New organized systems based on amphiphilic oxyethylated calix[4]arene

The aggregation of amphiphilic oxyethylated calix[4]arene is studied in the absence and presence of polyethyleneimine. At low calixarene concentrations, large ensembles with a hydrodynamic diameter of about 100 nm are formed and coexist with small (smaller than 10 nm) aggregates, which are observed in the entire concentration range. It is established that calixarene-based systems catalyze the neutral hydrolysis of bis(chloromethyl)phosphinic acid p-nitrophenyl ester, with the catalytic effect being as high as two orders of magnitude in the presence of La(III) ions. The rate of hydrolysis of phosphonates depends on the composition of the supramolecular system. The maximum acceleration exceeds three orders of magnitude in comparison with alkaline hydrolysis of the substrates.     

Sterically and guest-controlled self-assembly of calix[4]arene derivatives

In solvents such as chloroform or benzene, tetraurea calix[4]arenes 1 form dimeric capsules in which one solvent molecule is usually included as guest. To explore the structural requirements for the formation of such hydrogen-bonded dimers we replaced one p-tolylurea residue by a simple acetamide function. The resulting calix[4]arene 2 a, substituted at its wide rim with one acetamide and three p-tolylurea functions, assumes a C(1)-symmetrical conformation in apolar solvents as shown by (1)H NMR, which is not compatible with the usual capsule. In the crystalline state, four molecules of 2 a, adopting a pinched cone conformation, assemble into a quasi S(4)-symmetrical tetramer stabilized by a cyclic array of 24 NH.O==C hydrogen bonds and four NH.pi interactions. Four acetamide groups are hydrogen-bonded to each other and pack tightly in the center of the assembly. All polar residues are buried inside the tetramer, the surface of which is lipophilic. Extensive NMR studies revealed similar structures in apolar solvents such as [D]chloroform or [D(6)]benzene for calixacetamides 2 a-c. The formation of these tetramers in solution is critically dependent on the size of the amide fragment, so that propionamide 2 d, butyramide 2 e, and p-tolylamide 2 f form only ill-defined aggregates. This is caused by steric crowding inside the tetrameric assembly. The tetramers persist during molecular dynamics simulations, and the optimized average structure of the MD run is similar to that found in the crystalline state. Theoretical studies revealed that cooperation of hydrogen bonds with multiple NH.pi, C--H.pi, and pi.pi attractions make the tetramer more stable than the capsular dimer with the solvent as guest. In the presence of tetraethylammonium salts, however, compounds 2 a-e form dimeric capsular assemblies, each incorporating a single ammonium cation. Only one of two possible regioisomeric dimers is formed, in which both acetamide groups are surrounded by two urea residues. These examples give striking evidence of how self-assembly in solution can be strongly dependent on subtle structural factors and of how the formation of dimeric capsules can be induced by the presence of an appropriate guest.     

New calix[4]resorcinols containing aldehyde fragments in the molecule

A reaction of calix[4]resorcinols with 3-ethylamino-2,2-dimethylpropanal and aqueous formaldehyde results in new calix[4]resorcinol derivatives including aldehyde fragments aminomethylated at the higher rim of the molecule. Depending on the structure of calixarenes and experimental conditions, products of mono and tetra substitution can be obtained.     

Selective electrodes for silver based on polymeric membranes containing calix[4]arene derivatives

Silver ion-selective electrodes were prepared with polymeric membranes based on two calix[4]arene derivatives functionalized by two hydroxy and two benzothiazolylthioethoxy groups. The electrodes all gave a good Nernstian response of 58?mV decade^–1 for silver in the activity range 5 × 10^–6–10^–1 M, the limits of detection reached 10^–5.8 M and exhibited high selectivity towards alkali, alkaline earth and some transition metal ions. The electrode was used as indicator electrode in titrations of Ag⁺ with Cl^– ion.     

Heterodimerization studies of calix[4]arene derivatives in polar solvents

[reaction: see text] Several calix[4]arene derivatives propylated on the lower rim and substituted on the upper rim with amino or carboxyl groups have been synthesized. Examples include calixarenes substituted with alanino (C- and N-linked), amino, carboxy, carboxyphenyl, and amidino groups. The self-assembly of these derivatized calixarenes into heterodimers has been studied by NMR in DMSO-d(6) or CD(3)OD with 5% aqueous phosphate buffer.     

