92003-62-8

Upstream product

• 189832-67-5 5,11,17,23,29,35-hexakis(tert-butyl)-37,38,39,40,41-hexakis(hydroxy)calix[6]arene 
• 105-39-5 chloroacetic acid ethyl ester 
• 105-36-2 ethyl bromoacetate 

Relevant academic research and scientific papers

Complexation characteristics of permethylated cycloinulohexaose, cycloinuloheptaose, and cycloinulooctaose with metal cations

The host-guest complexation behavior of cyclic oligosaccharides, permethylated cycloinulohexaose 1, permethylated cycloinuloheptaose 2, and permethylated cycloinulooctaose 3 with metal cations has been characterized by means of UV-visible, NMR, and electrospray ionization (ESI) mass spectrometry. In the crystal state, the structures of 1·K+, 1·Rb+, and 1·Cs+ were same as that of the 1·Ba2+ complex which has a u-u-d-u-u-d (u = up, d = down) furanose ring arrangement for the plane of the crown ring moiety. The association constants (Ks) in THF and in [2H6]acetone at 298 K were evaluated. The binding ability of host 1 with metal cations was of the same degree as that of calix[6]arene derivative 4 and much higher than those of hosts 2 and 3. The thermodynamic parameters of the complexation of host 1 with metal cation in THF were determined, and it was suggested that the entropy change for the solvation of the metal cations was one of the important factors in the complexation equilibrium. It was clarified that the structure of the host 1·K+ complex in solution at low temperature (furanose ring arrangement: u-d-u-d-u-d) was different from that in the crystal state (u-u-d-u-u-d arrangement) by the coalescence behavior in 1H-NMR. The relative peak intensity of the complex ions of host 1 or 2 with two alkali metal ions in ESI mass spectrometry (in acetone) showed a correlation in the first order approximation with the ratio of the corresponding complex ion concentrations estimated from the Ks values.

P-tert-Butylcalix[6]arene hexacarboxylic acid conformational switching and octahedral coordination with Pb(ii) and Sr(ii)

p-tert-Butylcalix[6]arene hexaacetic acid is in a symmetric cone conformation in CHCl3, but it becomes conformationally flexible in CHCl3/CH3CN (1:1). In this mixture the host has a strong binding affinity towards Pb(ii) and instantly forms a complex of low symmetry-shortly thereafter structural reorganization occurs resulting in a high symmetry complex of Pb(ii) in an octahedral cage of carboxylates. Sr(ii) and Ba(ii) display similar behavior over a longer period of time.

Syntheses of ester and amide derivatives of calix[6]arene and their complexation affinities towards La3+, Eu3+, and Yb3+

One hexaester (1) and three hexaamide derivatives (2–4) of calix[6]arenes were prepared for the first time in one synthetic step, under microwave radiation. Compounds 2 and 3 were novel ones, while ester calix[6]arene derivative 1 and amide derivative 4 were prepared previously, by conventional syntheses. Microwave-assisted syntheses shortened the reaction times from 48 to 2 h. The binding properties of calix[6]arenes towards selected lanthanide cations (La3+, Eu3+, Yb3+) were studied by spectroscopic and mass spectrometric techniques. No complexation was observed with the ester derivative, while compounds 2–4 formed 1:1 complexes. Based on spectrophotometric titrations, the stability constants of resulting complexes could only be estimated (lg K ≥ 6). Calixarene derivatives, as well as their complexes, were analysed by ESI MS and MS/MS spectrometry. Corresponding fragmentation pathways were proposed, and in some cases confirmed by MS3 experiments. The results obtained by different techniques were in accordance.

NEW METAL CATION-SELECTIVE IONOPHORES DERIVED FROM CALIXARENES

Ethoxycarbomethyl derivatives of calixarene and calixarene prepared by the reaction of bromoacetic acid ester with the calixarenes exhibited distinct size-selectivity in their ion-extracting behaviors towards Cs+ and K+ ions.

