Covalent organic frameworks(COFs)with photoactive units have attracted significant interest in visible light photocatalysis and can present a metal‐free scenario for activating O_(2).As a typical photoactive unit,thi...Covalent organic frameworks(COFs)with photoactive units have attracted significant interest in visible light photocatalysis and can present a metal‐free scenario for activating O_(2).As a typical photoactive unit,thiazolo[5,4‐d]thiazole(TzTz)has rarely been added to COFs.However,circumventing the low reversibility of TzTz,it could be embedded into the building blocks beforehand,along with other bonds likeβ‐ketoenamine in forming COFs.TzTz was embedded into 1,1′‐biphenyl‐4,4′‐diamine(BD)using this approach to produce 4,4′‐(TzTz‐2,5‐diyl)dianiline(DTz).Under organobase‐modulated solvothermal conditions,combining 1,3,5‐triformylphloroglucinol(Tp)with BD and DTz resulted in the production ofβ‐ketoenamine‐linked TpBD‐COF and TpDTz‐COF.Both TpDTz‐COF and TpBD‐COF are microspheres.TpDTz‐COF possessed more adequate separation and charge migration than TpBD‐COF.This resulted in superior performance for the blue light photocatalytic selective oxidation of benzylamine with O_(2).Furthermore,with O_(2) as the main oxidant,a wealth of benzylamines could be converted into imines over TpDTz‐COF.Mechanistic investigations substantiate that oxidation of benzylamines obeys an electron transfer pathway,in which superoxide anion(O_(2)•–)is the crucial reactive oxygen species.This study highlights the superiority of TzTz‐embedded COFs in developing effective photocatalytic systems for organic transformations.展开更多
Herein,we report an asymmetric two-component alkenyl Catellani reaction for the construction of C—N axial chirality through a palladium/chiral norbornene cooperative catalysis and an axial-to-axial chirality transfer...Herein,we report an asymmetric two-component alkenyl Catellani reaction for the construction of C—N axial chirality through a palladium/chiral norbornene cooperative catalysis and an axial-to-axial chirality transfer process.Various partially aromatic iodinated 2-pyridones,quinolones,coumarin and uracil substrates react with 2,6-disubstituted aryl bromides with a tethered amide group,to afford a wide variety of polycyclic C—N atropisomers(38 examples,up to 97%e.e.).The obtained C—N axial chirality originates from the preformed transient C—C axial chirality with high fidelity.The synthetic utility of this chemistry is demonstrated by facile prepa-ration of complex quinoline and pyridine based C—N atropisomers through a N-deprotection and aromatization sequence.In addi-tion,a remote axial-to-central diastereoinduction process dictated by C—N axial chirality is observed with excellent diastereocontrol.展开更多
This work presents the visible-light photocatalytic selective oxidation of thiols to disulfides with molecular oxygen(O2) on anatase TiO2. The high specific surface area of anatase TiO2 proved to be especially critica...This work presents the visible-light photocatalytic selective oxidation of thiols to disulfides with molecular oxygen(O2) on anatase TiO2. The high specific surface area of anatase TiO2 proved to be especially critical in conferring high photocatalytic activity. Herein, surface complexation between thiol and TiO2 gives rise to photocatalytic activity under irradiation with 520 nm green light-emitting diodes(LEDs), resulting in excellent reaction activity, substrate scope, and functional group tolerance. The transformation was extremely efficient for the selective oxidation of various thiols, particularly with substrates bearing electron-withdrawing groups(reaction times of less than 10 min). To date, the longest wavelength of visible light that this system can utilize is 520 nm by the surface complex of substrate-TiO2. Importantly, O2 was found to act as the electron and proton acceptor, rather than to incorporate into the substrates. Our findings regarding this surface complex-based photocatalytic system can allow one to understand the interaction between the conduction band electrons and O2.展开更多
Electrocatalytic CO_(2) reduction has attracted growing attention as a promising route to realize artificial carbon recycling.Proton transfer plays an essential role in CO_(2) reduction and dramatically impacts produc...Electrocatalytic CO_(2) reduction has attracted growing attention as a promising route to realize artificial carbon recycling.Proton transfer plays an essential role in CO_(2) reduction and dramatically impacts product distribution.However,the precise control of proton transfer during CO_(2) reduction remains challenging.In this study,we present a well-controlled proton transfer through the modification of several purines with similar molecular structures,and reveal a direct correlation between surface proton transfer capability and CO_(2) reduction selectivity over Cu electrode.With a moderate proton transfer capability,the guanine modification can remarkably boost CH_(4) production and suppress C2 products formation.In-situ ATR-SEIRAS suggests a weakened^(*)CO intermediate adsorption and a relatively low local pH environment after the guanine modification,which facilitates the^(*)CO protonation and detachment for CH_(4) generation.展开更多
