Synthesis and Crystal Structure of Complex of Sodium Perrhenate with Tetraethyl p-tert-Butylcalix[4]arene Tetraacetate

Recently,theconformationofthecalixarenehasbeenshowntobeimportantincontrollingtheseIectivityofthereceptor.Forexample,sodiumioncouldbeboundverystronglybyesterderivativesofcalix[4]areneintheconeconformationl.Wehavefoundthatinthepresenceofcertainamountofsodiumion,microamountofReO4-canbequantitativelyextractedintol,2-dichloroethanebytheligandtetraethylp-tert-butylcalix[4]arenetetraacetate(L).ItshowsthatthepresenceofNa inaqueoussolutioncanpromotetheformationofhydrophobiccomplex[NaL] .ReO'-whichc…     

Complexation Thermodynamics of p-tert-Butylcalix[4]arene Derivatives with Light Lanthanoid Nitrates in Acetonitrile

Abstract

Calorimetric titrations have been performed for the first time in anhydrous acetonitrile at 25°C to give the complex stability constant (K _S) and thermodynamic quantities for the complexation of light lanthanoid(III) nitrates (La-Gd) with 5,11,17,23-tetra-tert-butyl-26,28-bis(cyanomethoxy)-25,27-dihydroxy-calix[4]arene (1) and 5,11,17,23-tetra-tert-butyl-26, 28-bis(2-aminoethoxy)-25,27-dihydroxycalix[4]arene (2). X-ray crystallographic structures of 1 and 2 were also determined and compared. Possessing the cyanomethoxy and aminoethyl substituents, 1 and 2 displayed strikingly different cation binding abilities and selectivity profiles with much higher K _S values for La³⁺ and Ce³⁺, which may be related to the original structures in the solid state. Thus, the binding profile for 2 showed a rapid decrease in K _S with decreasing ionic diameter from La³⁺ to Pr³⁺ and then became flat up to Gd³⁺, while 1 gave a very flat profile which is superimposable with that for 2 between Pr³⁺-Gd³⁺. Thermodynamically, the complexation is driven absolutely by enthalpy which compensates the entropic loss arising from the structural freezing of the calix[4]arene derivatives upon simultaneous binding of lanthanoid ion by the phenolic oxygen and acetonitrile molecule in the cavity. The general validity and the meaning of the compensative enthalpy-entropy relationship observed are discussed.     

Thiocalix[4] arenes. I. Synthesis and structure of ethylthiocalix[4]arene methyl ether and the related structure of bromocalix[4]arene methyl ether

Bromocalix[4]arene methyl ether serves as a precursor in the synthesis of the title thiocalixarene via the reagent CuSEt. Ethylthiocalix[4]arene methyl ether crystallizes in the monoclinic space groupP2₁/c witha = 20.577(9),b, = 10.722(5),c = 20.315(9) Å, = 120.46(4)°, andD _c = 1.24 g cm^–3 forZ = 4. Refinement based on 1441 observed reflections led toR = 0.080. The configuration of the calixarene lies between the partial cone and the 1,3-altemate conformations. Bromocalix[4]arene methyl ether crystallizes in the triclinic space groupPI witha = 12.283(7),b = 17.658(9),c = 18.118(6) Å, = 90.25(6), = 105.95(4), = 105.11(6)°, andD _c = 1.68 g cm^–3 forZ = 4. Refinement based on 3028 observed reflections led toR = 0.083. The unit cell also contains four CHCl₃ molecules which exist pairwise enclathrated by six calixarenes. The partial cone conformation of the bromocalixarene is identical to that of ethylthiocalix[4]arene methyl ether.     

Synthesis of Flavin–Calix[4]arene Conjugate Derivatives

The synthesis of two new flavin substituted calix[4]arene derivatives, 9 and 10 , is described. The first flavin substituted calix[4]arene derivative 9 was synthesized by the reaction of 3‐methylalloxazine ( 5 ) with 25,27‐bis(3‐bromopropoxy)‐26,28‐dihydroxy‐5,11,17,23‐tetra(tert‐butyl)calix[4]arene ( 4 ) in high yield (92%). The other derivative 10 was prepared from 3‐methylalloxazine‐1‐acetic acid ( 7 ) and 25,27‐bis(3‐cyanopropoxy)calix[4]arene ( 3 ). All new compounds were characterized by a combination of FT‐IR and ¹H‐NMR spectroscopy, and elemental‐analysis techniques.     

