Visible-Light-Promoted Radical Cascade Cyclization of 2-Vinyl Benzimidazoles: Access to Benzo[4,5]imidazo[1,2-b]isoquinolin- 11(6H)-ones.

A visible-light-enabled photoredox radical cascade cyclization of 2-vinyl benzimidazole derivatives is developed. This chemistry is applicable to a wide range of N-aroyl 2-vinyl benzimidazoles as acceptors, and halo compounds, including alkyl halides, acyl chlorides and sulfonyl chlorides, as radical precursors. The Langlois reagent also serves as an effective partner in this photocatalytic oxidative cascade process. This protocol provides a robust alternative for rendering highly functionalized benzo[4,5]imidazo[1,2-b]isoquinolin-11(6H)-ones.

Diazotization-Enabled Deaminative Late-Stage Functionalization of Primary Sulfonamides.

We, for the first time, disclosed a simple and efficient strategy for the late-stage functionalization of primary sulfonamides by diazotization, leading to sulfonyl chlorides, sulfonates, and complex sulfonamides. This protocol obviates the requirement for the prefunctionalization of sulfonamides. Its applicability is exemplified by the late-stage functionalization of sulfonamide-type drugs.

Photocatalytic synthesis of azaheterocycle-fused piperidines and pyrrolidines via tandem difunctionalization of unactivated alkenes.

A variety of azaheterocycle-fused piperidines and pyrrolidines bearing CF3 and CHF2 functionalities were obtained using CF3SO2Na and CHF2SO2Na by visible light photocatalysis. This protocol involves a radical cascade cyclization via tandem tri- and difluoromethylation-arylation of pendent unactivated alkenes. Benzimidazole, imidazole, theophylline, purine, and indole serve as applicable anchors, thereby enriching the structural diversity of piperidine and pyrrolidine derivatives. This method features mild, additive-free and transition metal-free conditions.

Mitochondria-Targeted Nanosystem Enhances Radio-Radiodynamic-Chemodynamic Therapy on Triple Negative Breast Cancer.

Radiodynamic therapy (RDT), which produces 1O2 and other reactive oxygen species (ROS) in response to X-rays, can be used in conjunction with radiation therapy (RT) to drastically lower X-ray dosage and reduce radio resistance associated with conventional radiation treatment. However, radiation-radiodynamic therapy (RT-RDT) is still impotent in a hypoxic environment in solid tumors due to its oxygen-dependent nature. Chemodynamic therapy (CDT) can generate reactive oxygen species and O2 by decomposing H2O2 in hypoxic cells and thus potentiate RT-RDT to achieve synergy. Herein, we developed a multifunctional nanosystem, AuCu-Ce6-TPP (ACCT), for RT-RDT-CDT. Ce6 photosensitizers were conjugated to AuCu nanoparticles via Au-S bonds to realize radiodynamic sensitization. Cu can be oxidized by H2O2 and catalyze the degradation of H2O2 to generate •OH through the Fenton-like reaction to realize CDT. Meanwhile, the degradation byproduct oxygen can alleviate hypoxia while Au can consume glutathione to increase the oxidative stress. We then attached mercaptoethyl-triphenylphosphonium (TPP-SH) to the nanosystem, targeting ACCT to mitochondria (colocalization Pearson coefficient 0.98) to directly disrupt mitochondrial membranes and more efficiently induce apoptosis. We confirmed that ACCT efficiently generates 1O2 and •OH upon X-ray irradiation, resulting in strong anticancer efficacy in both normoxic and hypoxic 4T1 cells. The down-regulation of hypoxia-inducible factor 1α expression and reduction of intracellular H2O2 concentrations suggested that ACCT could significantly alleviate hypoxia in 4T1 cells. ACCT-enhanced RT-RDT-CDT can successfully shrink or remove tumors in radioresistant 4T1 tumor-bearing mice upon 4 Gy of X-ray irradiation. Our work thus presents a new strategy to treat radioresistant hypoxic tumors.

The ethanol extract of Edgeworthia gardneri (Wall.) Meisn attenuates macrophage foam cell formation and atherogenesis in ApoE-/- mice.

