Vesterdavidson0883

Because of a charge-dipole interaction involving nonbonding electron pairs on fluorine, protonation of trifluoromethyl allenes leads to tri- or tetrasubstituted alkenes with high (Z)-selectivity. Treatment of the same allenes with catalytic Au(I) initiates a reaction cascade that produces isoxazolines in high yield.Specific molecular arrangements within H-/J-aggregates of cyanine dyes enable extraordinary photophysical properties, including long-range exciton delocalization, extreme blue/red shifts, and excitonic superradiance. Despite extensive literature on cyanine aggregates, design principles that drive the self-assembly to a preferred H- or J-aggregated state are unknown. We tune the thermodynamics of self-assembly via independent control of the solvent/nonsolvent ratio, ionic strength, or dye concentration, obtaining a broad range of conditions that predictably stabilize the monomer (H-/J-aggregate). Diffusion-ordered spectroscopy, cryo-electron microscopy, and atomic force microscopy together reveal a dynamic equilibrium between monomers, H-aggregated dimers, and extended J-aggregated 2D monolayers. We construct a model that predicts the equilibrium composition for a range of standard Gibbs free energies, providing a vast aggregation space which we access using the aforementioned solvation factors. selleck compound We demonstrate the universality of this approach among several sheet-forming cyanine dyes with tunable absorptions spanning visible, near, and shortwave infrared wavelengths.Polystyrene nanoparticles (PS-NPs) derived from both environmental and occupational sources are an important class of ultrafine particles associated with human pulmonary disorders. The effects of surface charges of particle internalization and toxicity to alveolar cells, especially under conditions comparable to those found during breathing, have not been examined. Here, we applied cyclic stretches (CS) to human alveolar cells during nanoparticle exposure and show an enhanced accumulation of positively charged polystyrene nanoparticles as compared to similar negatively charged particles. The cellular uptake of the positive particles into live cells was visualized with three-dimensional optical diffraction tomography (3-D ODT). The simultaneous application of both periodic stretching as well as positively charged nanoparticles led to blebbing morphology and activation of apoptotic signaling compared to control cells. Our findings provide a better understanding of how surface charge mediates the uptake and toxicity of nanoplastics under the dynamical mechanical conditions relevant for breathing exposures.Attempts to functionalize polycyclic quinones using lithium diisopropylamide as a base led to the unexpected formation of acenes. This reaction proceeds by electron transfer from the base to the electron deficient quinone, whose radical anion can react with a variety of electrophiles. Siloxy derivatives synthesized by this method could be easily isolated but showed poor photostability. In situ reduced intermediate generation is a convenient approach to functionalization of oxidatively unstable hydroquinones.The intercalation strategy is successfully applied in tuning the interlayer distance of 2D membranes for efficient desalination and ion sieving. However, it is difficult to pursue a intercalant that is few nanometers in size and suitable for further chemical modification . Here, for the first time, we report the intercalation of soft particles-polyacrylonitrile gel particles (PAN GPs) inside the graphene oxide (GO) membranes, which allows for a tunable interlayer distance via the deformation of soft particles. Furthermore, the base-induced hydrophobic/hydrophilic structure of PAN GPs facilitates the water diffusion through the GO membrane. A fast and selective water permeation was observed through separation Cu-EDTA2-from water, with the permeance of 4-13 times higher than the reported 2D membranes. Intercalation of soft particles represents a promising strategy to fabricate high-performance 2D membranes.We systematically evaluated the physicochemical properties of a series of M[FTA]-[C4C1pyrr][FTA] ionic liquids (ILs) (M = alkali metal, FTA = (fluorosulfonyl)(trifluoromethylsulfonyl)amide, C4C1pyrr = N-butyl-N-methylpyrrolidinium) as electrolytes for alkali metal-ion batteries. First, the viscosity (η), ionic conductivity (σ), and density (ρ) of the M[FTA]-[C4C1pyrr][FTA] ILs at x(M[FTA]) = 0.20 (x(M[FTA]) = molar fraction of M[FTA]) were measured. The σ values ranged from 1-3 mS cm-1 at 298 K and increased as follows Na less then Li less then K less then Rb less then Cs, which indicated that the Li-based IL did not obey the trend predicted by the charge densities of alkali metal cations. Second, the Li-based IL exhibited slightly lower vertical intercept values than the other FTA-based ILs in the Walden plots obtained using the results of η, σ, and ρ measurements. Third, the electrochemical stability of the ILs was investigated by cyclic voltammetry, and the redox potentials of the alkali metals (E(M+/M)) were determined. The E(M+/M) values of the FTA-based ILs increased as follows Cs less then Rb less then K less then Li less then Na. Subsequently, we compared the obtained E(M+/M) values with those of other general electrolytes, such as propylene carbonate (PC)-based electrolytes and aqueous solutions. The trend in E(M+/M) values of the FTA-based ILs was similar to that of PC-based electrolytes and was significantly different from that of aqueous solutions. In particular, the FTA- and FSA-based ILs (FSA = bis(fluorosulfonyl)amide) presented the most negative E(Na+/Na) and E(K+/K) values among various electrolytes, which indicated that utilization of these IL electrolytes for the development of Na- and K-ion batteries would present significant advantages.The structure and vibrational spectra of protonated Ar clusters Ar n H+ (n = 2-3) are studied using potential energy surfaces at the CCSD(T)/aug-cc-pVTZ level and basis set. Ar binding energies, as well as position isomerism in Ar3H+, were investigated. In our previous work, the spectra of Ar2H+ reveal a strong progression of combination bands, which involves the asymmetric Ar-H+ stretch with multiple quanta of the symmetric Ar-H+ stretch. In this work, insights on the origin of such progression were examined using an adiabatic model. In addition, contributions from mechanical and electrical anharmonicity on the progressions' intensities were also examined. Comparison of the calculated spectrum for the bare and Ar-tagged ions reveals that the reduction of the symmetry group, from D∞h to either C∞v or C2v, results in a richer vibrational structure in the 500-1700 cm-1 region. When compared with previously reported action spectra (D. C. McDonald III, D. T. Mauney, D. Leicht, J. H. Marks, J. A. Tan, J.-L. Kuo, and M.