杯芳烃衍生物的合成和性质的研究5

通过对特丁基杯(4)芳烃的酚羟基的选择性醚化制备了一系列一烃基,1,3-二烃基和四烃基醚,烃基分别含有缩醛、酰胺、氰基等活泼官能团。醚化反应的区域选择性主要取于使用的碱的种类和反应时间的长短。     

Computational study of calix[4]arene derivatives and complexation with Zn

High level DFT was applied to study structure and conformational equilibrium of amino and mercaptocalix[4]arenes possessing methylene groups or sulfur atoms at their four junctions. All the calculations point to cone and 1,3-alternate as the most stable conformers for sulfur and methylene bridged compounds, respectively. The presence of four sulfur atoms in place of the methylene bridges can lead to novel features in the complexation with transition metals. The host–guest 1:1 complexes between Zn²⁺ and each conformer of tetraaminothiacalix[4]arene were also investigated at the same DFT level. The four nitrogens of amino groups play a dominant role in the interaction with Zn²⁺ via distorted tetrahedral coordination for 1,3-alternate, or distorted square planar for partial cone and 1,2-alternate. On the other hand, the 2:1 complexes with cone show that the sulfur bridges can also bind Zn²⁺ and contribute to form two sets of five-membered chelated rings with two N donor atoms.     

Synthesis and anti-integrase evaluation of novel calix[4]arene derivatives containing the triazolyl 1,3-diketo moiety

A series of novel calix[4]arene derivatives incorporating two triazolyl 1 3-diketo subunits in alternate positions at the lower rim were synthesized and screened for HⅣ integrase inhibition activity.The chemical structures of these compounds were confirmed by means of1H NMR 13C NMR,and ESI-MS.Preliminary bioassays indicated that calix[4]arene derivatives proved to be more active than p-tertbutylcalix[4]arene derivatives.In particular,compound 4g presented the most potent integrase strand transfer inhibitory activity with an IC50value of 6.1 mmol/L.     

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.     

Supramolecular interaction between water-soluble calix[4]arene and ATP--the catalysis of calix[4]arene for hydrolysis of ATP

The catalysis effect of water-soluble calix[4]arene C[4] (calix[4]arene-5,11,17,23-tetrasulfonate) on hydrolysis of ATP in aqueous solution was studied by HPLC. Using laser photolysis and pulse radiolysis, the supramolecular interaction between water-soluble calix[4]arene and ATP was investigated.     

Guest controlled aggregation of amphiphilic sulfonatomethylated calix[4]resorcinarenes in aqueous solutions

Supramolecular nanoaggregates formed through the association of amphiphilic sulfonatomethylated calix[4]resorcinarenes with different substituents on the lower rim (methyl, pentyl, heptyl) and number of aromatic, aliphatic, and cationic guests differing in their shapes and sizes were investigated in aqueous solution by various NMR techniques ((1)H, 2D NOESY, FT-PGSE). It was shown that slight variations of the alkyl chain length on the lower rim of calixresorcinarenes dramatically change their aggregation behavior. Unlike the other calixresorcinarenes studied, the "head-to-tail" packing mode is observed for calixresorcinarene with pentyl moieties on the lower rim, which is unusual for amphiphilic calixarene aggregates. This calixresorcinarene demonstrates the stronger binding capacity toward the guest molecules due to their encapsulation into the capsule-like aggregate subunits. The guest-host complexation modifies the properties of both components, with the size of the resulted colloid particles being controlled by the guest nature.     

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     

Stimuli-responsive supramolecular nanostructure from amphiphilic calix[4]arene and its three-dimensional dendritic silver nanostructure

We synthesized a tetrameric amphiphilic molecule ( 1) based on a calix[4]arene building block that self-assembled into different tunable and stable aggregation structures at different pH values in aqueous solution. The amphiphilic calix[4]arene molecule ( 1) formed a spherical structure at pH 3. However, 1 formed a hollow necklacelike structure of 500 nm diameter at pH 7. These results indicate that the self-assembled morphologies of 1 are strongly dependent on pH values. In addition, a 3D dendritic silver nanostructure was obtained by the self-assembly of 1 at pH 7.     

Synthesis and fluorescence sensing properties of novel pyrene-armed calix[4]arene derivatives

Fluorogenic tert-butylcalix[4]arenes bearing two pyrene pendant groups at the lower rim were synthesized. Based on ratiometric changes of monomer and excimer emissions, the pyrene amine derivative of calix[4]arene has been found to act as a selective sensor for Pb²⁺ and Cu²⁺ ions, respectively, due to a conformational change upon chelation of these ions.     

