Observing High‐Pressure Chemistry in Graphene Bubbles

Using IR spectroscopy, high‐pressure reactions of molecules were observed in liquids entrapped by graphene nanobubbles formed at the graphene–diamond interface. Nanobubbles formed on graphene as a result of thermally induced bonding of its edges with diamond are highly impermeable, thus providing a good sealing of solvents within. Owing to the optical transparency of graphene and diamond, high‐pressure chemical reactions within the bubbles can be probed with vibrational spectroscopy. By monitoring the conformational changes of pressure‐sensitive molecules, the pressure within the nanobubble can be calibrated as a function of temperature and it is about 1 GPa at 600 K. The polymerization of buckministerfullerene (C₆₀), which is symmetrically forbidden under ambient conditions, is observed to proceed in well‐defined stages in the pressurized nanobubbles.     

Band‐Gap Manipulations of Monolayer Graphene by Phenyl Radical Adsorptions: A Density Functional Theory Study

Phenyl radical (Ph^.) adsorption on monolayer graphene sheets is used to investigate the band‐gap manipulation of graphene through density functional theory. Adsorption of a single Ph^. on graphene breaks the aromatic π‐bond and generates an unpaired electron, which is delocalized to the ortho or para position. Adsorption of a second radical at the ortho or para position saturates the radical by electron pairing and results in semiconducting graphene. Adsorption of a second radical at the ortho position (ortho–ortho pairing) is found to be more favorable than adsorption at the para position (ortho–para pairing), and the ortho–ortho pairing has stronger effects on band‐gap opening compared with ortho–para pairing. Adsorption of even numbers of Ph^. on graphene by ortho–ortho and ortho–para pairings, in general, increases the band gap. Our study shows promise of band‐gap manipulation in monolayer graphene by Ph^. adsorption, leading to potential wider applications of graphene.     

Fabrication and sensing property for conducting polymer nanowire-based biosensor for detection of immunoglobulin G

Conducting polymers are excellent sensing materials in the design of bioanalytical sensors because of their electronic conductivity, low energy optical transitions, biocompatibility, and room temperature operation. Among them, Polypyrrole (Ppy) is one of the most extensively used conducting polymers because of a number of properties such as redox activity, rapid electron transfer, and ability to link a variety of biomolecules to pyrrole groups by chemical treatment. In this study, Ppy nanowires were synthesized by an electrospinning method. The nanowires were prepared from a solution mixture of Ppy and poly(ethylene oxide). The method of detection in such a device is based on the selective binding of antigen onto an antibody that is covalently attached to the nanowires. Thus, anti-IgG was immobilized on Ppy nanowires using an EDC {[N-(3-dimethyl aminopropyl)-N₂-ethylcarbodiimide hydrochloride]}-NHS(N-hydrosuccinimide) modified technique. Fluorescence images of BSA–FITC (fluorescein isothiocyanate labeling of bovine serum albumin) conjugation demonstrated that antibody was functionalized on the Ppy nanowires without non-specific binding and facilitated selective detection of antigen. Current–voltage (I–V) characterization was used to monitor the change in the conductivity of nanowires while the specific binding interaction occurred. These results of electrical properties enable Ppy nanowire-based biosensors to detect biomolecules in real-time.     

Large-Scale Synthesis of MOF-Derived Superporous Carbon Aerogels with Extraordinary Adsorption Capacity for Organic Solvents

Carbon aerogels (CAs) with 3D interconnected networks hold promise for application in areas such as pollutant treatment, energy storage, and electrocatalysis. In spite of this, it remains challenging to synthesize high-performance CAs on a large scale in a simple and sustainable manner. We report an eco-friendly method for the scalable synthesis of ultralight and superporous CAs by using cheap and widely available agarose (AG) biomass as the carbon precursor. Zeolitic imidazolate framework-8 (ZIF-8) with high porosity is introduced into the AG aerogels to increase the specific surface area and enable heteroatom doping. After pyrolysis under inert atmosphere, the ZIF-8/AG-derived nitrogen-doped CAs show a highly interconnected porous mazelike structure with a low density of 24 mg cm⁻³, a high specific surface area of 516 m² g⁻¹, and a large pore volume of 0.58 cm⁻³ g⁻¹. The resulting CAs exhibit significant potential for application in the adsorption of organic pollutants.     

A Molecular Strategy to Lock‐in the Conformation of a Perylene Bisimide‐Derived Supramolecular Polymer

Locking‐in the conformation of supramolecular assemblies provides a new avenue to regulate the (opto)electronic properties of robust nanoscale objects. In the present contribution, we show that the covalent tethering of a perylene bisimide (PBI)‐derived supramolecular polymer with a molecular locker enables the formation of a locked superstructure equipped with emergent structure–function relationships. Experiments that exploit variable‐temperature ground‐state electronic absorption spectroscopy unambiguously demonstrate that the excitonic coupling between nearest neighboring units in the tethered superstructure is preserved at a temperature (371 K) where the pristine, non‐covalent assembly exists exclusively in a molecularly dissolved state. A close examination of the solid‐state morphologies reveals that the locked superstructure engenders the formation of hierarchical 1D materials which are not achievable by unlocked assemblies. To complement these structural attributes, we further demonstrate that covalently tethering a supramolecular polymer built from PBI subunits enables the emergence of electronic properties not evidenced in non‐covalent assemblies. Using cyclic voltammetry experiments, the elucidation of the potentiometric properties of the locked superstructure reveals a 100‐mV stabilization of the conduction band energy when compared to that recorded for the non‐covalent assembly.     

