Arene Bearing Research Articles

Achieving over 1,000 mW cm−2 Power Density Based on Locally High‐Density Cross‐Linked Polybenzimidazole Membrane Containing Pillar[5]arene Bearing Multiple Alkyl Bromide as a Cross‐Linker

AbstractCross‐linking is widely accepted as an effective method to improve the mechanical strength and durability of phosphoric acid (PA) doped polybenzimidazole (PBI) membranes. However, the cross‐linked membranes generally exhibit compromised overall performance since their compact network structures decrease the free volumes of membranes, leading to poor proton conductivity. In this study, a locally high‐density cross‐linked polybenzimidazole network based on pillar[5]arene bearing multiple alkyl bromide is constructed for the first time to achieve high proton conductivity, desired mechanical properties, and excellent fuel cell performance. The pillar[5]arene‐cross‐linked network considerably enhances the mechanical strength of membrane (14.6 MPa), particularly with high PA uptake, and provides loose PBI chain segment packing to retain PA (315.9%). Surprisingly, the pillar[5]arene‐cross‐linked PBI membrane displays a high‐power density of 1,084.1 mW cm−2 at 180 °C and 0.6 mg cm−2 Pt loading without backpressure and humidification, that is the highest value reported in cross‐linked membranes for high‐temperature proton exchange membrane fuel cells.

Fabrication of Cross‐Linked Anion Exchange Membranes Using a Pillar[5]arene Bearing Multiple Alkyl Bromide Head Groups as Cross‐Linker

AbstractA pillararene‐based macrocycle with up to 10 flexible chains bearing alkyl bromide head groups is synthesized and investigated for the first time as a multiarm cross‐linker for tertiary‐amine functionalized polyethersulfone. Different from any previously reported cross‐linker, this has a unique pillar‐shaped structure and abundant reactive sites to form multifunctional clusters in the conductive domain. This advantage enables cross‐linking to occur smoothly at the membrane‐casting stage and endows the cross‐linked membranes with improved performance. The cross‐linked anion exchange membranes are found to possess high conductivities and excellent alkaline stability. With a controllable swelling ratio of 19.5%, the maximum conductivity of a membrane can reach 155 mS cm–1 at 80 °C. Due to its local high‐density cross‐linked structure, a delay in degradation kinetics under alkaline condition can be observed, and the loss of conductivity is <10% after 400 h of alkaline stability test at 80 °C.

Synthesis of Bifunctional Derivatives of Calix[4]arene Bearing Azidoalkyl Fragments in Cone Stereoisomeric Form

A procedure for the chloromethylation of lipophilic distally di-O-substituted calix[4]arene derivatives has been developed to prepare dichloromethyl derivatives of calix[4]arenes with long-chain alkyl fragments in cone configuration in high yields. From the chloromethylated derivatives, ammonium/imidazolium salts containing azidopropyl moieties have been synthesized in high yields. The structure of all obtained compounds has been established by 1D and 2D NMR, IR spectroscopy, and MALDI spectrometry. They can be further used as precursors of polytriazole/polyimidazole polymer species as promising carriers for metal-complex catalysis.

Fabrication of Thin Films of Phosphonated Calix[4]Arene Bearing Crown Ether and Their Gas Sensing Properties

Calix[4]arenes bearing phosphate and crown ether groups are shown to hold considerable promise as the active layer in volatile organic compound (VOC) vapor sensor. Its chemical sensing selectivity and sensitivity can be altered by different alkyl side chains. These organic architectures were successfully deposited by the spin coating method on gold-coated glass surfaces. Surface plasmon resonance technique was used for VOCs detection to evaluate the chemical-sensing properties of these calix[4]arene derivatives. Spun thin films of calix[4]arene derivatives were exposed to a variety of VOC vapors, and the resonance angles changes of these films were recorded for the specific analyte vapors, such as chloroform, carbon tetrachloride, dichloromethane, ethanol, benzene, and toluene. Measurements were made at room temperature, and the responses were found to be fast and appeared to be completely reversible. The sensing results showed similar response patterns, and our data strongly indicate that response of used thin films of calix[4]arene derivatives to chloroform is much higher than those of any other VOCs used with the values of 0.47 x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , 1.042 x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , and 1.952 x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> (% / ppm) for the compounds 1, 2, and 3, respectively. Furthermore, gas sensing interaction mechanisms of the thin films were evaluated in terms of the molar volumes, dipole moments, and refractive indexes of the analyzed gas molecules.

