Dominant factors affecting extraction behavior of amino compounds by a calix[6]arene carboxylic acid derivative

A calix[6]arene carboxylic acid derivative was utilized as an extractant for various amino compounds including amino acids. The host compound exhibited a high extractability compared to that of commercially available extractants such as di(2-ethylhexyl)phosphoric acid (D2EHPA). The important factors for amino acid extraction were found to be its cyclic structure and its cavity size, the functional carboxylic groups, and the length of the alkyl chains. The hydrophobicity and the ionic property of guest molecules also affect the extraction efficiency. Calix[6]arene forms a stable complex with a guest molecule by entrapping it into the cavity. The molecular geometries of calixarene before and after extraction were also discussed using computational calculations with the PM3 type of semi-empirical method.     

基于杯芳烃的分子容器的合成及其对有机铵的可逆识别

将三(吡啶基甲基)胺(TPA)引入杯芳烃的下缘, 合成了一种新的具有杯状结构的杯芳烃衍生物, 研究了其对有机铵的分子识别行为.     

Synthesis of Oligomer and Styrene Polymer-supported Calix[4]arene Derivatives and Selective Extraction of Fe3+

Five new polymeric compounds containing more than one calix[4]arene have been synthesized by reacting an oligomer with 5,11,17,23-tetrakis[(diethylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (L1), 25,27-dimethyl-26,28-dihydroxy-p-tert-butylcalix[4]arene diketone (L2), and p-nitrocalix[4]arene (L3), and chloromethylated polystyrene with 25,27-dimethyl-26,28-dihydroxy-p-tert-butylcalix[4]arene diketone (L4) and p-nitrocalix[4]arene (L5). These compounds were studied by the selective extraction of Fe³⁺ cation from the aqueous phase into the organic phase and was carried out by using compounds L1–L5. It was observed that the polymer support attached to the lower rim of p-nitrocalix[4]arene was the most efficient carrier of Fe³⁺ in the extraction process.     

Synthesis of Chiral Calix[4]arene Derivative and Evaluation of its Recognition Properties

The article describes the synthesis and extraction properties of a new chiral calix[4]arene Schiff base ligand 5, which has been synthesized from 5,17-diformyl-25,27-bis-(4-nitrobenzyloxy)-26,28-dihidroxycalix[4]arene (4) by treatment with (S)-(-)-1-phenylethylamine. In this synthesis, it was thought to explore the role of chiral, as well as Schiff base sites in the recognition of targeted species ions (such as dichromate anions) as well as neutral/chiral molecules. At low pH, the ligand 5 is more effective for transferring the dichromate anions from an aqueous into a dichloromethane layer; may be due to the protonation of nitrogen atoms.

The extraction properties of ligand 5 towards the some selected α -amino acid methylesters are also reported. However, the ligand 5 did not display any selectivity towards the selected α-amino acid methylesters.     

Endo-cavity Complexes between Calix[6]arene Dianions and Aliphatic Ammonium Cations: Structure of a Hexylammonium Complex by X-ray Crystallography

The interactions of calix[6]arene and p-tert-butylcalix[6]arene with aliphatic amines in acetonitrile solution were studied by spectrophotometric titrations in the UV region and ¹H NMR spectrometry. Calix[6]arenes can undergo two deprotonations by aliphatic amines and the extent of the second proton transfer is mainly governed by the size of the α-substituent of the amine. ¹H NMR spectra show that the macrocycle adopts a 1,2,3-alternate conformation and that the α-hydrogens of the ammonium ions are shielded by the π-clouds of the aromatic rings. The X-ray crystal structure of the dihexylammonium complex of the p-tert-butylcalix[6]arene dianion, reported here, confirms the 1,2,3-alternate conformation and shows one of the two ammonium moieties encapsulated in the inner cavity of the macrocycle.     

