Latest ArticlesIntroducing covalently crosslinked network to polymer matrix can merge the advantages in reprocessing and durability of polymers. In this contribution, a series of high-performance vitrimeric elastomers were achieved via polycondensation. The topological structures of polymers were tuned by varying the feeding ratios of bisacetoacetate, hex–substituted bisacetoacetate, bisamine and tris(2-aminoethyl)amine. With these structural manipulations, the vitrimeric elastomers presented great elastic recovery properties (strain recovery value up to 80%) benefiting from the introduction of long chain branch. Furthermore, the elastomers exhibited excellent reprocessing property, water vapor/oxygen barrier and adhesive properties. Specially, the elastomers could be degraded into monomer under acid conditions which enabled the elastomer synthesis again in closed loop recycling system. The ease of the polycondensation in this work to prepare highly elastic and recyclable vitrimeric elastomers demonstrated exciting opportunities for the synthesis of sustainable polymers.
A meso-molecular muscle was prepared by capping the [c2]daisy chain based on a mono-functionalized copillar[5]arene with an imidazolium group in its axle. From its crystal structure, we observed that it was a cyclic dimer composed of two mirror image subcomponents, a pR- and a pS-copillar[5]arene. Their conformations were fixed by the doubly interlocked mechanical bond. By comparison of the 1H NMR and COSY spectra, we found that the length of this meso-molecular muscle could be controlled not only by the solvents, but also by the counter anions.
Fabrication of single atom catalysts (SACs) by a green and gentle method is important for their practical Fenton-like use. In this work, a high effective iron-based catalyst was prepared from the iron-rich Enteromorpha for NPX degradation via peroxymonosulfate (PMS). Both Fe-SACs and iron-clusters was fabricated from the intrinsic iron element in Enteromorpha after the urea saturation. The Fe-SACs/clusters can achieve 100% of NPX oxidation within 20 min with the kobs of 0.282 min−1. Quenching tests indicated that the radical pathways were not dominated in the catalytic systems, and strong electron transfer process can be induced in the Fe-SACs/clusters + PMS system by using the NPX as electron donor and Fe-SACs/clusters/PMS* complexes as electron acceptor. This result was consistent with the phenomenon observed in the galvanic oxidation system. In addition, the Fe-SACs/clusters was deposited onto the ceramic membrane (CM) by the spraying-crosslinking process to form a Fe-SACs/clusters@CM, which showed an effective and continuous NPX degradation in a heterogeneous PMS system.
The outbreak of COVID-19 has drawn great attention around the world. SARS-CoV-2 is a highly infectious virus with occult transmission by many mutations and a long incubation period. In particular, the emergence of asymptomatic infections has made the epidemic even more severe. Therefore, early diagnosis and timely management of suspected cases are essential measures to control the spread of the virus. Developing simple, portable, and accurate diagnostic techniques for SARS-CoV-2 is the key to epidemic prevention. The advantages of point-of-care testing technology make it play an increasingly important role in viral detection and screening. This review summarizes the point-of-care testing platforms developed by nucleic acid detection, immunological detection, and nanomaterial-based biosensors detection. Furthermore, this paper provides a prospect for designing future highly accurate, cheap, and convenient SARS-CoV-2 diagnostic technology.
Nitroaromatic hydrogenation catalysis without precious metals remains a longstanding challenge. The rate of electron transfer is the crucial factor affecting hydrogenation catalysis. Herein, an ionic Cd-based metal-organic framework (I-Cd-MOF) exhibiting a unique structure with one-dimensional (1D) opening nanochannels and good electron transfer ability was synthesized for catalyzing hydrogenation of 4-nitrophenol (4-NP). The catalytic activity of the unique I-Cd-MOF without noble metals is detected, which is higher than most reported noble metal catalysts. Remarkably, the reaction rate of I-Cd-MOF (4.28 min−1) is about 47.6 times higher than that of the Cd-based neutral MOF (N-Cd-MOF) with the similar crystalline structure. Liquid chromatograph mass spectrometer (LC-MS) and theoretical results demonstrate that 4-NP and five intermediates are stabilized in the channels of I-Cd-MOF, which increases the possibility of contact with H* and H2 generated at the Cd sites. The I-Cd-MOF was extended to other nitroaromatic hydrogenation catalysis, which still displays excellent activity. More importantly, the I-MOF@Filter membrane was successfully constructed for continuous hydrogenation catalytic reactions, which maintains a high catalytic performance after 7 cycles of recycling without washing. This work fills in the application of the I-MOFs in hydrogenation catalytic reactions and provides an effective way for the rapid and green degradation of nitroaromatic compounds.
