Ambient-Light-Promoted Stereospecific Synthesis of (Z)-Vinyl Thioesters under Solvent- and Catalyst-Free Conditions.

An ambient-light-promoted stereospecific olefinic C(sp2)-S bond construction of thioacids and 1,1-diarylethenes has been demonstrated, affording various (Z)-vinyl thioesters in 51-85% yields under solvent- and catalyst-free conditions. Mechanistic studies indicated that the formation of thioacid-olefin complexes is responsible for generating a carbonyl thiyl radical and dioxygen in the air participates in the reaction and functions as a traceless reagent. Moreover, synthetic applications have been demonstrated by the gram scale synthesis and aggregation-induced emission property of representative compound 3i.

Pore Space Partitioning MIL-88(Co): Developing Robust Adsorbents for CO2/CH4 Separation Featured with High CO2 Adsorption and Rapid Desorption.

Metal-organic frameworks (MOFs) have attracted significant attention as sorbents for gas separation and purification. Ideally, an industrially potential adsorbent should combine exceptional gas uptake, excellent stability, and a lower regeneration energy; however, it remains a great challenge. Here, by utilizing the pore space partition (PSP) strategy, we develop three isostructural MOF materials (Co-BDC-TPB, Co-DCBDC-TPB, and Co-DOBDC-TPB) based on pristine MIL-88(Co). The three pore-space-partitioned crystalline microporous MOFs have triangular bipyramid cages and segmented one-dimensional channels, and among them, Co-DOBDC-TPB exhibits the highest CO2 uptake capacity (4.35 mmol g-1) and good CO2/N2 (29.7) and CO2/CH4 (6.2) selectivity. The selectivity-capacity synergy endows it with excellent CO2/N2 and CO2/CH4 separation performance. Moreover, Co-DOBDC-TPB can complete desorption within 10 min. The satisfactory CO2 adsorption ability can be attributed to both microporous aperture arising from PSP and modification of the pore surface by the polar hydroxy group, which enhances the interaction between Co-DOBDC-TPB and CO2 molecules significantly. The exceptional regeneration property may be due to its lower CO2 isosteric heat of adsorption (23.6 kJ/mol). The developed pore-space-partitioned MIL-88(Co) material Co-DOBDC-TPB may have potential application to flue gas and natural gas purification.

Hydrophilic, Clean Graphene for Cell Culture and Cryo-EM Imaging.

The wettability of graphene is critical for numerous applications but is very sensitive to its surface cleanness. Herein, by clarifying the impact of intrinsic contamination, i.e., amorphous carbon, which is formed on the graphene surface during the high-temperature chemical vapor deposition (CVD) process, the hydrophilic nature of clean graphene grown on single-crystal Cu(111) substrate was confirmed by both experimental and theoretical studies, with an average water contact angle of ∼23°. Furthermore, the wettability of as-transferred graphene was proven to be highly dependent on its intrinsic cleanness, because of which the hydrophilic, clean graphene exhibited improved performance when utilized for cell culture and cryoelectron microscopy imaging. This work not only validates the intrinsic hydrophilic nature of graphene but also provides a new insight in developing advanced bioapplications using CVD-grown clean graphene films.

Passenger comfort and ozone pollution exposure in an air-conditioned bus microenvironment.

Ground-level ozone is the primary source of air pollution in China, particularly during the warmer months. In this study, we investigated the exposure status of ozone pollution and the temperature distribution in an air-conditioned bus in Jinan during the evening peak period based on field measurements obtained with a handheld portable particle counter and indigo disulfonate spectrophotometry. Statistical analysis showed that the passengers experienced poor air quality within the confines of the bus due to the poor air quality outside. Furthermore, the level of passenger comfort was dissatisfactory because of the high temperature, thereby highlighting the urgent need to improve the current situation. Numerical simulations were conducted using FLUENT software to explore the impacts of the air supply angle, the opening and closing of the bus door, and the chemical reaction between ozone and its precursors on the diffusion and distribution of ozone, the temperature, and the airflow field. The results indicated that high concentrations of ozone were present in the middle and front regions of the bus. Pollution can be reduced by keeping the bus door open for no longer than 20 s when waiting for other passengers, and the best optimization effect in relation to the temperature and passenger comfort was determined as an air supply angle of 30°. In addition, the average individual daily intake of ozone was combined with other relevant parameters to assess the exposure level. It is recommended that the elderly and children should avoid peak time travel to reduce their exposure to ozone (inhalation dose values > 60 µg/m3 and > 56 µg/m3 according to simulations, respectively). These findings are expected to effectively improve the air quality and passenger comfort levels in busses, thereby protecting the health of passengers and reducing carbon usage.

Photo- and dioxygen-enabled radical C(sp3)-N(sp2) cross-coupling between guanidines and perfluoroalkyl iodides.

