Latest ArticlesA cobalt-catalyzed ring-opening/hydroxylation cascade of highly strained cyclopropanols has been developed for the first time. The reaction was conducted under open-air atmosphere to afford a broad series of structurally diverse β-hydroxy ketones in moderate to good yields with high regioselectivity. The protocol features mild reaction conditions, simple operation, high-functional-group tolerance, facile scalability, and heterocycle compatibility.
The direct epoxidation of propylene by O2 is a significant and challenging topic. The key factor for this homogeneous aerobic epoxidation is the activation of molecular oxygen under mild conditions. In this work, the aerobic epoxidation of propylene catalyzed by manganese porphyrins was achieved in the presence of isoprene. Isoprene contains an allyl methyl group, and the α-H can be easily removed to achieve the activation of molecular oxygen. The conversion of propylene was 38% and the selectivity toward propylene oxide (PO) was up to 87%. The role of isoprene was demonstrated, and a plausible mechanism was proposed. The protocol reported herein is expected to provide a strategy for the simultaneous preparation of propylene oxide and isoprene monoxide.
Assembling MnO2 nanowires into macroscopic membrane is a promising engineered technology for catalyst separation and enhancement of Fenton-like reaction activity, yet its development is limited by the deficiencies in preparation and property modulation of the MnO2 nanowires. In this work, we developed a facile method using C2H5OH and CH3COOK as reductive and vital control reagents to react with KMnO4 by hydrothermal reaction at 140 ℃ for 12 h, to prepare the ultralong α-MnO2 nanowires up to tens of micrometers with high purity and aspect ratio. Such strategy not only had the advantages of being mild, easily controlled and environmental pollution-free, but also endowed α-MnO2 nanowires with excellent ability as a Fenton catalyst when assembled into free-standing membrane for degrading phenolic compounds (kobs = 0.0738 ~ 0.1695 min−1) in a continuous flow reaction. The reactive oxygen species (i.e., •OH) from Fenton-like reaction were enriched within this α-MnO2 nanowire membrane via nanoconfinement effect, which further enhanced the mass transportation of •OH available for phenolic contaminants. MnO2 nanowire membrane using our method possessed the high practical potential for water purify due to its easy-preparation and enhanced catalytic performances.
Aiming at the construction of novel rotaxanes with desired luminescent properties for practical applications, recently the rapid development of rotaxanes decorated with aggregation-induced emission (AIE) luminogens (i.e., AIEgens) has been witnessed. The combination of AIEgens and rotaxanes leads to the successful construction of a novel type of luminescent rotaxanes with many attractive features. In particular, the unique controllable dynamic feature of rotaxanes endows the resultant AIEgen-based rotaxanes precisely tunable emissions under external stimuli, leading to the construction of a novel type of smart luminescent materials. In this minireview, the recent progress of AIEgen-based rotaxanes has been summarized, with an emphasis on the design strategy and potential applications.
Alkaline phosphatase (ALP) activity assay is not only significant to the clinical diagnosis of some related disease, but also momentous to the construction of ALP-based enzyme-linked immunosorbent assay (ELISA). Herein, for the first time, we have discovered that ascorbic acid (AA) can specially react with N-methylethylenediamine (N-MEDA) to generate fluorescent non-conjugated polymer dots (NCPDs) under mild conditions. On the basis of the AA-responsive emission and ALP-catalyzed hydrolysis of ascorbic acid 2-phosphate (AA2P) to AA, we have exploited a fluorometric ALP activity assay with high sensitivity and selectivity. Furthermore, by means of conventional ALP-based ELISA platform, a conceptual fluorescent ELISA has been constructed and applied in the potential clinical diagnosis, during which cardiac troponin I (cTnI), a well-established biomarker of acute myocardial infarction, has been chosen as the model target. We envision that such original fluorescent NCPDs generation-enabled ELISA could become a versatile tool in biochemical sensing and medical diagnosis in the future.
