Latest ArticlesAn SN2-based photochemical strategy using dithiocarbamate anion as catalyst was developed for the activation of benzyl halides, which are extremely challenging to be applied as radical precursors in visible light photocatalysis. With this transition-metal-free and oxidant-free protocol, the benzylation (or cyanomethylation) of various heterocycles including quinoxalin-2(1H)-ones, coumarin, 2-phenyl-2H-indazole, 1-methyl-5-phenylpyrazin-2(1H)-one, 1-(fluoromethyl)cinnolin-4(1H)-one, and 2, 4-dibenzyl-1,2,4-triazine-3,5(2H, 4H)‑dione could be realized (46 examples, up to 98% yield). Importantly, some biologically relevant 3-benzylquinoxalin-2(1H)-ones were also be synthesized under mild conditions.
The electrooxidative [3 + 2] annulation of amidines with 2-arylideneindane-1,3-diones or 4-alkylidene pyrazolones is reported using NaI as a redox catalyst and electrolyte under constant current electrolysis in an undivided cell. The current strategy features excellent functional group tolerance, simple operation, and mild conditions, thus providing an environmentally benign and efficient access to spiroimidazolines in moderate to good yields.
The development of new carbon dots (CDs) for fluorescence-based cancer diagnosis has recently attracted extensive attention. Diagnosis methods based on ligand-receptor fluorescence suffer from the heterogeneity of receptor expression. Changes in the microenvironments of cancer cells provide opportunities for accurate and broad-spectrum cancer diagnosis. The lysosomes in cancer cells have lower polarity and higher viscosity than normal cells. Based on these two key microenvironmental parameters, dual-responsive CDs with inherent lysosome-targeting ability were synthesized via one-step hydrothermal treatment. The CDs exhibit many advantageous properties including facile synthesis, good water solubility, pH-independent emission, excellent photostability, good biocompatibility, and wash-free imaging ability. The CDs were successfully employed in the fluorescence-based discrimination of a broad spectrum of cancer cells from normal cells with high contrast. The CDs are promising candidates for use in the field of cancer diagnosis.
An efficient asymmetric alkenylation between 3-vinylindoles and isatin derivatives was developed under catalysis of a chiral copper complex. A series of optically active 3-alkenyl-3-substituted oxindoles were obtained in excellent yields and stereoselectivities. The reaction mechanism was proposed and supported by DFT calculation.
Herein, we report a highly efficient versatile synthetic route to Chiraphos derivatives through Rh/Ph-bod catalyzed asymmetric addition of aryl boronic acids to phosphinyl dienes. Various substituted phosphinyl dienes, both on the parent skeleton and the phosphine atoms, were well tolerated with this method and provided chiral phosphine oxides in satisfied yield and up to 95% ee. The corresponding Chiraphos derivative displayed an advantage over Chiraphos in the representative Pd-catalyzed asymmetric 1,4-addition reaction.
X-ray detection and imaging via scintillators has been utilized in missions worldwide within areas of scientific research, medical industry, military defense and homeland security. Commercial scintillators are costly with high energy consumption through the sintering. It is of great significance to seek alternative scintillating materials for sensitive X-ray detection in the next-generation. Herein, eight structure-defined Ln(Ⅲ)-based metal–organic frameworks (Ln-MOFs) were prepared, 2D [Ln2(1,4-ndc)3(DMF)4]n·nH2O (Ln = Sm 1, Eu 2, Dy 3, Tb 4) and 3D [Ln4(2,6-ndc)6(μ2H2O)2(H2O)4]n·2nH2O (Ln = Sm 5, Eu 6, Dy 7, Tb 8), where 1,4-H2ndc = 1,4-naphthalene dicarboxylate acid, 2,6-H2ndc = 2,6-napthalene dicarboxylate acid, DMF = N, N-dimethylformamide. Merely compounds 2 and 6 show remarkable X-ray scintillation performance via the characteristic red emissions of Eu(Ⅲ) ions, in which the absorbed energy from the triplet states of the organic moieties can be transferred more efficiently to the resonance emission levels of Eu(Ⅲ) ions than other lanthanide(Ⅲ) ions. The X-ray dosage rate detection limits of 2 and 6 are superior to the standard for the medical X-ray diagnosis dosage rate. As proofs-of-concepts, matrix-mixed membranes fabricated with 2 and 6 have achieved remarkable X-ray imaging with high resolution for practical object shooting.