A photo- and dioxygen-enabled intermolecular radical Csp3-Nsp2 cross-coupling between guanidines and perfluoroalkyl iodides has been developed. N2-Perfluoroalkacylguanidines, which are of biological importance, were obtained under mild conditions via Nsp2-perfluoroalkylation and subsequent hydrolysis. The role of dioxygen in the reaction system was tentatively elucidated; it was supposed to act as an electron shuttle (redox mediator).

Utilizing d-pπ Bonds for Ultralong Organic Phosphorescence.

Developing pure organic materials with ultralong lifetimes is attractive but challenging. Here we report a concise chemical approach to regulate the electronic configuration for phosphorescence enhancement. After the introduction of d-pπ bonds into a phenothiazine model system, a phosphorescence lifetime enhancement of up to 19 times was observed for DOPPMO, compared to the reference PPMO. A record phosphorescence lifetime of up to 876 ms was obtained in phosphorescent phenothiazine. Theoretical calculations and single-crystal analysis reveal that the d-pπ bond not only reduces the (n, π*) proportion of the T1 state, but also endows the rigid molecular environment with multiple intermolecular interactions, thus enabling long-lived phosphorescence. This finding makes a valuable contribution to the prolongation of phosphorescence lifetimes and the extension of the scope of phosphorescent materials.

Aza-tricycles containing a perfluoroalkyl group: synthesis, structure and fluorescence.

Perfluoroalkyl-containing aza-tricycles have been prepared in one synthetic operation via an ambient light-promoted three-component reaction of ß-oxo esters, perfluoroalkyl iodide and DBU. Intramolecular C-FO and double C-HF weak interactions and intermolecular C-HO and C-Hπ hydrogen bondings were observed partly due to the incorporation of the perfluoroalkyl group. The perfluoroalkylated non-planar aza-tricycles exhibit interesting room-temperature AIE fluorescence and acid-induced fluorescence enhancement characters.

t-BuONa-mediated direct C-H halogenation of electron-deficient (hetero)arenes.

An efficient halogenation of electron-deficient (hetero)arenes is described. The reaction utilizes common t-BuONa as a catalyst (for iodination) or a promoter (for bromination and chlorination), and perfluorobutyl iodide, CBr4 or CCl4 as the readily-available halogenating agents, respectively. The protocol features broad scope, high efficiency, mild conditions and gram scalability. An ionic pathway involving halogen bond formation and halophilic attack is proposed. The utility of the resulting iodinated heteroarenes is demonstrated in visible light-mediated Caryl-Caryl cross-coupling reaction.

Multicomponent reaction of chalcones, malononitrile and DMF leading to γ-ketoamides.

An efficient synthesis of γ-ketoamides was developed by the one-pot multicomponent reaction of chalcones, malononitrile and DMF (as both the reactant and solvent) in the presence of NaOH (3.0 equiv.). The reaction features high atom economy, easily available starting materials, operational simplicity, and good tolerance with diverse functional groups.

Hypervalent iodine(III)-mediated cyclopropa(e)nation of alkenes/alkynes under mild conditions.

Hypervalent iodine(III)-mediated dioxygenation and diamination of alkenes have been previously developed. In this study, the potential application of hypervalent iodine(III) reagent was successfully extended to the dialkylation and cyclopropa(e)nation of unsaturated alkenes and alkynes. The reactions of alkenes with malononitrile and other active methylene compounds as the carbon nucleophiles give access to multisubstituted cyclopropane derivatives in moderate to excellent yields. Both electron-rich and electron-deficient alkenes are suitable substrates. Alkynes, no matter terminal or internal alkynes, work well, affording the corresponding highly functionalized cyclopropenes efficiently. A plausible mechanism of iodo(III)cyclopropanation, ring opening attack by the carbon-nucleophile, and recyclization was proposed for the cyclopropanation of trans-alkene substrates. The cyclopropenation was thought to proceed via iodo(III)cyclopropanation, ring-opening attack by the carbon-nucleophile, recyclization into a four-membered iodo(III)cyclobutene and final reductive elimination. The protocol might provide a complementary route to cyclopropanation/cyclopropenation.

Controllable preparation of graphene glass fiber fabric towards mass production and its application in self-adaptive thermal management.