Various structures of G-quadruplex in biosystems play an important role in different diseases and are often regulated by a variety of molecular crowding environments induced by internal and even external factors (e.g., a solvent). Dimethyl sulfoxide (DMSO), a universal solvent, has been widely used in biological studies and for drug therapy, but little is known regarding its effect on G-quadruplex structure and stability. Here, we report the influence of molecular crowding environment induced by DMSO on the conformation and stability of G-quadruplex structure. We show that the G-quadruplex-forming sequences such as human telomeric sequence, which may have diverse conformations in different environments, tend to convert their topologies to parallel structures under the molecular crowding stimulated by DMSO. Moreover, DMSO can increase the stability of the parallel and antiparallel topologies, especially the parallel G-quadruplex sequence c-kit, but not the hybrid topologies. Further analysis of c-kit using the CD and NMR technique, combined with the unique structural characteristics of c-kit, reveals that the crowding, dehydration and interaction of DMSO are conductive to the formation and stability of the parallel G-quadruplex. The present study suggests that, DMSO, a common solvent used in DNA experiments, may have a nonnegligible influence on the structure and stability of G-quadruplex.
Understanding the regulatory mechanism of self-assembly processes is a necessity to modulate nanostructures and their properties. Herein, we have studied the mechanism of self-assembly in the C3 symmetric 1, 3, 5-benzentricarboxylic amino acid methyl ester enantiomers (TPE) in a mixed solvent system consisting of methanol and water. The resultant chiral structure was used for chiral recognition. The formation of chiral structures from the synergistic effect of multiple noncovalent interaction forces was confirmed by various techniques. Molecular dynamics simulations were used to characterize the time evolution of TPE structure and properties in solution. The theoretical results were consistent with the experimental results. Furthermore, the chiral structure assembled by the building blocks of TPE molecules was highly stereoselective for diamine compounds.
Pillar[n]arenes primarily comprise pillar[5]arenes and pillar[6]arenes, which belong to the new class of supramolecular macrocyclic hosts. Pillar[n]arenes have aroused wide attention because of their highly rigid and symmetrical architectures, controllable cavity size, and wide applications in a wide variety of areas. Although pillar[6]arene is difficult to synthesize, numerous studies have been conducted on it. In this review, the strategies to synthesize and functionalize pillar[6]arenes are investigated systematically. In addition, their host-guest properties in organic solvents and in aqueous solution are described. Moreover, pillar[6]arenes applied in different fields (e.g., molecular recognition, drug release, cancer therapy, and gas separation) are clarified. Hopefully, this study is capable of arousing more attention from increasing scientists to study large-cavity pillar[n]arenes.
It is cellular immunotherapy for the tumor that the in vitro modified immunocytes from patients or donors are reinfused into patients to kill tumor cells. Chimeric antigen receptor T cell (CAR-T) therapy, one of the most successful and representative tumor cellular immunotherapies, is now the weapon for cancer after extensive research. Although CAR-T immunotherapy achieves success in treating relapsed/refractory hematological tumors, its drawbacks, including the poor effect in solid tumors, cytokine release syndrome (CRS) or CAR-T-related encephalopathy syndrome (CRES), on-target, off-tumor effect, and high cost, cannot be overlooked. Nanotechnology is advantageous in the construction of CARs, the transfection of T cells, the expansion, delivery, and antitumor effect of CAR-T cells, and the reduction of CAR-T therapy-associated toxicities. Currently, introducing nanotechnology into CAR-T immunotherapy has already been performed in numerous studies with highly promising results. In this review, we summarized the nanotechnologies used in CAR-T immunotherapy and discussed the challenges and directions of CAR-T immunotherapy combined with nanotechnologies in the future.
Research into environmentally friendly strategies for hydrogen transfer reduction is increasing, along with the need for more elaborate heterocyclic platforms. Within this context, we develop a new approach for substituted dihydrobenzo[c]carbazoles and indoles. These compounds were synthesized through an iron-catalyzed hydrogen transfer reduction of nitroarenes, followed by intramolecular cyclization. This transformation involves using a Knölker-type catalyst, Cs2CO3 as the base, and benzyl alcohol as the non-expensive and low volatile hydrogen donor. We synthesize 30 examples of aza-heterocycles with moderate to excellent yields by applying this strategy. Additionally, DFT calculations demonstrated that the pathway reaction could follow an anionic mechanism.
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