Synthesis of methylene cyclopropane-fused chromenes and dihydroquinolines by sequential [4 + 2]- and [1 + 2]-annulation.

A base promoted sequential [4 + 2]- and [1 + 2]-annulation of 2-hydroxychalcones or 2-tosylaminochalcones with prop-2-ynylsulfonium salts has been developed to give the corresponding methylene cyclopropane fused dihydroquinolines or chromenes in moderate to good yields. This transformation has advantage of wide substrate scope and functional group tolerance as well as excellent regioselectivity. Prop-2-ynylsulfonium salts act as both C2 and C1 synthons in the tandem processes.

NIR-emitting semiconducting polymer nanoparticles for in vivo two-photon vascular imaging.

Two-photon fluorescence (TPF) imaging holds great promise for real-time monitoring of cerebral ischemia-reperfusion injury, which is important for the clinical diagnosis of stroke. However, biocompatible and photostable NIR-emitting probes for TPF imaging of ischemic stroke are lacking. Herein, we report the first NIR-emitting TPF probe (named NESPN) prepared using semiconducting polymers for TPF imaging of cerebral ischemia.

Molecular Mechanism for Azeotrope Formation in Ethanol/Benzene Binary Mixtures through Gibbs Ensemble Monte Carlo Simulation.

Azeotropes have been studied for decades due to the challenges they impose on separation processes but fundamental understanding at the molecular level remains limited. Although molecular simulation has demonstrated its capability of predicting mixture vapor-liquid equilibrium (VLE) behaviors, including azeotropes, its potential for mechanistic investigation has not been fully exploited. In this study, we use the united atom transferable potentials for phase equilibria (TraPPE-UA) force field to model the ethanol/benzene mixture, which displays a positive azeotrope.

Synthesis of cyclobutane-fused oxygen-containing tricyclic framework via thermally promoted intramolecular cycloaddition of cyclohexadienone-tethered allenes.

We have developed a unique approach for the thermally promoted cycloaddition of cyclohexadienone-tethered allenes to form a versatile cyclobutane-fused oxygen-containing tricyclic framework in an environmentally friendly and atomic economic fashion with high regioselectivity. The reaction encompasses a broad substrate scope and functional group tolerance of cyclohexadienone moieties. Moreover, the cycloaddition was also applicable to the late-stage functionalization of pharmaceutically relevant compounds.

Chemical transformations of quaternary ammonium salts via C-N bond cleavage.

Quaternary ammonium salts are readily prepared and show good reactivity in various organic transformations via C-N bond cleavage. In this review we summarize reactions of aryl, benzyl, allyl and propargyl quaternary ammonium salts including cross-coupling with organometallic reagents, as arylation or benzylation reagents in C-H functionalization, reductive deamination, reductive coupling, nucleophilic substitution, carboxylation with CO, and carbonylation with CO to construct C-C, C-H and C-heteroatom bonds.

Two-dimensional nanochannel membranes for molecular and ionic separations.

Two-dimensional (2D) nanosheets have emerged as promising functional materials owing to their atomic thickness and unique physical/chemical properties. By using 2D nanosheets as building blocks, diverse kinds of two-dimensional nanochannel membranes (2DNCMs) are being actively explored, in which mass transport occurs in the through-plane and interlayer channels of 2D nanosheets. The rational construction and physical/chemical microenvironment regulation of nanochannels are of vital significance for translating these 2D nanosheets into molecular separation membranes and ionic separation membranes.

NiH-Catalyzed Migratory Defluorinative Olefin Cross-Coupling: Trifluoromethyl-Substituted Alkenes as Acceptor Olefins to Form gem-Difluoroalkenes.

We report a NiH-catalyzed migratory defluorinative coupling between two electronically differentiated olefins. A broad range of unactivated donor olefins can be joined directly to acceptor olefins containing an electron-deficient trifluoromethyl substituent in both intra- and intermolecular fashion to form gem-difluoroalkenes. This migratory coupling shows both site- and chemoselectivity under mild conditions, with the formation of a tertiary or quaternary carbon center.

Enhanced cellular uptake and nuclear accumulation of drug-peptide nanomedicines prepared by enzyme-instructed self-assembly.

Subcellular delivery of nanomedicines has emerged as a promising approach to enhance the therapeutic efficacy of anticancer drugs. Nuclear accumulation of anticancer drugs are essential for its therapeutic efficacy because their targets are generally located within the nucleus. However, strategies for the nuclear accumulation of nanomedicines with anticancer drugs rarely reported.

