Calix[6]pyrrole and hybrid calix[n]furan[m]pyrroles (n+m=6): syntheses and host-guest chemistry

Calix[6]pyrrole 2 and the "hybrid systems" calix[3]furan[3]pyrrole 12, calix[2]furan[4]pyrrole 13, and calix[1]furan[5]pyrrole 14, have been synthesized by increasing conversion of the furan units present in the readily accessible calix[6]furan 3 to pyrroles. The host-guest chemistry of these novel macrocycles towards a number of anions, including halogen ions, dihydrogen phosphate, hydrogen sulfate, nitrate, and cyanide has been investigated in solution by (1)H NMR titration techniques and/or phase transfer experiments. The solid-state structures of the free receptors 2, 12, and 13, the 1:1 complexes of calix[6]pyrrole 2 with chloride and bromide, and the 1:1 complex of 14 with chloride are also reported.     

杯芳烃偶氮类衍生物对金属离子的萃取作用

通过杯芳烃的酚羟基的直接烃基化反应,在杯芳烃的下缘引入2,3′-二甲基-4-氨基偶氮苯发色团,得到了一系列杯芳烃偶氮衍生物(n=4,6,8)a-c.研究了它们对碱金属,碱土金属及过渡金属等十种金属离子的萃取作用.结果表明此类杯芳烃偶氮衍生物对过渡金属离子有良好的选择性识别作用,其中空腔较大的杯[8]芳烃偶氮衍生物c的萃取效果尤为显著.     

Bridged Calix[6]arenes

Bridging including capping of calix[6]arene is not only an importantroute to synthesize new host molecules, but also an efficient route to reduce the mobility of conformationof calix[6]arene. This article reviews the syntheses, conformations and complexation behavior of this kindof host molecules.     

Synthesis and Properties of a Series of Novel Calix[6]arene Diazo Derivatives

In this study, seven new compounds p-(4-butyl-phenylazo)calix[6]arene(1), p-(4-(phenylazo)phenylazo)calix[6]arene (2),p-(4-hydroxyphenylazo)calix[6]arene (3),p-{4-[N-(thiazol-2-yl)sulfamoyl]phenylazo\}calix[6]arene(4), p-(4-acetamidophenylazo)calix[6]arene (5),p-(thiazol-2-ylazo)calix[6]arene (6) andp-(2-sulfanylphenylazo)calix[6]arene (7) have been synthesizedfrom calix[6]arene by diazo coupling with the corresponding aromaticamines. UV-Vis, IR, ¹H and ¹³C NMR spectral data have been used to elucidate the structures of the compounds elemental analyses     

Regioselective Bridging Calix[6]arenes: Synthesis and X-ray Structure of Trisbridged Calix[6]arene

The preparation and characterization of gold nanoparticles (～6 nm in diameter) modified with mono-6-thio-β-cyclodextrin (II) is described. The resulting monolayer-protected gold nanoparticles are water-soluble and more stable. The concentration of II plays a crucial role for the distribution of the modified nanoparticles. When the ratio of concentration of II to HAuCl₄,[II]/[HAuCl₄] ≥ 0.93, a stable gold nanoparticle with uniform distribution and diameter of 6.0 ± 0.9 nm will be obtained. The recognition of modified gold nanoparticles to organic guest molecule is researched. The modified gold nanoparticles can make the electrochemical reduction current of nitrobenzene decrease and can be self-assembled in three-dimensional to form spherical clusters with ligand of methylene green.     

四对-乙酰胺苯磺酰氧基杯[4]芳烃的合成

以对叔丁基苯酚为起始原料,通过缩合、取代反应合成了25,26,27,28-四对-乙酰胺苯磺酰氧基对叔丁基杯[4]芳烃,其结构经FT—IR,^1H NMR和FAB-MS表征。     

Structural Selectivity of Calix[m]pyrroles[n]furans (m + n = 4) as Ionophores in Ag(I) Ion-Selective Electrodes

