An approach to the synthesis of chemically modified bisazocalix[4]arenes and their extraction properties

Bisazocalix[4]arenes [N,N′-bis(5-azo-25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene)benzene (1), N,N′-bis(5-azo-25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene)biphenyl (2) and N,N′-bis(5-azo-25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene)-2,2′-dinitro biphenyl (3)] have been synthesized from 25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene by diazocoupling with the corresponding aromatic diamines (p-phenylenediamine, 4,4′-diamino biphenyl and 4,4′-diamino-2,2′-dinitrobiphenyl). Extraction studies of bisazocalix[4]arenes 1, 2, and 3 show no difference in their extraction behavior and selectivity, whereas azocalix[4]arenes are a poor extractant for heavy metal cations. The absorption spectra of the prepared bisazocalix[4]arenes are discussed, both the effect of varying pH and solvent upon the absorption ability of bisazocalix[4]arenes.     

A New Approach to Dendrimers made from p-tert-Butyl Calix[4]arenes

A new family of hyperbranched molecules and dendrimers has been constructed from a diamide–dicalix derivative prepared from monocarbomethoxymethyl p-tert-butyl calix[4]arene and tris(2-aminoethyl)amine (‘tren’) via amide-formation reactions. The selective 1,3-di-O-functionalization of p-tert-butyl calix[4]arene moieties allows the synthesis of first- (G1) and second-generation (G2) calix-dendrimers. Replacement of the quadridentate amine by a trithia-ether-triamine-mono-ol, ’hyten’, again results in acylation of the amino groups, but with the generation of a central cavity with different complexing properties.

A new family of hyperbranched molecules and dendrimers has been constructed from a diamide–dicalix derivative prepared from monocarbomethoxymethyl p-tert-butyl calix[4]arene and tris(2-aminoethyl)amine (‘tren’) via amide-formation reactions. The selective 1,3-di-O-functionalization of p-tert-butyl calix[4]arene moieties allows the synthesis of first- (G1) and second-generation (G2) calix-dendrimers     

Azocalixarenes. 6: Synthesis, complexation, extraction and thermal behaviour of four new azocalix[4]arenes

Four new azocalix[4]arenes {5,11,17,23-tetrakis[(2-hydroxy-5-tert-butylphenylazo)]-25,26,27,28-tetrahydroxycalix[4]arene (1), 5,11,17,23-tetrakis[(2-hydroxy-5-nitro phenylazo)]-25,26,27,28-tetrahydroxycalix[4]arene (2), 5,11,17,23-tetrakis[(2-amino-5-carboxylphenylazo)]-25,26,27,28-tetrahydroxycalix[4]arene (3) and 5,11,17,23-tetrakis[(1-amino-2-hydroxy-4-sulfonicacidnapthylazo)]-25,26,27,28-tetrahydroxycalix[4]arene (4)} have been synthesized from p-tert-butylphenol, p-nitrophenol, p-aminobenzoic acid and 1-amino-2-hydroxy-4-sulphonic acid by diazo coupling reaction with p-aminocalix[4]arene. The resulting ligands (1–4) were treated with three transition metal salts (e.g., CuCl₂·2H₂O, NiCl₂·6H₂O or CoCl₂·6H₂O). Cu(II), Ni(II) and Co(II) complexes of the azocalix[4]arene derivatives were obtained and characterized by UV-vis, IR, ¹H-NMR spectroscopic techniques and elemental analysis. All the complexes have a metal:ligand ratio of 2:1. The Cu(II) and Ni(II) complexes of azocalix[4]arenes are square-planar, while the Co(II) complexes of azocalix[4]arenes are octahedral with water molecules as axial ligands. The solvent extraction of various transition metal cations from the aqueous phase to the organic phase was carried out by using azocalix[4]arenes (1–4). It was found that, azocalix[4]arenes 1, 2 and 3 examined selectivity for transition metal cations such as Ag⁺, Hg⁺ and Hg²⁺. In addition, the thermal stability of metal:azocalix[4]arene complexes were also reported. Dedicated to Prof. Dr. Mustafa Yılmaz on the occasion of his 50th birthday     