N,Cl co-doped fluorescent carbon dots as nanoprobe for detection of tartrazine in beverages.

Chemical doping with heteroatoms was employed to prepare N,Cl co-doped fluorescent carbon dots (N,Cl-FCDs) which may be designed for the detection of tartrazine. Using urea as the N source and FeCl · 6HO as the Cl source, N,Cl-FCDs were synthesized by hydrothermal method with carbon dots prepared from aloe. Compared with pure carbon dots (CDs), N,Cl-FCDs resulted in dramatic improvement in the fluorescence properties and surface physical chemical properties.

Self-assembly and self-delivery nanodrug of bortezomib: a simple approach to achieve the trade-off between functionality and druggability.

Bortezomib, dietary tannic acid and an FDA-approved excipient poloxamer were used as building blocks without any chemical syntheses and modifications to construct a dynamic self-delivery nanodrug with high drug loading, outstanding stability, tunable size and pH-controlled release. This strategy with high druggability, reproducibility and productivity might be desirable and useful for pharmaceutical formulations of bortezomib.

Curved corannulene dually targets mitochondria and endoplasmic reticulum, and initiates apoptosis via localized ROS induction upon light triggering.

Organelle-targeting agents are promising in both fundamental and applied biomedicine research, but such materials are very limited. As a curved 2D carbon material, corannulene (Cor) displays an uneven intramolecular electron distribution, producing a large dipole moment that can favor the electrostatic interaction. Based on the large negative mitochondrial membrane potential and the presence of a connection structure between mitochondria and endoplasmic reticulum (ER), we hypothesized that Cor could simultaneously target both mitochondria and ER.

Tunable oligo-histidine self-assembled monolayer junction and charge transport by a pH modulated assembly.

Histidine works as an important mediator in the charge transport process through proteins via its conjugate side group. It can also stabilize a peptide's secondary structure through hydrogen bonding of the imidazole group. In this study, the conformation of the self-assembled monolayer (SAM) and the charge transport of the tailor-made oligopeptide hepta-histidine derivative (7-His) were modulated through the pH control of the assembly environment.

Indandione-Terminated Quinoids: Facile Synthesis by Alkoxide-Mediated Rearrangement Reaction and Semiconducting Properties.

A series of 1,3-indandione-terminated π-conjugated quinoids were synthesized by alkoxide-mediated rearrangement reaction of the respective alkene precursors, followed by air oxidation. This new protocol allows access to quinoidal compounds with variable termini and cores. The resulting quinoids all show LUMO levels below -4.

Spinel-based ceramic membranes coupling solid sludge recycling with oily wastewater treatment.

Highly efficient and economic treatment of wastewater sludges and wastewaters in one way is a challenging issue in the water treatment field. Herein we present a waste-to-resource strategy for rational fabrication of low-cost ceramic membranes, which simultaneously addresses the treatment of heavy metal-laden sludges and the separation of oil-in-water (O/W) emulsions. A thermal conversion mechanism is proposed for complicated reactions between simulated nickel-laden wastewater sludge and bauxite mineral.

Triggered All-Active Metal Organic Framework: Ferroptosis Machinery Contributes to the Apoptotic Photodynamic Antitumor Therapy.

Nanoscale photodynamic therapy (PDT) is an appealing antitumor modality for which apoptosis is the major mechanism of toxicity induction. It was postulated that the highly reactive singlet oxygen in PDT could deplete glutathione (GSH) and activate ferroptosis, the extent to which could be further manipulated by a redox-responsive nanocarrier. To validate this, a disulfide-bearing imidazole ligand coordinated with zinc to form an all-active metal organic framework (MOF) nanocarrier where a photosensitizer (chlorin e6/Ce6) was encapsulated.

Superlithiophilic Amorphous SiO-TiO Distributed into Porous Carbon Skeleton Enabling Uniform Lithium Deposition for Stable Lithium Metal Batteries.

Lithium (Li) metal anodes have garnered increasing interest in recent years as its high theoretical capacity and low electrochemical potential promises a myriad of opportunities for various applications. However, one critical issue to overcome is the inhomogeneous deposition of Li during the plating and stripping process. This inhomogeneous deposition could result in uncontrollable dendrite growth, further leading to poor coulombic efficiency, shorter lifecycles, and safety concerns due to internal short circuit and thermal runaways.

