[4]arene derivatives, i.e. 5,11,17,23-tetra-tert-butyl -25,27-bis[2-[(2-hydroxy-5-(4-nitroazo)benzylidene)amino]ethoxy]-26,28-dihydroxy-calix[4]-arene (4), 5,11,17,23-tetra-tert-butyl-25,27-bis[2-[(2-hydroxy-5-(2-nitroazo)benzylidene) amino]ethoxy]-26,28-dihydroxycalix[4]arene (5), 5,11,17,23-tetra-tert-butyl-25,27-bis[2-[(2-hydroxy-5-(4-chloroazo)benzylidene)amino]ethoxy]-26,28-dihydroxycalix[4]arene (6), have been synthesized as an selective chromoionophore for Na⁺. The complexation behavior of ligands 4-6 with alkali metal ions Na⁺, K⁺, Rb⁺and Cs⁺ has been evaluated by using UV-Vis spectrometry in CH₃CN-H₂O (99:1/V:V) solution at 25°C. The UV-Vis spectra show that the complexation of 4-6 with Na⁺exhibits obvious bathochromic shifts (λ_max 379→480 nm) and there is a unique color change in the solution from yellow to red upon complexation. The binding constants for Na⁺ are higher than that of other alkali metal ions, giving the highest cation selectivity up to 7 for Na⁺/K⁺. The binding ability and photophysical behavior of alkali cations by calix[4]arene derivatives 4-6 are discussed from the point of view of substituted effects at the lower rim of parent calix[4]arene and size-fit concept between host calix[4]arenes and guest cations.     

Stilbene-bridged 1,3-alternate calix[4]arene crown ether for selective alkali ion extraction

A series of stilbene-bridged calix[4]arenes was synthesized through an intramolecular reductive McMurry coupling of bisbenzaldehyde calix[4]arene in high yields. Tetra- and pentaethylene glycol chains were tethered to the phenolic groups of calix[4]arene to form stilbene-bridged calix[4]arene crown-5 and crown-6, respectively. The presence of stilbene bridge over the calix[4]arene rim effectively prevented the connection of the polyether chains in the cone conformation resulting in the exclusive formation of 1,3-alternate stilbene-bridged calix[4]arene crown product. Compared to the cone analogues, the 1,3-alternate calix[4]arene crown ethers showed a greater extraction ability and selectivity toward Cs⁺.     

Synergistic extraction of cesium,strontium, and europium with adamantylated thiacalix[4]arenes in the presence of chlorinated cobalt dicarbollide

Synergistic extraction of long-lived fission products ¹³⁷Cs⁺, ⁸⁵Sr²⁺, and ¹⁵²Eu³⁺ from dilute HNO3 into dichloroethane with ligands derived from p-(1-adamantyl)thiacalix[4]arene in mixtures with chlorinated cobalt dicarbollide was studied. An extraordinary synergistic effect is observed in extraction of europium with p-(1-adamantyl)thiacalix[4]arene tetraacetate derivative. Amides of p-(1-adamantyl)thiacalix-[4]arene tetracarboxylic acid are selective toward europium, although their extraction ability toward the examined ions is lower than that of the classical extractant, p-(1-adamantyl)calix[4]arene tetracarboxylic acid diethylamide.     

Synthesis and complexation study of calix[4]arene diamine derivative incorporated in a polymeric backbone with chiral monomers

The novel chiral polymeric compounds containing more than one calix[4]arene have been synthesized by reacting a new calix[4]arene diamine derivative with two chiral monomers. These newly prepared compounds were studied by extraction of toxic heavy metal (Cu²⁺, Co²⁺, Cd²⁺, Hg²⁺), silver and alkali metal (Na⁺, K⁺) cations from aqueous phase. It was observed that the resulting calixarene-based polymers have a good complexing ability towards silver, alkali metal and toxic heavy metal cations.     