Synthesis and structural characterization of a binuclear zirconium complex of tetraanionic p-tert-butylthiacalix[4]arene bridged by methanol

A zirconium complex with the p-tert-butylthiacalix[4]arene anion was synthesized and its crystal structure was determined by single-crystal X-ray analysis. The complex [Zr(μ₂-CH₃OH)(p-tert-butylthiacalix[4]arene)]₂·9H₂O (1) belongs to the orthorhombic system, space group Pnnm, with a?=?20.436(16), b?=?12.160(8), c?=?20.305(12)?Å, V?=?6774(7)?ų and Z?=?2. In Complex 1 zirconium coordinates to four phenolic anions of the deprotonated p-tert-butylthiacalix[4]arene and is bridged by two methanol molecules; the p-tert-butylthiacalix[4]arene adopts a cone conformation.     

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.     

Calixarene Complexes of Anion-bridged Oligouranyl Species

The syntheses and structures of uranyl complexes of p-t-Bu-calix[6]arene (calix[6]H₆) and p-t-Bu-calix[9]arene (calix[9]H₉) are reported, further developing the role of calixarenes as 'cluster keepers'. The calix[6]arene complex, formulated as [(HO){UO₂(calix[6]H₄)(dmso)}₃H], is trinuclear and linked symmetrically by the hydroxyl O atom. The calix[9]arene complex is binuclear, with a carbonate atom bridging between the two uranyl cations to give the complex, (HNEt₃)₃[(OCO₂)(UO₂)₃(calix[9]H₄)].     

Proparacaine complexation with β‐cyclodextrin and p‐sulfonic acid calix[6]arene,as evaluated by varied 1H‐NMR approaches

This study focused on the use of NMR techniques as a tool for the investigation of complex formation between proparacaine and cyclodextrins (CDs) or p‐sulfonic acid calix[6]arene. The pH dependence of the complexation of proparacaine with β‐CD and p‐sulfonic acid calix[6]arene was studied and binding constants were determined by ¹H NMR spectroscopy [diffusion‐ordered spectroscopy (DOSY)] for the charged and uncharged forms of the local anesthetic in β‐CD and p‐sulfonic acid calix[6]arene. The stoichiometries of the complexes was determined and rotating frame Overhauser enhancement spectroscopy (ROESY) 1D experiments revealed details of the molecular insertion of proparacaine into the β‐CD and p‐sulfonic acid calix[6]arene cavities. The results unambiguously demonstrate that pH is an important factor for the development of supramolecular architectures based on β‐CD and p‐sulfonic acid calix[6]arene as the host molecules. Such host–guest complexes were investigated in view of their potential use as new therapeutic formulations, designed to increase the bioavailability and/or to decrease the systemic toxicity of proparacaine in anesthesia procedures. Copyright © 2009 John Wiley & Sons, Ltd.     

New Synthetic Method of p-Nitrocalixarenes

Calixarenes 1 were directly nitrated with potassium nitrate and aluminum chloride to give p-nitrocalixarenes 2 in good yields. Formation of p-nitrocalix[4]arene (2a) from reaction of p-bromomethylcalix[4]arene (3) with silver nitrate is also described.     

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.     

新型大环分子受体: 四同二氧杂杯[6]芳烃衍生物的合成及其络合性质

Several tetrahomodioxacalix[6]arene hexaesters, hexaacid and hexaamide derivatives were synthesized from tetrahomodioxacalix[6]arene by etherification with ethyl bromoacetate. It was found that p-tert-butyltetrahomodioxacalix[6]arene hexaethylester exhibited high selectivity towards lithium ion. p-tert-Butyltetrahomodioxacalix[6]arene hexaamides showed high ion-binding ability towards transition metal ions.     