Yttrium dialkyl supported by a silaamidinate ligand: synthesis, structure and catalysis on cyclotrimerization of isocyanates.

A sterically demanding silaamidine (ArN = Si(L)NHAr) ligand was synthesized and employed for the preparation of a yttrium dialkyl complex, which catalytically enabled the cyclotrimerization of isocyanate with high activity and excellent functional group tolerance.

Two-dimensional supramolecular assemblies based on β-cyclodextrin-grafted graphene oxide for mitochondrial dysfunction and photothermal therapy.

β-Cyclodextrin (CD)-grafted graphene oxide (GO) is an emerging drug carrier for human diseases therapy. Herein, we report two-dimensional nano-supramolecular assemblies to specifically target and disrupt tumor cell mitochondria in a photocontrollable manner. Moreover, the nanoassemblies displayed extremely high near-infrared-induced photothermal efficiency.

Triggered ferroptotic polymer micelles for reversing multidrug resistance to chemotherapy.

Drug-tolerant persister cancer cells (PCCs) play an important role in the development of multidrug resistance (MDR) to anti-cancer drugs. This is due to the strong link between PCCs formation and epithelial-mesenchymal transition (EMT), as well as the low numbers of PCCs. In addition, PCC removal by traditional cytotoxic agents is poor due to the intrinsic high MDR activity in these cells.

Visible-light-initiated manganese-catalyzed Giese addition of unactivated alkyl iodides to electron-poor olefins.

Herein, we report a mild protocol for direct visible-light-initiated Giese addition of unactivated alkyl iodides to electron-poor olefins (Michael acceptors) with catalysis by decacarbonyl dimanganese, Mn(CO), an inexpensive earth-abundant-metal catalyst. This protocol is compatible with a wide array of sensitive functional groups and has a broad substrate scope with regard to both the alkyl iodide and the Michael acceptor.

Targeted imaging and targeted therapy of breast cancer cells via fluorescent double template-imprinted polymer coated silicon nanoparticles by an epitope approach.

Targeting is vital for precise positioning and efficient therapy, and integrated platforms for diagnosis and therapy have attracted more and more attention. Herein, we established dual-template molecularly imprinted polymer (MIP) coated fluorescent silicon nanoparticles (Si NPs) by using the linear peptide of the extracellular region of human epidermal growth factor receptor-2 (HER2) and adopting doxorubicin (DOX) as templates for targeted imaging and targeted therapy. Benefiting from the epitope imprinting approach, the imprinted sites generated by peptides on the MIP surface can be employed for recognizing the corresponding protein, which allowed the MIP to specifically and actively target HER2-positive breast cancer cells.

Layer-by-Layer Assembly of Microgel Colloidal Crystals via Photoinitiated Alkyne-Azide Click Reaction.

Layer-by-layer (LBL) assembly of colloidal crystals (CCs) allows for the fine control of the thickness and architecture of the resulting crystals. Various methods have been developed for the LBL assembly of CCs of hard spheres. However, these methods are inapplicable for microgel CCs owing to the softness and deformability of microgel spheres.

Thermodynamic Parameters of Elementary Steps for 3,5-Disubstituted 1,4-Dihydropyridines To Release Hydride Anions in Acetonitrile.

A series of 3,5-disubstituted 1,4-dihydropyridine derivatives including the derivative with two chiral centers, (R = CH, CHPh), as a new type of organic hydride source were synthesized and characterized. The thermodynamic driving forces (defined as enthalpy changes or standard redox potentials) of the 6 elementary steps for the organic hydrides to release hydride ions in acetonitrile were measured by isothermal titration calorimetry and electrochemical methods. The impacts of the substituents and functional groups bearing the N1 and C3/C5 positions on the thermodynamic driving forces of the 6 elementary steps were examined and analyzed.

Multiscale Buffering Engineering in Silicon-Carbon Anode for Ultrastable Li-Ion Storage.

Silicon-carbon (Si-C) hybrids have been proven to be the most promising anodes for the next-generation lithium-ion batteries (LIBs) due to their superior theoretical capacity (∼4200 mAh g). However, it is still a critical challenge to apply this material for commercial LIB anodes because of the large volume expansion of Si, unstable solid-state interphase (SEI) layers, and huge internal stresses upon lithiation/delithiation. Here, we propose an engineering concept of multiscale buffering, taking advantage of a nanosized Si-C nanowire architecture through fabricating specific microsized wool-ball frameworks to solve all the above-mentioned problems.