A series of octamethylcalix[m]pyrroles[n]furans (m + n = 4), such astrans-octamethylcalix[2]pyrroles[2]furans L ₁ ),cis-octamethylcalix[2]pyrroles[2]furans (L ₂ ) and octamethylcalix[1]pyrrole[3]furans (L ₃ ) have been studied as sensors in liquid membrane ion-selective electrodes for Ag(I) ion. The electrode based on L ₁ , trans-N₂O₂ porphyrinogen, gave the best results with a wide working concentration range of 1.0 × 10^-1 - 1.0 × 10^5.6 M and a Nernstian slope of 57.0 mV/decade. This electrode exhibited a fast response time of 30 s and high selectivity over a number of mono-, di- and tri-valent cations, with only Tl(I) and Hg(II) ion interferences. The effect of anion excluders on the performance of the membrane electrodes has been also studied. The electrode based on L ₁ showed no significant potential changes in the range 2.5 < pH < 7.5. The crystalstructure of L ₃ , NO₃ porphyrinogen, was determined by single crystal X-ray analysis. The crystallographic analysis of L ₃ reveals that its structure is a saddle-shaped 1,3-alternate conformation with enough space to accommodate Ag(I) in the three dimensional cavity.     

Anti-thrombotic Activity of Water-soluble Calix[n]arenes

The parent p-sulfonato-calix[n]arenes and six O-monosubstituted derivatives were investigated in vitro for anticoagulant activity. Different concentrations of calixarenes were tested, showing that the compound 49-mono-(2-carboxymethoxy)-5,11,17,23,29,35,41,47-octa-sulfonato-calix[8]arene (C8SMA) has a significantly strong prolongation on the activated partial thromboplastin time (APTT) and on the thrombin time (TT) than the other calixarenes. Secondly, investigation of whether the anticoagulant behaviour was via interaction with antithrombin or Heparin Cofactor II was determined. Thrombin inhibition mediated by antithrombin (AT) and Heparin Cofactor II (HCII) activation was investigated in comparison to the biological activators, Heparin (Hep) and Dermatan sulfate (DS). The results show that the 49-mono-(2-carboxymethoxy)-5,11,17,23,29,35,41,47-octa-sulfonato-calix[8]arene (C8SMA) and 5,11,17,23,29,35-hexa-sulfonato-calix[6]arene (C6S) produce activation of HCII at 500 μM comparable to that induced by DS at 100 μM. However, activation of AT by all of the investigated calixarenes is between 10 and 50 times lower than that observed in the presence of heparin. The mechanism of the anticoagulant effect of these calixarenes is as activators of HCII and not as activators of AT.in final form: 24 November 2004This revised version was published online in July 2005 with a corrected issue number.     

Anti-thrombotic Activity of Water-soluble Calix[n]arenes

The parent p-sulfonato-calix[n]arenes and six O-monosubstituted derivatives were investigated in vitro for anticoagulant activity. Different concentrations of calixarenes were tested, showing that the compound 49-mono-(2-carboxymethoxy)-5,11,17,23,29,35,41,47-octa-sulfonato-calix[8]arene (C8SMA) has a significantly strong prolongation on the activated partial thromboplastin time (APTT) and on the thrombin time (TT) than the other calixarenes. Secondly, investigation of whether the anticoagulant behaviour was via interaction with antithrombin or Heparin Cofactor II was determined. Thrombin inhibition mediated by antithrombin (AT) and Heparin Cofactor II (HCII) activation was investigated in comparison to the biological activators, Heparin (Hep) and Dermatan sulfate (DS). The results show that the 49-mono-(2-carboxymethoxy)-5,11,17,23,29,35,41,47-octa-sulfonato-calix[8]arene (C8SMA) and 5,11,17,23,29,35-hexa-sulfonato-calix[6]arene (C6S) produce activation of HCII at 500 μM comparable to that induced by DS at 100 μM. However, activation of AT by all of the investigated calixarenes is between 10 and 50 times lower than that observed in the presence of heparin. The mechanism of the anticoagulant effect of these calixarenes is as activators of HCII and not as activators of AT.     

