Hybrids of MnO<Subscript>2</Subscript> nanoparticles anchored on graphene sheets as efficient sulfur hosts for high-performance lithium sulfur batteries

Lithium–sulfur (Li–S) battery is considered as a promising option for electrochemical energy storage applications because of its low-cost and high theoretical capacity. However, the practical application of Li–S battery is still hindered due to the poor electrical conductivity of S cathode and the high dissolution/shuttling of polysulfides in electrolyte. Herein, we report a novel physical and chemical entrapment strategy to address these two problems by designing a sulfur–MnO₂@graphene (S–MnO₂@GN) ternary hybrid material structure. The MnO₂ particles with size of ~ 10 nm are anchored tightly on the wrinkled and twisted GN sheets to form a highly efficient sulfur host. Benefiting from the synergistic effects of GN and MnO₂ in both improving the electronic conductivity and hindering polysulfides by physical and chemical adsorptions, this unique S–MnO₂@GN composite exhibits excellent electrochemical performances. Reversible specific capacities of 1416, 1114, and 421 mA h g^?1 are achieved at rates of 0.1, 0.2, and 3.2 C, respectively. After a 100 cycle stability test, S–MnO₂@GN composite cathode could still maintain a reversible capacity of 825 mA h g^?1.     

A high-efficiency and low-cost AEE polyurethane chemo-sensor for Fe3+ and explosives detection

An aggregation enhanced emission (AEE) polyurethane named STMPU-211 containing 0.13% mole concentration of 4,4′-((1Z,3Z)-1,4-diphenylbuta-1,3-diene-1,4-diyl) dibenzaldehyde (TABDAA) in the soft segments was synthesized and proved to be sensitive to Fe³⁺ and nitroaromatic explosives. The fluorescence of the AEE polyurethane was reduced in the presence of Fe³⁺, and almost quenched when 5000?μM Fe³⁺ was added. Meanwhile, the fluorescence intensity of STMPU-211 solution in DMF/water mixture was decreased when explosives like 2,4,6-trinitrophenol (PA) and 3-nitro-1,2,4-triazol-5-one (NTO) were applied. Especially, the quenching coefficient K_SV value of PA was 5.7?×?10⁶?M^?1, confirming that the polyurethane STMPU-211 could be a highly sensitive sensor for the detection of PA. Therefore, AEE polyurethanes with low concentration of TABDAA have promising applications in biological probe, environment monitoring and antiterrorism fields.     

Catalytic activities of NHC‐PdCl2 species based on functionalized tetradentate imidazolium salt in three types of C‐C coupling reactions

A functionalized tetradentate imidazolium salt 9,10‐bis{di[2′‐(N‐ethylimidazolium‐1‐yl)ethyl]aminomethyl}anthracene tetrakis(hexafluorophosphate) ( 1 ) has been synthesized and characterized. The catalytic activity of the NHC‐PdCl₂ species formed by compound 1 and PdCl₂ was tested in Suzuki‐Miyaura, Heck‐Mizoroki and Sonogashira reactions. The results showed that this catalytic system was effective for above three types of C‐C coupling reactions.     

[Bis(imidazolyl)–BH2]+[Bis(triazolyl)–BH2]− Ionic Liquids with High Density and Energy Capacity

[Bis(imidazolyl)–BH₂]⁺[bis(triazolyl)–BH₂]^? and [bis(imidazolyl)–BH₂]⁺[tris(triazolyl)–BH]^? were synthesized, the cations and anions of which were functionalized with B?H groups and azoles. As B?H groups contribute to the hypergolic activity and azole groups improve the energy output, the resulting ionic liquids exhibited ignition delay times as low as 20 ms and energy outputs as high as 461.1 kJ mol^?1. In addition, densities (1.07–1.22 g cm^?3) and density‐specific impulse (≈360 s g cm^?3) values reached a relatively high level. These ionic liquids show great promise as sustainable rocket fuels.     

Iron(II)‐Catalyzed Direct Synthesis of NH Sulfoximines from Sulfoxides

Free NH‐sulfoximines were directly prepared from sulfoxides through iron catalysis by applying a readily available, shelf‐stable hydroxylamine triflic acid salt. No additional oxidant is needed, and the substrate scope is broad, including a range of heterocyclic compounds.     