Visible light photocatalysis of covalent organic frameworks(COFs) has made significant progress in recent years. Benzotrithiophene(BTT), a planar, electron-rich building block, turns out to be foundational in assembli...Visible light photocatalysis of covalent organic frameworks(COFs) has made significant progress in recent years. Benzotrithiophene(BTT), a planar, electron-rich building block, turns out to be foundational in assembling COFs in which the fullπ-conjugation of BTT is essential to facilitate electron transfer. Herein, a sp~2 carbon-conjugated COF, namely BTT-sp~2c-COF, is assembled from benzo[1,2-b:3,4-b′:5,6-b′′]trithiophene-2,5,8-tricarbaldehyde and [1,1′:4′,1′′-terphenyl]-4,4′′-dicarbonitrile towards photocatalysis. More importantly, TEMPO(2,2,6,6-tetramethylpiperidin-1-yl)oxyl, 1 mol%) could considerably accelerate the selective oxidation of organic sulfides with O_(2) over BTT-sp~2c-COF. TEMPO mediates hole transfer between BTT-sp~2c-COF and organic sulfides, and O-atoms are incorporated into sulfoxides via an electron transfer pathway. Merging BTT-sp~2c-COF photocatalysis with TEMPO generally applies to transforming organic sulfides into sulfoxides. This work implies the full π-conjugation of electron-rich building blocks into COFs is a viable strategy for selective visible light photocatalysis.展开更多
Tuning F?rster resonance energy transfer(FRET)in metal-organic frameworks for fluorescence turn on sensing is rarely reported.Herein,we designed and synthesized several FRET-based metal-organic frameworks(MOFs)with di...Tuning F?rster resonance energy transfer(FRET)in metal-organic frameworks for fluorescence turn on sensing is rarely reported.Herein,we designed and synthesized several FRET-based metal-organic frameworks(MOFs)with different donor/acceptor ratios.Through the oxidation of the acceptor,the FRET process in MOFs can be efficiently modulated so as to turn-on the fluorescence of the framework in a controlled manner.Interestingly,the MOF with an optimized donor/acceptor ratio of 7.0 was used as an efficient fluorescence turn on sensor for Hg(Ⅱ)ions with good sensitivity and selectivity.We believe our present study will not only give a useful method to construct fluorescence turn-on sensors but also trigger the construction of novel FRET-based MOFs for the fluo-rescence turn-on sensing of target analytes in the future.展开更多
Thermally activated delayed fuorescence(TADF)small molecule bis-[3-(9,9-dimethyl-9,10-dihydroacridine)-phenyl]-sulfone(m-ACSO2)was used as a universal host to sensitize three conventional fuorescent polymers for maxim...Thermally activated delayed fuorescence(TADF)small molecule bis-[3-(9,9-dimethyl-9,10-dihydroacridine)-phenyl]-sulfone(m-ACSO2)was used as a universal host to sensitize three conventional fuorescent polymers for maximizing the electroluminescent performance.The excitons were utilized via inter-molecular energy transfer and the non-radiative decays were successfully refrained in the condensed states.Therefore,the signifcant enhancement of the electroluminescent efciencies was demonstrated.For instance,after doping poly(9,9-dioctylfuorene-co-benzothiadiazole)(F8BT)into m-ACSO2,the external quantum efciency(EQE)was improved by a factor of 17.0 in the solution-processed organic light-emitting device(OLED),as compared with the device with neat F8BT.In terms of the other well-known fuorescent polymers,i.e.,poly(para-phenylene vinylene)copolymer(Super Yellow,SY)and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene](MEH-PPV),their EQEs in the devices were respectively enhanced by 70%and 270%,compared with the reference devices based on the conventional host 1,3-di(9H-carbazol-9-yl)benzene(mCP).Besides the improved charge balance in the bipolar TADF host,these were partially ascribed to reduced fuorescence quenching in the mixed flms.展开更多
Lewis acid−base adducts resulting from instantaneous interactions provide a cost-effective strategy for color tuning and anticounterfeiting information.Herein,we report the construction of luminescent Lewis acid−base ...Lewis acid−base adducts resulting from instantaneous interactions provide a cost-effective strategy for color tuning and anticounterfeiting information.Herein,we report the construction of luminescent Lewis acid−base adducts via inkjet printing.Due to the unique weak coordination bond of B→N,it is feasible to construct anticounterfeiting information that is easy to erase.The in situ postsynthesis of the luminescent quick response codes via inkjet printing facilitates precision chemistry control to change the emission ranging from deep-blue(peaking at 407 nm)to orange-red(peaking at 597 nm).The encrypted information can be quickly erased either by modulating the temperature to dissociate the weak coordination or strong Lewis base to promote a neutralization reaction.展开更多
