Synthesis of two new p-tert-butylcalix[4]arene β-ketoimin derivatives for extraction of dichromate anion

In this study the selective derivatization of p-tert-butylcalix[4]arene was carried out and two new p-tert-butylcalix[4]arene β-ketoimin, 5,11,17,23-tetra-tert-butyl-25,27-bis-3-methyl-[(β-ketoimine)-ethoxy]-26,28-dihydroxycalix[4]arene (4), and 5,11,17,23-tetra-tert-butyl-25,27-bis-3-chloro-[(β-ketoimine)-ethoxy]-26,28-dihydroxycalix[4]arene (5) have been synthesized. In the synthesis, the lower rim of p-tert-butylcalix[4]arene was modified in order to acquire binding site for the recognition of dichromate anion. It was observed that these ionophores 4 and 5 showed high affinity towards dichromate anion. The protonated Schiff-base forms of the receptors were effective for transferring the HCr₂O₇ ^? anion from aqueous phase to a dichloromethane phase.     

Synthesis of new water-soluble phosphonate calixazacrowns and their use as drug solubilizing agents

This study presents the selective chloromethylation of calix[4](aza)crown ethers 2a–c, using chloromethyl n-octyl ether and SnCl₄ in chloroform at room temperature in good yield for the first time. Chloromethylated products 2a–c are used as key intermediates to synthesize new water-soluble p-phosphonato calix[4](aza)crown ethers 5a–c. Liquid–liquid phase extraction and phase solubility studies with poor water soluble drug molecules such as nifedipine, niclosamide and furosemide are performed to evaluate their binding properties. Among the studied drugs, furosemide was the most effectively dissolved drug by p-phosphonato calix[4](aza)crown ethers 5a–c in water.     

Square-like Functions Generated by a Composite Wavelet Transform

The classical square functions play important role in Harmonic Analysis and have a very direct connection with L ₂-estimates and Littlewood-Paley theory. In this paper we introduce a new variant of square-like functions generated by some composite wavelet transform. We establish Calderón-type reproducing formula and then prove L ₂-boundedness of newly defined square-like functions.     

Upper rim-functionalized calix[4]arene-based l-proline as organocatalyst for direct asymmetric aldol reactions in water and organic media

The synthesis of upper rim-functionalized calix[4]arene-based l-proline was described, and its catalytic efficiency as organocatalyst for the enantioselective aldol reaction in water was investigated. The results showed that the nature of the hydrophobic cavity of calixarene is critical for catalytic activity in water. The products of the reaction between various ketones and aldehydes with anti-configuration were obtained in high yields (up to 94%) with high diastereo- (up to 95:5 dr) and enantioselectivities (up to 80% ee).     

Synthesis of macrocyclic polyethers and polyether diesters and preparation of their cationic complexes

New macrocyclic polyethers, 2,3,5,6-bis-[5′(5′)-chlorobenzo]-1,7,10-trioxacyclododeca-2,5-diene (I), 2,3,5,6-bis-[5′(5′)-chlorobenzo]-1,7,10,13-tetra oxacyclo pentadeca-2,5-diene (II), and 2,3,5,6-bis-[5′(5′)-chlorobenzo]-1,7,10,13,16-penta oxa cyclo octadeca-2,5-dien (III), and macrocylic lactones 2,3,5,6-bis-[5′(5′)-chlorobenzo]-1,7,10,13-tetraoxacyclopentadeca-2,5-diene-8,15-dione (IV) and 2,3,5,6-bis[5′(5′)-chlorobenzo]-1,7,10,13,16-pentaoxacyclooctadeca-2,5-diene-8,18-dione (V) were synthesized. Complexes of ligands III and V with metal cations were prepared. Furthermore, their metal-picrate extraction with some metal salts was attempted. Structures of the ligands and complexes were confirmed using spectroscopic techniques.     

Magnetic ordering and spin waves in Na0.82CoO2

NaxCoO2, the parent compound of the recently synthesized superconductor Na(x)CoO(2):yH(2)O, exhibits bulk antiferromagnetic order below approximately 20 K for 0.75相似文献   

A first-principle study of the structural and lattice dynamical properties of CaX (X=S,Se, and Te)

We have studied structural, elastic, thermodynamic (Debye temperature and melting temperature), and lattice dynamical (phonon dispersion curves, heat capacity, and entropy) properties of CaX via ab initio calculations within the local density approximations. The results are compared with the available experimental and other theoretical data, and the agreement is, generally, quite good. We also predict the temperature and/or pressure-dependent behaviors of some mechanical, lattice dynamical, and thermodynamic properties for the same compounds.     

Intermolecular interactions and binding mechanism of inclusion complexation between sulfonate calix[<Emphasis Type="Italic">n</Emphasis>]arenes and ethidium bromide

In this work, the interactions between ethidium bromide (ET) and water-soluble sulfonate calix[n]arenes (n: 4, 6, and 8) were investigated by NMR, FT-IR, and fluorescence spectroscopic methods. The aim was to evaluate both the stoichiometry and the mechanism of the possible complex structure between sulfonate calix[n]arenes and ET. The spectroscopic data revealed that a 1:1 binding mode between calixarene and ET was occurred. Furthermore, thermodynamic parameters and fluorescence titration experiments were studied at different temperatures to determine both the quenching mechanism and the type of intermolecular forces in complex formation. Host–guest complexation of sulfonate calix[n]arenes and ET could be used to overcome some adverse effects related to the using of ethidium bromide during biological applications as a DNA marker treatment.     

Humic-makeup approach for simultaneous functionalization of polyacrylonitrile nanofibers during electrospinning process,and dye adsorption study

A useful methodology is represented to functionalize polyacrylonitrile nanofibers by using humic acid as a makeup agent in electrospinning process. Both morphology and surface chemistry of polyacrylonitrile nanofiber mats were understood to be influenced by incorporation of humic acid into the structure. Physicochemical changes were evidenced by Fourier transform infrared spectroscopy, scanning electron microscope, and surface charge measurements. Unlike some anionic dyes (i.e., methyl orange, methyl red, and Congo red), there was an enhancement in crystal violet (a cationic dye) adsorption after incorporation of humic acid. The Langmuir model fitted well to crystal violet data, and monolayer adsorption capacity was calculated as 81.6 mg/g (r² = 0.998).