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Biochemical communication is ubiquitous in life. Biology uses chemical reaction networks to regulate concentrations of myriad signaling molecules. Recent advances in supramolecular and systems chemistry demonstrate that feedback mechanisms of such networks can be rationally designed but strategies to transmit and process information encoded in molecules are still in their infancy. Here, we designed a polyelectrolyte reaction network maintained under out‐of‐equilibrium conditions using pH gradients in flow. The network comprises two weak polyelectrolytes (polyallylamine, PAH, and polyacrylic acid, PAA) in solution and one immobilized on the surface (poly‐l‐lysine, PLL). We chose PAH and PAA as their complexation process is known to be history‐dependent (i. e., the preceding state of the system can determine the next state). Surprisingly, we found that the hysteresis diminished as the PLL‐coated surface supported rather than perturbed the formation of the complex. PLL‐coated surfaces are further exploited to establish that reversible switching between the assembled and disassembled state of polyelectrolytes can process signals encoded in the frequency and duration of pH pulses. We envision that the strategy employed to modulate information in this polyelectrolyte reaction network could open novel routes to transmit and process molecular information in biologically relevant processes. [ABSTRACT FROM AUTHOR]

DGA (diglycolamide) ligands show a different extraction behavior of trivalent metal ions by changing the branching alkyl chain length as well as the branching at the methylene position. There are no studies of these factors on the extraction efficiency of these DGA derivatives for the extraction of tetravalent actinides. We have evaluated four different DGA derivatives for the extraction of Np, Pu, and Th from molecular diluents. The n-butyl derivative shows enhanced extraction efficiency and branching gives rise to a reduction in the extraction efficiency of tetravalent ions. The distribution ratios are higher in pure octanol than in a mixture of 30% octanol and 70% n-dodecane. This behavior is in marked difference to that of the extraction of trivalent ions where the addition of an alcohol generally decreases the distribution ratio of trivalent ions due to the ligand-modifier intercation, poor aggregation or micelle formation tendency of DGAs in polar solvents. This suggests that micelle-mediated extraction may not be the dominating factor for the extraction of tetravalent metal ions. Slope analysis suggests the involvement of only two DGA molecules in the extracted species suggesting no/poor possibility of micelle formation in the present system. The higher extraction in pure octanol may be due to a better solubility of the extracted complexes in this polar medium compared to the mixture of octanol and n-dodecane. The water and acid uptake, the back extraction, and the radiation stability of the solvent systems were also investigated. DFT studies were performed to get a better insight into the extraction and complexation of the different DGA solvent systems. [ABSTRACT FROM AUTHOR]

Solar-powered electrochemical production of hydrogen through water electrolysis is an active and important research endeavor. However, technologies and roadmaps for implementation of this process do not exist. In this perspective paper, we describe potential pathways for solar-hydrogen technologies into the marketplace in the form of photoelectrochemical or photovoltaic-driven electrolysis devices and systems. We detail technical approaches for device and system architectures, economic drivers, societal perceptions, political impacts, technological challenges, and research opportunities. Implementation scenarios are broken down into short-term and long-term markets, and a specific technology roadmap is defined. In the short term, the only plausible economical option will be photovoltaic-driven electrolysis systems for niche applications. In the long term, electrochemical solar-hydrogen technologies could be deployed more broadly in energy markets but will require advances in the technology, significant cost reductions, and/or policy changes. Ultimately, a transition to a society that significantly relies on solar-hydrogen technologies will benefit from continued creativity and influence from the scientific community.

Two new carbon pivoted tripodal amide-containing ligands with different spacers (LI: -CH2- spacer; LII: -CH2-CH2- spacer) have been investigated for the liquid–liquid extraction of tetravalent plutonium and hexavalent uranium from nitric acid feed solutions. The studies were carried out using the ligand solutions prepared in 95% n-dodecane + 5% isodecanol. Pu(IV) extraction was higher than that of U(VI) at 3 M HNO3 for ligand LI which was just the opposite for ligand LII. Increase of the nitric acid concentration resulted in increasing extraction of both metal ions. Isodecanol variation studies exhibited decrease in the extraction of Pu(IV) and U(VI) with increasing isodecanol content in the organic phase. Greater that 98% stripping of Pu(IV) and U(VI) was obtained from the complexes of LI and LII using 0.5 M HNO3 + 0.1 M HEDTA and 1 M Na2CO3, respectively. The slope analysis study suggested the formation of 1:2 (ML2) species with Pu(IV) as well as U(VI) with both ligands at 3 M HNO3. Temperature variation studies showed that the extraction of U(VI) and Pu(IV) with both ligands is exothermic in nature. Supported liquid membrane transport experiments using 0.11 M ligands (LI and LII) in 95% n-dodecane + 5% isodecanol indicated poor transport (<10% after 2 h) of U(VI) and Pu(IV). [ABSTRACT FROM AUTHOR]

In the last two decades, perchlorate salts have been identified as environmental pollutants and recognized as potential substances affecting human health. We describe self‐assembled monolayers (SAMs) of novel semiaza‐bambus[6]urils (semiaza‐BUs) equipped with thioethers or disulfide (dithiolane) functionalities as surface‐anchoring groups on gold electrodes. Cyclic voltammetry (CV) with Fe(CN)63−/4− as a redox probe, together with X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and ellipsometry, were employed to characterize the interactions at the interface between the anchoring groups and the metal substrate. Data showed that the anion receptors′ packing on the gold strongly depends on the anchoring group. As a result, SAMs of BUs with lipoic amide side chains show a concentration‐dependent layer thickness. The BU SAMs are extremely stable on repeated electrochemical potential scans and can selectively recognize perchlorate anions. Our electrochemical impedance spectroscopy (EIS) studies indicated that semiaza‐BU equipped with the lipoic amide side chains binds perchlorate (2–100 mM) preferentially over other anions such as F−, Cl−, I−, AcO−, H2PO4−, HPO42−, SO42−, NO2−, NO3−, or CO32−. The resistance performance is 10 to 100 times more efficient than SAMs containing all other tested anions. [ABSTRACT FROM AUTHOR]

This work describes a competing activation network, which is regulated by chemical feedback at the liquid‐surface interface. Feedback loops dynamically tune the concentration of chemical components in living systems, thereby controlling regulatory processes in neural, genetic, and metabolic networks. Advances in systems chemistry demonstrate that chemical feedback could be designed based on similar concepts of using activation and inhibition processes. Most efforts, however, are focused on temporal feedback whereas biological networks are maintained by the interplay between temporal and spatial organization. Here, we designed a feedback system comprising a simple acid‐base equilibrium that can be perturbed by two opposing activation processes. Crucially, one of the processes is immobilized on the surface of a microfluidic channel using poly‐l‐lysine (PLL). We measured the capacity of the PLL‐coated channels to resist changes in pH in flow using a pH‐sensitive indicator, phenol red, and showed that this capacity can be increased by employing polyelectrolyte multilayers. Specifically, we found that the rate of local activation (i. e., the deprotonation of the immobilized lysine residues) could be significantly increased to delay the otherwise fast equilibrium. This effect allowed for encoding read and write operations, providing the potential to bestow CRNs with the capacity of molecular information processing. [ABSTRACT FROM AUTHOR]