Synthesis and thermal properties of novel calix[4]arene derivatives containing 1,2,3-triazole moiety via K2CO3-catalyzed 1,3-dipolar cycloaddition reaction

Two calix[4]arene derivatives containing 1,2,3-triazole moiety were synthesized via K2CO3-catalyzed1,3-dipolar cycloaddition reaction between calix[4]arene-based azide and active methylene compounds in good yields.The structures of the two compounds synthesized herein were fully confirmed by 1HNMR,,（13）C NMR,and MS（ESI）.The thermal analysis showed that the mass losses of the synthesized compounds 4 and 5 containing 1,2,3-triazole groups are similar to each other.     

Synthesis and cationic selectivity studies of novel calix[4]arene derivatives containing heteroatom at the lower rim

A series of calixarene derivatives 2―5 containing heteroatom at the lower rim have been synthesized. 1H NMR studies and crystallographic structures demonstrated that the calix[4]arene derivatives adopted cone conformations. Their cationic binding abilities and selectivities towards heavy and tran- sition metal ions have been evaluated by solvent extraction of aqueous metal picrates. The obtained results indicated that the introduction of nitrogen, sulfur, and/or phosphor atoms to the calix[4]arene framework could effectively enhance their binding ability and selectivity for heavy and transition metal ions, such as Pb2 or Ag .     

新型杯[4]芳烃衍生物的合成及其氨基酸萃取性能

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),化合物(2)与异硫氰酸苯酯反应得到含酰胺和硫脲单元的新型杯[4]芳烃衍生物(3).总产率达70%.系列氨基酸萃取实验表明化合物(3)对异亮氨酸有较好的选择性萃取能力.     

Synthesis of derivatives of p-tert-butylcalix[4]arene containing on lower rim fragments of 2-aminoalkylbenzimidazoles

Reactions of calix[4]arene carboxymethoxy derivatives with 2-aminoalkylbenzimidazoles in the presence of dicyclohexylcarbodiimide and hydroxybenzotriazole afforded a series of p-tert-butylcalix[4]arene derivatives containing on the lower rim N-(2-benzimidazolylalkyl)carbamoylmethoxy fragments. The reaction carried out in the absence of hydroxybenzOtriazole resulted in macrocycles containing one N-(2-benzimidazolylalkyl)carbamoyl fragment and a fragment of N-(acyl)dicyclohexylisourea.     

Synthesis of calix[4]arene(amido)monocrowns and their photoresponsive derivatives

A series of new calix[4]arene(amido)mono-crown compounds have been synthesized through aminolysis of calix[4]arene esters and intramolecular cyclization of the intermediates. The title compounds were converted into their nitro and azo substituted derivatives to provide novel photoresponsive molecular receptors for transition metal ions. Single crystal X-ray analysis of calix[4]arene(ethyleneamido)mono-crown (2a) revealed that the compound is present in a cone conformation with an amido loop that caps the lower rim of calix[4]arene cavity to result in stacking along axis a and axis c to provide supramolecular aggregates in the solid state. Evaluation of synthesized macrocycles in the solution phase for recognition of transition metal cations (Cr³⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Cd²⁺, Pb²⁺, Hg⁺, Hg²⁺, Pd²⁺, and Pt²⁺) by UV-visible spectroscopy revealed that p-tert-butyl-calix[4]arene mono-(amidocrown) 1c selectively shows a blue shift at 38 nm on interaction with Hg⁺ ions.     

Allosteric coextraction of sodium and metal ions with calix[4]arene derivatives 1

Solvent extraction of three alkali metal ions with p-t-octylcalix[6]arene hexacarboxylic acid, p-t-octylcalix[4]arene tetracarboxylic acid, corresponding linear trimeric and monomeric analogs was investigated. Cyclic tetramer selectively extracts sodium ion among alkali ions at extremely low pH, while the corresponding cyclic hexamer, the trimer, and the monomer exhibited only poor extraction ability for all alkali metals examined. The detailed extractive investigation of sodium ions with the cyclic tetramer was carried out. It was found that two sodium ions are simultaneously extracted by a single molecule of calix[4]arene derivative and that the second sodium extraction is facilitated by the uptake of the first sodium. The self-coextraction mechanism of sodium ions proposed in the present paper also strongly supports allosteric coextraction of sodium and other metal ions. In the competitive extraction of four alkali metal ions, potassium ion was slightly extracted as the second ion at low pH region, whereas it was hardly extracted in the individual extraction system. The result also supports the coextraction mechanism and role of the first-extracted sodium ion as an allosteric trigger. The extraction equilibrium constants of the cyclic tetramer and two sodium ions, K _ex1 and K _ex2, were estimated.