“Union is strength”.In the realm of organic molecules,the macroscopic performance of molecular aggregates is not just the simple overlay of single molecules,and in many cases,new properties can be created by molecul...“Union is strength”.In the realm of organic molecules,the macroscopic performance of molecular aggregates is not just the simple overlay of single molecules,and in many cases,new properties can be created by molecular uniting with particular packing modes[1–4].As to the organic emissive materials,various changes can be rea-lized from single molecules to aggregates(Fig.1),in-cluding the emerged bright emission,the varied emission color,the different emission forms,and the arisen new excitation processes.展开更多
Researchers investigated the organic optoelectronic materials and facilitated their development in organic light-emitting diodes(OLEDs),chemo-and biosensors,organic solar cells,data storage,and anticounterfeiting devi...Researchers investigated the organic optoelectronic materials and facilitated their development in organic light-emitting diodes(OLEDs),chemo-and biosensors,organic solar cells,data storage,and anticounterfeiting devices.Atoms make up molecules through chemical bonds,and molecular aggregates are formed through weak intermolecular interactions.The opto-electronic performance of these materials depends on not only the properties of the well-designed molecules with specific function groups,but also their aggregate states.The molecular aggregates in the form of nanoparticles can be applied in biological imaging,and films can be applied to photovoltaic and photodeformable devices,in which,the alignment of optoelectronic molecules can be either an ordered crystalline or an amorphous state.Generally,the crystalline materials could be deeply investigated by single crystal/powder X-ray diffraction analysis,which could provide the accurate information about molecular conformations,interactions and packing characteristics.It afforded a convenient way to investigate the possible relationship between molecular aggregates and opto-electronic properties.Among various opto-electronic materials,organic room temperature phosphorescence(RTP)materials exhibit the extremely sensitive luminescence property to molecular aggregates,even the dynamic properties can be detected by the tiny change of molecular aggregates.Thus,we selected the organic RTP emission as the output information of molecular aggregates,and afforded typical examples to find the possible relation between RTP effect and molecular packing.Accordingly,molecular packing can be adjusted by the external force as light,mechanical force,temperature,electric field,and so on,as well as the molecular structures as the building blocks,and the systematic investigation in the dynamic and static aggregation structures is of great value to the design of various optoelectronic materials.This review discusses the relationship among molecular structures,aggregation behaviors and corresponding optoelectronic properties by a comprehensive summary of recent research in our group,and the concept of molecular uniting set identified characteristic(MUSIC)is afforded.展开更多
The excitons in organic semiconductors undergo either radiative or non-radiative decay after excitation.Unlike the singlets in the fluorescence counterparts,the triplets in the heavy-metal based phosphorescent emitter...The excitons in organic semiconductors undergo either radiative or non-radiative decay after excitation.Unlike the singlets in the fluorescence counterparts,the triplets in the heavy-metal based phosphorescent emitter,thermally activated delayed fluorescence emitter with a small singlet-triplet gap,and metal-free room-temperature phosphorescence emitter with strong spinorbital coupling,respectively,could be feasibly harvested for photon generation, which are responsible for the theoretical 100% internal quantum efficiency.展开更多
Designing visible light photocatalysts with a metal oxide semiconductor as the starting material could expand a new horizon for the conversion and storage of solar energy.Here,the benchmark photocatalyst TiO_(2) was u...Designing visible light photocatalysts with a metal oxide semiconductor as the starting material could expand a new horizon for the conversion and storage of solar energy.Here,the benchmark photocatalyst TiO_(2) was used to pursue this goal by anchoring aromatic acids.Extending the aromatic acid was strategically deployed to design TiO_(2) complexes with violet light-induced selective aerobic oxidation of sulfide as the probe reaction.With benzoic acid(BA)as the initial molecule,horizontally extending one or two benzene