Complex Nanoparticle Diffusional Motion in Liquid-Cell Transmission Electron Microscopy

Liquid-cell transmission electron microscopy (LCTEM) is a powerful in situ videography technique that has the potential to allow us to observe solution-phase dynamic processes at the nanoscale, including imaging the diffusion and interaction of nanoparticles. Artefactual effects imposed by the irradiated and confined liquid-cell vessel alter the system from normal "bulk-like" behavior in multiple ways. These artefactual LCTEM effects will leave their fingerprints in the motion behavior of the diffusing objects, which can be revealed through careful analysis of the object-motion trajectories. Improper treatment of the motion data can lead to erroneous descriptions of the LCTEM system's conditions. Here, we advance our anomalous diffusion object-motion analysis (ADOMA) method to extract a detailed description of the liquid-cell system conditions during any LCTEM experiment by applying a multistep analysis of the data and treating the x/y vectors of motion independently and in correlation with each other and with the object's orientation/angle

Bio-inspired CO 2 reduction by a rhenium tricarbonyl bipyridine-based catalyst appended to amino acids and peptidic platforms: incorporating proton relays and hydrogen-bonding functional groups

Herein, we report a new approach to bio-inspired catalyst design. The molecular catalyst employed in these studies is based on the robust and selective Re(bpy)(CO)3Cl-type (bpy = 2,2'-bipyridine) homogeneous catalysts, which have been extensively studied for their ability to reduce CO2 electrochemically or photochemically in the presence of a photosensitizer. These catalysts can be highly active photocatalysts in their own right. In this work, the bipyridine ligand was modified with amino acids and synthetic peptides. These results build on earlier findings wherein the bipyridine ligand was functionalized with amide groups to promote dimer formation and CO2 reduction by an alternate bimolecular mechanism at lower overpotential (ca. 250 mV) than the more commonly observed unimolecular process. The bio-inspired catalysts were designed to allow for the incorporation of proton relays to support reduction of CO2 to CO and H2O. The coupling of amino acids tyrosine and phenylalanine led to the formation of two structurally similar Re catalyst/peptide catalysts for comparison of proton transport during catalysis. This article reports the synthesis and characterization of novel catalyst/peptide hybrids by molecular dynamics (MD simulations of structural dynamics), NMR studies of solution phase structures, and electrochemical studies to measure the activities of new bio-inspired catalysts in the reduction of CO2

Water Permeability and Elastic Properties of an Archaea Inspired Lipid Synthesized by Click Chemistry

Researchers report the synthesis of a new archaea-inspired tetraether lipid and study the mechanical elastic properties of membranes made from this bolalipid. To access structural diversity in the hydrophobic moiety of the lipids and to tune membrane properties, they have used used Huisgen 1,3-dipolar cycloaddition strategy to design and synthesize a tetraether lipid incorporating phytanyl side chains and polar 1,4 triazole rings known to change lipid packing. The researchers demonstrate the first example of the synthesis of phytanyl side chain incorporated tetraether lipids with 1,4-triazole rings. They also confirm the ability of lipids incorporating 1,4-triazole rings to form stable small and giant vesicles and examined their physical and mechanical properties using a micropipette aspiration technique