Cation- and anion-assisted binding of triethylenediamine by zinc bisporphyrinates

The complexation of zinc calix[4]arene or calix[4]pyrrole bisporphyrinates with alkali metal cations, halide anions, and triethylenediamine was studied by ¹H NMR spectroscopy. It was established that the binding of molecules and/or charged particles by various fragments of calix[4]arene and calix[4]pyrrole porphyrins are interrelated processes. This makes it possible to use one process (for example, complexation of the calix[4]arene fragment of the macrocycle with alkali metal cations or complexation of the calix[4]pyrrole fragment with halide ions) as a tool for controlling another process (complexation of the porphyrin fragments of the macrocycle with neutral molecules).     

Anion-dependent binding of zinc calix[4]pyrrole-bisporphyrinate triethylenediamine

The complexation properties of zinc 10,20-bis[5-(2,3,7,8,12,13,17,18-octaethylporphyrinate)ethynylphenyl]-5,5′,10′,15,15′,20′-hexamethylcalix[4]pyrrole toward halide ions, triethylenediamine, and 4,4′-bipyridyl were studied by spectrophotometric titration and ¹H NMR spectroscopy. The influence of binding of anions (F⁻ and Cl⁻) by the calix[4]pyrrole fragment of zinc calixpyrrole-bisporphyrinate on the complexation properties of its interporphyrin cavity toward the bidentate organic ligand triethylenediamine.     

Calix[4]tubes: a new class of potassium-selective ionophore

A new class of cryptand-like ionophore based on a bis calix[4]arene structure has been developed. These molecules proved highly selective for complexation of potassium over all group I metal cations and barium. A range of symmetric and asymmetric calix[4]tubes featuring either alkyl or phenyl substituents at the upper rim have been synthesized in exceptional yield. Alteration of the calix[4]arene upper rim environment enables fine-tuning of the rate of potassium uptake, which can be evaluated through the conformational change on binding by NMR studies. Selectivity of potassium complexation has been demonstrated using NMR and electrospray mass spectral techniques. Molecular modeling studies, derived from crystallographic data, confirm that the potassium metal cation is complexed via the axial route, passing through the calix[4]arene annulus, and provide evidence for complexation rate and selectivity.     

含酰胺和席夫碱单元的杯[4]芳烃衍生物的合成与配合性能

杯[4]-1,3-二乙酸乙酯衍生物1与水合肼反应生成杯[4]芳烃酰肼衍生物2, 然后进一步与相应的芳醛反应, 高产率地合成了三个新型的含酰胺和席夫碱单元的杯[4]芳烃衍生物3a～3c和一例新型杯[4]冠醚4. 阳离子萃取实验表明新型杯芳烃衍生物比只含有酰胺基或席夫碱基的杯芳烃衍生物有更强的软金属离子配合性能, 杯[4]冠醚4还对Ag^＋有较好的选择性萃取能力.     

Potassium selective calix[4]semitubes

A new class of ionophore consisting of two calix[4]arene units linked through the lower rim by two ethylene chains, in combination with propyl ether and phenolic functional groups, has been developed. These calix[4]semitube molecules exhibit remarkable selectivity and fast complexation kinetics for potassium over all Group 1 metal cations. Molecular modelling studies, using structural models derived from crystallographic data, suggest the potassium cation is complexed by a horizontal, side-on route and not through the calix[4]arene annulus. The length of the bridging alkylene chain between the respective calix[4]arenes of the semitube structure dictates the strength and selectivity of alkali metal cation binding.     