Plasmonic Hotspots in Air: An Omnidirectional Three‐Dimensional Platform for Stand‐Off In‐Air SERS Sensing of Airborne Species

Molecular‐level airborne sensing is critical for early prevention of disasters, diseases, and terrorism. Currently, most 2D surface‐enhanced Raman spectroscopy (SERS) substrates used for air sensing have only one functional surface and exhibit poor SERS‐active depth. “Aerosolized plasmonic colloidosomes” (APCs) are introduced as airborne plasmonic hotspots for direct in‐air SERS measurements. APCs function as a macroscale 3D and omnidirectional plasmonic cloud that receives laser irradiation and emits signals in all directions. Importantly, it brings about an effective plasmonic hotspot in a length scale of approximately 2.3 cm, which affords 100‐fold higher tolerance to laser misalignment along the z‐axis compared with 2D SERS substrates. APCs exhibit an extraordinary omnidirectional property and demonstrate consistent SERS performance that is independent of the laser and analyte introductory pathway. Furthermore, the first in‐air SERS detection is demonstrated in stand‐off conditions at a distance of 200 cm, highlighting the applicability of 3D omnidirectional plasmonic clouds for remote airborne sensing in threatening or inaccessible areas.     

An Assembled Nanocomplex for Improving both Therapeutic Efficiency and Treatment Depth in Photodynamic Therapy

Photodynamic therapy (PDT) shows unique selectivity and irreversible destruction toward treated tissues or cells, but still has several problems in clinical practice. One is limited therapeutic efficiency, which is attributed to hypoxia in tumor sites. Another is the limited treatment depth because traditional photosensitizes are excited by short wavelength light (<700 nm). An assembled nano‐complex system composed of oxygen donor, two‐photon absorption (TPA) species, and photosensitizer (PS) was synthesized to address both problems. The photosensitizer is excited indirectly by two‐photon laser through intraparticle FRET mechanism for improving treatment depth. The oxygen donor, hemoglobin, can supply extra oxygen into tumor location through targeting effect for enhanced PDT efficiency. The mechanism and PDT effect were verified through both in vitro and in vivo experiments. The simple system is promising to promote two‐photon PDT for clinical applications.     

{Nb288O768(OH)48(CO3)12}: A Macromolecular Polyoxometalate with Close to 300 Niobium Atoms

A protein‐sized (ca. 4.2×4.2×3.6 nm³) non‐biologically derived molecule {Nb₂₈₈O₇₆₈(OH)₄₈(CO₃)₁₂} ( Nb₂₈₈ ) containing up to 288 niobium atoms has been obtained, which is by far the largest and the highest nuclearity polyoxoniobate (PONb). Particularly, in terms of metal nuclearity number, Nb₂₈₈ is the second largest cluster so far reported in classic polyoxometalate chemistry (V, Mo, W, Nb, and Ta). Nb₂₈₈ can be described as a giant windmill‐like cluster aggregate of six nanoscale high‐nuclearity PONb units {Nb₄₇O₁₂₈(OH)₆(CO₃)₂} ( Nb₄₇ ) joined together by six additional Nb ions. Interestingly, the 47‐nuclearity Nb₄₇ units generated in situ can be isolated and bridged by copper complexes to form an inorganic–organic hybrid three‐dimensional PONb framework, which exhibits effective catalytic activity for hydrolyzing nerve agent simulant of dimethyl methylphosphonate. The unique Nb₄₇ cluster also provides a new type of topology to very limited family of Nb‐O clusters.     

A Rapidly Self‐Healing Host–Guest Supramolecular Hydrogel with High Mechanical Strength and Excellent Biocompatibility

It is still a challenge to achieve both excellent mechanical strength and biocompatibility in hydrogels. In this study, we exploited two interactions to form a novel biocompatible, slicing‐resistant, and self‐healing hydrogel. The first was molecular host–guest recognition between a host (isocyanatoethyl acrylate modified β‐cyclodextrin) and a guest (2‐(2‐(2‐(2‐(adamantyl‐1‐oxy)ethoxy)ethoxy)ethoxy)ethanol acrylate) to form “three‐arm” host–guest supramolecules (HGSMs), and the second was covalent bonding between HGSMs (achieved by UV‐initiated polymerization) to form strong cross‐links in the hydrogel. The host–guest interaction enabled the hydrogel to rapidly self‐heal. When it was cut, fresh surfaces were formed with dangling host and guest molecules (due to the breaking of host–guest recognition), which rapidly recognized each other again to heal the hydrogel by recombination of the cut surfaces. The smart hydrogels hold promise for use as biomaterials for soft‐tissue repair.     

Cross‐Linked Aptamer–Lipid Micelles for Excellent Stability and Specificity in Target‐Cell Recognition

The specific binding ability of DNA–lipid micelles (DLMs) can be increased by the introduction of an aptamer. However, supramolecular micellar structures based on self‐assemblies of amphiphilic DLMs are expected to demonstrate low stability when interacting with cell membranes under certain conditions, which could lead to a reduction in selectivity for targeting cancer cells. We herein report a straightforward cross‐linking strategy that relies on a methacrylamide branch to link aptamer and lipid segments. By an efficient photoinduced polymerization process, covalently linked aptamer–lipid units help stabilize the micelle structure and enhance aptamer probe stability, further improving the targeting ability of the resulting nanoassembly. Besides the development of a facile cross‐linking method, this study clarifies the relationship between aptamer–lipid concentration and the corresponding binding ability.