Introduction: Atherosclerotic cardiovascular disease is the leading cause of death worldwide. The Edgeworthia gardneri (Wall.) Meisn is a Tibetan medicine commonly used to prepare herbal tea to alleviate the local people's metabolic diseases. However, the anti-atherosclerotic effect of ethanol extract of the flower of E. gardneri (Wall.) Meisn (EEEG) and its underlying mechanism remain unknown. Methods: EEEG was used to treat low-density lipoprotein (ox-LDL)-induced macrophages to detect macrophage foaminess, cholesterol binding and uptake, and lipid transport-related gene expression. eEEG treated ApoE-/- mice fed a high-fat diet for 16 weeks to detect atherosclerotic plaque area, macrophage infiltration, and liver and small intestine lipid transport-related gene expression. Results: EEEG inhibited macrophage-derived foam cell formation induced by oxidized low-density lipoprotein (ox-LDL) by reducing CD36-mediated lipoprotein uptake. EEEG significantly alleviated atherosclerosis in ApoE-/- mice fed a high-fat diet for 16 weeks. EEEG treatment significantly decreased atherosclerotic plaque area, macrophage infiltration, and increased collagen content. Moreover, EEEG treatment significantly downregulated mRNA expression of hepatic Srb1 and intestinal Npc1l1 and increased expression of hepatic Cyp7a1. Conclusion: Our study highlighted that EEEG played a role in attenuating atherosclerotic plaque formation by reducing macrophage foam cell formation.

Visible-Light Photoredox Catalyzed Double C-H Functionalization: Radical Cascade Cyclization of Ethers with Benzimidazole-Based Cyanamides.

A visible-light photoredox catalyzed radical cascade cyclization of simple ethers with cyanamides is developed at room temperature. This strategy involves sequential inert Csp3-H/Csp2-H functionalizations through intermolecular addition reaction of oxyalkyl radicals to N-cyano groups followed by radical cyclization of iminyl radicals in situ generated with C-2 aryl rings. This method allows for efficient synthesis of tetracyclic benzo[4,5]imidazo[1,2-c]quinazolines. Importantly, this is the first example of an intermolecular-intramolecular radical cascade cyclization reaction of cyanamides.

Copper-Catalyzed Three-Component Reaction of Alkynes, TMSN3, and Ethers: Regiocontrollable Synthesis of N1- and N2-Oxyalkylated 1,2,3-Triazoles.

A new copper-catalyzed selective synthesis of N1- and N2-oxyalkylated 1,2,3-triazoles has been developed through a three-component reaction of alkynes, TMSN3, and ethers. Through this methodology, a series of N1- and N2-oxyalkylated 1,2,3-triazoles could be efficiently and regioselectively obtained from simple and readily available starting materials with favorable functional group tolerance.

Graphdiyne-Doped P3CT-K as an Efficient Hole-Transport Layer for MAPbI3 Perovskite Solar Cells.

Here we reported the doping of graphdiyne in P3CT-K in MAPbI3 perovskite solar cells as hole-transport materials. The doping could improve the surface wettability of P3CT-K, and the resulting perovskite morphology was improved with homogeneous coverage and reduced grain boundaries. Simultaneously, it increased the hole-extraction mobility and reduced the recombination as well as improved the performance of devices. Therefore, a high efficiency of 19.5% was achieved based on improved short-circuit current and fill factor. In addition, hysteresis of the J- V curve was also obviously reduced. This work paves the way for the development of highly efficient perovskite solar cells.

Graphdiyne as a Host Active Material for Perovskite Solar Cell Application.

This work demonstrates a novel photovoltaic application in which graphdiyne (GD) can be employed as a host material in a perovskite active layer for the first time. In the device fabrication, the best molar ratio for active materials is verified as PbI2/MAI/GD being 1:1:0.25, yielding a peak power-conversion efficiency of 21.01%. We find that graphdiyne, as the host material, exerts significant influence on the crystallization, film morphology, and a series of optoelectronic properties of the perovskite active layer. A uniform MAPbI3 film with highly crystalline qualities, large domain sizes, and few grain boundaries was realized with the introduction of graphdiyne. Moreover, the current-voltage hysteresis was negligible, and device stability was significantly improved as well. The results indicate that graphdiyne as the host active material presents great potential for the enhancement of the performance of perovskite solar cells.

A Ratiometric Two-Photon Fluorescent Cysteine Probe with Well-Resolved Dual Emissions Based on Intramolecular Charge Transfer-Mediated Two-Photon-FRET Integration Mechanism.

