Supramolecular catalytic systems based on calixarenes and cyclodextrins

A number of supramolecular metal complex catalitic system based on cyclodextrins and calixarenes have been developed. Particular attention has been given to design of new metal complexes with molecular recognition abilities. Data on application catalytic systems based on receptor molecules capable to formation of inclusion “host-guest” complexes in hydroformylation and Wacker-oxidation are given. Influence of different factors on activity, stability, selectivity of metal complex supramolecular catalytic systems is discussed.     

Controlled drug delivery systems based on calixarenes

Recent advances on calixarene-based drug delivery systems in the form of inclusion complexes, amphiphilic self-assembly nanocarriers including micelles, hydrogels, vesicles and liposomes, and supramolecular nanovalves on mesoporous silicas, were reviewed and discussed.     

Solubilizing and catalytic properties of supramolecular systems based on gemini surfactants

Quantitative parameters characterizing the aggregation behavior of dicationic surfactants of the 12-s-12 type in aqueous solutions were determined: critical micelle concentrations, aggregation numbers, and surface potentials. The effects of the spacer length of the surfactants on their solubilizing effect with respect to hydrophobic (dye Orange OT) and water-soluble (p-nitrophenol) spectral probes and on their ability to shift acid-base equilibria were studied. The kinetics of alkaline hydrolysis of p-nitrophenyl acetate and p-nitrophenyl caprinate in 12-s-12 solutions was studied by spectrophotometry. A correlation between the micellar catalytic effect and the surface potential of micelles was established. The pronounced substrate specificity was revealed: the maximum acceleration of hydrolysis is observed in solutions of 12-6-12, attaining 1760 times for p-nitrophenyl caprinate.     

Hyperbranched molecules based on calixarenes

Synthesis of the diamide 2 derived from tris(2-aminoethyl)amine and monocarboxymethylcalix[4]arene provides a starting material useful for the preparation of a variety of hyperbranched molecules. Metal ion binding is one of the potentially useful properties of these new materials.     

Catalytic properties of microheterogeneous systems based on cationic surfactants in transesterification processes

The kinetic parameters of the transesterification processes of carboxylic acid esters under the action of alkylphenolates in aqueous micellar solutions of cetyltrimethylammonium bromide (CTAB) are found. The observed catalytic effect is due to a complex mechanism of the solvent effect, which includes a shift of acid-base equilibria in the nucleophile and the formation of mixed CTAB/alkylphenol micelles. The dynamic structure of these aggregates (size, diffusion mobility, and molecular packing density in a surface layer) has been characterized by spin-probe EPR spectroscopy and high-resolution pulsed-field gradient ¹H NMR spectroscopy.     

Photosensitive supramolecular systems based on amphiphilic crown ethers

An amphiphilic crown-ether styryl dye was synthesized and its properties at the interfaces were investigated. This dye, which in monolayers interacts with some cations and shows reversible changes of the light reflection after photoactivation near the absorption maximum, is an excellent component of functional organized systems.     

手性杯芳烃的合成及性质

手性杯芳烃是一类重要的主体化合物，在手性识别、对映体分离、不对称催化 等方面有潜在的用途、综述了手性杯芳烃的合成及其在手性识别、对映体分离方面 的性能。     

Spectroscopic study on the complex formation of chromogenic bridged calixarenes with aliphatic amines

The complex formation between chromogenic capped calix 4 arene derivatives comprising indophenol indicator group(s), and aliphatic amines has been studied by UV/Vis spectroscopy. The equilibrium constants have been determined in ethanol, and—for one ligand—also in dimethylsulfoxide. The results have been interpreted in terms of various types of host–guest interactions and of steric effects.     

Functional supramolecular systems with highly cooperative and responding properties

The dynamic processes of host–guest interactions contribute to the multistep regulation of various molecular functions such as the catalysis of chemical reactions, transport of materials, control of reaction pathways, and cooperative and responsive phenomena particularly in biological systems. In this review, we describe artificial metallo‐supramolecular systems, which exhibit highly cooperative and responsive functions to external stimulus, by utilizing formation of the metal complexes and their characteristic properties. Pseudomacrocycles such as pseudocrown ethers and pseudocryptands have been synthesized to control macrocyclic and macrobicyclic effects on guest recognition by using a metal ion as an effector, and remarkably positive and negative allosteric effects have been achieved. Highly cooperative stepwise regulation of the affinity to anions has also been achieved by a pseudocryptand and a salt‐binding host. The electrostatic interactions between the anions and cations are important for the combination specificity of the salts. We also introduce a linear bis‐salamo ligand as a precursor for a novel multimetal cooperative host. A trinuclear zinc complex was formed cooperatively and only the central zinc ion was replaced by lanthanide and calcium ions in a transmetalation way. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 240–251; 2008: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20153     

Environmental analysis based on luminescence in organized supramolecular systems

The use of organized supramolecular systems—including micellar media and cyclodextrin inclusion complexes—combined with luminescence techniques in the study and determination of compounds and elements of environmental interest from 1990 to 2005 is reviewed. Analyses of environmental samples performed using fluorescence, photochemically induced fluorescence and phosphorescence spectroscopy as well as liquid chromatography, capillary electrophoresis and flow injection with luminescence detection in the presence of these organized media are described in detail.     