Synthesis of nucleobase-calix[4]arenes via click chemistry and evaluation of their complexation with alkali metal ions and molecular assembly

In this study, calix[4]arene derivatives (11–14) bearing a single nucleobase (adenine, thymine, cytosine or guanine) were synthesised via click chemistry. The complexation ability of the synthesised derivatives with alkali metal ions was measured using MALDI-TOF mass spectrometry, and their molecular assembly in CDCl₃ was determined using ¹H NMR. Calix[4]arene derivatives (11–14) formed 1:1 complexes with all alkali metal ions and the rank order for the complexation selectivity was Rb⁺ > Cs⁺ > K⁺ ? Na⁺ > Li⁺. The attachment of nucleobase at the upper rim of calix[4]arene had little effect on its complexation selectivity for alkali metal ions. Thymine-, adenine- and guanine-calix[4]arenes formed self-assembled structures in CDCl₃ via base–base interactions. In addition, adenine-calix[4]arene (11) bound to thymine-calix[4]arene (12) to form a discrete species via Hoogsteen hydrogen bonding.     

Silver(I)‐Selective PVC Membrane Potentiometric Sensor Based on a Recently Synthesized Calix[4]arene

A new PVC membrane potentiometric sensor for Ag(I) ion based on a recently synthesized calix[4]arene compound of 5,11,17,23‐tetra‐tert‐butyl‐25,27‐dihydroxy‐calix[4]arene‐thiacrown‐4 is developed. The electrode exhibits a Nernstian response for Ag(I) ions over a wide concentration range (1.0×10^?2?1.0×10^?6 M) with a slope of 53.8±1.6 mV per decade. It has a relatively fast response time (5–10 s) and can be used for at least 2 months without any considerable divergence in potentials. The proposed electrode shows high selectivity towards Ag⁺ ions over Pb²⁺, Cd²⁺, Co²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Sr²⁺, Mg²⁺, Ca²⁺, Li⁺, K⁺, Na⁺, NH₄⁺ ions and can be used in a pH range of 2–6. Only interference of Hg²⁺ is found. It is successfully used as an indicator electrode in potentiometric titration of a mixture of chloride, bromide and iodide ions.     

Spectrophotometric studies of alkali and alkali earth metal ions complexes of mono amino derivative of calix[4]arene

The synthesis and complexive abilities of 5,11,17-tris(tert-butyl)-23 amino-25,26,27,28-tetra-propoxycalix[4]arene towards alkali cations Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺ and alkali earth cations Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺ in methanol-chloroform mixture have been evaluated at 25°C, using UV-Vis spectrophotometric techniques. The results showed that the ligand is capable to complex with all the cations by 1: 1 metal to ligand ratios. The selectivity presented considering the calculated formation constants are in the order Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺ and Mg²⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺ with the ligand.     

A tetraester derivative of fluorescent calix[4]arene bearing a proton-ionizable moiety for highly sensitive extraction-fluorometric determination of sodium ion

In this study, we report the highly sensitive extraction-fluorometric detection system of Na⁺ using flow injection analysis with a tetraester derivative of fluorescent calix[4]arene. In liquid-liquid extraction experiments, the fluorescent intensity of calix[4]arene derivative 1 bearing a p-nitrophenol moiety was highly dependent on pH and the Na⁺ concentration in the aqueous phase. On the other hand, such phenomenon was not observed in the case of calix[4]arene derivative 2, which is almost the same structure as 1 except for a p-nitrophenol moiety. These results show that the proton dissociation of the p-nitrophenol moiety decisively affects the fluorescence intensity of 1. Owing to these fluorescence responsiveness, a calibration graph of the Na⁺ concentration could be successfully prepared using flow injection analysis with good linearity at the tens of nanomolar level. The tetraester scaffold of calix[4]arene was essential to the detection of Na⁺ in such a very low concentration range.     