The development of an efficient ratiometric two-photon fluorescence imaging probe is crucial for in situ monitoring of biothiol cysteine (Cys) in biosystems, but the current reported intramolecular charge transfer (ICT)-based one suffers from serious overlap between the shifted emission bands. To address this issue, we herein for the first time constructed an ICT-mediated two-photon excited fluorescence resonance energy transfer (TP-FRET) system consisting of a two-photon fluorogen benzo[ h]chromene and a Cys-responsive benzoxadiazole-analogue dye. Different from a previous mechanism that utilized single two-photon fluorogen to acquire a ratiometric signal, ICT was used to switch on the TP-FRET process of the energy transfer dyad by eliciting an absorption shift of benzoxadiazole with Cys to modulate the spectral overlap level between benzo[ h]chromene emission and benzoxadiazole absorption, resulting in two well-separated emission signal changes with large emission wavelength shift (120 nm), fixed two-photon excitation maximum (750 nm), and significant variation in fluorescence ratio (over 36-fold). Therefore, it can be successfully employed to ratiometrically visualize Cys in HeLa cells and liver tissues. Importantly, this new ICT-mediated TP-FRET integration mechanism would be convenient for designing ratiometric two-photon fluorescent probes with two well-resolved emission spectra suitable for high resolution two-photon fluorescence bioimaging.

Ternary CuZnS Nanocrystals: Synthesis, Characterization, and Interfacial Application in Perovskite Solar Cells.

Ternary CuZnS nanocrystals (NCs) are synthesized via a facile, scalable, noninjection method at low temperatures for the first time, wherein sodium ascorbate plays the dual roles of reducing agent and capping ligand in the preparation process. These NCs can be dispersed well in a polar solvent like dimethyl sulfoxide, and the average size is ∼4 nm as measured by transmission electron microscopy. The results of X-ray diffraction and X-ray photoelectron spectroscopy indicate that the crystal structure of CuZnS NCs displays covellite CuS-like structure and the Zn element partly occupies the Cu position. Also, the crystal structure of CuZnS NCs is completely converted from a covellite CuS structure into a digenite Cu9S5 structure when the NCs are treated above 350 °C. Moreover, CuZnS NCs demonstrate favorable hole transport properties. When it is employed in MAPbI3-based perovskite solar cells as a hole transport layer, a peak power conversion efficiency of 18.3% is achieved. Simultaneously, the devices based on CuZnS exhibit a remarkably reduced J-V hysteresis. The results indicate that CuZnS is a promising hole transport layer for enhancing perovskite solar cell performance and presents great potential for optoelectronic applications, as well.

Controllable Spatial Configuration on Cathode Interface for Enhanced Photovoltaic Performance and Device Stability.

The molecular structure of cathode interface modification materials can affect the surface morphology of the active layer and key electron transfer processes occurring at the interface of polymer solar cells in inverted structures mostly due to the change of molecular configuration. To investigate the effects of spatial configuration of the cathode interfacial modification layer on polymer solar cells device performances, we introduced two novel organic ionic salts (linear NS2 and three-dimensional (3D) NS4) combined with the ZnO film to fabricate highly efficient inverted solar cells. Both organic ionic salts successfully decreased the surface traps of the ZnO film and made its work function more compatible. Especially NS4 in three-dimensional configuration increased the electron mobility and extraction efficiency of the interfacial film, leading to a significant improvement of device performance. Power conversion efficiency (PCE) of 10.09% based on NS4 was achieved. Moreover, 3D interfacial modification could retain about 92% of its initial PCE over 160 days. It is proposed that 3D interfacial modification retards the element penetration-induced degradation without impeding the electron transfer from the active layer to the ZnO film, which significantly improves device stability. This indicates that inserting three-dimensional organic ionic salt is an efficient strategy to enhance device performance.

Performance Enhancement of Inverted Perovskite Solar Cells Based on Smooth and Compact PC61BM:SnO2 Electron Transport Layers.

