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A series of large macrocyclic calixarene bishydrazones were efficiently synthesized by [2+2] condensation reactions of calix[4]arene 1,3-disubstituted aldehydes with hydrated hydrazine. The X-ray single crystal diffraction showed that macrocycles form a distinctive calixtube-liking shape. [ABSTRACT FROM AUTHOR]

A series of salicylidenimine functionalized p-tert-butylcalix[n]arene-core dendrimers 7a-b were synthesized in higher yields by divergent method from the corresponding ethyl p-butylcalix[n]arylacetates 2a-b (n = 6, 8). 2a-b were first treated with excess of 1,6-diaminohexane to give amide derivatives with free amine terminal groups 3a-b, which in turn reacted with salicylaldehyde in alcohol to yield the first generation of Schiff bases 4a-b. 3a-b reacted with ethyl acrylate, ammonolized with 1,6-diaminohexane and condonsated with salicylaldehyde successfully to give the second generation of Schiff bases 7a-b. The extraction and binding properties of the dentritic Schiff bases 4a-b and 7a-b for several kinds of metal ions were studied with UV-Vis spectroscopy and atomic absorption spectroscopy. In which they showed a great affinity for soft Cu2 + ions and formed 1:1 or 1:2 stoichiometric complexes. [ABSTRACT FROM AUTHOR]

Abstract: A series of aryl pyrogallol[4]arenes were efficiently synthesized in excellent yields by cyclocondensation of pyrogallol with aromatic aldehydes under microwave irradiation. The structures of aryl pyrogallol[4]arenes were confirmed by characterization of their acylated derivatives. Under microwave irradiation, alkylation reactions of aryl pyrogallol[4]arenes with some alkylating reagents such as n-butyl iodide, benzyl chloride, and ethyl α-chloroacetate were also finished quickly to yield fully O-alkylated products. The 1H NMR spectra and crystal structures showed that the acylated and alkylated aryl pyrogallol[4]arenes existed mainly in rctt (cis–trans–trans) configuration. [Copyright &y& Elsevier]

Dendritic p-t-butylcalix[ n]arene amide derivatives with terminal amino groups of the first and second generations were synthesized by using divergent methods from ammonolysis of ethyl calixarylacetate with 1,6-diaminohexane and Michael addition of methyl acrylate. Their structures were confirmed by IR, 1H NMR. The recognition properties of these amide derivatives for several kinds of metal ions were studied with UV-Vis spectroscopy. The results showed a great affinity for soft Ag+ and UO2 2+ ions and formed 1:2 or 1:3 stoichiometric complexes. [ABSTRACT FROM AUTHOR]

Thiourea‐bridged peracetylated glycoside calixarenes have been smoothly synthesized by the addition reactions of tetraacetylglycosyl isothiocyanates with amidoamine derivatives of calix[4]resorcinarene and p‐tert‐butylcalix[n]arenas ( n =6, 8) in high yields (40–75%). All the glycoside‐containing calixarenes were characterized by 1 H NMR, IR spectroscopy, and elemental analysis. [ABSTRACT FROM AUTHOR]

An approach for the synthesis of calixarene derivatives 3a–d, which contain ethylene glycol ether units at the lower rim in moderate yields, is described. The above compounds have been achieved by treating p-Butylcalix[n]arenes 1a–b(n = 6, 8) with chloroacetate 2a–b of 2-methoxyethanol and 2-(2-butoxyethoxy)ethanol in the system of K2CO3/KI/acetone. [ABSTRACT FROM AUTHOR]

A novel surfactant sensitized fluorescent chemosensor for safranine T (ST) based on calixarene-1,3-diacyl hydrazone (CADH) in sodium dodecyl sulfate (SDS) medium was investigated. The fluorescence intensity of CADH was quenched by ST due to the formation of weak fluorescent inclusion complex (ST-CADH), and the fluorescence quenching (Δ F = F CADH − F ST-CADH ) was sensitized in SDS. Under the optimal conditions, the linear range of calibration curve for the determination of ST was 0.02–3.00 μg/m and the detection limit estimated 0.015 μg/mL with RSD 2.2% ( n = 3, c = 1.0 μg/mL). The mechanism of determination was discussed with the fluorescence quenching type, the inclusion of CADH with ST and surfactant sensitized effect. This method has been applied for the detection of ST in real samples with satisfactory results. [ABSTRACT FROM AUTHOR]

To date, the knowledge about the properties of calixarene-based surfactants have been limited although it is hypothesized that the calixarene framework may endow calixarene-based surfactants with unique properties. In the present study, the adsorption and micellization behaviors of amphiphilic calix[4]resorcinarenes and their interactions with proteins were studied by various techniques, including surface tension measurement and fluorescence, UV–vis absorption, and 1H NMR spectroscopy; the amphiphilic calix[4]resorcinarenes were obtained by modifying tetramethoxyresorcinarenes with ammonium and imidazolium groups on the upper rim and alkyl groups on the opposite rim. We found that a tetramethoxyresorcinarene with a very short alkyl chain exhibited good surface activity and the critical micelle concentration (cmc) was much lower than that for the conventional surfactant having a long alkyl chain. Moreover, the cmc and saturated adsorption values (Γ max) decreased but the surface tension (γ) at the cmc (γ cmc) and single molecular cross-sectional area (A min) increased with increasing alkyl chain length. In the presence of proteins, the surface tension remained unchanged at less than stoichiometric tetramethoxyresorcinarene concentrations; however, at higher tetramethoxyresorcinarene concentrations, the surface tension began to decrease drastically, much faster than the case without protein. In addition, the binding of the tetramethoxyresorcinarene to the protein increased the protein activity, and the degree of enhancement in the protein activity was closely related to the protein structure. The molecular simulations further explained the binding modes of the tetramethoxyresorcinarenes to the protein. • Tetramethoxyresorcinarene-based cationic surfactant exhibited good surface activity. • γ with protein remained unchanged at less than stoichiometric tetramethoxyresorcinarene concentrations. • Protein made γ decreased much faster in a proper range of tetramethoxyresorcinarene content. • The tetramethoxyresorcinarene increased protein activity. • The degree of enhancement in protein activity was related to protein structure. [ABSTRACT FROM AUTHOR]