Synthesis and Cation Binding Properties of p-Tert-butyl-calix[4]arene Bearing 8-Hydroxyquinoline Units

Synthesis and Cation Binding Properties of p-Tert-butyl-calix[4]arene Bearing 8-Hydroxyquinoline Units

Calix[4]arene-based crab-like molecular sensors for highly selective detection of mercury and copper ions

In this work, two novel chemosensors based on calix[4]arene bearing (thio)barbituric acid groups (BC1 and BC2) were synthesised, and their structures were characterised by HRMS, NMR and FTIR. Furthermore, their binding properties towards various biologically relevant metal ions were studied by fluorescence titrations, 1H NMR spectroscopies and Job’s plot evaluations. The chemosensor BC1 displayed excellent binding affinity and selectivity towards Cu2+, which was characterised using fluorescence spectroscopy. On the other hand, BC2 exhibited a very remarkable fluorescence enhancement as well as visible colour change from pale green to sunset yellow, in presence of Hg2+ ions. Finally, Job’s plot method revealed 1:1 binding stoichiometry for both BC1:Cu2+ complex and BC2:Hg2+ complex.

Inclusion Extraction of Alkali Metals by Emulsion Liquid Membranes and Nano-baskets of p-tert-Calix[4]arene Bearing Di-[N-(X)sulfonyl Carboxamide] and Di-(1-propoxy) in ortho-cone Conformation

Nano-assisted inclusion separation of alkali metals from basic solutions was reported by inclusion-facilitated emulsion liquid membrane process. The novelty of this study is application of nano-baskets of calixarene in the selective and efficient separation of alkali metals as both the carrier and the surfactant. For this aim, four derivatives of [4]arene bearing different sulfonamide moieties were synthesized and their inclusion-extraction parameters were optimized including the calixarene scaffold (4 wt %) as the carrier/demulsifier, the commercial kerosene as diluent in membrane, sulphonic acid (0.2 M) and ammonium carbonate (0.4 M) as the strip and the feed phases, the phase and the treat ratios of 0.8 and 0.3, mixing speed (300 rpm), and initial solute concentration (100 mg/L). The selectivity of membrane over more than ten interfering cations was examined and the results reveled that under the optimized operating condition, the degree of inclusion-extraction of alkali metals was as high as 98-99%.

Synthesis and characterization of novel chiral calix[4]arene bearing (R)-(+)-1-phenylethylamine bonded silica particles

Two novel chiral di- and tri-amide derivatives of p-tert-butylcalix[4]arene were synthesized by (R)-(+)-1-Phenylethylamine via convenient reactions and then immobilized on aminopropyl functionalized silica particles. The prepared chiral calix[4]arenes and their silica polymers (Calix-SP1 and Calix-SP2) were characterized using 1H NMR, 13C NMR, FT-IR, and thermal and elemental analysis techniques.

Enantioselective nanofiber-spinning of chiral calixarene receptor with guest

Chiral para-tert-butylcalix[4]arene bearing (S)-alpha-methylbenzylamine groups at lower rim only self-assembles with one of two enantiomers of 2,3-dibenzoyltartaric acid into coiled nanofibers and the coiled nanofibers only stack with the nanofibers having the same handedness to construct bigger ribbon-like fibers bearing porosity.

New Neutral Receptors for Fluoride Based on Calix[4]arene Bearing Thiourea and Amide

Two-armed neutral anion receptors (4, 5), calix[4]arenes bearing thiourea and amide binding sites, were prepared and examined their anion-binding ability by the UV-vis spectra. The results of non-linear curve fitting and Job plot indicate that 4 or 5 forms 1:1 stoichiometry complex with fluoride by hydrogen bonding interactions. Receptors 4 and 5 have an excellent selectivity for fluoride but have no binding ability with acetate, dihydrogen phosphate and the halogen anions (Cl-, Br-, I-).

Ion Extraction of Alkali Metal Cations by a Calix[4]arene Bearing Two Ester Groups

Ion Extraction of Alkali Metal Cations by a Calix[4]arene Bearing Two Ester Groups

Modulation of metal recognition by a novel calix[4]arene bearing two bipyridine units as a molecular gate.

[reaction: see text] A novel multiregulation system of ion recognition was constructed by utilizing a molecular gate. Interaction between the host and an Ag(+) is controlled with an Na(+) ion.

Calix[6]arene Bearing Carboxylic Acid and Amide Groups in Polymeric CTA Membrane

Calix[6]arene having both carboxylic acid (1,3,5-) and carboxamide (2,4,6-) in an alternative way was synthesized. Transport rates of alkali and alkaline-earth metal ions were tested in bulk liquid membrane and polymer inclusion membrane. Ba2+ ion was found to give the highest transport rate among tested metal ions in both BLM and PIM systems. In PIM system, high durability (longer than 30 days) of the membrane was observed.