Synthesis of calix[4]arene(amido)monocrowns and their photoresponsive derivatives

A series of new calix[4]arene(amido)mono-crown compounds have been synthesized through aminolysis of calix[4]arene esters and intramolecular cyclization of the intermediates. The title compounds were converted into their nitro and azo substituted derivatives to provide novel photoresponsive molecular receptors for transition metal ions. Single crystal X-ray analysis of calix[4]arene(ethyleneamido)mono-crown (2a) revealed that the compound is present in a cone conformation with an amido loop that caps the lower rim of calix[4]arene cavity to result in stacking along axis a and axis c to provide supramolecular aggregates in the solid state. Evaluation of synthesized macrocycles in the solution phase for recognition of transition metal cations (Cr³⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Cd²⁺, Pb²⁺, Hg⁺, Hg²⁺, Pd²⁺, and Pt²⁺) by UV-visible spectroscopy revealed that p-tert-butyl-calix[4]arene mono-(amidocrown) 1c selectively shows a blue shift at 38 nm on interaction with Hg⁺ ions.     

杯芳烃接枝超细SiO2的制备及其对Cu2+、Ag+萃取性能的研究

通过对杯[4]芳烃以及杯[6]芳烃上缘进行烯丙基化和硅氢加成2步衍生化反应得到硅氢化杯[4]芳烃以及硅氢化杯[6]芳烃,再将这2种硅氢化杯芳烃衍生物分别接枝到超细SiO₂上。在不同的pH值条件下,就2种杯芳烃接枝超细SiO₂衍生物对水合Cu²⁺及Ag⁺的萃取性能进行了研究。结果表明,与对叔丁基杯芳烃相比较,杯芳烃接枝超细SiO₂衍生物对Cu²⁺和Ag⁺的萃取率都有所提高,其中杯[4]芳烃接枝超细SiO₂对Ag⁺的最高萃取率达到98.78%,杯[6]芳烃接枝超细SiO₂对Cu²⁺的最高萃取率达到67.74%。     

Complexation of alkali metal cations by calix[4]Arene-bis-crown-6 in methanol,acetonitrile and propylene carbonate

Résumé The interactions of Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺ with the double-crown calix, calix[4]arene-bis-crown-6, have been studied in methanol, acetonitrile, and propylene carbonate at 25°C using precise conductivity measurements. For Li⁺ and Na⁺ in solutions containing this calix[4]arene, only 1:1 cation:ligand complexes are formed which permit the determination of the thermodynamic complexation formation constants,K _f. The conductivity data strongly suggest that 2:1 cationcalixarene complexes form with K⁺, Rb⁺, and Cs⁺. The existence of 2:1 complexes was experimentally confirmed for the potassium systems by a mass spectroscopic method.     

Metal ion complexation in acetonitrile by upper-rim allyl-substituted, di-ionized calix[4]arenes bearing two dansyl fluorophores

The influence of Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Ag⁺, Cd²⁺, Co²⁺, Fe²⁺, Hg²⁺, Mn²⁺, Pb²⁺, Zn²⁺ and Fe³⁺ on the spectroscopic properties of two dansyl (1-dimethylaminonaphthalene-5-sulfonyl) groups linked to the lower rims of a series of three, structurally related, di-ionized calix[4]arenes is investigated by means of absorption and emission spectrophotometry. Di(tetramethylammonium) salts of the di-ionized ligands, L, L1, and L2, which differ in having no, two and four allyl groups, respectively, on the upper rim of the calix[4]arene scaffold, are utilized for the spectrofluorimetric titration experiments in MeCN. On complexation by alkaline earth metal cations, the emission spectra undergo marked red shifts and quenching of the dansyl fluorescence. These effects are weaker with alkali metal cations. Transition metal cations and Pb²⁺ interact strongly with the ligands. In particular, Fe³⁺, Hg²⁺ and Pb²⁺ cause greater than 99% quenching of the dansyl fluorescence.     

