Polarity and functionality tailored conjugated microporous polymer coatings on silica microspheres for enhanced pollutant adsorption.

Many sources of pollution that are generated by modern society are not addressable by conventional methods. Especially organic compounds, like pharmaceutics, are particularly hard to remove from waterbodies. Herein, a new approach is presented using conjugated microporous polymers (CMPs) to coat silica microparticles yielding specifically tailored adsorbents. The CMPs are generated with three different monomers: 2,6-dibromonaphthalene (DBN), 2,5-dibromoaniline (DBA) and 2,5-dibromopyridine (DBPN) respectively coupled to 1,3,5-triethynylbenzene (TEB) via Sonogashira coupling. By optimizing the polarity of the silica surface, all three CMPs were converted into microparticle coatings. The resulting hybrid materials feature the advantages of being adjustable in polarity and functionality, as well as morphology. Sedimentation allows facile removal of the coated microparticles after the adsorption. Further, the expansion of the CMP to a thin coating increases the accessible surface area compared to the bulk material. These effects were demonstrated by the adsorption of the model drug diclofenac. Thereby, the aniline-based CMP proved to be most advantageous due to a secondary crosslinking mechanism of amino and alkyne functionalities. An outstanding adsorption capacity of 228 mg diclofenac per gram of the aniline CMP within the hybrid material was achieved. This represents a five-fold increase compared to the value obtained by the pure CMP material underlining the advantages of the hybrid material.

An Anode-Free Zn-Graphite Battery.

The anode-free battery concept is proposed to pursue the aspiration of energy-dense, rechargeable metal batteries, but this has not been achieved with dual-ion batteries. Herein, the first anode-free Zn-graphite battery enabled by efficient Zn plating-stripping onto a silver-coated Cu substrate is demonstrated. The silver coating guides uniform Zn deposition without dendrite formation or side reaction over a wide range of electrolyte concentrations, enabling the construction of anode-free Zn cells. In addition, the graphite cathode operates efficiently under reversible bis(trifluoromethanesulfonyl)imide anion (TFSI- ) intercalation without anodic corrosion. An extra high-potential TFSI- intercalation plateau is recognized at 2.75 V, contributing to the high capacity of graphite cathode. Thanks to efficient Zn plating-stripping and TFSI- intercalation-deintercalation, an anode-free Zn-graphite dual-ion battery that exhibits impressive cycling stability with 82% capacity retention after 1000 cycles is constructed. At the same time, a specific energy of 79 Wh kg-1 based on the mass of cathode and electrolyte is achieved, which is over two times higher than conventional Zn-graphite batteries (<30 Wh kg-1 ).

An Efficient Rechargeable Aluminium-Amine Battery Working Under Quaternization Chemistry.

Rechargeable aluminium (Al) batteries (RABs) have long-been pursued due to the high sustainability and three-electron-transfer properties of Al metal. However, limited redox chemistry is available for rechargeable Al batteries, which restricts the exploration of cathode materials. Herein, we demonstrate an efficient Al-amine battery based on a quaternization reaction, in which nitrogen (radical) cations (R3 N.+ or R4 N+ ) are formed to store the anionic Al complex. The reactive aromatic amine molecules further oligomerize during cycling, inhibiting amine dissolution into the electrolyte. Consequently, the constructed Al-amine battery exhibits a high reversible capacity of 135 mAh g-1 along with a superior cycling life (4000 cycles), fast charge capability and a high energy efficiency of 94.2 %. Moreover, the Al-amine battery shows excellent stability against self-discharge, far beyond conventional Al-graphite batteries. Our findings pave an avenue to advance the chemistry of RABs and thus battery performance.

Cationic polythiophene-anionic fullerene pair in water and water-dioxane: studies on hydrogen bonding capabilities, kinetic and thermodynamic properties.

Despite the vast array of solution- and solid-state bio-analytical, bioelectronic and optoelectronic applications of cationic polythiophenes (CPTs), the number of studies focused on the role of hydrogen bonding (H-bonding) between these and other molecules is scarce, regardless of whether H-bonding is expected to play an important role in several such applications. Also, despite the advantages of using cosolvents to systematically examine the molecular interactions, there are no such studies for CPTs to our knowledge. This work presents a steady-state UV-vis/fluorescence spectroscopic, kinetic and thermodynamic study on the H-bonding interactions between a water-soluble, cationic-anionic (isothiouronium-tetraphosphonate), polythiophene-fullerene donor-acceptor pair with two-point, charge-assisted H-bonding (CAHB) capabilities, tuned using water or a 1,4-dioxane-water mixture (W-DI). Both solvents generate photoinduced electron transfer (PET), fluorescence resonance energy transfer (FRET), spontaneous binding, H-bonding, ground-state complexing via multiple site binding, formation of micelle-like aggregates and equivalence points at a similar concentration of the quencher. However, in comparison with water, W-DI promotes less-ordered, less packed micellar aggregates, due to hydrophobic desolvation of the H-bond and larger solvent displacement during the PT1-4Fo complexation. This would decrease the extent of charge-transfer and the size of the sphere-of-quenching, mainly by displacements or rotations of the H-bonds, instead of elongations, together with a possible larger extent of diffusion-controlled static quenching. At [4Fo] larger than the equivalence point the micelles formed in water do not have available binding sites due to a tighter aggregation, causing a decrease in the quenching efficiency, while the micelles formed in W-DI start showing larger quenching efficiencies, possibly due to an increase in entropy that overcomes the desolvation of the H-bonding. These results could be useful when analyzing outputs from systems including CPTs with H-bonding capabilities, operating in (or casted from) solvents with clear differences in polarity and/or H-bonding capacity.

Effects of Weak Nonspecific Interactions with ATP on Proteins.

