Inherently chiral calixarenes, whose chirality is based on the absence of a planar symmetry or an inversion center in the molecules as a whole through the asymmetric array of several achiral groups upon the three-dimensional calix-skeletons, are challenging and attractive chiral molecules, because of their potential in supramolecular chemistry. The synthesis and optical resolution of all varieties of inherently chiral calixarenes are systematically discussed and classified, and their applications in chiral recognition and asymmetric catalysis are thoroughly illustrated in this review.

Novel chiral mono and diamide derivatives of calix[4]arene have been prepared from the aminolysis reaction of 5,11,17,23-tetra-tert-butyl-25,27-diethoxycarbonyl-methoxy-26,28-dihydroxycalix[4]arene 1 and 25,27-diethoxycarbonyl-methoxy-26,28-dihydroxycalix[4]arene 2 with chiral (S)-(-)-1-phenylethylamine (PEA) and (1S,2S)-(+)-2-amino-1-(4-nitrophenyl)-1,3-propanediol, respectively. Spectrophotometric titrations have been performed in CHCl(3) at 20-30 degrees C in order to obtain the binding constants (K) and the thermodynamic quantities (DeltaH and DeltaS) for the stoichiometric 1:1 inclusion complexation of various chiral amines with these new host compounds. Preliminary experiments were undertaken to confirm the complexation properties of receptors 9 and 13 with PEA by (1)H NMR in CDCl(3) at room temperature. The molecular recognition abilities and enantioselectivities for guests (R and S)-alpha-PEA and (R and S)-cyclohexylethylamine (CHEA) are discussed from a thermodynamic point of view. Chirality, 2007.(c) 2007 Wiley-Liss, Inc.

Bisurea calix[4]arenes 1 and 2 possessing l-amino acid moieties at the lower rim were synthesized by reaction of the methyl esters of glycine, l-alanine, or l-isoleucine with the appropriate isocyanate (12 or 13), obtained with a safe and efficient Curtius rearrangement from the corresponding carboxylic acid derivatives. The conformational properties of the ligands 1 and 2 were investigated by means of a combined NMR and molecular modeling study which evidences that they are deeply influenced by strong intramolecular H-bonds between the urea NH groups and the vicinal phenolic oxygen atoms or the opposite urea C=O group. Complexation studies performed by ESI-MS and NMR spectroscopy in acetone solution show that the binding ability of these bisurea hosts decreases by increasing the side chain size of the amino acid. Host 2b has a remarkable binding ability for the N-acetyl-d-phenylalaninate anion with an interesting enantioselectivity (%@mt;sys@%%@ital@%K%@rsf@%%@sx@%ass%@be@%D%@sxx@%%@mx@%/%@mt;sys@%%@ital@%K%@rsf@%%@sx@%ass%@be@%L%@sxx@%%@mx@%= 4.14), which is explained on the basis of a three-point interaction mode of binding.

The title compound, 5,11,17,23-tetra-carboxy-25,26,27,28-tetradodecyloxy-calix[4]arene, 1, has been studied at the air-water interface, self-assembled as Langmuir monolayers, for its ability to interact with an active pharmaceutical ingredient (API), acetaminophen (APAP), and to initiate its crystallization. The Π/A isotherm study shows that there is a clear interaction between 1 and APAP causing an expansion of the monolayer. In addition to the known phase transition occurring at a surface tension of 38mNm(-1), an additional kink is observed in the compression isotherm for concentrations of APAP above 40mM suggesting that this API is causing an additional phase transition of the monolayer. Interface-initiated crystallization studies show that the presence of a monolayer spread on a supersaturated solution of APAP (26gL(-1)) triggers this API crystal growth from the interface. The transfer of 1-based monolayers on glass surfaces has been carried out using the Langmuir-Blodgett technique. The so-produced monolayers have been shown to template the crystallization of APAP. LB films of 1 have characterized using imaging and spectroscopic ellipsometry. The results suggest that each monolayer has an average thickness of 18Å, which is consistent with the molecular structure of 1 self-organized parallel to the interface with the alkyl chains pointing out parallel to the axis of the macrocycle and without interdigitation of the alkyl chains. The presence of APAP in the subphase during the LB transfer causes a limited but relevant increase in the layer thickness. The study of the capabilities of the LB films to initiate crystallization of APAP is also demonstrated showing the influence of the monolayer packing on the quantity of formed crystals.

