Hydrochloric Acid-Promoted Intermolecular 1,2-Thiofunctionalization of Aromatic Alkenes

An efficient method for making 1,2-thiofunctionalized products via the difunctionalization of aromatic alkenes was developed. In this method, cheap and readily available hydrochloric acid was used to promote 1,2-thiofunctionalization of aryl alkenes with <i>N</i>-arylsulfenylphthalimide and different types of nucleophiles. Importantly, extension of nucleophiles can reach aryl ethers, indoles, and carboxylic acids with good reactivity. This practical and convenient method has broad substrate scope and high yields under metal-free and mild conditions. Furthermore, we achieved conversion and application for making sulfoxide and sulfone by oxidation

Characteristic Length of the Glass Transition in Isochorically Confined Polymer Glasses

We report the effect of isochoric confinement on the characteristic length of the glass transition (ξ_α) for polystyrene (PS) and poly­(4-methylstyrene) (P4MS). Utilizing silica-capped PS and P4MS nanoparticles as model systems, ξ_α values are determined from the thermal fluctuation model and calorimetric data. With decreasing nanoparticle diameter, ξ_α decreases, suggesting a reduction in the number of segmental units required for cooperative motion at the glass transition under confinement. Furthermore, a direct correlation is observed between ξ_α and the isochoric fragility (<i>m</i>_v) in confined polymers. Due to a nearly constant ratio of the isochoric to isobaric fragility in confined polymer nanoparticles, a correlation between ξ_α and <i>m</i>_v also implies a correlation between ξ_α and the volume contribution to the temperature dependence of structural relaxation. Lastly, we observe that when the fragility and characteristic length are varied in the same system the relationship between the two properties appears to be more correlated than that of across different bulk glass-formers

Sulfamic Acid-Catalyzed Lead Perovskite Formation for Solar Cell Fabrication on Glass or Plastic Substrates

Lead perovskite materials such as methylammonium triiodoplumbate­(II) (CH₃NH₃PbI₃, PV) are promising materials for printable solar cell (SC) applications. The preparation of PV involves a series of energetically costly cleavages of the μ-iodo bridges via conversion of a mixture of PbI₂ (PI) and methylammonium iodide (CH₃NH₃I, MAI) in <i>N</i>,<i>N</i>-dimethylformamide (DMF) into a precursor solution containing a polymeric strip of a plumbate­(II) dimer [(MA⁺)₂(PbI₃^–)₂·(DMF)₂]_<i>m</i>, which then produces a perovskite film with loss of DMF upon spin-coating and heating of the substrate. We report here that the PI-to-PV conversion and the PV crystal growth to micrometer size can be accelerated by a small amount of zwitterionic sulfamic acid (NH₃SO₃, SA) and that sulfamic acid facilitates electron transfer to a neighboring electron-accepting layer in an SC device. As a result, an SC device on indium tin oxide (ITO)/glass made of a 320 nm thick PV film using 0.7 wt % SA showed a higher short-circuit current, open-circuit voltage, and fill factor and hence a 22.5% higher power conversion efficiency of 16.02% compared with the device made without SA. The power conversion efficiency value was reproducible (±0.3% for 25 devices), and the device showed very small hysteresis. The device without any encapsulation showed a respectable longevity on a shelf under nitrogen under ambient light. A flexible device similarly fabricated on ITO/poly­(ethylene naphthalate) showed an efficiency of 12.4%

Air-Stable and Solution-Processable Perovskite Photodetectors for Solar-Blind UV and Visible Light

Stable perovskite CH₃NH₃PbI_3–<i>x</i>Cl_<i>x</i> for a photodetector was prepared through spin-coating of a fluorous polymer as a light protection layer. The best responsivity of photodetector was 14.5 A/W to white light and 7.85 A/W for solar-blind UV light (λ = 254 nm). The response time was in the submicrosecond range. The fluorous polymer coating increases the lifetime of the devices to almost 100 days

One-Pot Self-Assembled Three-Dimensional TiO₂‑Graphene Hydrogel with Improved Adsorption Capacities and Photocatalytic and Electrochemical Activities

We reported the development of a new type of multifunctional titanium dioxide (TiO₂)-graphene nanocomposite hydrogel (TGH) by a facile one-pot hydrothermal approach and explored its environmental and energy applications as photocatalyst, reusable adsorbents, and supercapacitor. During the hydrothermal reaction, the graphene nanosheets and TiO₂ nanoparticles self-assembled into three-dimensional (3D) interconnected networks, in which the spherical nanostructured TiO₂ nanoparticles with uniform size were densely anchored onto the graphene nanosheets. We have shown that the resultant TGH displayed the synergistic effects of the assembled graphene nanosheets and TiO₂ nanoparticles and therefore exhibited a unique collection of physical and chemical properties such as increased adsorption capacities, enhanced photocatalytic activities, and improved electrochemical capacitive performance in comparison with pristine graphene hydrogel and TiO₂ nanoparticles. These features collectively demonstrated the potential of 3D TGH as an attractive macroscopic device for versatile applications in environmental and energy storage issues

Mobility of Long-Lived Fullerene Radical in Solid State and Nonlinear Temperature Dependence

A singly bonded fullerene dimer [C₆₀R]₂ in the solid state thermally generates a pair of fullerene radicals C₆₀R^• that dissociate reversibly and irreversibly upon heating and cooling of the solid. The temperature dependence of the electron mobility of the solid shows striking nonlinearity, caused by the dissociation of a strongly interacting radical pair into two free radicals, which interact with the neighboring fullerene molecules to increase the mobility 10 times to a value of 1.5 × 10^–3 cm² V^–1 s^–1. The nonlinearity is due to the plastic crystalline nature of fullerene crystals

