Functionalized Anion-Exchange Membranes Facilitate Electrodialysis of Citrate and Phosphate from Model Dairy Wastewater.

In this study, the preparation of a new, functional anion-exchange membrane (AEM), containing guanidinium groups as the anion-exchanging sites (Gu-100), is described as well as the membrane characterization by XPS, water uptake, permselectivities, and electrical resistances. The functional membrane was also employed in pH-dependent electrodialysis experiments using model dairy wastewater streams. The properties of the new membrane are compared to those of a commercially available anion-exchange membrane bearing conventional quaternary ammonium groups (Gu-0).

Effect of Divalent Cations on RED Performance and Cation Exchange Membrane Selection to Enhance Power Densities.

Reverse electrodialysis (RED) is a membrane-based renewable energy technology that can harvest energy from salinity gradients. The anticipated feed streams are natural river and seawater, both of which contain not only monovalent ions but also divalent ions. However, RED using feed streams containing divalent ions experiences lower power densities because of both uphill transport and increased membrane resistance.

Molecular Basis for the Recognition of Higher Fullerenes into Ureidopyrimidinone-Cyclotriveratrylene Self-Assembled Capsules.

Fullerenes C60 , C70 , and C84 may be readily encaged within a hydrogen-bonded dimeric capsule, based on two concave cyclotriveratrylene (CTV) scaffolds, each containing three self-complementary 2-ureido-4-[1H]-pyrimidinone (UPy) subunits. NMR spectroscopy and circular dichroism studies, complemented by dispersion-corrected DFT calculations, are reported with the aim of characterizing such capsule-fullerene complexes both structurally and energetically. Six fullerenes are considered: in agreement with experiments, calculations find that encapsulation is most favorable for C84 (on a par with C90 ), and follows the trend C60 View Article and Find Full Text PDF

Triggering activity of catalytic rod-like supramolecular polymers.

Supramolecular polymers based on benzene-1,3,5-tricarboxamides (BTAs) functionalized with an L- or D-proline moiety display high catalytic activity towards aldol reactions in water. High turnover frequencies (TOF) of up to 27×10(-4) s(-1) and excellent stereoselectivities (up to 96% de, up to 99% ee) were observed. In addition, the catalyst could be reused and remained active at catalyst loadings and substrate concentrations as low as 0.

A modular approach to introduce function into single-chain polymeric nanoparticles.

Here, a modular approach is reported to introduce a specific function into single-chain polymeric nanoparticles (SCPNs). Hereto, an amphiphilic polymer with pendant benzene-1,3,5-tricarboxamide (BTA) units is mixed with a "free" BTA that contains a functional group, either a fluorescent naphthalimide or a catalytically active l-proline. Taking advantage of hydrophobic interactions and self-recognition properties of the BTA units, the "free" BTAs are captured into the interior of the SCPN in water as evidenced by fluorescence studies.

Tripodal exTTF-CTV hosts for fullerenes.

A receptor for fullerenes featuring three exTTF units linked to a CTV scaffold is described. The exTTF-CTV host forms remarkably stable complexes with both C(60) (log K(a) = 5.3 +/- 0.

Preferential separation of fullerene[84] from fullerene mixtures by encapsulation.

The encapsulation of fullerenes with a cyclotriveratrylene derivative, capable to self assemble into a dimer by means of three strong 4-ureidopyrimidinone quadruple hydrogen bonds is described. The system shows preference for C84, allowing its easy enrichment directly from fullerene mixtures.

A highly directional fourfold hydrogen-bonding motif for supramolecular structures through self-assembly of fullerodendrimers.

Supramolecular dendrimers resulting from the dimerization of fullerene-functionalized dendrons through a quadruple hydrogen-bonding motif were prepared. The synthetic strategy is based on the esterification of a tert-butoxycarbonyl (Boc)-protected 2-ureido-4-[1H]pyrimidinone precursor possessing an alcohol function with fullerodendrons bearing a carboxylic acid unit at the focal point. Subsequent acidic treatment to cleave the protecting group and reaction of the resulting amine with octylisocyanate affords the targeted compounds.