以两种杯[4]芳烃衍生物为载体的PVC膜季铵盐正离子选择电极的研究

研究了两种新型杯[4]芳烃衍生物5，ll，17，23-四叔丁基-25，26，27，28-四-[3．(甲氧基羰基)苄氧基]杯[4]芳烃(I)和5，ll，17，23-四叔丁基-25，26，27，28-四-[3-(乙氧基羰基)苄氧基]杯[4]芳烃(Ⅱ)为载体的PVC膜电极的响应行为；实验结果表明，两电极对季铵盐正离子均具有优良的能斯特电位响应性能，以(I)为载体的电极对Bu4N^ 、Et4N^ 和Me4N^ 的线性响应范围分别为10^-6～10^-1mol／L、10^-6～10^-1mol／L和10^-4～10^-1mol／L，相应的斜率为59．2、55．0和55．9mV／pc；以(Ⅱ)为载体的电极对Bu4N^ 、Et4N^ 和Me4N^ 的线性响应范围分别为10^-6～10^-1mol/L，10^-5～10^-1mol/L和10^-4～10^-1mol／L，相应的斜率为59．8、56．6和56．0mV／pc；电极具有读数稳定，重复性好，可在pH值较宽范围内测定等优点；将该电极用于药品溴丙胺太林中丙胺太林含量的测定，所得结果与药典法基本一致。     

单炔基桥联双杯[4]芳烃的合成与对溶剂分子的包合性能

对叔丁基杯[4]芳烃直接与1,4-二氯-2-丁炔反应,一步制备了单炔基单桥联双杯[4]芳烃和单炔基双桥联双杯[4]芳烃,并证实单桥联双杯[4]芳烃是双桥联双杯[4]芳烃的中间产物.经¹HNMR,¹³CNMR和ESI-MS分析证实了产物的结构.ESI-MS结果表明两种产物对DMF和H₂O有不同的包合能力.     

Synthesis and Complexation Properties of Novel Biscalixarene Composed of Calix[4]arene and Thiacalix[4]arene Subunits

Biscalixarenes, as examples of higher order molecular architectures than normal calixarene derivatives, were studied extensively in the recent years due to they possess two calixarene cavities which have the potential for complexing with two guests in two…     

1,3-Disubstituted p-tert-Butylcalix[4]arenes as Cholinesterase Inhibitors

The inhibitory effect of 1,3-substituted p-tert-butylcalix[4]arenes on butyrylcholinesterase from horse serum has been discovered and kinetically investigated with photometric microassay techniques. The interaction of calix[4]arene with the enzyme is described in accordance with the formal kinetics of competitive reversible inhibition. The inhibition constants calculated depend on the substituent in the lower rim of the calix[4]arene and vary in the range of (5–110) × 10^-6 M. The proposed mechanism of inhibition involves the cooperative interaction of indophenyl acetate used as a substrate, calix[4]arene and the enzyme without any covalent or electrostatic binding of the functional groups in the active site of cholinesterase. This results in the coordination of the calixarene on the enzyme surface in the proximity of the enzyme active site. Such interaction prevents the substrate from entering the enzyme active site.     