rings furnishes 2-naphthoic acid(2-NA)and 2-anthracene acid(2-AA).Moreover,triethylamine(TEA),an electron transfer mediator,was introduced to maintain the integrity of the anchored aromatic acids.Notably,there was a direct correlation between theπ-conjugation of aromatic acid ligand and the selective aerobic oxidation of sulfides.Among the three aromatic acids,2-AA delivered the best result over TiO_(2) due to the most extensiveπ-conjugated system.Ultimately,violet light-induced selective aerobic oxidation of sulfides into corresponding sulfoxides was conveniently realized by cooperative photocatalysis of 2-AA-TiO_(2) with 10 mol%of TEA.This work affords an extending strategy for designing the next-generation ligands for semiconductors to expand visible light-induced selective reactions.展开更多
Main observation and conclusion A redox-neutral Fe-catalyzed intramolecular C-H amidation of N-benzoyloxyureas is described.This methodology employs a simple iron complex in situ generated from Fe(OTf)2 and bipyridine...Main observation and conclusion A redox-neutral Fe-catalyzed intramolecular C-H amidation of N-benzoyloxyureas is described.This methodology employs a simple iron complex in situ generated from Fe(OTf)2 and bipyridine as the catalyst and N-benzoyloxyureas as the nitrene precursors without using exogenous oxidants.An array of cyclic ureas were synthesized via aliphatic C(sp^(3))-H amidation in excellent yields.In addition,this catalytic system is also amenable to aryl C(sp^(2))-H nitrene insertion to provide benzimidazolones in moderate yields.展开更多
Carbon dots(CDs)have gradually become a widely favored type of fluorescent nanomaterials with unlimited and promising applications.This work reports a means of breaking the shackle of method to develop new red and whi...Carbon dots(CDs)have gradually become a widely favored type of fluorescent nanomaterials with unlimited and promising applications.This work reports a means of breaking the shackle of method to develop new red and white CDs by introducing free radicals.The resulting white emissive CDs in this strategy are employed to demonstrate electroluminescent white-light-emitting diodes(WLEDs)and achieve a record-high external quantum efficiency(0.95%)of one-step-produced white CDs(WCD)-LEDs,which dramatically simplifies the whole fabrication processes of WLEDs.With additional passivation treatment,the red CDs(RCD2)with excellent properties such as N and S co-doping,bright(quantum yield=49%)and stable photoluminescence(PL),large positive zeta potential(+20.5 mV),and two-photon fluorescence are obtained.Such RCD2 are used for rapid staining(5 min)of yeast cells.The two CDs synthesized via this method have outstanding performance in different aspects,which provides new promise of CDs for further functionalization and applications.展开更多
Li-rich manganese-based oxides (LRMO) with high capacities are attractive cathode materials for next-generation lithium-ion batteries.However,poor cycling stability is one of the key issues impeding their commercializ...Li-rich manganese-based oxides (LRMO) with high capacities are attractive cathode materials for next-generation lithium-ion batteries.However,poor cycling stability is one of the key issues impeding their commercialization.Here,for the first time,we employed trimethoxy(3,3,3-trifluoropropyl)silane (TMTFS) as a multifunctional electrolyte additive to stabilize the LRMO cathode interphase and elevate its cycling performance.The LRMO electrode delivered a high reversible capacity of 250.4 mAh·g^(-1) with a stable capacity retention of 91% after 200 cycles.展开更多
Active demethylation of 5-methylcytosine(5mC)can be realized through ten-eleven translocation(TET)dioxygenase-mediated oxidation of 5mC to 5-hydroxymethylcytosine(5hmC),5-formylcytosine(5fC),and 5-carboxylcytosine(5ca...Active demethylation of 5-methylcytosine(5mC)can be realized through ten-eleven translocation(TET)dioxygenase-mediated oxidation of 5mC to 5-hydroxymethylcytosine(5hmC),5-formylcytosine(5fC),and 5-carboxylcytosine(5caC),followed by thymine DNA glycosylase(TDG)-initiated base excision repair(BER).The TDG-BER pathwaymay lead to the generation of DNA strand breaks,potentially compromising genome integrity.Alternatively,direct decarboxylation of TET-produced 5caC is highly attractive because this mechanism allows for conversion of 5mC to cytosine without the formation of DNA strand breaks.However,cleavage of the C–C bond in 5caC in human cells remains an open question.We examined this reaction in cell extract and live cells using 5caC-carrying hairpin DNA substrate.After incubation with whole-cell protein extract or transfection into human cells,we monitored the transformation of 5caC to cytosine through direct decarboxylation or BER using liquid chromatography–tandem mass spectrometry(LCMS/MS)analyses at both the mononucleotide and oligodeoxynucleotide levels.Our results clearly showed the direct conversion of 5caC to cytosine in human cells,providing evidence to support a novel pathway for active DNA demethylation.展开更多