邻甲氧基羰基苄氧基取代杯[4]芳烃衍生物的合成及其性？…

杯芳烃是继冠醚、环糊精之后的第三代主体分子 [1] .据文献 [2 ,3]报道 ,在杯 [4]芳烃下沿酚氧原子上连接乙酸酯得到的四取代衍生物对 Na+ 有很高的选择性 ,核磁与晶体结构研究均证实这是由于羧酸酯的羰基和酚氧基参与了对 Na+ 的配位 ,而且配位基团所形成的包络空间大小与钠离子相匹配 .一般认为 ,随着包络空间改变 ,对金属离子的识别作用会有所变化[4] .但目前对这方面的工作并没有给予更多的重视 .我们发现 ,用 2 -溴甲基苯甲酸甲酯与杯 [4 ]芳烃反应 ,得到了一种新的四取代杯 [4]芳烃衍生物 2 ,萃取研究结果表明 ,该化合物对钾离子有较…     

新型杯[4]芳烃氨基苯酚类衍生物的合成及对La3 的选择性识别

设计合成了下缘连有氨基苯氧基结构的杯[4]芳烃衍生物:5,11,17,23-四叔丁基-25-[2-(2-氨基苯氧基)乙氧基]-27-(2-羟基乙氧基)-26,28-二羟基杯[4]芳烃(化合物C),增加了与阳离子的结合位点,有利于通过配位作用对金属离子进行识别。化合物C的结构通过红外光谱、1H NMR、13C NMR和质谱进行了表征。通过紫外可见光谱和荧光发射光谱对化合物C与24种金属阳离子的络合作用进行了研究,结果发现,其对La3+有特殊的识别作用,化合物C与La3+的络合比为1∶1。     

Investigation of Metal Ion Complexation of π-Coordinate Calixarene Derivatives by Electrospray-Ionization Mass Spectrometry

Complexation of π-coordinate calix[4]arene derivatives toward soft metal ions, silver and thallium (I) ions, has been studied by electrospray-ionization mass spectrometry. Competitive metal–ion complexation of three calix[4]arene derivatives demonstrates a significant effect of olefinic substituents and its location on the silver ion complexation, but there was no effect of them on the thallium ion complexation. The stability constants for the metal ion complexes of the calixarene derivatives in methanol have been successfully determined by a mass-spectrometric method using 18-crown-6 as the reference ligand.     

First synthesis and structure of beta-ketoimine calix[4]arenes: complexation and extraction studies

The synthesis of a new series of beta-ketoimine calix[4]arene derivatives is described. The reaction of calix[4]arene or p-tert-butylcalix[4]arene with bromoacetonitrile or bromobutyronitrile afforded di-, tri-, and tetranitrile calixarene derivatives (3-8, 3a), which were then reduced into the corresponding amine (9-13, 3b). The condensation of these aminocalixarenes with acetylacetone led to six beta-ketoimine calix[4]arene derivatives (14-18, 3c) as a class of selective receptors toward transition metals. Molecular structures of 4, 7, and 17 have been determined by X-ray diffraction. The packing of 17 revealed a network of intramolecular and intermolecular hydrogen bonds. The complexation properties of receptors 15, 17, and 3c toward different metal ions have been investigated by UV-vis titrations in organic media. The stoichiometries of complexes with 17 were determined by both the mole ratio method and Job plots. These novel receptors selectively complex Cu2+, Hg2+, and Ag+. Moreover, the extraction properties of 17 toward cations have been studied by liquid-liquid extraction and atomic absorption spectrometry. Compound 17 has good affinity and selectivity toward Pb2+.     

Self-assembled monolayers of organosulphur molecules bearing calix[4]arene moieties

We investigate the self-assembly of modified calix[4]arene on gold surfaces. Calix[4]arene was modified through a reaction sequence which led to assembling of the crown-5 moiety and to the insertion of two thioether groups into the starting molecule. The so-obtained calix[4]arene-crown-5 bis(7-thiatridecyloxy) (hereafter called calix[4]arene) was in the stable 1,3-alternate conformation. The calix[4]arene/gold interface was investigated by means of spectroscopic ellipsometry (SE), scanning tunneling microscopy (STM) and cyclic voltammetry (CV). SE data indicate a layer thickness compatible with the formation of a monomolecular layer. This result is confirmed by STM imaging which shows the formation of a high density of small pits, one gold layer deep, a typical feature of self-assembled organosulphur monolayers on gold. CV measurements performed in presence of the [Ru(NH(3))(6)(2+/3+)] redox couple indicate a passivation of the metal electrode, resulting in a reduction of the redox current, after the layer deposition. CV has also been used to investigate the selectivity properties of calix[4]arene-covered gold electrodes by measuring the redox current decrease in the presence of different salt solutions. It is found that calix[4]arene-covered electrodes are able to complex K(+) and Ba(2+), while no complexation is observed in the case of Li(+), Na(+), Cs(+), Mg(2+) and Ca(2+).     