Receptors for organochlorine pesticides based on calixarenes

The water soluble 4-sulfocalix[n]arenes (with n?=?4,6,8) have been investigated as potential synthetic receptors for cyclodiene organochlorine pesticides. Steady state fluorescence experiments in ethanol solution have shown that only the cavitands with n equal to 6 and 8 form complexes, of comparable stability, with heptachlor. Electrochemical data, obtained in water solution, confirmed the ability of 4-sulfocalix[6]arene to bind the heptachlor, unlike the smaller calixarene. Moreover, a significant increase in the stability constant is observed in water solutions. This stability is caused by the sterical hindrance of pesticides with respect to the cavity dimension of the calixarene. This results in a selective interaction of this molecule with other organochlorine pesticides. Binding experiments, carried out with endosulfan have shown that, despite of chemical similarity, 4-sulfocalix[6]arene and 4-sulfocalix[8]arene behave in a very different way: the former is unable to bind this pesticide, while the latter shows a binding constant of 4.7?×?10⁵ with endosulfan. To investigate the molecular features of the interactions, molecular dynamic simulations of 4-sulfocalix[6]arene in presence of heptachlor in water solution have been performed. These simulations show that different configurations of heptachlor inside the calixarene cavity are equally populated and easily interconverting, suggesting that a non specific hydrophobic interaction plays a key role in the complex stability. These studies have permitted to individuate versatile synthetic receptors for organochlorine pesticides.     

Fluorene‐based materials and their supramolecular properties

Fluorene‐based π‐conjugated polymers and oligomers combine several advantageous properties that make them well‐suited candidates for applications in organic optoelectronic devices and chemical sensors. This review highlights strategies to synthesize these materials and to tune their absorption and emission colors. Furthermore, methods to control their supramolecular organization will be discussed. In many cases, a delicate interplay between the chemical structure and the processing conditions are found, resulting in a high sensitivity of both structural features and optical properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4215–4233, 2009     

Dual-response colorimetric sensor array for the identification of amines in water based on supramolecular host-guest complexation

Amines have been found as a challenging compound class in previous works on chemical tongues. Herein, we describe the successful application of libraries based on host-guest inclusion complexes in cyclodextrins (CDs) and cucurbiturils (CBs) for the discrimination of primary, secondary, tertiary, aliphatic and aromatic as well as linear and branched amines in water. Besides the clear need for new detection, identification and quantification techniques of organic compounds in water, the main advantage of our approach is that an array made by combining six simple basic dyes with seven commercial organic capsules allows a perfect discrimination among 14 amines (see list in Table S1 in Supplementary data) with only very subtle structural differences.     

Encapsulation of quantum dots in supramolecular systems based on amphiphilic compounds and polyelectrolytes

Supramolecular nanocontainers based on monocationic and gemini surfactants and oppositely charged polyelectrolytes (polyacrylic acid, polyethyleneimine) for the stabilization and enhancement of solubility of hydrophobic quantum dots CdSe/ZnS were formed. The size (from 2 to 70 nm depending on the type of nanocontainers) and shape of aggregates containing quantum dots were determined by transmission electron microscopy. It was shown that the nature of the stabilizing agent influences the morphology of aggregates. The increase in photostability of quantum dots in micellar solutions of gemini surfactants and the possibility of their preservation in the polyelectrolyte capsules are identified.     

Catalytic properties of Pd-containing systems based on SBA-15 molecular sieve modified with imidazolium ionic liquid

Palladium(II) ions were incorporated in SBA-15 molecular sieve modified with imidazolium-based ionic liquids. The synthesized materials were characterized using differential thermic analysis, low-temperature nitrogen adsorption, transmission electron spectroscopy and elemental analysis. The materials obtained basing on a grafted ion liquid, in 1-hexene hydrogenetion were shown to exhibit the catalytic activity significanly higher than those prepared via ion liquid adsorption on supports.     

Catalytic effect of supramolecular system based on cationic surfactant and monopodands in nucleophilic substitution of phosphorus esters

The data are presented on the synthesis of podands with terminal quinoxaline fragments of rings and their influence on both the micellization properties of cetyltrimethylammonium bromide in a water—DMF solution and kinetics of basic hydrolysis of O-p-nitrophenyl O-ethyl chloromethylphosphonate and O-p-nitrophenyl O-hexyl chloromethylphosphonate in the absence and presence of surfactants. The mechanism of the podand effect on the reaction rate depends on the structures of phosphonate and podand. 1,8-Bis(3-ethyl-1,2-dihydro-2-oxoquinoxalin-1-yl)-3,6-dioxaoctane inhibits the basic hydrolysis of the substrates to 3—4 times. In a micellar solution of the surfactant, an approximately 20-fold acceleration of the reaction rate constant is observed. The observed rate constant decreases when podand is added to a micellar solution. The catalytic effect of the polycomponent system is due to concentrating of the reactants. The micellar microenvironment can exert both positive and negative effects on the reactivity of phosphonates.