杯[4]芳烃衍生物的合成和构象研究

以对取代酚亚甲基桥三聚体和２，６－二溴甲基对取代酚为原料，在ＴｉＣｌ４催化下环化得到６种新的含不同取代基［Ｃｌ，Ｂｒ，ＣＨ３，Ｃ（ＣＨ３）３］的杯［４］芳烃衍生物，核磁共振谱研究表明：它们在溶液中的优势构象为锥形构象。     

Synthesis and structures of malonate derivative-calix[4]arene conjugates

A series of novel malonate derivatives-calix[4]arene conjugates were synthesized through Knoevenagel condensation reaction, and the structures of these functionalized calix[4]arenes have been determined     

Aminolysis reaction of calix [ 4 ] arene esters and crystal structures and conformational behaviors of calix[4]arene amides

We first make use of aminolysis of calix[4]arene esters to synthesize calix[4]arene amides. When the two ethyl esters of the calix[4]arene esters are aminolysized, the 1, 3-amide derivative is formed selectively. The crystal structures of the calix-[4]arene with two butyl amide (3b) and four butyl amide moieties (4b) were determined. The intermolecular hydrogen bonds make 4b form two-dimensional net work insolid state. The 1H NMR spectra prove that 3b is of a pinched cone conformation, while 4b and tetraheptylamide-calix[4]arene (6b) take fast interconversion between two C2v isomers in solution and appear an apparent cone conformation at room temperature. As decreasing temperature, the interconversion rate decreases gradually and, finally, the interconversion process is frozen at Tc = -10℃, which makes both conformations of 4b and 6b the pinched cone structures. The hydrogen bond improves the interconversion barrier, and the large different values of the potential barrier between 6b and 4b (or 6b) may     

Calix[4]quinones. Part 4: The ClO2 oxidation of calix[4]arene dialkyl ethers

Except for the special case of calix[4]arene diethyl ether 1, the chlorine dioxide oxidation of dialkyl ethers 2-5 yielded only the corresponding calix[4]diquinone dialkyl ethers 8-11. Chlorine dioxide oxidation of calix[4]arene diethyl ether 1 produced two isomeric products 6 and 7, which were stable enough to be isolated by column chromatography. However, a slow conformational interconversion between isomeric pair 6 and 7 was observed at room temperature, and the equilibrium was reached after 400 h at 18 °C with an amount of 5:3 in favor of syn-isomer.     

Synthesis, Characterisation and UV-Vis Properties of Azocalix[4]crowns

This article describes the synthesis, structure andUV properties of azocalixcrowns in which the photoresponsivetrans-cis azo benzene unit has been introduced in the glycolicchains of the calix[4]crowns. The synthesis proceeded via the selective-1,3O-dialkylation of calix[4]arene with glycolic chains terminated bynitrophenyl residues. After reduction of thenitro groups into amino functions,intramolecular oxidative coupling produced thecapping of the calixarene. Thesynthetic approaches and the cis-transstructure of these new ligandsare discussed and full details on synthesesand structural data are given. Apreliminary example of cesium complexation byone of the ligands is proposed.     

The enhancement of luminescent properties of Tb3+ complexes with tetra-1,3-diketone ligands promoted by the tetrathiacalix[4]arene scaffold

This is the first report on the synthesis and characterization of tetra-1,3-diketone derivatives of tetrthia- and calix[4]arenes substituted by acetylacetonyl or dipivaloylmethanyl moieties at the upper rim and bearing hydroxyl groups at the lower rim as ligands for Tb³⁺ complexes. The spatial structure and tautomeric content for the synthesized ligands have been determined by means of X-ray, IR and NMR spectroscopy. Comparison of the sensitizing properties of tetrathiacalix[4]arenes and their calix[4]arene analogues on the Tb³⁺-centered luminescence in DMF solutions has been performed. A substantial enhancement of the luminescent properties of Tb³⁺- complexes with tetra-1,3-diketone ligands promoted by the tetrathiacalix[4]arene scaffold was established.     

Synthesis and ESR behaviors of nitroxide monoradical based on calix[4]arene

A novel paramagnetic calix[4]arene 6 with an N-O monoradical on the upper rim was synthesized and studied by ESR spectroscopy. Its ESR behaviors were mainly induced by its intrinsic conformational flexibility. The effects of varying temperature and complexation of silver ions on its ESR behaviors were also investigated.     

