Continuous Synthesis and Processing of Covalent Organic Frameworks in a Flow Reactor.

Covalent organic frameworks (COFs) are typically prepared in the form of insoluble microcrystalline powders using batch solvothermal reactions that are energy-intensive and require long annealing periods (>120 °C, >72 h). Thus, their wide-scale adoption in a variety of potential applications is impeded by complications related to synthesis, upscaling, and processing, which also compromise their commercialization. Here we report a strategy to address both the need for scalable synthesis and processing approaches through the continuous, accelerated synthesis, and processing of imine- and hydrazone-linked COFs using a flow microreactor.

Brownian Diffusion of Hexagonal Boron Nitride Nanosheets and Graphene in Two Dimensions.

Two-dimensional (2D) nanomaterials have numerous interesting chemical and physical properties that make them desirable building blocks for the manufacture of macroscopic materials. Liquid-phase processing is a common method for forming macroscopic materials from these building blocks including wet-spinning and vacuum filtration. As such, assembling 2D nanomaterials into ordered functional materials requires an understanding of their solution dynamics.

Hexagonal boron nitride exfoliation and dispersion.

Research on hexagonal boron nitride (hBN) 2-dimensional nanostructures has gained traction due to their unique chemical, thermal, and electronic properties. However, to make use of these exceptional properties and fabricate macroscopic materials, hBN often needs to be exfoliated and dispersed in a solvent. In this review, we provide an overview of the many different methods that have been used for dispersing hBN.

Photochemical iron-catalyzed decarboxylative azidation via the merger of ligand-to-metal charge transfer and radical ligand transfer catalysis.

Ligand-to-metal charge transfer (LMCT) using stoichiometric copper salts has recently been shown to permit decarboxylative C-N bond formation via an LMCT/radical polar crossover (RPC) mechanism; however, this method is unable to function catalytically and cannot successfully engage unactivated alkyl carboxylic acids, presenting challenges to the general applicability of this approach. Leveraging the concepts of ligand-to-metal charge transfer (LMCT) and radical-ligand-transfer (RLT), we herein report the first photochemical, iron-catalyzed direct decarboxylative azidation. Simply irradiating an inexpensive iron nitrate catalyst in the presence of azidotrimethylsilane allows for a diverse array of carboxylic acids to be converted to corresponding organic azides directly with broad functional group tolerance and mild conditions.

Evaluating the inhibitory activity of ferrocenyl Schiff bases derivatives on 5-lipoxygenase: Computational and biological studies.

In the search for new 5-LOX inhibitors, two ferrocenyl Schiff base complexes functionalized with catechol ((ƞ-(E)-CH-NCH-3,4-benzodiol)Fe(ƞ-CH) (3a)) and vanillin ((ƞ-(E)-CH-NCH-3-methoxy-4-phenol)Fe(ƞ-CH) (3b)) were obtained. Complexes 3a and 3b were biologically evaluated as 5-LOX inhibitors showed potent inhibition compared to their organic analogs (2a and 2b) and known commercial inhibitors, with IC = 0.17 ± 0.

Probing the Rotary Cycle of Amine-Substituted Molecular Motors.

An understanding of the rotary cycle of molecular motors (MMs), a key component of an approach to opening cells using mechanical motion, is important in furthering the research. Nuclear magnetic resonance (NMR) spectroscopy was used for analysis of illuminated light-active MMs. We found that the presence of a ,-dimethylethylenediamine in a position conjugated to the central olefin results in changes to the rotation of a second-generation Feringa-type MM.

Liquid crystals of neat boron nitride nanotubes and their assembly into ordered macroscopic materials.

Boron nitride nanotubes (BNNTs) have attracted attention for their predicted extraordinary properties; yet, challenges in synthesis and processing have stifled progress on macroscopic materials. Recent advances have led to the production of highly pure BNNTs. Here we report that neat BNNTs dissolve in chlorosulfonic acid (CSA) and form birefringent liquid crystal domains at concentrations above 170 ppmw.

A simple graphene modified electrode for the determination of antimony(III) in edible plants and beverage.

Antimony(III) is a rare electroactive specie present on Earth, whose concentration is not typically determined. The presence of high concentrations of antimony is responsible for a variety of diseases, which makes it desirable to find convenient and reliable methods for its determination. We have developed a convenient glassy carbon modified electrode with electroreduced graphene oxide GC/rGO for the first time determination of Sb(III) in commercial lettuce, celery, and beverages.

Real-Time Visualization and Dynamics of Boron Nitride Nanotubes Undergoing Brownian Motion.

We report the first real-time imaging of individualized boron nitride nanotubes (BNNTs) via stabilization with a rhodamine surfactant and fluorescence microscopy. We study the rotational and translational diffusion and find them to agree with predictions based on a confined, high-aspect-ratio rigid rod undergoing Brownian motion. We find that the behavior of BNNTs parallels that of individualized carbon nanotubes (CNTs), indicating that BNNTs could also be used as model rigid rods to study soft matter systems, while avoiding the experimental disadvantages of CNTs due to their strong light absorption.

Defect-Engineering-Enabled High-Efficiency All-Inorganic Perovskite Solar Cells.

The emergence of cesium lead iodide (CsPbI ) perovskite solar cells (PSCs) has generated enormous interest in the photovoltaic research community. However, in general they exhibit low power conversion efficiencies (PCEs) because of the existence of defects. A new all-inorganic perovskite material, CsPbI :Br:InI , is prepared by defect engineering of CsPbI .

Interrogating Amyloid Aggregates using Fluorescent Probes.

