查看更多>>摘要：Herein,we report an efficient and practical protocol for the photoinduced dehalocyclization of ortho-halophenylacrylamides with formate by the engagement of a CO2 radical anion to access substituted oxindoles.This method proceeds smoothly under mild conditions and exhibits a wide range of substrate as well as remarkable functional group compatibility.
查看更多>>摘要：The structural and surface properties of nanomedicines play an important role in determining their biological fate.Surface chemistry of nanomedicines is one of the key parameters,where researchers used various strategies such as PEGylation to avoid the undesired clearance of nanoparticles(NPs)for enhanced targeting effect.Nevertheless,the fine-tuning of surface chemistry through polymer functionalization remains largely unexplored.In this concise report,we find that the incorporation of only 10 mol％valine residues into the surface-anchored poly(L-glutamic acid)significantly lowered the macrophage uptake of NPs.The introduction of other hy-drophobic amino acid residues,however,increased the NPs internalization instead.The chirality and the side-chain structure of va-line played an important role in the unexpected uptake behavior.We believe this work highlights the impact of slight changes of the surface-anchored polymer structure on the behavior of NPs,drawing people's attention to the careful design of surface chemistry to optimize the nanomedicine design.
查看更多>>摘要：Investigating the quantum interference effect in single molecules is essential to comprehensively understand the underlying mecha-nism of single-molecule charge transport.In this study,we employed the mother molecule m-OPE and introduced a series of side groups with various electronic effects at the 2-position of the central phenyl ring,creating four daughter m-OPE derivatives.The sin-gle molecular conductivities of these molecule wires were measured using the scanning tunneling microscope breaking junction technique.Our findings demonstrate that the substitutions regularly modulate the destructive quantum interference occurring within the m-OPE molecules.By combining optical and electrochemical investigations,along with density functional theory compu-tations,we discover that the conductivity of the molecules corresponds to the electron-donating/withdrawing ability of the substit-uents.Specifically,by adjusting the electron structures of the molecular backbone,we can systematically tailor the destructive quantum interference in the m-OPE molecules.
查看更多>>摘要：Stability against oxygen is an important factor affecting the performance of organic semiconductor devices.Improving photooxida-tion stability can prolong the service life of the device and maintain the mechanical and photoelectric properties of the device.Gen-erally,various encapsulation methods from molecular structure to macroscopic device level are used to improve photooxidation sta-bility.Here,we adopted a crystallization strategy to allow 14H-spiro[dibenzo[c,h]acridine-7,9'-fluorene](SFDBA)to pack tightly to re-sist fluorescence decay caused by oxidation.In this case,the inert group of SFDBA acts as a"steric armor",protecting the photosen-sitive group from being attacked by oxygen.Therefore,compared with the fluorescence quenching of SFDBA powder under 2 h of sunlight,SFDBA crystal can maintain its fluorescence emission for more than 8 h under the same conditions.Furthermore,the pho-toluminescence quantum yields(PLQYs)of the crystalline film is 327％higher than that of the amorphous film.It shows that the crystallization strategy is an effective method to resist oxidation.
查看更多>>摘要：A visible-light-enabled,photocatalyst-free hydroacylation reaction of azodicarboxylic acid derivatives was described.This radical conjugate addition(RCA)protocol relied on the dual role of 4-acyl-1,4-dihydropyridine(acyl-DHP)reagents that besides being as radical reservoirs,they also enabled the conversion of radical adducts to anion intermediates via reduction.Under"cata-lyst-oxidant-additive free"conditions,a wide range of structurally different acyl hydrazide products were readily obtained in 56％-99％yields.The utility of this transformation was further demonstrated by the scale-up synthesis and downstream derivatiza-tion.
查看更多>>摘要：Kasha's exciton model proposes that T1 energy levels of organic compounds are insensitive to molecular aggregation and microenviron-ment change because of negligible small transition dipole moments ofTistates.This model holds true in most organic systems till now.Here we report the fabrication of twisted organic phosphors with intramolecular charge transfer characters and flexible molecular struc-tures.When doped into different organic matrices,the twisted phosphor adopts different conformation,exhibits distinct phosphores-cence colors and T1 energy levels,which violates Kasha's exciton model in organic system.Given that the change of phosphorescence col-ors and maxima can be readily distinguished by human eyes and conventional instrument,the twisted phosphors would be exploited as a new type of molecular probe,which would exhibit potential application in optical sensing and stimuli-responsive systems.