Synthesis of Coumarin-functionalized Calix[4]arene and Selective Recognition for L-Tryptophan

We report a novel calixarene derivative using 4-bromomethyl-7-methoxycoumarin as the pre-organized unit and apply it to investigate selectively discriminate L-tryptophan from other amino acids in DMF-acetonitrile. 5, 11, 17, 23-Tetra-tert-butyl-25,27-bis-…     

An Inherent Chiral Calix[4]arene Bearing Chiral Groups without Forming Sub-ring

Parent calixarenes are inherently highly symmetrical and are, therefore, achiral molecules. Hence, two strategies have been developed to prepare chiral calixarenes. The first method involves the construction of the asymmetric calixarene frame by introduci…     

硫、硒杯[4]芳烃萃取银

以5,11,17,23-四（1,1-二甲基乙基）-25,27-二羟基-26,28-二[（2-乙基硫）乙氧基]杯[4]芳烃（1）和5,11,17,23-四（1,1-二甲基乙基）-25,27-二羟-26,28-二[（2-乙基硒）]乙氧基杯[4]芳烃（2）为萃取剂,研究了在弱酸性条件下杯芳烃衍生物与银的络合行为。杯芳烃衍生物与银形成1：1萃取络合物,在大量碱金属、碱土金属、常见过渡金属离子存在下,对银离子有很高的萃取率和选择性。     

Calix[8]arene anions: solid state structure of an inclusion compound with a tetrabutylammonium cation

Octakis(dimethylsiloxy)-octa-p-tert-butylcalix[8]arene was prepared from the parent p-tert-butylcalix[8]arene and 1,1,3,3-tetramethyldisilazane. Desilylation of the siloxy-calix[8]arene with tetrabutylammonium fluoride hydrate under different conditions afforded di- and tetraanionic derivatives. Determination of the solid state structure of the dianion revealed the formation of an inclusion compound with one tetrabutylammonium cation inside the macrocyclic cavity.     

含腺嘌呤的杯芳烃衍生物的合成、表征及其对核苷碱基的分子识别性质

设计合成了一种新型含腺嘌呤基的杯芳烃衍生物(AC)5,11,17,23-四叔丁基-25, 27-二羟基-26-[1-(9-腺嘌呤)-丙氧基]-28-溴丙氧基杯芳烃, 通过红外光谱、元素分析、核磁共振谱和电喷雾质谱等手段对其进行了表征,确认为目标产物; 并采用紫外分光光度法研究了AC的分子识别作用, 通过测定AC与不同浓度、不同组分的核苷、碱基混合体系的吸光度, 证明了AC对尿嘧啶、尿苷具有分子识别作用, 能从其它核苷或碱基共存的体系中将尿苷或尿嘧啶识别出来.     

Inclusion Complexation of Diphenylamine-4-diazonium Chloride and p-Sulfonatocalix[4]arene

Inclusion complexation of p-sulfonatocalix[4]arene (SC4A) and diphenylamine-4-diazonium chloride (DDC) in aqueous solution was investigated in this study. The inclusion of DDC in the cavity of SC4A leads to ¹H NMR chemical shifts of DDC moving towards higher magnetic field. The complexation of SC4A also results in a bathochromic shift and a decrease in optic intensity of the absorption spectrum of DDC. In the presence of SC4A, the thermal stability of DDC in aqueous solution increases significantly while its photosensitivity still remains high.     

A characteristic effect of pressure on inclusion complexation of phenothiazine dyes with p-sulfonatocalix[6]arene in a room-temperature ionic liquid

The inclusion complexation of p-sulfonatocalix[6]arene (Calix-S6) with three kinds of phenothiazine dyes was studied spectrophotometrically in a mixture of a room-temperature ionic liquid [bmim]BF₄ (1-butyl-3-methylimidazolium tetrafluoroborate) and ethanol. We have determined the association constants of Calix-S6 with phenothiazine dyes under external static pressure up to 767 bar in the [bmim]BF₄-ethanol and alcohol-water mixtures. With increasing external pressure, the inclusion equilibrium in the alcohol-water mixtures was shifted to the dissociation side. Conversely, the inclusion equilibrium of methylene blue (MB) and azure A (AA) in the ionic liquid mixture was shifted to the association side. From the analysis of the pressure effects, the reaction volumes ΔV for inclusion complexation were estimated as −7 to 9 cm³ mol⁻¹ in the [bmim]BF₄-ethanol mixture and 20–32 cm³ mol⁻¹ in the alcohol-water mixtures. Based on the results, we have suggested that there is a competing complexation between the included dye and [bmim]BF₄ molecules in the ionic liquid.     