A novel pillar[5]arene (P5DPB) that includes a classical π-conjugated molecule, 4,4'-(1,4-phenylenedi-2,1-ethenediyl) bis-pyridine (DPB), was designed and synthesized as a substituent. Because of this modification, P5DPB exhibits several unique properties that differ from those of common pillar[5]arenes. The P5DPB neutral pyridine shows good selectivity for Ag+ and Fe3+. The presence of Ag+ ions cause a blue shift (from yellow-green to green) and a decrease in the intensity of the P5DPB emission, while the addition of Fe3+ significantly quenches the P5DPB fluorescence. In addition, P5DPB satisfies the conditions for the construction of an energy transfer system with the commonly used Rhodamine B dye and shows great potential for the development of artificial light-harvesting systems. This work provides a new approach for the construction of energy transfer systems and a new reference for metal detection based on derivatized pillar[n]arenes, greatly enriching the applications of these systems.
Intelligent nanoplatform that combines multimodal imaging and therapeutic effects holds great promise for precise and efficient cancer therapy. Herein, folate-targeted polymersomes with stimuli-responsiveness were fabricated and evaluated by near-infrared fluorescence (NIRF) and optical coherence tomography angiography (OCTA) dual-imaging for photo-chemo-antiangiogenic therapy against cancer. The folate-targeted polymersomes (FA-MIT-SIPS) not only integrated ammonium bicarbonate (ABC) and mitoxantrone (MIT) into their hydrophilic cavity but also encapsulated indocyanine green (ICG) and sorafenib (SOR) within their hydrophobic layer. NIRF imaging demonstrated that FA-MIT-SIPS effectively accumulated and retained in the tumors. Upon 808 nm laser irradiation, the ICG produced hyperthermia and reactive oxygen species (ROS) for efficient photothermal and photodynamic therapy. In addition, the decomposition of ABC in responsive to acidic tumor environment and ICG-induced hyperthermia accelerated drug release. The released MIT accumulated in nucleus to inhibit DNA synthesis, while the released SOR destructed tumor vascularization. Notably, OCTA imaging was applied to observe the tumor blood flow upon the combination therapy, demonstrating that FA-MIT-SIPS obviously decreased the vessels area density. Moreover, the synergistic photo-chemo-antiangiogenic therapy of FA-MIT-SIPS achieved excellent antitumor effect with 40% of the 4T1 tumor-bearing mice being completely cured without recurrence. The multifunctional polymersomes provide a promising dual-modal imaging-evaluated synergistic strategy for tumor therapy.
Graphene oxide (GO) has been widely used in the modification of membranes due to its excellent properties, i.e., huge specific surface area, good electrical conductivity, good hydrophilicity and various functional groups. The addition of GO in membranes were proved to exhibit improved properties in water permeability, molecular selectivity, membrane fouling mitigation and contaminants decomposition. Recently, the development of laminated GO in membranes achieved both high selectivity and high water permeability, conquering the limitations of conventional polymeric or inorganic membranes. By analyzing the separation mechanisms and the performance of GO composite membranes, this review systematically summarized the applications of GO composite membranes in three highlighted areas of environmental fields: desalination, gas separation and wastewater treatment, with challenges discussed faced with GO composite membranes.
Highly selective binding of structurally similar substrates is common for biomolecular recognition, but is often challenging to realize in synthetic hosts. Herein, we report highly selective binding of methyl viologen over other analogues by an endo-functionalized naphthobox. X-ray single crystal structure and Density Functional Theory (DFT) calculations revealed that the endo-functionalized groups in the cavity of the naphthobox is important for the high binding selectivity through the formation of multiple C–H…N, C–H…π, and π…π interactions with methyl viologen.
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