Cation transport at 25°c from binary Na+Mn+, Cs+Mn+ and Sr2+Mn+ nitrate mixtures in a H2OCHCl3H2O liquid membrane system containing a series of macrocyclic carriers

Cation fluxes from binary mixtures of either Na⁺, Cs⁺ or Sr²⁺ with other alkali metal cations, alkaline earth metal cations, and Pb²⁺ through a H₂OCHCl³H₂O bulk liquid membrane system containing one of several macrocyclic carriers have been determined Nitrate salts were used in all cases. The most selective transport of Na⁺ over all other cations studied was found with the carrier cryptand [2.2.1]. Selective transport of Na⁺ relative to Li⁺, Cs⁺ and the alkaline earth cations was found with cryptand [2.2.2B] and cryptand [2.2.2D]. The ligands 21-crown-7 and dibenzo-24-crown-8 showed selective transport of Cs⁺ over the second cation in all cases. Several macrocycles showed selectivity for Sr²⁺ over the second cation with the macrocycle 1,10-diaza-18-crown-6 showing the highest selectivity for this cation of all ligands studied. Relative fluxes from binary cation mixtures are rationalized in terms of macrocycle cavity size, donor atom type and ring substituents.     

Aminopyridyl derivative of thiacalix[4]arene-carboxylic acid as ionizable highly selective Ag+ ionophore

A novel mono-ionizable receptor 2 possessing three aminopyridyl and one carboxylic group in 1,3-alternate conformation based on thiacalix[4]arene, confirmed by single crystal X-ray analysis, was prepared. For competitive solvent extraction of alkali metal (Na⁺, K⁺ and Cs⁺) and some transition metal (Cu²⁺, Zn²⁺, TI⁺, Ag⁺) cations from aqueous solutions into chloroform, it was found that the introduction of proton-ionizable group (carboxylic acid moiety) into the aminopyridyl-thiacalix[4]arene derivative could further improve its Ag⁺ extractability with high selectivity.     

Novel Ca-selective merocyanine-type chromoionophore derived from calix[4]arene-diamide

The synthesis and calcium-selective chromogenic ion binding properties of benzothiazolium derivative of calix[4]arene are described. The merocyanine-type ionophore derived from calix[4]arene-diamide showed selective chromogenic properties toward Ca²⁺ ions in aqueous methanol. The compound showed significant Ca²⁺ ion dependent changes in UV-vis spectral properties in the presence of other physiologically important metal ions (Na⁺, K⁺, and Mg²⁺). The pH sensitive chromogenic behavior also suggests that the compound can be used as a sensitive pH indicator around pH 6.5.     

Metal ions recognition by 1,2,3-triazolium calix[4]arene esters synthesized via click chemistry

Two triazole-modified calix[4]arene diesters were synthesized via Huisgen 1,3-dipolar cycloaddition between azides esters and alkynylcalixarenes. Their structures had been deduced from ¹H NMR, element analysis and ESI-MS. Two-phase extraction experiments indicated that triazole-modified calix[4]arene diethylester 3a exhibited Cs⁺ selectivity.     

Metal ion complexation in acetonitrile by di-ionized calix[4]arenes bearing two dansyl fluorophores

The influence of metal cations (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Ag⁺, Cd²⁺, Co²⁺, Fe²⁺, Hg²⁺, Mn²⁺, Pb²⁺, Zn²⁺ and Fe³⁺) on the spectroscopic properties of two dansyl (1-dimethylaminonaphthalene-5-sulfonyl) groups linked to the lower rims of a series of three, structurally related, di-ionized calix[4]arenes was investigated by means of absorption and emission spectrophotometry. Di(tetramethylammonium) salts of the di-ionized ligands, (TMA)₂L1, (TMA)₂L2 and (TMA)₂L3, which differ in having zero, two and four tert-butyl groups, respectively, on the upper rim of the calix[4]arene scaffold were utilized for the spectrofluorimetric titration experiments in acetonitrile. On complexation by alkaline earth metal cations, both the absorption and emission spectra undergo marked red shifts and quenching of the dansyl fluorescence. These effects are weaker with alkali metal cations. Transition metal cations interact strongly with the ligands. In particular, Fe³⁺, Hg²⁺ and Pb²⁺ cause greater than 97% quenching of the dansyl fluorescence in the di-ionized ligands.