Adenosine triphosphate (ATP) is an immensely well-studied metabolite serving multiple key biochemical roles as the major chemical energy currency in living systems, a building block of ribonucleic acids, and a phosphoryl group donor in kinase-mediated signaling. Intriguingly, ATP has been recently proposed to act as a hydrotrope that inhibits aggregation of amyloidogenic proteins; however, the underlying mechanism and the general physicochemical effect that coexistence with ATP exerts on proteins remain unclear. By combining NMR spectroscopy and MD simulations, here we observed weak but unambiguously measurable and concentration-dependent noncovalent interactions between ATP and various proteins. The interactions were most pronounced for an intrinsically disordered protein (α-synuclein) and for residues in flexible regions (e.g., loops or termini) of two representative folded proteins (ubiquitin and the dimeric ubiquitin-binding domain of p62). As shown by solution NMR, a consequence of the ATP-protein interaction was altered hydration of solvent-exposed residues in the protein. The observation that ATP interacted with all three proteins suggests that ATP is a general nonspecific binder of proteins. Several complementary biophysical methods further confirmed that, at physiological concentrations of ∼5-10 mM, ATP starts to form oligomeric states via magnesium-chelating and chelation-independent mechanisms, in agreement with previous studies. Although the observed ATP-protein interaction was relatively weak overall, the high ratio of ATP (monomeric free ATP, mono- and divalent ion-bound ATP, oligomeric and chelated ATP) to proteins in cells suggests that most proteins are likely to encounter transient interactions with ATP (and chemically similar metabolites) that confer metabolite-mediated protein surface protection.

Characterization of chitosan with different degree of deacetylation and equal viscosity in dissolved and solid state - Insights by various complimentary methods.

In recent years, chitosan has attracted considerable interest in many fields due to its sufficient charge density under biological, non-hazardous conditions. Since chitosan originates from natural resources and has two different monomer units, its characterization must be carried out in a goal-oriented and precise manner. This work focuses on the characterization of chitosans most important parameters - solubility, crystallinity, degree of deacetylation (DD) and molecular weight - in a simple and convenient way. The DD was determined using Nuclear Magnetic Resonance spectroscopy (NMR), Particle Charge Detection (PCD), Fourier Transform Infrared spectroscopy (FTIR), CHN elemental analysis (CHN-EA) and conductometric/potentiometric titration with special attention to its physical state as solid or liquid. Investigation of DD by FTIR was successfully determined by calculating peak heights, peak areas and peak deconvolution from a linear combination of Gaussian and Lorentzian functions. Asymmetrical flow field flow fractionation with light scattering detection (AF4-LS) was applied in order to calculate molar masses and radii. In addition, pH-potentiometric titrations demonstrated a reproducible displacement of the point of zero charge (PZC) in form of a hysteresis depending on the titration direction. The DD affects the crystallinity, which was determined by deconvolution of the crystalline and amorphous domains.

A High-Voltage, Dendrite-Free, and Durable Zn-Graphite Battery.

The intrinsic advantages of metallic Zn, like high theoretical capacity (820 mAh g-1 ), high abundance, low toxicity, and high safety have driven the recent booming development of rechargeable Zn batteries. However, the lack of high-voltage electrolyte and cathode materials restricts the cell voltage mostly to below 2 V. Moreover, dendrite formation and the poor rechargeability of the Zn anode hinder the long-term operation of Zn batteries. Here a high-voltage and durable Zn-graphite battery, which is enabled by a LiPF6 -containing hybrid electrolyte, is reported. The presence of LiPF6 efficiently suppresses the anodic oxidation of Zn electrolyte and leads to a super-wide electrochemical stability window of 4 V (vs Zn/Zn2+ ). Both dendrite-free Zn plating/stripping and reversible dual-anion intercalation into the graphite cathode are realized in the hybrid electrolyte. The resultant Zn-graphite battery performs stably at a high voltage of 2.8 V with a record midpoint discharge voltage of 2.2 V. After 2000 cycles at a high charge-discharge rate, high capacity retention of 97.5% is achieved with ≈100% Coulombic efficiency.

Polymer Chain Mobility under Shear-A Rheo-NMR Investigation.

The local dynamics in polymer melts and the impact of external shear in a Couette geometry have been investigated using rheological nuclear magnetic resonance (NMR). The spin-spin relaxation time, T2, which is sensitive to chain-segment motion, has been measured as a function of shear rate for two samples of poly(dimethylsiloxane). For the low-molecular-weight sample, a mono-exponential decay is observed, which becomes slightly faster with shear, indicating restrictions of the polymer chain motion. For the high-weight sample, a much faster bi-exponential decay is observed, indicative of entanglements. Both components in this decay become longer with shear. This implies that the free polymer segments between entanglements become effectively longer as a result of shear.

Palladium-catalyzed annulation reactions for diastereoselective cyclopentene synthesis.

Palladium-catalyzed annulation reactions of conjugate acceptors and allenyl boronic ester provide substituted cyclopentenes in high yields and, where applicable, diastereoselectivities. This method provides rapid assembly of building blocks for natural product synthesis, including polycyclic lactone and lactam products. Reactions are hypothesized to initiate by conjugate addition of a nucleophilic propargylpalladium complex.

Palladium-catalyzed conjugate allylation reactions of alpha,beta-unsaturated N-acylpyrroles.

Conjugate allylation reactions of alpha,beta-unsaturated N-acylpyrroles using allylboronic ester are catalyzed by a palladium complex that is ligated by a bidentate N-heterocyclic carbene. A variety of functional groups are tolerated, and substrates functionalized with electron-withdrawing groups react to afford the highest yields of products. Regioselectivity for 1,4-allylation over 1,2-allylation is demonstrated, and mechanistic experiments are consistent with formation of nucleophilic allylpalladium intermediates.