Conformational features and recognition properties of a conformationally blocked calix[7]arene derivative

The shaping of a calix[7]arene macrocycle into cone-like structure 3, through exhaustive alkylation of doubly bridged calix[7]arene derivative 2 with bulky groups, has been investigated. Conformational details about the structure adopted by calix[7]arene derivative 3 in solution have been obtained by using chemical shift surface maps, as previously reported by our group. Thus, chemical shift contour plots indicated that 3 adopted a cone-shaped structure in solution analogous to that adopted by the known p-tert-butylcalix[7]arene heptacarboxylic acid derivative 4. Interestingly, the X-ray structure of derivative 3 showed a high degree of similarity to the theoretical structure, which confirmed the validity of the contour plots method. The preorganized calix[7]arene host 3 showed interesting recognition abilities toward both organic and alkali cations. In fact, an unprecedented endo-cavity complexation of linear and branched alkyl ammonium cations with a larger calix[7]arene host was evidenced. A comparable affinity for branched tBuNH(3)(+) and linear nBuNH(3)(+) guests was observed.     

Synthesis and Properties of Upper Rim Schiff Base Calix[4]arenes

The synthesis and properties of upperrim Schiff base calix[4]arenes are described in thisarticle. Tetrakis-p-bromomethylcalix[4]arene(1) reacts with hexamethylenetetramine to givetetrakis-p-formylcalix[4]arene (2) in highyield. Then upper rim Schiff base calix[4]arenes 3 can be easily synthesized by 2 reacting withappropriate alkylamines. The complexation ability of3 toward transition metals Pb²⁺, Cu²⁺and Co²⁺ was studied by UV-VIS spectrophotometry.     

An electron-rich three dimensional receptor based on a calixarene-tetrathiafulvalene assembly

The synthesis of a calix[4]arene scaffold persubstituted with four redox-active tetrathiafulvalene (TTF) moieties at the lower rim is described. This assembly strongly binds sodium cation, and the binding process is accompanied by a conformational change of the receptor, as shown from NMR titration and by an X-ray diffraction led on the complex. This dynamic behavior remarkably results in a modification of the electrochemical response of TTF probes, which behave independently after sodium complexation.     

Inclusion behavior of water-soluble thiacalix- and calix[4]arenes towards substituted benzenes in aqueous solution

Inclusion abilities of thiacalix- and calix[4]arenetetrasulfonate (3 and 4) towards mono-substituted benzenes were investigated in neutral aqueous solution. In general, the hosts regioselectively encapsulated the guests from the aromatic moiety except the complexation of toluene by 4, in which the guest penetrated from either the aromatic or the methyl group. Stabilities of the inclusion complexes increased with the electron-withdrawing ability of the substituent on the guest, suggesting pi-pi electronic interaction between the host and guest. In spite of the lower electron density of the aromatic ring, thiacalix[4]arene 3 showed higher inclusion ability than calix[4]arene 4, suggesting that the size rather than the electron density of the calix framework is a more important factor in determining the inclusion ability.     

Thallium pi-cation complexation by calix[4]tubes: (205)Tl NMR and x-ray evidence

Thallium cation complexation by calix[4]tubes has been investigated by a combination of (205)Tl, (1)H NMR and ES MS demonstrating the solution formation of a dithallium complex in which the cations are held in the calix[4]arene cavities. In addition, the structure of the complex has been determined in the solid state revealing the cations to be held exclusively by pi-cation interactions. Furthermore, this crystal structure has been used as the basis for molecular dynamics simulations to confirm that binding of the smaller K(+) cation in the calix[4]tube cryptand like array occurs via the axial route featuring a pi-cation intermediate.     