Amyloids are a broad class of proteins and peptides that can misfold and assemble into long unbranched fibrils with a cross-β conformation. These misfolding and aggregation events are associated with the onset of a variety of human diseases, among them, Alzheimer's disease, Parkinson's disease, and Huntington disease. Our understanding of amyloids has been greatly supported by fluorescent molecular probes, such as thioflavin-T, which shows an increase in fluorescence emission upon binding to fibrillar aggregates.

Monitoring the Formation of Amyloid Oligomers Using Photoluminescence Anisotropy.

The formation of oligomeric soluble aggregates is related to the toxicity of amyloid peptides and proteins. In this manuscript, we report the use of a ruthenium polypyridyl complex ([Ru(bpy)(dpqp)]) to track the formation of amyloid oligomers at different times using photoluminescence anisotropy. This technique is sensitive to the rotational correlation time of the molecule under study, which is consequently related to the size of the molecule.

Adverse Effect of PTFE Stir Bars on the Covalent Functionalization of Carbon and Boron Nitride Nanotubes Using Billups-Birch Reduction Conditions.

The functionalization of nanomaterials has long been studied as a way to manipulate and tailor their properties to a desired application. Of the various methods available, the Billups-Birch reduction has become an important and widely used reaction for the functionalization of carbon nanotubes (CNTs) and, more recently, boron nitride nanotubes. However, an easily overlooked source of error when using highly reductive conditions is the utilization of poly(tetrafluoroethylene) (PTFE) stir bars.

Sensing Temperature in Vitro and in Cells Using a BODIPY Molecular Probe.

Boron dipyrromethene (BODIPY) molecular rotors have shown sensitivity toward viscosity, polarity, and temperature. Here, we report a 1,3,5,7-tetramethyl-8-phenyl-BODIPY modified with a polyethylene glycol (PEG) chain, for temperature sensing and live cell imaging. This new PEG-BODIPY dye presents an increase in nonradiative decay as temperature increases, which directly influences its lifetime.

Lead-Free Double Perovskite Cs SnX : Facile Solution Synthesis and Excellent Stability.

Long-term instability and possible lead contamination are the two main issues limiting the widespread application of organic-inorganic lead halide perovskites. Here a facile and efficient solution-phase method is demonstrated to synthesize lead-free Cs SnX (X = Br, I) with a well-defined crystal structure, long-term stability, and high yield. Based on the systematic experimental data and first-principle simulation results, Cs SnX displays excellent stability against moisture, light, and high temperature, which can be ascribed to the unique vacancy-ordered defect-variant structure, stable chemical compositions with Sn , as well as the lower formation enthalpy for Cs SnX .

Surfactant-assisted individualization and dispersion of boron nitride nanotubes.

Boron nitride nanotubes (BNNTs) belong to a novel class of material with useful thermal, electronic and optical properties. However, the study and the development of applications of this material requires the formation of stable dispersions of individual BNNTs in water. Here we address the dispersion of BNNT material in water using surfactants with varying properties.

Soft-Lithographic Patterning of Luminescent Carbon Nanodots Derived from Collagen Waste.

Luminescent carbon dots (Cdots) synthesized using inexpensive precursors have inspired tremendous research interest because of their superior properties and applicability in various fields. In this work, we report a simple, economical, green route for the synthesis of multifunctional fluorescent Cdots prepared from a natural, low-cost source: collagen extracted from animal skin wastes. The as-synthesized metal-free Cdots were found to be in the size range of ∼1.

An Insight into the Phase Transformation of WS upon Fluorination.

The transformation from semiconducting to metallic phase, accompanied by a structural transition in 2D transition metal dichalcogenides has attracted the attention of the researchers worldwide. The unconventional structural transformation of fluorinated WS (FWS ) into the 1T phase is described. The energy difference between the two phases debugs this transition, as fluorination enhances the stability of 1T FWS and makes it energetically favorable at higher F concentration.

Exfoliation of a non-van der Waals material from iron ore hematite.

With the advent of graphene, the most studied of all two-dimensional materials, many inorganic analogues have been synthesized and are being exploited for novel applications. Several approaches have been used to obtain large-grain, high-quality materials. Naturally occurring ores, for example, are the best precursors for obtaining highly ordered and large-grain atomic layers by exfoliation.

Singular wavelength dependence on the sensitization of lanthanides by graphene quantum dots.

In this manuscript, we study the sensitization of Tb3+ ions by the excited state of GQD. We found that Tb3+ cations can bind to GQDs and display photoluminescence. Excitation dependent experiments show that the Tb3+ emission is stronger at shorter excitation wavelengths, which is likely due to pseudo-isolated small aromatic moieties produced during the synthesis of the GQDs.

Laser-Induced Conversion of Teflon into Fluorinated Nanodiamonds or Fluorinated Graphene.

Laser-assisted materials fabrication is an advanced technique that has propelled recent carbon synthesis approaches. Direct laser writing on polyimide or lignocellulose materials by a CO laser has successfully transformed the substrates into hierarchical graphene. However, formation of other carbon allotropes such as diamond and fullerene remains challenging.

A novel electroluminescent device based on a reduced graphene oxide wrapped phosphor (ZnS:Cu,Al) and hexagonal-boron nitride for high-performance luminescence.

Reduced graphene oxide (rGO) has recently emerged as a very promising family of exotic carbon material with augmented performance in electronic and optoelectronic devices. Herein, we report an efficient and novel inorganic electroluminescent device geometry, where a new phosphor composite, reduced graphene oxide wrapped ZnS:Cu,Al, acts as an active emitting layer and an exfoliated hexagonal boron nitride (h-BN) as a dielectric layer. The roles of rGO in the active layer as a conductive support and local electric field enhancing agent are attributed to its wrinkles being unraveled compared with other carbon exotic nano-forms such as carbon nanotubes, graphite, charcoal and activated carbon, which significantly improves the brightness of the device (∼50 cd m for 0.