查看更多>>摘要：Seventeen undescribed lindenane-related sesquiterpenoid dimers,chlorajaponins A-Q(1-17),and 13 reported analogs(18-30)were isolated from Chloranthus japonicus Sieb.Compound 1 possesses an unprecedented 3/5/7/5/5/6/5/3 fused octacyclic scaffold,featuring a 6(5→4)-abeo-lindenane monomer,while 2 exhibits a 3/5/6/6/5/6/5/3 fused octacyclic scaffold.Their structures were de-termined through a combination of spectroscopic analyses and X-ray crystallography.Compounds 1,2,and 18 demonstrated signifi-cant inhibitory effects on lipid accumulation and effectively reduced the levels of triglycerides and total cholesterol,as well as the lev-els of aspartate aminotransferase and alanine aminotransferase in a HepG2 cell model.In addition,compounds 1,2,and 18 signifi-cantly suppressed the protein expression of the fatty acid synthase(FASN)and the sterol regulatory element-binding protein 1(SREBP1).Moreover,the anti-inflammatory assay showed that compounds 19-22 and 25 inhibited the NO production induced by lipopolysaccharide in RAW 264.7 macrophages with IC50 values of 7.89±0.44,6.25±0.46,2.98±0.29,10.77±0.60,and 3.60±0.28μmol/L.
查看更多>>摘要：The crystallization of chiral molecules is of great significance to understand the origin and evolution of hierarchical chirality and reveal the relationships between structural chirality and circularly polarized luminescence(CPL)activity.Here,we report two pairs of chiral metal-organic frameworks(MOFs)(DCF-17/LCF-17,DCF-18/LCF-18)by utilizing tetradentate ligands tetra(3-imidazoylphenyl)ethylene(TIPE)and 4,4'-[4',5'-bis[4-(4-pyridinyl)phenyl][1,1':2',1"-terphenyl]-4,4"-diyl]bis[pyridine](TPPP)as linkers.It can be observed that the spontaneous resolution of the achiral ligands is converted into the induced resolution,and the ligands form the absolute configu-ration by using enantiopure camphoric acid(cam)as chiral induced reagent(CIR).As a result,the racemate MOFs can be driven to generate absolute homochiral crystallization.Another two achiral MOFs[Cd(D-cam)(TPPP)0.5](AF-1,AF=achiral framework)and[Cd(L-cam)(TPPP)0.5](AF-2)were prepared.The position disorder of D/L-cam skeleton causes the generation of nonchiralization,fur-ther leading to disappearance of symmetry breaking of TPPP.For the perspective of structure,this is the first report which reveals the chiral transfer and nonchiralization between chiral induced agents and tetradentate ligands.Besides,DCF-17 and LCF-17 show CPL with luminescence dissymmetry factor(glum)of-1.0 × 10-2 and+9.2 × 10-3,respectively.This work provides the useful evidences to reveal the induced chiral crystallization and the construction of CPL-active crystalline materials.
查看更多>>摘要：As one of the most common structural motifs in natural products,cyclopentenones usually can be fabricated by Nazarov cyclization using divinyl ketones or functionalized tertiary divinyl carbinols(TDCs)as substrates.However,straightforward method for trans-forming unfunctionalized TDCs to their corresponding cyclopentenones is currently lacking.Herein,we wish to report the total syn-theses of four structurally distinct terpenoids,namely laurane-type marine sesquiterpenoids isolaurene,debromoaplysin and aplysin,and guaiane sesquiterpenoid guaiadienone A,all using a novel synthetic method,named oxidative Nazarov cyclization,as the key step.This work demonstrated our robust method is suitable for synthesizing various highly substituted cyclopentenones.
查看更多>>摘要：Charge generation,a critical process in the operation of organic solar cell(OSC),requires thorough investigation in an ultrafast per-spective.This work demonstrates that the utilization of alloy model for the non-fullerene acceptor(NFA)component can regulate the crystallization properties of active layer films,which in turn affects exciton diffusion and hole transfer(HT),ultimately influencing the charge generation process.By incorporating BTP-eC7 as a third component,without expanding absorption range or changing molecular energy levels but regulating the ultrafast exciton diffusion and HT processes,the power conversion efficiency(PCE)of the optimized PM6:BTP-eC9:BTP-eC7 based ternary OSC is improved from 17.30％to 17.83％,primarily due to the enhancement of short-circuit current density(Jsc).Additionally,the introduction of BTP-eC7 also reduces the trap state density in the photoactive layer which helps to reduce the loss of Jsc.This study introduces a novel approach for employing ternary alloy models by incorporat-ing dual acceptors with similar structures,and elucidates the underlying mechanism of charge generation and Jsc in ternary OSCs.
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