Direct synthesis of graphene on nonmetallic substrates via chemical vapor deposition (CVD) has become a frontier research realm targeting transfer-free applications of CVD graphene. However, the stable mass production of graphene with a favorable growth rate and quality remains a grand challenge. Herein, graphene glass fiber fabric (GGFF) was successfully developed through the controllable growth of graphene on non-catalytic glass fiber fabric, employing a synergistic binary-precursor CVD strategy to alleviate the dilemma between growth rate and quality. The binary precursors consisted of acetylene and acetone, where acetylene with high decomposition efficiency fed rapid graphene growth while oxygen-containing acetone was adopted for improving the layer uniformity and quality. Notably, the bifurcating introducing-confluent premixing (BI-CP) system was self-built for the controllable introduction of gas and liquid precursors, enabling the stable production of GGFF. GGFF features solar absorption and infrared emission properties, based on which the self-adaptive dual-mode thermal management film was developed. This film can automatically switch between heating and cooling modes by spontaneously perceiving the temperature, achieving excellent thermal management performances with heating and cooling power of ∼501.2 and ∼108.6 W m-2, respectively. These findings unlock a new strategy for the large-scale batch production of graphene materials and inspire advanced possibilities for further applications.

Overcoming the Incompatibility Between Electrical Conductivity and Electromagnetic Transmissivity: A Graphene Glass Fiber Fabric Design Strategy.

Conventional conductive materials such as metals are crucial functional components of conductive systems in diverse electronic instruments. However, their severe intrinsic impedance mismatch with air dielectric causes strong reflection of incident electromagnetic waves, and the resulting low electromagnetic transmissivity typically interferes with surrounding electromagnetic signal communications in modern multifunction-integrated instruments. Herein, graphene glass fiber fabric (GGFF) that merges intrinsic electrical and electromagnetic properties of graphene with dielectric attributes and highly porous macrostructure of glass fiber fabric (GFF) is innovatively developed. Using a novel decoupling chemical vapor deposition growth strategy, high-quality and layer-limited graphene is prepared on noncatalytic nonmetallic GFF in a controlled manner; this is pivotal to realizing GGFF with the desired compatibility among high conductivity, low electromagnetic reflectivity, and high electromagnetic transmissivity. At the same sheet resistance over a wide range of values (250-3000 Ω·sq-1), the GGFF exhibits significantly lower electromagnetic reflectivity (by 0.42-0.51) and higher transmissivity (by 0.27-0.62) than those of its metal-based conductive counterpart (CuGFF). The material design strategy reported herein provides a constructive solution to eliminate the incompatibility between electrical conductivity and electromagnetic transmissivity faced by conventional conductive materials, spotlighting the applicability of GGFF in electric heating scenarios in radar, antenna, and stealth systems.

Multispecies-coadsorption-induced rapid preparation of graphene glass fiber fabric and applications in flexible pressure sensor.

Direct chemical vapor deposition (CVD) growth of graphene on dielectric/insulating materials is a promising strategy for subsequent transfer-free applications of graphene. However, graphene growth on noncatalytic substrates is faced with thorny issues, especially the limited growth rate, which severely hinders mass production and practical applications. Herein, graphene glass fiber fabric (GGFF) is developed by graphene CVD growth on glass fiber fabric. Dichloromethane is applied as a carbon precursor to accelerate graphene growth, which has a low decomposition energy barrier, and more importantly, the produced high-electronegativity Cl radical can enhance adsorption of active carbon species by Cl-CH2 coadsorption and facilitate H detachment from graphene edges. Consequently, the growth rate is increased by ~3 orders of magnitude and carbon utilization by ~960-fold, compared with conventional methane precursor. The advantageous hierarchical conductive configuration of lightweight, flexible GGFF makes it an ultrasensitive pressure sensor for human motion and physiological monitoring, such as pulse and vocal signals.

Graphene-skinned alumina fiber fabricated through metalloid-catalytic graphene CVD growth on nonmetallic substrate and its mass production.

Graphene growth on widely used dielectrics/insulators via chemical vapor deposition (CVD) is a strategy toward transfer-free applications of CVD graphene for the realization of advanced composite materials. Here, we develop graphene-skinned alumina fibers/fabrics (GAFs/GAFFs) through graphene CVD growth on commercial alumina fibers/fabrics (AFs/AFFs). We reveal a vapor-surface-solid growth model on a non-metallic substrate, which is distinct from the well-established vapor-solid model on conventional non-catalytic non-metallic substrates, but bears a closer resemblance to that observed on catalytic metallic substrates. The metalloid-catalytic growth of graphene on AFs/AFFs resulted in reduced growth temperature (~200 °C lower) and accelerated growth rate (~3.4 times faster) compared to that obtained on a representative non-metallic counterpart, quartz fiber. The fabricated GAFF features a wide-range tunable electrical conductivity (1-15000 Ω sq-1), high tensile strength (>1.5 GPa), lightweight, flexibility, and a hierarchical macrostructure. These attributes are inherited from both graphene and AFF, making GAFF promising for various applications including electrical heating and electromagnetic interference shielding. Beyond laboratory level preparation, the stable mass production of large-scale GAFF has been achieved through a home-made roll-to-roll system with capacity of 468-93600 m2/year depending on product specifications, providing foundations for the subsequent industrialization of this material, enabling its widespread adoption in various industries.