γ‐Glutamylcysteine‐ and Cysteinylglycine‐Directed Growth of Chiral Gold Nanoparticles and their Crystallographic Analysis

Chiral optical metamaterials with delicate structures are in high demand in various fields because of their strong light–matter interactions. Recently, a scalable strategy for the synthesis of chiral plasmonic nanoparticles (NPs) using amino acids and peptides has been reported. Reported herein, 3D chiral gold NPs were synthesized using dipeptide γ‐Glu‐Cys and Cys‐Gly and analyzed crystallographically. The γ‐Glu‐Cys‐directed NPs present a cube‐like outline with a protruding chiral wing. In comparison, the NPs synthesized with Cys‐Gly exhibited a rhombic dodecahedron‐like outline with curved edges and elliptical cavities on each face. Morphology analysis of intermediates indicated that γ‐Glu‐Cys generated an intermediate concave hexoctahedron morphology, while Cys‐Gly formed a concave rhombic dodecahedron. NPs synthesized with Cys‐Gly are named 432 helicoid V because of their unique morphology and growth pathway.     

Australian Honeypot Ant (Camponotus inflatus) Honey—A Comprehensive Analysis of the Physiochemical Characteristics,Bioactivity, and HPTLC Profile of a Traditional Indigenous Australian Food

Despite its cultural and nutritional importance for local Aboriginal people, the unusual insect honey produced by Western Australian honeypot ant (Camponotus inflatus) has to date been rarely investigated. This study reports on the honey’s physicochemical properties, its total phenolic, major sugars and 5-hydroxymethylfurfural contents, and its antioxidant activities. The honey’s color value is 467.63 mAU/63.39 mm Pfund, it has a pH of 3.85, and its electric conductivity is 449.71 µSiemens/cm. Its Brix value is 67.00, corresponding to a 33% moisture content. The total phenolics content is 19.62 mg gallic acid equivalent/100 g honey. Its antioxidant activity measured using the DPPH* (2,2-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing–antioxidant power) assays is 1367.67 µmol Trolox/kg and 3.52 mmol Fe⁺²/kg honey, respectively. Major sugars in the honey are glucose and fructose, with a fructose-to-glucose ratio of 0.85. Additionally, unidentified sugar was found in minor quantities.     

Soft‐Chemical Exfoliation Route to Layered Cobalt Oxide Monolayers and Its Application for Film Deposition and Nanoparticle Synthesis

A colloidal suspension of exfoliated, layered cobalt oxide nanosheets has been synthesized through the intercalation of quaternary tetramethylammonium ions into protonated lithium cobalt oxide. According to atomic force microscopy, exfoliated nanosheets of layered cobalt oxide show a plateau‐like height profile with nanometer‐level height, underscoring the formation of unilamellar 2D nanosheets. The exfoliation of layered cobalt oxide was cross‐confirmed by X‐ray diffraction, UV/Vis spectroscopy, and transmission electron microscopy. The maintenance of the hexagonal in‐plane structure of the cobalt oxide lattice after the exfoliation process was evidenced by selected‐area electron diffraction and Co K‐edge X‐ray absorption near‐edge structure analysis. The zeta‐potential measurements clearly demonstrated the negative surface charge of cobalt oxide nanosheets. Adopting the nanosheets of layered cobalt oxide as a precursor, we were able to prepare the monodisperse CoO nanocrystals with a particle size of ≈10 nm as well as the heterolayered film composed of cobalt oxide monolayer and polycation.     

Isomer-specific influences on the composition of reaction intermediates in dimethyl ether/propene and ethanol/propene flame

This work provides experimental evidence on how the molecular compositions of fuel-rich low-pressure premixed flames are influenced as the oxygenates dimethyl ether (DME) or ethanol are incrementally blended into the propene fuel. Ten different flames with a carbon-to-oxygen ratio of 0.5, ranging from 100% propene (phi = 1.5) to 100% oxygenated fuel (phi = 2.0), are analyzed with flame-sampling molecular-beam mass spectrometry employing electron- or photoionization. Absolute mole fraction profiles for flame species with masses ranging from m/z = 2 (H2) to m/z = 80 (C6H8) are analyzed with particular emphasis on the formation of harmful emissions. Fuel-specific destruction pathways, likely to be initiated by hydrogen abstraction, appear to lead to benzene from propene combustion and to formaldehyde and acetaldehyde through DME and ethanol combustion, respectively. While the concentration of acetaldehyde increases 10-fold as propene is substituted by ethanol, it decreases as propene is replaced with DME. In contrast, the formaldehyde concentration rises only slightly with ethanol replacement but increases markedly with addition of DME. Allyl and propargyl radicals, the dominant precursors for benzene formation, are likely to be produced directly from propene decomposition or via allene and propyne. Benzene formation through propargyl radicals formed via unsaturated C2 intermediates in the decomposition of DME and ethanol is negligibly small. As a consequence, DME and ethanol addition lead to similar reductions of the benzene concentration.     

Synthesis and size control of monodisperse copper nanoparticles by polyol method

We describe herein the synthesis of metallic copper nanoparticles in the presence of poly(vinylpyrrolidone), employed as a protecting agent, via a polyol method in ambient atmosphere. The obtained copper particles were confirmed by XRD to be crystalline copper with a face-centered cubic (fcc) structure. We observed monodisperse spherical copper nanoparticles with a diameter range 45+/-8 nm. The particle size and its distribution are controlled by varying the synthesis parameters such as the reducing agent concentration, reaction temperature, and precursor injection rate. The precursor injection rate plays an important role in controlling the size of the copper nanoparticles. On the basis of XPS and HRTEM results, we demonstrate that the surface of the copper is surrounded by amorphous CuO and that poly(vinylpyrrolidone) is chemisorbed on the copper surface.