杯[4]芳烃黄原酸酯衍生物的合成与阳离子萃取性能

以二氧六环作溶剂, 杯[4]芳烃二甲氧基二羟乙氧基衍生物2与氢氧化钾、二硫化碳作用合成了杯芳烃黄原酸盐衍生物3, 并进一步与碘甲烷或氯化苄反应首次合成了含黄原酸酯基的杯芳烃衍生物4a和4b. 阳离子萃取试验表明该新型杯芳烃衍生物比单硫杂杯芳烃衍生物具有更好的过渡金属离子萃取性能.     

Comparison of pillar[5]arene and calix[4]arene anion receptor ability in aqueous media

Abstract

Recognition ability of both cationic pillar[5]arene and calix[4]arene has been studied in aqueous media. Anion complexation can be evaluated from their ability to complex their counterions as well as an added external organic anion. DOSY NMR experiments and fluorescence quenching show that pillararenes have a larger ability for including their own counterions than calixarenes irrespective of the anion (tetrafluoroborate or chloride or bromide) and the structure of the cationic moiety (trimethylammonium or methylimidazolium). Counterion complexation shows a picture where four to five positive charges of the pillar[5]arene are neutralised, meanwhile only one positive charge of the calixarene is neutralised for a 1 mM solution of the macrocycle. Irrespective of the smaller net positive charge in the pillar[5]arene, its binding ability for organic anions (toluenesulfonate or hydroxybenzoate) is larger than for calix[4]arene allowing a better accommodation of the guest in its cavity. The larger separation between the cationic groups of the receptor and its electron-rich aromatic region improves the anion recognition ability for pillar[5]arene.     

邻甲氧基羰基苄氧基取代杯[4]芳烃衍生物的合成及其性能研究

杯芳烃是继冠醚、环糊精之后的第三代主体分子[1].据文献[2,3]报道,在杯[4]芳烃下沿酚氧原子上连接乙酸酯得到的四取代衍生物对Na+有很高的选择性,核磁与晶体结构研究均证实这是由于羧酸酯的羰基和酚氧基参与了对Na+的配位,而且配位基团所形成的包络空间大小与钠离子相匹配.一般认为,随着包络空间改变,对金属离子的识别作用会有所变化[4].但目前对这方面的工作并没有给予更多的重视.我们发现,用2-溴甲基苯甲酸甲酯与杯[4]芳烃反应,得到了一种新的四取代杯[4]芳烃衍生物[2]萃取研究结果表明,该化合物对钾离子有较好的选择性.此外,在合成该衍生物的过程中,还得到了另一新的二取代衍生物(3).     

Complexation and chromatographic studies involving water soluble calixarenes and nitrophenols

Summary In this study, an investigation of the utilisation of the sodium salts of 4-sulphonic calix[4]arene and 4-sulphonic calix[6]arene as mobile phase additives in reversed phase HPLC is described. Consistent with earlier work these mobile phase additives were shown to strongly influence the retention behaviour and separation factor of 2-, 3- and 4-nitrophenols. Proton NMR and UV spectroscopic data is presented to demonstrate that this chromatographic behaviour is due to pH effects and not due to complexation between the nitrophenols and the calixarenes.     

Extraction Behavior of Amino Acids by Calix[6]arene Carboxylic Acid Derivatives

A series of calixarene carboxylic acid derivatives were synthesized for the extraction of amino acids. A calix[6]arene carboxylic acid derivative showed the highest extractability to the target tryptophan ester. The main driving forcefor the complexation was the interaction between the ammonium cation of the aminoacid and the oxygen atoms of the host molecule. Stripping of amino acids was alsoaccomplished by contacting the organic solution with a fresh acidic solution. Basedon slope and Job method analyses, it was confirmed that the calix[6]arene formsa 1 : 1 complex with the amino acid ester. The structure of the complex between the calix[6]arene and the amino acid was investigated by ¹H-NMR and CD spectra. The calix[6]arene includes a guest molecule in the cavity, and the inclusion induces the asymmetrization of the host molecule. This host compound functions as a novel recognition tool for amino acids.