Synthesis, X-ray crystal structure and anti-tumor activity of calix[n]arene polyhydroxyamine derivatives

Calixarene-based compounds are highly effective therapeutic agents against cancer. This study aims to prepare a series of calix [n]arene (n?=?4, 6, 8) polyhydroxyamine derivatives (3a–3m) and to study their potential antitumor activities. The single crystal structure of calixs[4]arene derivative 3a was determined through X-ray diffraction. We assessed the ability of the prepared calix [n]arene polyhydroxyamine derivatives to induce cytotoxicity in six cancer cell lines by performing cancer cell growth inhibition assays. Results demonstrated that compounds 3a–3d achieved IC50values ranging from 1.6?μM to 11.3?μM. Among the different compounds, 3a and 3b exerted the strongest cytotoxic effect in inhibiting the growth of SKOV3 cells. In relation to the underlying mechanisms of cytotoxic effects, cell cycle analysis revealed that the exposure of SKOV3 cells to 3a induced cell cycle arrest in the G0/G1 phase, suggesting a reduction in DNA synthesis. Immunofluorescent staining indicated that the protein expression levels of caspase-3 and p53 in cells significantly increased, whereas that of Bcl-2 was effectively suppressed. Meanwhile, no significant changes in Bax were observed in SKOV3 cells. These results highlight that calixarene 3a can be further studied as a potential anticancer agent.

Highly selective and efficient extraction of two Pb2+ ions with a p-tert-butylcalix[6]arene hexacarboxylic acid ligand: An allosteric effect in extraction

Solvent extraction behavior of p-tert-butylcalix[6]arene hexacarboxylic acid towards Pb2+ and other divalent transition metal ions has been studied to investigate the selectivity, extraction mechanism, stoichiometry of complexation and composition of the complex in the organic phase. Extractability and selectivity of the cyclic ligand were analyzed in comparison with the acyclic analog. The macrocyclic effect was genuinely operative and the size-match effect was the governing factor for cation selectivity. Accordingly, the cyclic ligand selectively extracted the Pb2+ ion in a pH range fairly more acidic than the acyclic ligand. The cations were extracted by ion exchange mechanism, and the electroneutral complexes were resulted by the exchange of two protons for a divalent cation. A molecule of p-tert-butyl calix[6]arene hexacarboxylic acid ligand extracted two Pb2+ ions. One Pb2+ was extracted due to the size-fit effect inside the hydrophilic cavity of calix[6]arene composed by phenoxy and carbonyl oxygen atoms. The macrocyclic ring inversion was obstructed due to guest encapsulation, and the encapsulated Pb2+ ion acted as a template for aggregation of the carboxyl groups. This binding event caused a positive allosteric effect and led to the extraction of the second Pb2+ ion at the aggregated functional group site.

Novel synthesis of calix[n]arene amidoazobenzene derivatives

A series of calix[n]arenas and calix[4]resorciarenes containing azo chromophores on the lower rim were synthesised with two routes. The first direct route involved alkylating calixarenes with 4-chloroacetoaminoazobenzene. The second indirect route was by acylating 4-aminoazobenzene with calix[n]arylacetyl chloride. Their extracting abilities for transition metal ions were tested.

Synthesis, X-ray Crystal Structures, and Cation-Binding Properties of Alkyl Calixaryl Esters and Ketones, a New Family of Macrocyclic Molecular Receptors