Calix[4]arene Polyaza Derivatives: Novel Effective Neutral Receptors for Cations and (a)-Amino Acids

Introduction Calixarenes are one of the most important supramolecular building blocks, which can be modified by introducing different functional and/or structrual groups to create a specific interaction between the host and the target molecules, such as metal cations and small organic molecules[1,2]. In particular, the recognition of amino acids is an interesting theme in biomimetic chemistry[3].     

Synthesis of calix[4]arene alkylamine derivatives as new phase-transfer catalysts for esterification reaction

This study reports the synthesis of calix[4]arene-based phase-transfer catalysts derived from the reaction of 5,17-di-tert-butyl-25,27,26,28-tetrahydroxycalix[4]arene with N-ethylpiperazine, diallylamine or 4-benzylpiperidine. The catalytic efficiency of the calix[4]arenes alkylamine derivatives was evaluated by carrying out the ester-forming reaction of alkali metal carboxylates (sodium butyrate or sodium caprylate) with p-nitrobenzyl bromide. It has been observed that the ester-forming reaction of alkali metal carboxylates with p-nitrobenzyl bromide, using the N-ethylpiperazine amine derivative of calix[4]arene as a phase-transfer catalyst in dichloromethane at 25 °C, provided the best yields.     

Comparative study of calix[4]arene derivatives: implications for ligand design

The first comparative theoretical study of three parent calix[4]arene analogues (calix[4]arene, thiacalix[4]arene, and homooxacalix[4]arene) has been performed using molecular dynamic simulations and density functional theory (MPWB1K/6-311G^∗∗//B3LYP/6-311G^∗∗) methods. The theoretical observations herein including optimized geometry, polarity, and atomic charge data provide that homooxacalix[4]arene would offer more efficient platform for metal ion recognition compared to thiacalix[4]arene or calix[4]arene.     

Calix[4]arene Schiff bases—potential ligands for fluorescent studies

A series of novel double-armed calix[4]arene derivatives incorporating imine substituents were synthesised from the Schiff-base reaction of 25,27-bis[2-[(1-formyl-2-phenyl)oxy]ethyl]-p-tert-butylcalix[4]arene (1) with the appropriate amine or hydrazone. All compounds were characterised by various spectroscopic and analytical techniques, and in three cases, by X-ray crystallographic studies. In the case of compound 2, inclusion compounds were synthesised with both m-xylene and dimethylformamide and their X-ray structures revealed these inclusion sites—between the pendant arms and in the upper cavity, respectively. In all cases, the pendant arms are bent away from each rather than adopting a face-to-face conformation.     

Potentiometric sensors based on poly(3,4-ethylenedioxythiophene) (PEDOT) doped with sulfonated calix[4]arene and calix[4]resorcarenes

Potentiometric ion sensors have been prepared by galvanostatic electrosynthesis of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with p-sulfonated calix[4]arene (C[4]S) and p-methylsulfonated calix[4]resorcarenes (R_n[4]S) with alkyl substituents of different chain length (R₁=CH₃; R₂=C₂H₅; R₃=C₆H₁₃). The bowl-shape of these doping ions makes them suitable as ionic recognition sites, and their bulky character is expected to prevent them from leaching out of the conducting polymer membrane. For comparison, sensors based on PEDOT doped with poly(styrene sulfonate) (PSS) and poly(vinyl sulfonate) (PVS) were also constructed. The resulting GC/PEDOT electrodes were conditioned in 0.01 mol L^–1 AgNO₃ and their performance as Ag⁺ ion-selective electrodes (ISEs) studied. Results reveal that selectivity and lifetime of the electrodes is affected by the doping anion structure, although all electrodes show selectivity towards Ag⁺ ions. Interaction of Ag⁺ with sulfur atoms present in the conducting polymer backbone is considered to be the main reason for this behavior. A second set of electrodes was constructed and conditioned in 0.1 mol L^–1 KCl. These electrodes were tested in chloride solutions of quaternary ammonium cations, showing that C[4]S and R₂[4]S exhibit significant sensitivity towards pyridinium.Dedicated to Professor György Horányi on the occasion of his 70th birthday in recognition of his outstanding contributions to electrochemistry