Core–Shell Fe₃O₄ Polydopamine Nanoparticles Serve Multipurpose as Drug Carrier, Catalyst Support and Carbon Adsorbent

We present the synthesis and multifunctional utilization of core–shell Fe₃O₄ polydopamine nanoparticles (Fe₃O₄@PDA NPs) to serve as the enabling platform for a range of applications including responsive drug delivery, recyclable catalyst support, and adsorbent. Magnetite Fe₃O₄ NPs formed in a one-pot process by the hydrothermal approach were coated with a polydopamine shell layer of ∼20 nm in thickness. The as prepared Fe₃O₄@PDA NPs were used for the controlled drug release in a pH-sensitive manner via reversible bonding between catechol and boronic acid groups of PDA and the anticancer drug bortezomib (BTZ), respectively. The facile deposition of Au NPs atop Fe₃O₄@PDA NPs was achieved by utilizing PDA as both the reducing agent and the coupling agent. The nanocatalysts exhibited high catalytic performance for the reduction of <i>o</i>-nitrophenol. Furthermore, the recovery and reuse of the catalyst was demonstrated 10 times without any detectible loss in activity. Finally, the PDA layers were converted into carbon to obtain Fe₃O₄@C and used as an adsorbent for the removal of Rhodamine B from an aqueous solution. The synergistic combination of unique features of PDA and magnetic nanoparticles establishes these core–shell NPs as a versatile platform for multiple applications

Spontaneous Iodide Activation at the Air–Water Interface of Aqueous Droplets

We present experimental evidence that atomic and molecular iodine, I and I2, are produced spontaneously in the dark at the air–water interface of iodide-containing droplets without any added catalysts, oxidants, or irradiation. Specifically, we observe I3– formation within droplets, and I2 emission into the gas phase from NaI-containing droplets over a range of droplet sizes. The formation of both products is enhanced in the presence of electron scavengers, either in the gas phase or in solution, and it clearly follows a Langmuir–Hinshelwood mechanism, suggesting an interfacial process. These observations are consistent with iodide oxidation at the interface, possibly initiated by the strong intrinsic electric field present there, followed by well-known solution-phase reactions of the iodine atom. This interfacial chemistry could be important in many contexts, including atmospheric aerosols

Diketopyrrolopyrrole-Containing Quinoidal Small Molecules for High-Performance, Air-Stable, and Solution-Processable n-Channel Organic Field-Effect Transistors

We report the synthesis, characterization, and application of a novel series of diketopyrrolopyrrole (DPP)-containing quinoidal small molecules as highly efficient n-type organic semiconductors in thin film transistors (TFTs). The first two representatives of these species exhibit maximum electron mobility up to 0.55 cm² V^–1 s^–1 with current on/current off (<i>I</i>_on/<i>I</i>_off) values of 10⁶ for <b>1</b> by vapor evaporation, and 0.35 cm² V^–1 s^–1 with <i>I</i>_on/<i>I</i>_off values of 10⁵–10⁶ for <b>2</b> by solution process in air, which is the first demonstration of DPP-based small molecules offering only electron transport characteristics in TFT devices. The results indicate that incorporation of a DPP moiety to construct quinoidal architecture is an effective approach to enhance the charge-transport capability

Naphthalenediimide-Based Copolymers Incorporating Vinyl-Linkages for High-Performance Ambipolar Field-Effect Transistors and Complementary-Like Inverters under Air

We report the synthesis of two novel donor–acceptor copolymers poly­{[<i>N</i>, <i>N</i>′-bis­(alkyl)-1,4,5,8-naphthalene diimide-2,6-diyl-<i>alt</i>-5,5′-di­(thiophen-2-yl)-2,2′-(<i>E</i>)-2-(2-(thiophen-2-yl)­vinyl)­thiophene]} (PNVTs) based on naphthalenediimide (NDI) acceptor and (<i>E</i>)-2-(2-(thiophen-2-yl)­vinyl)­thiophene donor. The incorporations of vinyl linkages into polymer backbones maintain the energy levels of the lowest unoccupied molecular orbits at −3.90 eV, therefore facilitating the electron injection. Moreover, the energy levels of the highest occupied molecular orbits increase from −5.82 to −5.61 eV, successfully decreasing the hole injection barrier. Atomic force microscopy measurements indicate that PNVTs thin films exhibit larger polycrystalline grains compared with that of poly­{[<i>N</i>, <i>N</i>′-bis­(2-octyldodecyl)-1,4,5,8-naphthalene diimide-2,6-diyl]-<i>alt</i>- 5,5′-(2,2′-bithiophene)} [P­(NDI2OD-T2)], consistent with the stronger <i>π</i>–<i>π</i> stacking measured by grazing incidence X-ray scatting. To optimize devices performance, field-effect transistors (FETs) with three devices configurations have been investigated. The results indicate that the electron mobility of the vinyl-containing PNVTs exhibit about 3–5 times higher than that of P­(NDI2OD-T2). Additionally, the vinyl-linkages in PNVTs remarkably enhance ambipolar transport of their top-gate FETs, obtaining high hole and electron mobilities of 0.30 and 1.57 cm² V^–1 s^–1, respectively, which are among the highest values reported to date for the NDI-based polymers. Most importantly, ambipolar inverters have been realized in ambient, exhibiting a high gain of 155. These results provide important progresses in solution-processed ambipolar polymeric FETs and complementary-like inverters