Mannich-type reactions are a widely used method for the synthesis of amines due to the readily availability of nucleophiles and electrophiles. However, the inclusion of alkylarenes instead of active carbon pronucleophiles such as aldehydes and ketones in these addition reactions has been a challenge due to the inherent difficulty of benzylic deprotonation. In this study, we present a novel approach for the construction of N-sulfonyl amines via rhodium-catalyzed addition of unbiased benzylic CH bonds to cyclic N-sulfonyl ketamines through π-coordination. This strategy enables the synthesis of a diverse range of N-sulfonyl amines, and subsequent diversification of the addition products showcases the synthetic potential of this protocol.
Photothermal therapy (PTT) is a cutting-edge cancer treatment that can kill cancer cells in hypoxic environments without relying on oxygen. Seeking of the ideal photothermal agents with a high absorption coefficient in the near-infrared region, and a high excellent photothermal conversion efficiency is of great significance. Sulfone-Rhodanmine dye has showed an impressive absorption wavelength over 700 nm, but suffered from a stability issue. In this study, we synthesized five sulfone rhodamines and investigated the substitution effects on stability. SO2R2 showed high stability and strong absorbance at 714 nm with an excellent photothermal conversion efficiency of 53.06%, making it suitable for accurate photoacoustic imaging-guided photothermal therapy in vivo.
Organic electrochemical transistors (OECTs) have emerged as one type of promising building block for neuromorphic systems owing to their capability of mimicking the morphology and functions of biological neurons and synapses. Currently, numerous kinds of OECTs have been developed, while self-healing performance has been neglected in most reported OECTs. In this work, the OECTs using self-healing polymer electrolytes as dielectric layers are proposed. Several important synaptic behaviors are simulated in the OECTs by doping the channel layers with ions from the electrolytes. Benefitting from the dynamic hydrogen bonds in the self-healing polymer electrolytes, the OECTs can successfully maintain their electrical performance and the ability of emulating synaptic behaviors after self-healing compared with the initial state. More significantly, the sublinear spatial summation function is demonstrated in the OECTs and their potential in flexible electronics is also validated. These results suggest that our devices are expected to be a vital component in the development of future wearable and bioimplantable neuromorphic systems.
Small-molecule drugs are widely used in daily life. There are still issues with the current industrial synthesis techniques for small-molecule drugs, such as the use of expensive metal catalysts, convoluted reaction processes, and non-recyclable catalysts. The benefits of photocatalytic organic synthesis over conventional techniques are mild conditions, environmental friendliness, and great selectivity. Porous framework materials can precisely modulate catalytic sites’ electronic state and ligand structure to improve photocatalytic performance. In particular, MOFs, COFs and PCCs based photocatalysts have received extensive research interest due to their unique morphology, structural adjustability, high photocatalytic performance, unique recyclability, excellent chemical stability, easy synthesis and low cost. Therefore, a key area for future research is the development of porous framework materials as photocatalysts for the synthesis of small-molecule drugs or drug precursors.
Macrocyclic materials have attracted much attention due to their particular chemical and physical properties. Herein we report the precise synthesis and characterization of a new bismacrocycle structure base on cycloparaphenylene (CPP) and pillar[5]arene, named cycloparaphenylene-pillar[5]arenes (CPPn[5]). The bismacrocycle was fully characterized by NMR and HR-MS. The photophysical properties of CPPn[5] were investigated by UV–vis, and the maximum absorption peak was located at 331 nm, which was consistent with density functional theory (DFT) calculations. The fluorescence spectrum was further studied and the emission peak was maximized at 458 nm. The computational results indicate the strain energy of CPPn[5] is 27.80 kcal/mol and the HOMO-LUMO gap is 3.39 eV Notably, CPPn[5] showed interesting supramolecular properties.
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