In this work, PC61BM:SnO2 electron transport layers (ETLs) were applied in inverted CH3NH3PbI3 perovskite solar cells, and a high power conversion efficiency of 19.7% could be obtained. It increased by 49.0% in comparison with the device based on PC61BM-only ETL (13.2%). SnO2 nanocrystals with excellent dispersibility were employed here to fill the pinholes and cover the valleys of PC61BM layer, forming smooth and compact PC61BM:SnO2 layers. Simultaneously, the electron traps caused by deep-level native defects of SnO2 were reduced by PC61BM, proved by the space charge limited current analysis. Thus, PC61BM:SnO2 ETLs can inhibit both of the defects in PC61BM and SnO2 layers which contribute to the electron transport improvement and reduce the recombination loss. Moreover, the device stability based on the bilayer was significantly improved in comparison with the PC61BM-only device and the performance of 85% could be maintained after 1 month.

Facile preparation and characterization of ZnCdS nanocrystals for interfacial applications in photovoltaic devices.

Recently, ZnCdS nanocrystals (NCs) have attracted intense attention because of their specific optical properties and electrical characteristics. In this paper, a green and facile solution method is reported for the preparation of ZnCdS nanocrystals using dimethylsulfoxide as small molecular ligands. The ZnCdS nanocrystals are used as an interface modification material in the photovoltaic devices. It is found that the modification of ZnCdS on TiO2 surface not only suppresses the recombination loss of carriers but also reduces the series resistance of TiO2/active layer. Consequently, both of the short circuit current (Jsc) and the fill factor (FF) of the solar cells were significantly improved. Power conversion efficiency (PCE) of 7.75% based on TiO2/ZnCdS was achieved in contrast to 6.65% of the reference devices based on pure TiO2 film in organic solar cells. Furthermore, the PCE of perovskite solar cells based on TiO2/ZnCdS was observed with 8.3% enhancement compared to that of pure TiO2-based ones.

Aerobic oxidative acylation of nitroarenes with arylacetic esters under mild conditions: facile access to diarylketones.

A facile and regioselective base-mediated aerobic oxidative acylation of nitroarenes to access diarylketones under mild conditions has been developed. It features the use of bench-stable and readily available arylacetates as acyl surrogates, and the absence of transition-metals and synthetic oxidants. This protocol involves a cascade CDC/oxidative decarboxylation process.

Formal aromaticity transfer for palladium-catalyzed coupling between phenols and pyrrolidines/indolines.

We herein describe a palladium-catalyzed formal aromaticity transfer coupling reaction between phenols and pyrrolidines or indolines to generate the corresponding N-cyclohexyl pyrroles or indoles. In this transformation, the aromaticity of phenols is formally passed on to the pyrrolidine or indoline units. Substituted phenols thus can serve as latent cyclohexyl equivalents for the fast construction of various N-cyclohexyl pyrroles and indoles.

1,3-Dimethyl-1H-indole-2-carbonitrile.

The title compound, C(11)H(10)N(2), crystallizes with two mol-ecules in the asymmetric unit, both of which are essentially planar (r.m.s. deviations = 0.014 and 0.016 Å). In the crystal, aromatic π-π stacking inter-actions occur [shortest centroid-centroid separation = 3.5569 (11) Å].

N-(4-tert-Butyl-benz-yl)phthalimide.

The mol-ecule of the title compound [systematic name: 2-(4-tert-butyl-benz-yl)isoindoline-1,3-dione], C(19)H(19)NO(2), is V-shaped with a dihedral angle of 74.15 (7)° between the mean planes of the phthalimide unit and the benzene ring. The methyl groups of the tert-butyl substituent are disordered over two sets of positions, with an occupancy ratio of 0.700 (4):0.300 (4). In the crystal, inter-molecular C-H⋯O hydrogen bonds link adjacent mol-ecules into centrosymmetric dimers. An additional weak C-H⋯O contact, together with weak C-H⋯π and π-π inter-actions [centroid-centroid distance = 3.961 (2) Å] generate a three-dimensional network.

2-[(N-Benzyl-4-methyl-benzene-sul-fon-amido)meth-yl]pyridinium nitrate.

In the title compound, C(20)H(21)N(2)O(2)S(+)·NO(3) (-), the dihedral angle between the pyridinium and phenyl rings is 81.77 (19)°, that between the pyridinium and tolyl rings is 1.36 (18)°, and that between the phenyl and tolyl rings is 82.69 (19)°. In the crystal, the components are linked by strong charge-assisted bifurcated N(+)-H⋯(O,O) hydrogen bonds and the packing is consolidated by numerous weak C-H⋯O bonds and π-π stacking inter-actions [for the latter, centroid-centroid separation = 3.868 (2) Å].