Synthesis of a glutaraldehyde derivative of calix[4]arene as a cross-linker reagent for lipase immobilization

This article describes the synthesis of a new calix[4]arene 1,3-distal glutaraldehyde derivative 4 as a cross-linker-reagent for immobilization of Candida rugosa lipase (CRL). p-tert-Butylcalix[4]arene 1,3-distal diaminoalkyl derivative (3) synthesized via aminolysis reaction of 5,11,17,23-tert-butyl-25,27-ethoxycarbonylmethoxy-26,28-hydroxycalix[4]arene (2) with 1,8-diaminooctane. Compound 3 was converted to its aldehyde derivative (4) by the treatment with glutaraldehyde solution. 4 was used in lipase immobilization in order to see the role of calix[4]arene binding site on the lipase activity and stability. It was observed that the immobilized lipase activity was maintained at levels exceeding 95% of its original activity after 40 min.     

Synthetic and NMR Studies on Calix[n]Arene (n = 4,6,8) Triflates,Mesylates, and Tosylates

Abstract

The synthesis and full characterization of eight new calix[n]arene sulfonate esters including their conformational analysis were carried out. While p-tBucalix[6]arene and p-tBu-calix[8]arene esters are conformationally labile in the temperature interval of 25–100°C, p-tBu-calix[4]arene mono-and diesters were isolated as stable conformers at ambient temperature. Two 1,3-functionalised compounds of these derivatives, p-tert-butylcalix[4]arene ditriflate (5) and dimesylate (6) were shown unexpectedly high conformational stability up to 100°C by dynamic NMR measurements. The NMR measurements confirm the pinched-cone conformation for both derivatives. For the dealkylated calix[4]arene derivatives the partial cone conformer of the triesters have been obtained as major products in all cases.     

Synthesis and crystal structures of Ag and Hg complexes of bis(N-heterocyclic carbenes) on p-tert-butylcalix[4]arene platform

A series of p-tert-butylcalix[4]arene 1,3-diimidazolium salts were successfully prepared by the alkylation of p-tert-butylcalix[4]arene with dibromoalkanes, and sequential substitution reaction with 1-alkylimidazole. Furthermore, coordination reactions of p-tert-butylcalix[4]arene 1,3-diimidazolium salts with silver oxide and mercury acetate gave novel Ag and Hg complexes of bis(N-heterocyclic carbenes) on p-tert-butylcalix[4]arene platform. The single-crystal structures of four p-tert-butylcalix[4]arene 1,3-diimidazolium salts and three metal complexes were successfully determined by X-ray diffraction. An Ag–Ag argentophilic interaction (Ag–Ag bond length is 3.1599(6) Å) is formed between the two Ag–NHC complexes and a dimetallic coordination mode exists in Hg–NHC complexes.     

Synthesis and Solid-State Conformation of a Calix[8]arene 1,5-Diquinone Derivative

The first example of a calix[8]quinone derivative, hexamethoxy-p-tert-butylcalix[8]-1,5-diquinone 5, has been synthesized from p-tert-butylcalix[8]arene 1by exploiting a protection-deprotection procedure. The structure of the 5·toluene inclusion compound has been determined by a single crystal X-ray diffraction study. The calix[8]arene molecule possesses a crystallographic inversion centre and assumes a ‘pseudo-chair-like’ conformation, with two opposite 3/4-cone moieties, which resembles the previously reported chair-like conformation of p-tert-butylcalix[8]arene. The 4 toluene molecules per unit cell occupy interstitial voids and are released in the temperature range of 30–160 °C.This revised version was published online in July 2005 with a corrected issue number.     

Surfactant Ion Selective Membrane Electrodes

Abstract

Calix[8]arene ethers, carboxylic esters having various p-substituents and acid are synthesized and studied. In a bulk membrane transport of dodecylpyridinium the better carrier is the simplest host, calix[8]arene octamethyl ether. Inversely, it is the worst carrier for dodecyltrimethylammonium; the better here is carboxy ester with adamantyl p-substituents. Various calixarenes are successfully used in plasticized membrane ion-selective electrodes (ISE) for both above ammonium and pyridinium surfactants. Operational characteristics, potentiometric selectivity and optimal membrane compositions are reported. Typical limit of detection is at the level of nx10^?6 - 1x10^?5 M, response time 5-10 s, and lifetime is at least 6 months. ISE's selectivity is significantly better than that of ion-association and crown-ether based electrodes.     