Three amidophenol-modified calixarenes have been produced reacting the parent 5,11,17,23-tetracarboxy-25,26,27,28-tetradodecyloxycalix[4]arene with o-, m-, and p-aminophenol. The produced amphiphiles have been shown to form stable monomolecular Langmuir layers on water. Working on subphases containing 1 mM acetaminophen (APAP), it has been demonstrated that the produced amphiphiles interact with this active pharmaceutically ingredient (API) with a relevant preference for the para-derivative that possesses in its structure substituents that are analogous to the target. Working at supersaturating concentrations of APAP, it has been demonstrated that the so-produced calixarene Langmuir monolayers do favor crystallization of APAP (polymorph I), with a clear effect of the packing density of the amphiphile at the interface on the quantity of produced crystals. Monolayers of the para-derivative have been transferred on solid substrates using the Langmuir-Blodgett technique; the so-produced ultrathin films have been shown to initiate surface crystal nucleation of APAP. The produced solids have been analyzed by single-crystal X-ray crystallography and shown to preferentially grow in the [010] direction.

Among all crystalline complexes of calix-type calix[n]arenes those with organic molecules which are biologically relevant are especially of interest due to their potential medical and pharmaceutical applications. The co-crystallization of drugs with water-soluble calixarenes offers the opportunity to modify chemical and physical properties of APIs (active pharmaceutical ingredients) and to control drug conformation. Such co-crystallization can improve solubility, bioavailability and stability of pharmaceutically active molecules and/or eliminate polymorphism. In this article the solid-state interactions between calixarene hosts and biologically relevant guest molecules are summarized for the currently available structures solved by single-crystal X-ray crystallography.

An extremely complex solid state structure described by two virtual channels and a 2-D square grid of hydrogen bonds is generated by four carboxylic acids groups of calix[4]arene tetrabutyroxycarboxylic acid.

Chiral calix[4]arene alpha-aminophosphonic acids were obtained through diastereoselective Pudovik-type addition of sodium ethyl phosphites to the chiral calixarene imines, removal of chiral auxiliary groups, and mild dealkylation of phosphonate fragments. The diacids obtained show inhibitory activity toward porcine kidney alkaline phosphatase that depends considerably on the absolute configuration of the alpha-carbon atoms.

A calix[4]arene functionalized at one phenolic group with a pendant ethoxy acetate group, forms an inclusion complex that is stable even in the presence of other potential guest molecules.

Two microporous copper isonicotinate polymers [Cu(OH)(INA)] and [Cu(INA)2] have been formed hydrothermally in good yield and purity; each have 1D channels of ca. 4 x 6 A dimension, but with quite different hydrophilicities; both frameworks retain structural integrity to above 200 degrees C, however whilst [Cu(OH)(INA)] is also chemically stable,[Cu(INA)2] is highly labile and readily transforms to the molecular complex [Cu(INA)2(H2O)4] in water at room temperature.

We report on investigations of reactions of tBu(2) Zn with 8-hydroxyquinoline (q-H) and the influence of water on the composition and structure of the final product. A new synthetic approach to photoluminescent zinc complexes with quinolinate ligands was developed that allowed the isolation of a series of structurally diverse and novel alkylzinc 8-hydroxyquinolate complexes: the trinuclear alkylzinc aggregate [tBuZn(q)](3)(1(3)), the pentanuclear oxo cluster [(tBu)(3) Zn(5)(μ(4)-O)(q)(5)](2), and the tetranuclear hydroxo cluster [Zn(q)(2)](2)[tBuZn(OH)](2)(3). All compounds were characterized in solution by (1) H NMR, IR, UV/Vis, and photoluminescence (PL) spectroscopy, and in the solid state by X-ray diffraction, TGA, and PL studies. Density functional theory calculations were also carried out for these new Zn(II) complexes to rationalize their luminescence behavior. A detailed analysis of the supramolecular structures of 2 and 3 shows that the unique shape of the corresponding single molecules leads to the formation of extended 3D networks with 1D open channels. Varying the stoichiometry, shape, and supramolecular structure of the resulting complexes leads to changes in their spectroscopic properties. The close-packed crystal structure of 1(3) shows a redshifted emission maximum in comparison to the porous crystal structure of 2 and the THF-solvated structure of 3.