Protein Dimerization on a Phosphonated Calix[6]arene Disc

Complex formation between cationic cytochrome c and the water‐soluble, poly‐anionic p ‐phosphonatocalix[6]arene (pclx₆) was investigated. A crystal structure (at 1.8 Å resolution) revealed a remarkable dimeric disc of pclx₆ that acts like glue to mediate a symmetric (C ₂) protein dimer. The calixarene disc has a diameter of about 1.5 nm and masks about 360 Ų of protein surface. The key protein–calixarene contacts occur via two linchpin lysines, with additional contacts provided by a small hydrophobic patch. The protein–calixarene supramolecular assemblies were observed in solution by size‐exclusion chromatography with multi‐angle light scattering and NMR spectroscopy. Using isothermal titration calorimetry and NMR data, an apparent K _d in the low micromolar range was determined for the charge‐rich protein–calixarene complex. In contrast to p ‐sulfonatocalix[4]arene, the larger pclx₆ has a single, well‐defined binding site that mediates the assembly of cytochrome c in solution.     

Di-ionizable p-tert-butylcalix[4]arene-1,2-monothiacrown-3 ligands in the cone conformation: synthesis and metal ion extraction

A series of di-ionizable calix[4]arene-1,2-crown-3 compounds with a sulfur-containing unit bridging the proximate phenolic oxygens have been synthesized. The ionizable groups are oxyacetic acid and N-(X)sulfonyl oxyacetamide groups with X=methyl, phenyl, 4-nitrophenyl, and trifluoromethyl, which ‘tunes’ the acidity of the latter. The efficiency and selectivity of these novel ligands are assessed for competitive solvent extractions of alkali metal cations and of alkaline earth metal cations from aqueous solutions into chloroform. Also the efficiencies for single species extractions of Pb²⁺ and of Hg²⁺ are determined. The results are compared with those reported previously for related ligands in which only oxygen heteroatoms are present in the crown ether unit.     

An Interesting Approach to Bis-calix[5]arene Analogue from Calix[6]arene

Calix [n] arenas {n = 4, 6 or 8} are easily prepared from formaldehyde and para-substituted phenols via cyclic condensation under alkaline conditions in one step. It is not surprising that the calyx [n] arene (n = 4, 6, 8) chemistry has been developing very rapidly during the latest 20 years1. However, it is not the case for calixarenes with odd benzene rings (for example, n = 5). The yield of p-tert-butylcalix [5] arene synthesized in one-step from p-tert-butylphenol and formaldehyde was a…     

Calix[4]dithiacrown-6 and Its Platinum Complex

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First Synthesis and Properties of Calix[4]arene with Two Alternately Arranged Phloroglucinols and Two p-tert-Butylphenols

The Calix[4]arene 1 including two alternately arranged phloroglucinols and p-tert-butylphenols was synthesized via the “3+1” coupling procedure, and its pKa values were estimated to be 3–4 and 7.5, while those of the other six phenolic hydroxyls were approximately 11. Its UV–vis spectrum at pH 11 and ¹H and ¹³C NMR spectra in NaOD-D₂O solution (pH 12.8) showed a dramatic change like those of the phloroglucinol when compared to those in acidic or neutral solution, which suggests a change in the phloroglucinol moiety to the keto-form. During the solvent extraction for alkali metal species using 1, Li⁺ was only extracted in the low yield of 15% at pH 11. The cyclic voltammetry study of 1 was used to compare it with the phloroglucinol and p-tert-butylphenol. The redox potential of the corresponding two phloroglucinols was observed in 1.     

Di-ionizable calix[4]arene-1,2-crown-5 and -crown-6 ethers in cone conformations: synthesis and divalent metal ion extraction

Two series of di-ionizable calix[4]arene-1,2-crown-5 and -crown-6 ethers in cone conformations are synthesized. The ionizable groups are oxyacetic acid moieties and N-(X)sulfonyl oxyacetamide units with X=methyl, phenyl, 4-nitrophenyl, and trifluoromethyl, which ‘tunes’ their acidity. For competitive solvent extraction of alkaline earth metal cations from aqueous solutions into chloroform, the new ligands with N-(X)sulfonyl carbamoyl groups are efficient extractants with Ba²⁺ selectivity. On the other hand, the dicarboxylic acid analogues exhibit little selectivity in extraction of alkaline earth metal cations. For single species extractions of Pb²⁺, the ligands with both types of ionizable groups show very good extractions abilities. In single species extractions of Hg²⁺, the N-(X)sulfonyl carboxamide ligands are highly efficient, in contrast to the dicarboxylic acid compounds. Influences of the ionizable group identity, the crown ether ring size, and the presence of upper-rim p-tert-butyl groups on divalent metal ion extraction are explored.