Combination Of Calix Research Articles

New Concept for the Study of the Fluid Dynamics of Lithium Extraction Using Calix[4]arene Derivatives in T-Type Microreactor Systems

Lithium extraction remains a challenge in the hydrometallurgy process due to its economic value and maldistribution sources. Employing calix[4]arene derivatives in solvent extraction techniques results in high selectivity and extraction capability, but a slow extraction rate. The slow kinetics of batch-wise extraction can be drastically accelerated by using a T-type microreactor system. Therefore, a combination of calix[4]arene and a microreactor system serves as an ideal platform for efficient lithium extraction. In this work, the fluid dynamics of lithium extraction using a monoacetic acid calix[4]arene derivative in a T-type microreactor system were studied. Increasing the O/A ratio increases the average length, surface area, and volume of the organic droplets, but decreases the specific surface area. In contrast, increasing the Reynolds number decreases the average length, surface area, and volume of the organic droplets, but increases the specific surface area. It was found that shorter diffusion distance, larger specific surface area, and faster vortex velocity were the factors that play the most pivotal roles in achieving great extraction rate enhancement in T-type microreactor systems compared to batch-wise systems. These findings represent an important new concept in the study of the fluid dynamics of lithium extraction using monoacetic acid calix[4]arene derivatives in T-type microreactor systems.

Fabrication of magnetic functionalised calix[4]arene composite for highly efficient and selective adsorption towards uranium(VI)

Environmental contextUranium-containing wastewaters have high potential to harm the environment and human health. We found that the combination of calix[4]arene with magnetic Fe3O4 particles produced good adsorption of uranium from wastewater. In addition, this material can be recycled and reused, so it has good prospects in practical applications for uranium remediation. AbstractA magnetic functionalised calix[4]arene composite consisting of Fe3O4 and calix[4]arene phosphonate derivative (CPD) was prepared through a facile self-assembly method. The composite was characterised by scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR). The as-synthesised Fe3O4/CPD composite was used to remove UVI from aqueous solutions under different conditions. Meanwhile, the adsorption isotherm, kinetics and thermodynamics were fitted and analysed. The results show that the Fe3O4/CPD composite may be a promising adsorption material for the separation and enrichment of UVI from aqueous solutions in the cleanup of environmental pollution.

Synthesis of (Hemi)Carceplex Adsorbates for Self-Assembly on Gold

The synthesis of sulfide-functionalized (hemi)carceplexes suitable for self-assembly on gold is described. A noncentrosymmetrical carceplex 9 (guest DMF) was synthesized by the combination of calix[4]arene 4 and resorcin[4]arene 3, while a noncentrosymmetrical hemicarceplex 12 (guest NMP) was prepared by the combination of two different resorcin[4]arenes, 3 and 10. These adsorbates form ordered self-assembled monolayers on gold with their quasi C4v axis perpendicular to the surface. The two positions possible for the incarcerated guest lead to diastereotopic surfaces.

Head-to-Head Linked Double Calix[4]arenes: Convenient Synthesis and Complexation Properties.

Combination of calix[4]arenes functionalized at the upper rim at the 5- and 17-positions with amino and formyl groups, respectively, gives a new series of "head-to-head" linked double calix[4]arenes in nearly quantitative yield. The X-ray structure of a modified double calix[4]arene is reported. The novel, highly preorganized receptor molecules complex silver(I) ions (K(ass) = 9.5 x 10(5) M(-)(1) in CDCl(3)); the selectivity of complexation was studied by supported liquid membrane transport experiments and chemically modified field effect transistor measurements.

Synthesis of supramolecular structures via combination of calix[4]arenes with other medium-sized building blocks

Abstract

Combination of Calix[4]arenes and Resorcin[4]arenes for the Complexation of Steroids

Receptor molecules with large cavities synthesized by the combination of building blocks that already possess a cavity, viz. calix[4]arenes and resorcin[4]arenes, are described. These receptor molecules are synthesized by reaction of one or two upper rim 1,2-difunctionalized calix[4]arene fragments oriented either endo or exo toward a cavitand unit. The endo:exo ratio depends on the substituents at the 3- and 4-positions of the calix[4]arenes. These novel receptor molecules complex steroids with association constants of (0.9−9.5) × 102 M-1 in CDCl3.

Hydrophobic Concave Surfaces and Cavities by Combination of Calix[4]arenes and Resorcin[4]arenes

AbstractCoupling reactions of calix[4]arenes and modified resorcin[4]arenes have been investigated. Reaction of mono(chloroacetamido)calix[4]arene 4 with tetrahydroxycavitand 9 gave the 1:1 coupled product 13 in 61% yield. Combination of upper‐rim 1,3‐difunctionalized calix[4]arene 5 with 9 afforded predominantly the 2:1 calix‐resorcinarene 18 in 47% yield. Reaction of 1,2‐difunctionalized calix[4]arene 6 with 9 gave five products, namely, endo 1:1 (19), exo 1:1 (20), endo‐endo 2:1 (21), endo‐exo 2:1 (22), and exo‐exo 2:1 (23) in ratios that depend on the reaction conditions. The stereochemistry of the different products was determined with NOESY experiments. The structures of 21 a and 23 b were calculated by using molecular mechanics, which revealed that intramolecular hydrogen bonds are only present in the former. Reaction of 1,2‐bis(chloroacetamido)calix[4]arene 26, which has two additional nitro groups at the remaining aromatic rings, with 9 yielded three different products, namely, endo 1:1 (28), endo‐endo 2:1 (30), and endo‐exo 2:1 (32) in ratios that depend on the reaction conditions. There is a preference for the endo orientation in the formation of the 1:1 coupled product, probably owing to an interaction of the nitro groups with the cavitand in the transition state. After conversion of the nitro groups in 28 into chloroacetamido moieties, reaction with Cs2CO3 in DMF under high‐dilution conditions afforded holand 33 in 26% yield together with calix[4]arene‐based carceplex 34 with an encapsulated DMF molecule (27% yield). Holand 33 was obtained in 33% yield by reaction of the tetrakis(chloroacetamide) endo‐endo 2:1 isomer 31 with tetrahydroxycavitand 9. Holand 33 contains a cavity of nanosize dimensions. Molecular mechanics simulations indicate that holand 33 adopts a conformation with eight hydrogen bonds and a large, preorganized cavity with two entrances of smaller dimensions. Molecular dynamics simulations of holand 33 in both CHCl3 and THF showed that four solvent molecules can be accommodated in the cavity at well‐defined positions.