In this work, the enantioseparation of 15 structurally similar chiral solutes is studied, and analysis of the retention factors is performed using a genetic algorithm and multiple linear regression analysis technique. The present quantitative structure-enantioselective retention relationship model generated for retention factors' data has confirmed the importance of a number of descriptors altering the retention behavior and enantioselectivity of the studied compounds. Thus, fragment-based descriptor PSA, which encodes polar surface area, has confirmed the crucial role of heteroatoms in the retention behavior exhibited by pyrroliddin-2-ones. The presence of E(LUMO) descriptor, which represents a quantum-chemical property, has indicated the role of charge transfer interactions between the chiral stationary phase and enantiomers to retention factors, showing that lowest unoccupied molecular orbital energy is significantly different between enantiomers. The developed model exhibits a very good performance characterized by following statistical parameters: r(2) = 0.93 for training set and r(2) = 0.99 for the validation set. The selected three-variable model displays high predictive ability, catching the main factors affecting the enantioselectivity of studied chiral compounds, and therefore can be used for prediction of retention factors of other chiral compounds of similar structure to improve the separation process and so on. Chirality, 2011. © 2011 Wiley Periodicals, Inc.

The group index for TE modes in an asymmetrical slab waveguide is investigated, and a simple analytical expression is derived. It is shown that the product of the phase and group indices is related to the power fraction in each of the three layers of the waveguide. The results are of interest in the analysis of double heterostructure semiconductor lasers.compared.Theoretical and experimental results for lasers emitting at 1.55 microm are compared.

Heart rate variability related to heart rate decelerations and accelerations is reduced in patients with type 1 diabetes compared to healthy individuals both in resting 10-min and ambulatory 24-h ECGs.

Summary The mechanical movement of the pinnae and petioles of Mimosa pudica was investigated by applying a low electrical voltage and charge to the pulvinus, petiole, secondary pulvinus, or pinna to induce movement. The threshold value was 1.3-1.5 V of applied voltage and 2-10microC of charge for the closing of the pinnules. Both voltage and electrical charge were responsible for the electro stimulated closing of a leaf. The kinetics of Mimosa pudica leaf movements can be closely described by the hydroelastic curvature mechanism.

Luminescent heteroleptic Cu(I) complexes based on asymmetrical iminephosphine ligands exhibit improved electrochemical and photochemical stability as compared to the analogous complexes based on traditional diimine or diphosphine ligands.

A new magnesium metal-organic framework (MOF) based on an asymmetrical ligand, biphenyl-3,4',5-tricarboxylate (H(3)BPT), has been synthesized and structurally characterized. MOF Mg(3)(BPT)(2)(H(2)O)(4)(1) consists of 1D hexagonal nanotube-like channels and exhibits pronounced hydrogen-sorption hysteresis at medium pressure.

New dissymmetric and asymmetric p-tert-butylthiacalix[4]arene derivatives were prepared as a result of the reaction of p-tert-butylthiacalix[4]arene with diethyl bromomalonate in the presence of different alkali metals (Cs, K and Na) in refluxing acetone for 7 days. The structures of the prepared compounds were investigated by IR,(1)H-NMR and MALDI-TOF mass spectroscopy.

Morphological studies showed that the model of compression static asymmetric degenerative diseases of intervertebral disks in rats developed by us corresponds to degenerative diseases of the spine in humans. Three-month compression led to a significant reduction of the total disk height by 15.3% and a reduction in the content of notochondrial cells by 64.8%.

New research supports it where other risks are higher.

It is shown that uncompensated cell resistance in controlled-potential polarography can be decreased by the use of asymmetrical polarisation of the dropping-mercury electrode.

The concise enantioselective total synthesis of C 2 -asymmetrical (-)-deoxocuscohygrine and (-)-dihydrocuscohygrine are described. Double-diastereoselective additions of normal Grignard reagent to bis(1,3-oxazolidine) have been deployed to construct chiral diamine fragments as a key step.