Separation of xylenes by extractive crystallization with calixarenes

Several calixarenes1–5 and benzopinacolone6 were recrystallized from 1:1:1 mixtures of the three xylene isomers.p-Iso-propylcalix[4]arene 1 was shown to extractp-xylene with 86% selectivity.p-Iso-propylbishomooxacalix[4]arene5 extractso-xylene with 84% selectivity.     

基于对叔丁基杯[8]芳烃的3d-5f核簇化合物（MxThy, M=Co、Ni、Zn）的合成、结构与磁性研究

本文以对叔丁基杯[8]芳烃（H₈C₈A）为配体,在溶剂热条件下制得了3个3d-5f化合物,[Co₂Th₄（HC8A）₂O₂（OH）₂（DMF）₆]（1）、[Ni₂Th₅（H₂C8A）（C₈A）O₄（OH）₂（DMF）₅（CH₃OH）₂]（2）、[Zn₂Th₆（HC8A）（C8A）O₅（CH₃O）（C₃H₆NO₂）₂（DMF）₅（CH₃OH）]（3）（其中H₈C8A=对叔丁基杯[8]芳烃,DMF=N,N-二甲基甲酰胺）。X-射线单晶测试表明,这3个化合物均为2个以尾对尾方式排列的杯[8]芳烃分子中间夹1个3d-5f核簇的三明治型结构。杯[8]芳烃均表现为双锥式构型,且每个锥式空腔下缘结合1个钍离子,双锥的连接处及2个杯芳烃分子之间由过渡金属离子或钍离子连接。不同过渡金属离子不同的配位环境导致3种不同核簇的形成。化合物1的磁性研究表明,该化合物在低温下表现出弱铁磁性相互作用。     

Structures and properties of solvated and unsolvated isopropyl functionalised calix[4]arenes

The tetra-isopropyl ethers of calix[4]arene and p-t-butylcalix[4]arene have been isolated in the cone conformation, and structurally characterised as chloroform solvates. Thermogravimetric analysis demonstrated that the parent isopropylcalix[4]arene solvate is significantly more stable than the p-t-butylcalix[4]arene analogue, retaining the solvent up to a temperature of 125°C. It was found that the calix[4]arene ether sublimes at atmospheric pressure, and solvent-free crystals appropriate for structure determination were produced at reduced pressure. The p-t-butylcalix[4]arene ether was also isolated without solvent in the lattice, but in this case the calixarene was crystallised from acetone, as sublimation did not produce crystals of sufficient quality.     

Studies on Properties of p—Nitrophenylazo Calix[4]arene Derivatives

The p-nitrophenylazo calix[4] arene derivatives la-ld with nonlinear optical(NLO)properties were prepared by the diazo-coupling reaction of calix[4]arene with p-nitrophenyl diazonium.The diazotization reaction of p-nltroaniline was caried out with isoamyl nitrite as a source of nitrous acid in EtONa/EtOH under refluxing conditon.X-Ray crystallographic analysis and ^1H NMR sptectra reveal that they exist as cone conformation in crystal state or in soution.HRS measurements at 1064 nm in THF indicate that p-nitrophenylazo calix[4]arenes have higher hyperpolarizability βz values than the corresponding reference compound 4-(4-nitrophenylazo)-2,6-dimethyl-phenol,without red shift of the charge transfer band.The tetrakis p-nitropheylazo calix[4]arene(2)with longer alkyl chains can form monolayer aht the air/water interface.     

Novel PEGylated calix[5]arenes as carriers for Rose Bengal

Amphiphilic PEGylated calix[5]arenes 1 and 2 were obtained in one step from the parent p-tert-butylcalix[5]arene and p-methylcalix[5]arene. Very low critical micellar concentrations (0.5 and 4.5 μM for 1 and 2 respectively) were determined by the Rose Bengal micellization method. Aggregation features were studied by means of ¹H and DOSY NMR as well as by AFM. Release of Rose Bengal from the micellar environment was accomplished by increasing the temperature.