Extracellular Disintegration of Viral Proteins as an Innovative Strategy for Developing Broad-Spectrum Antivirals Against Coronavirus

The coronavirus disease 2019(COVID-19)pandemic,caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),has claimedmillions of lives and caused innumerable economic losses worldwide.Unfortunately,state-of-the-art treatments still lag behind the continual emergence of new variants.Key to resolving this issue is developing antivirals to deactivate coronaviruses regardless of their structural evolution.Here,we report an innovative antiviral strategy involving extracellular disintegration of viral proteins with hyperanion-grafted enediyne(EDY)molecules.The core EDY generates reactive radical species and causes significant damage to the spike protein of coronavirus,while the hyperanion groups ensure negligible cytotoxicity of the molecules.The EDYs exhibit antiviral activity down to nanomolar concentrations,and the selectivity index of up to 20,000 against four kinds of human coronavirus,including the SARS-CoV-2 Omicron variant,suggesting the high potential of this new strategy in combating the COVID-19 pandemic and a future“disease X.”

Synthesis of cycloparaphenylene under spatial nanoconfinement

Suzuki coupling reactions between symmetrical monomers were conducted in various mesoporous silica nanoreactors grafted with palladium catalysts,enabling the selective formation of[12]cycloparaphenylene precursor with separate yield up to 25%in one-pot reactions,much higher than that in homogeneous reaction.The spatial nanoconfinement of the nanoreactors promotes the macrocyclization while limits the concomitant linear oligomer formation,offering more possibilities for the synthesis of macrocycles from symmetrical monomers in one-pot reaction.

Catalytic alkane dehydrogenations

Olefins find widespread applications in the synthesis of polyolefins and fine chemicals. With an increasing demand for olefins, the technologies for alkane dehydrogenation have drawn much attention. Several types of heterogeneous catalysts have found applications in industry for the dehydrogenation of light alkanes, mainly ethane, propane, and butane. In the past three decades, a number of transition-metal complexes,particularly pincer-ligated iridium complexes, have been developed as the homogeneous catalysts for alkane dehydrogenations. The homogeneous catalyst systems operate under much milder conditions compared with the heterogeneous systems, and some systems exhibit good activity and high regioselectivity in dehydrogenation of alkanes longer than butane.

Recent advances of the Bergman cyclization in polymer science

The Bergman cyclization has strongly impacted on a number of fields including pharmaceutics, synthetic chemistry, and material science. The diradical intermediates stemmed from enediynes can not only cause DNA cleavage under physiological conditions but also function as monomer or initiator participants in polymer science. The homo-polymerization of enediynes through the Bergman cyclization to fabricate conjugated polymers is a fascinating strategy due to the advantages of facial operation, high efficiency, tailored structure, and catalyst-free operation. Moreover, conjugated polymers generated through the Bergman cyclization show many remarkable properties, such as excellent thermal stability, good solubility, and processability, which enables these polymers to be further manufactured into carbon-rich materials. Recent times have seen extensive efforts devoted to the application of the Bergman cyclization in polymer science and materials chemistry. A variety of synthetic strategies have been developed to fabricate structurally unique materials via the Bergman cyclization, including the fabrication of rod-like polymers with polyester, dendrimers and chiral imide side chains, functionalization of carbon nanomaterials by surface-grafting conjugated polymers, formation of nanoparticles by intramolecular collapse of single polymer chains, and the construction of carbon nanomembranes with different morphologies. Future developments involving the Bergman cyclization in polymer science, probably by altering the reaction mechanism to precisely control the microstructure of polymeric products, are also proposed in this review article.

Palladium-catalyzed Cycloaromatization Polymerization of Enediynes

Bergman cyclization has shown great promise in constructing conjugated polymers. However, the application of this reaction in polymer science is still limited due to the harsh reaction condition and ill-defined structure of the achieved polymers. To this end, the cycloaromatization polymerization of enediynes catalyzed by a series of transition metal catalysts is investigated in this work, by taking advantage of the coordination chemistry of the enediyne with the transition metal complexes. According to the nuclear magnetic resonance（NMR）, Fourier transform infrared（FTIR）, ultraviolet-visble（UV-Vis） spectroscopies and matrix-assisted laser desorption/ionization time-offlight mass spectrometry（MALDI-TOF MS） analysis, the cycloaromatization polymerization of enediynes proceeds under milder conditions and in a more controlled manner in the presence of palladium（II） complexes, giving structurally regulated conjugated polymers in high yields.

Self-Delivery Nanoparticles of Amphiphilic Acyclic Enediynes for Efficient Tumor Cell Suppression

Summary of main observation and conclusion Four acyclic maleimide-based enediyne compounds with different hydrophilicity were synthesized through Sonogashira reaction to reveal a self-delivery antitumor drug platform. As proved by ESR analysis, the enediyne compounds undergo Bergman- like cyclizati on and generate diradical in termediates at physiological temperature, which are able to induce DNA-cleavage through the abstraction of H atoms from the sugar-phosphate backbones. When the critical aggregation concentration is reached in water, the amphiphilic enediyne compounds self-assemble into nanoparticles and possess the self-delivery ability to be facilely admitted by tumor cells, resulting in greatly improved cytotoxicity (IC50 down to 10 μmol·L^-1) and much higher tumor cell apoptosis rate (up to 86.6%) in comparison with either the hydrophilic or the lipophilic enediyne compound. The enhanced endocytosis of the amphiphilic en ediyne compo unds was further confirmed through con focal laser scan ning microscopy analysis. The unveiled relationship between the hydrophilicity of enediyne drugs and their therapeutic efficacy will provide a guideline for the design of new self-delivery drugs employed in medicinal applications.

Controlled Step-Growth Polymerization

Conjugated polymers are attractive components of modern plastic electronics and photovoltaic devices.They are synthesized mainly through a step-growth polymerization(SGP)mechanism.However,due to the uncontrollable characteristic of classical SGP,this effort leads to batch-to-batch variations in solubility,uncontrolled molecular weight,and broad polydispersity of the polymers obtained,thus,severely limiting their processing properties and performance.Here we demonstrate a general theoretical model of controlled SGP process by examining the possibility of the polymer chains further involvement in the SGP and how this correlated with their respective molecular weights.Subsequently,we proposed a practical method by which the SGP system was confined in nano-sized reactors.This method enabled the synthesis of a variety of polymers,having precisely controlled molecular weights with narrow polydispersity.We anticipate that this venture would exemplify a starting point for a more sophisticated molecular and structural design of functional polymers in widespread applications.