Otherwise inert reaction of sulfonamides/carboxamides with formamides via proton transfer-enhanced reactivity.

NBS-mediated addition-elimination reaction of sulfonamides/carboxamides and formamides afforded N-sulfonylamidines and N-formylarylamides, respectively, depending on the different mechanism of elimination. Hydrogen bond-induced proton transfer leads to enhanced reactivities and was proposed as the key driving force for the reaction to take place. The protocol demonstrates the possibility of constructing chemical bonds based on a proton transfer strategy induced by noncovalent hydrogen bond interaction.

Halonium-initiated double oxa-cyclization cascade as a synthetic strategy for halogenated furo[3,2-c]pyran-4-ones.

The reaction of 1-alkenoylcyclopropane carboxylic acids with NBS or NIS was investigated, which provides an efficient route to biologically important 7-halogenated furo[3,2-c]pyran-4-ones in a one-pot transformation. The major pathway for the formation of the O-O heterocycles was proposed as a halo-oxa-cyclization, HBr elimination, cyclopropane ring-opening and recyclization (intramolecular oxa-cyclization), and bromination cascade. The double-oxa-cyclization represents a novel synthetic strategy towards functionalized furo[3,2-c]pyranones.

Boosting the Phosphorescence Efficiency in Doped Organic Crystals: Critical Role of Hydrogen Bonding.

Host-guest doping systems with phthalimides (BI) and N-methylphthalimide (NMeBI) as the host and 1,8-naphthalimide (NI) and 4-bromo-1,8-naphthalimide (4BrNI) as the guest have been developed. The 0.2% NI/BI (molar ratio) with a strong C=O···H-N hydrogen bond exhibited a phosphorescence quantum efficiency (29.2%) higher than that of NI/NMeBI with a weak C=O···H-C hydrogen bond (10.1%). A similar trend was observed in the 4BrNI guest system. A remarkable phosphorescent efficiency of 42.1% was achieved in a 0.5% 4BrNI/BI composite, which represents the highest value in NI-based phosphors. This research indicates stronger hydrogen bonding may have a greater contribution in boosting the phosphorescence efficiency.

Scalable Fabrication of Dual-Function Fabric for Zero-Energy Thermal Environmental Management through Multiband, Synergistic, and Asymmetric Optical Modulations.

Solar heating and radiative cooling techniques have been proposed for passive space thermal management to reduce the global energy burden. However, the currently used single-function envelope/coating materials can only achieve static temperature regulation, presenting limited energy savings and poor adaption to dynamic environments. In this study, a sandwich-structured fabric, composed of vertical graphene, graphene glass fiber fabric, and polyacrylonitrile nanofibers is developed, with heating and cooling functions integrated through multiband, synergistic, (solar spectrum and mid-infrared ranges) and asymmetric optical modulations on two sides of the fabric. The dual-function fabric demonstrates high adaption to the dynamic environment and superior performance in a zero-energy-input temperature regulation. Furthermore, it demonstrates ≈15.5 and ≈31.1 MJ m-2 y-1 higher annual energy savings compared to those of their cooling-only and heating-only counterparts, corresponding to ≈173.7 MT reduction in the global CO2 emission. The fabric exhibits high scalability for batch manufacturing with commercially abundant raw materials and facile technologies, providing a favorable guarantee of its mass production and use.

Fast synthesis of large-area bilayer graphene film on Cu.

Bilayer graphene (BLG) is intriguing for its unique properties and potential applications in electronics, photonics, and mechanics. However, the chemical vapor deposition synthesis of large-area high-quality bilayer graphene on Cu is suffering from a low growth rate and limited bilayer coverage. Herein, we demonstrate the fast synthesis of meter-sized bilayer graphene film on commercial polycrystalline Cu foils by introducing trace CO2 during high-temperature growth. Continuous bilayer graphene with a high ratio of AB-stacking structure can be obtained within 20 min, which exhibits enhanced mechanical strength, uniform transmittance, and low sheet resistance in large area. Moreover, 96 and 100% AB-stacking structures were achieved in bilayer graphene grown on single-crystal Cu(111) foil and ultraflat single-crystal Cu(111)/sapphire substrates, respectively. The AB-stacking bilayer graphene exhibits tunable bandgap and performs well in photodetection. This work provides important insights into the growth mechanism and the mass production of large-area high-quality BLG on Cu.

Copper-catalyzed aerobic oxidative synthesis of α-ketoamides from methyl ketones, amines and NIS at room temperature.

A simple, efficient and practical copper-catalyzed aerobic oxidative synthesis of α-ketoamides from aryl methyl ketones, aliphatic amines and N-iodosuccinimide (NIS) has been developed. The one-pot reaction may proceed smoothly at room temperature in the open air. The possible mechanism for the formation of α-ketoamides was proposed. Molecular oxygen in air functions as both an oxidant and an oxygen source.