新型杯[4]芳烃衍生物的合成

以对叔丁基杯[4]芳烃为起始原料,通过一步或两步取代反应合成了对叔丁基杯[4]芳烃的衍生物(1和2),其结构经FT-IR,^1H NMR,FAB-MS表征．     

Calculation of 1H chemical shifts of [n]annuleno[m]annulenes and [n]annulenyl[m]annulenes

The ring current and local anisotropic contributions to the ¹H chemical shifts of [n]annuleno[m]annulenes and [n]annulenyl[m]annulenes with n, m = 12, 14, 18 and n, m = 13, 15 are calculated. The agreement between experimental and calculated shifts for the few known compounds is very good so that the predictions for the as yet unknown compounds are reliable. The effect of an annulene ring on the shifts of the protons at the other ring in these bicyclic compounds is discussed for several types of fusion of the two constituent annulenes.     

Preferred Conformations of Calix[4]- and Calix[6]arenes,Calculated ab initio

Ab initio STO-2G calculations showed that the preferred conformation of a series of calix[6]arenes substituted at the upper rim is a compressed cone stabilized by a pseudo-ring of six hydrogen bonds with close characteristics. The endocyclic dihedral angles between the benzene ring planes, characterizing the molecular shape of the above macrocyclic compounds in this conformation, were calculated. The calculation results are consistent with the conformational data obtained by other theoretical methods and describe the characteristics of hydrogen bonds more adequately, in agreement with the experimental data and with the existing concepts of the hydrogen bonding efficiency.     

Association Complexes of Calix[6]arenes with Amino Acids Explained by Energy-Partitioning Methods

Intermolecular complexes with calixarenes are intriguing because of multiple possibilities of noncovalent binding for both polar and nonpolar molecules, including docking in the calixarene cavity. In this contribution calix[6]arenes interacting with amino acids are studied with an additional aim to show that tools such as symmetry-adapted perturbation theory (SAPT), functional-group SAPT (F-SAPT), and systematic molecular fragmentation (SMF) methods may provide explanations for different numbers of noncovalent bonds and of their varying strength for various calixarene conformers and guest molecules. The partitioning of the interaction energy provides an easy way to identify hydrogen bonds, including those with unconventional hydrogen acceptors, as well as other noncovalent bonds, and to find repulsive destabilizing interactions between functional groups. Various other features can be explained by energy partitioning, such as the red shift of an IR stretching frequency for some hydroxy groups, which arises from their attraction to the phenyl ring of calixarene. Pairs of hydrogen bonds and other noncovalent bonds of similar magnitude found by F-SAPT explain an increase in the stability of both inclusion and outer complexes.     

Inclusion of Organic Cations by Calix[n]arenes

Calix[n]arenes represent an interestingclass of preorganized aromatic hostsexhibiting an enhanced ability forcation- interaction. Recent resultsobtained with the complexation of variouscalix[n]arenes and five structural typesof organic cations, namely ammonium ions,quaternary ammonium ions, phosphonium ions,iminium ions and tropylium ions are reviewed.The influence of both the guest structure and theshape and flexibility of the hosts on the complexstability in the gas phase and (mainly) in solutionis considered.     

新型正丁醛杯[4]芳烃醚衍生物的合成

以正丁醛间苯二酚杯[4]芳烃为原料,经酯化、水解、酰氯化后再与9-蒽甲醇反应,合成了蒽单取代的正丁醛间苯二酚型杯[4]芳烃醚衍生物。其结构经1H NMR和IR表征。     

新型主体分子噻唑偶氮基杯[n]芳烃衍生物的合成及其对重金属离子的识别

以2－氨基噻唑为原料，经重氮化－偶联反应合成了5，11，17，23－四（2－噻唑）偶氮基－25，26，27，28－四羟基杯[4]芳烃和5，11，17，23，29，35－六（2－噻唑）偶氮基－37，38，39，40，41，42－六羟基杯[6]芳烃，产物的结构经IR，^1H NMR和元素分析表征；研究了它们的光谱性能和对金属离子的识别状况，发现在pH=7.2的Tris介质中对Ag^ 和Hg^2 等有较好的光谱变化识别。     

Synthesis and metal complexation studies of [2n]thiacalix[m]arene[m]pyrazine

Novel [2_n]thiacalixarenepyrazine and [2_n]thiacalixarenetriazine systems were synthesised by one-pot S_NAr reactions. A screening of the metal-complexing ability of [2₆]hexathiacalix[3]arene[3]pyrazine revealed its affinity for Cu^I, Cu^II and Ag^I metal salts.     

Calix[4]dithiacrown-6 and Its Platinum Complex

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