Calixarenes (N=4,6,8) have been converted into polyfunctional esters and ketones in a search for new macrocycles capable of showing ionophoric activity.Treatment with alkyl bromoacetates furnished the calixaryl acetate series, whereas chloroacetone-potassium iodide, phenacyl chloride, 1-adamantyl bromomethyl ketone, and bromopinacolone were used to make the calixaryl ketones series.The crystal structures of ethyl calixaryl acetate (7), methyl calixaryl acetate (13), ethyl calixaryl acetate (11), and calixaryl methyl ketone (20) have been determined.Thecrystals of 7 are triclinic, space group P, with two molecules in the unit cell of dimensions a = 12.434(2) Angstroem, b = 15.033(3) Angstroem, c = 17.286(4) Angstroem, α = 103.01(2) deg, β = 102.97(1) deg and γ = 94.68(1) deg.The crystals of 13 are monoclinic, space group C2/c, with eight molecules in the unit cell of dimensions a = 27.066(6) Angstroem, b = 21.392(6) Angstroem, c = 21.348(7) Angstroem, and β = 119.32(2) deg.The crystals of 11 are monoclinic, space group C2/c, with four molecules in the unit cell of dimensions a = 21.906(4) Angstroem, b = 11.805(2) Angstroem, c = 23.534(4) Angstroem, and β = 91.79(2) deg.The crystals of 20 are orthorhombic, space group Pbcn, with four molecules in the unit cell of dimensions a = 19.644(7) Angstroem, b = 12.712(3) Angstroem, and c = 22.115(7) Angstroem.Both 11 and 20 have crystallographically imposed 2-fold molecular axes.The analysis establishes that all three tetramer derivatives possess the cone conformation in the solid state where the pendant-functionalized side chains are mutually syn with respect to the calixarene substructure and are thus preorganized for ionreception.NMR measurements confirm the existence of the cone conformation for these tetramers in solution at room temperature.In contrast, the centrosymmetric hexamer ester 11 has three adjacent groups syn, but the inversion symmetry places the other three ester groups in the anti position on the opposite side of the macrocycle.Extraction studies with alkali metal picrates from aqueous solution into dichloromethane, transport studies with alkali metal thiocyanates through a dichloromethane membrane, and stability constant measurements with alkali metal salts by UV absorption spectroscopy in methanol and acetonitrile were used to assess the ionophoric activity of these calixarene derivatives.The tetramer esters and ketones display peak selectivity for the sodium ion, the tetraketones being generally more efficient binders than the tetraesters.The hexaester extracts K(1+) better than Na(1+) and displays a plateau selectivity after K(1+).The octamers are the least effective ionophores.The selectivities shown by the picrate extraction technique are broadly mirrored in the transport studies.Stability constants range from 2 to 6, ...

Selective Extraction and Transport of UO22+ with Calixarene-based Uranophiles

Hexacarboxylate derivatives of p-t-butylcalixarene (2b) and p-hexylcalixarene (3b) extract uranyl ion (UO22+) efficiently and selectively from water into organic media.This high selectivity can be attributed to the nature of calixarene; this is suitably structured for the binding of UO22+, which requires a pseudo-planar hexaco-ordination.When trioctylmethylammonium cation (TMA+) is added to the organic phase, the stoicheiometry of the extraction species 2+/2(2b)> changes from 1:3 to 1:1-2.This implies that an additional 1-2 mol of UO22+ are adsorbed to (2b) to form 'neutral' extraction species and can be displaced by added TMA2+.UO22+ is transported by (2b) across a liquid membrane from a neutral IN (source) aqueous phase (pH 8.5) to an acidic OUT (receiving) aqueous phase (0.1 mol dm-3 HCl) in an active transport manner.The rate-determining step is the release of UO22+ from the membrane to the OUT aqueous phase.On the basis of these basic data, we have prepared polymer/liquid-crystal (N-4'-ethoxybenzylidene-4-butylaniline, EBBA/TMA+Cl-) composite membranes immobilising (2b) and have found that the rate of UO22+ transport is efficiently controlled by the changes in pH and temperature.These are novel examples for the selective transport of UO22+.

New Metal Cation-Selective Ionophores Derived from Calixarenes: Their Syntheses and Ion-Binding Properties

Various derivatives (ethoxycarbonylmethyl, carboxymethyl, and ethoxyethyl, etc.) of calixarene, calixarene, and calixarene have been synthesized and their ion-binding properties investigated by solvent extraction, ion-transport through liquid membranes, and u.v. spectroscopy.The extraction of various metal ions (as picrate salts) from the aqueous phase into dichloromethane by the calixarene derivatives showed that the ethoxycarbonylmethyl derivatives exhibited markedly increased extraction efficiency compared with their unsubstituted phenol analogues, and the efficiency was in general comparable to those of crown ethers.The most notable feature was the selectivities exhibited by their ethoxycarbonylmethyl derivatives; calixarene for Na(+), calixarene for Cs(+), and calixarene for K(+).A liquid membrane study with a water-chloroform-water system also indicated that the ion-transport efficiencies exhibited by calixarenes were found to be in accordance with their extraction abilities, confirming the strong participation of the ester carbonyl oxygen in this function.However, the ester derivative of calixarene was an exception in that inefficient carrier activity was observed in spite of high extraction efficiency.The pronounced Cs(+) selectivity exhibited by the calixarene ester was further confirmed by the changes in the u.v. spectrum of the ester from 277 and 270 nm to 275 and 267 nm upon interaction with Cs(+) ion in methanol.