The exploration of high-performance solution-processible host materials for blue and white electrophosphorescent devices is a key and fundamental challenge in the ongoing development of organic semiconductors.Herein,t...The exploration of high-performance solution-processible host materials for blue and white electrophosphorescent devices is a key and fundamental challenge in the ongoing development of organic semiconductors.Herein,two solution-processible resonance host materials with self-adaptive characteristics are delicately designed and constructed.Because of the dynamic tautomerization upon resonance variation,these smart hosts show self-adaptive and selectively enhanced charge carrier flux at high triplet energy levels.Conferred by the resonance molecules,solution-processed blue and white devices exhibit excellent maximum current efficiencies(CEs)of 29.8 and 57.3 cd A−1,and external quantum efficiencies(EQEs)up to 14.5%and 23.5%,respectively.Our works highlight the significant progress of the solution-processed phosphorescent organic light-emitting diodes(PhOLEDs)using resonance host molecules,potentially furnishing a leap forward in constructing advanced organic semiconductors for next-generation optoelectronic devices.展开更多
Organic semiconductors with bipolar transporting character are highly attractive as they offer the possibility to achieve high optoelectronic performance in simple device structures.However,the continual efforts in pr...Organic semiconductors with bipolar transporting character are highly attractive as they offer the possibility to achieve high optoelectronic performance in simple device structures.However,the continual efforts in preparing bipolar materials are focusing on donor-acceptor(D-A)architectures by introducing both electron-donating and electron-withdrawing units into one molecule in static molecular design principles.Here,we report a dynamic approach to construct bipolar materials using only electron-donating carbazoles connected by N-P=X resonance linkages in a donor-resonance-donor(D-r-D)structure.By facilitating the stimuli-responsive resonance variation,these D-r-D molecules exhibit extraordinary bipolar properties by positively charging one donor of carbazole in enantiotropic N^(+)=P-X-canonical forms for electron transport without the involvement of any acceptors.With thus realized efficient and balanced charge transport,blue and deep-blue phosphorescent organic light emitting diodes hosted by these D-r-D molecules show high external quantum efficiencies up to 16.2%and 18.3%in vacuum-deposited and spin-coated devices,respectively.These results via the D-r-D molecular design strategy represent an important concept advance in constructing bipolar organic optoelectronic semiconductors dynamically for high-performance device applications.展开更多
Ribosomal RNAs(rRNAs) provide the structural framework of ribosomes and play critical roles in protein translation.In ribosome biogenesis,rRNAs acquire various modifications that can influence the structure and cataly...Ribosomal RNAs(rRNAs) provide the structural framework of ribosomes and play critical roles in protein translation.In ribosome biogenesis,rRNAs acquire various modifications that can influence the structure and catalytic activity of ribosomes.However,rRNA modifications in plants have yet to be fully defined.Herein,we proposed a method to purify rRNAs by a successive isolation with different strategies,including poly A-based m RNA depletion and agarose gel electrophoresis-based purification,with which highly pure rRNAs could be obtained.In addition,we developed a liquid chromatography-electrospray ionization-tandem mass spectrometry(LC-ESI-MS/MS) method to systematically profile and characterize modifications from the isolated highly pure plant 18S rRNA and 25S rRNA.LC-ESI-MS/MS analysis showed that 10 and 12 kinds of modifications were present in plant 18S rRNA and 25S rRNA,respectively.Notably,among these identified modifications,2 kinds of modifications of N^(2),N^(2)-dimethylguanosine(m^(2,2)G)and N^(6),N^(6)-dimethyladenosine(m^(6,6)A) in 18S rRNA,and 4 kinds of modifications of m^(2,2)G,m^(6,6)A,N7-methylguanosine(m^(7)G) and 3-methyluridin(m^(3)U) in 25S rRNA,were first reported to be present in plants.Moreover,exposure of Arabidopsis thaliana to cadmium(Cd) led to significant changes of modifications in both 18S rRNA and 25S rRNA of plants,indicating that rRNA modifications play important roles in response to environmental stress.The discovery of new modifications in plant rRNAs improves the spectra of plant rRNA modifications and may promote the investigation of the functional roles of plant ribosomes in regulating gene expression.展开更多
6-Thioguanine(6TG)is a widely used chemotherapeutic agent for the treatment of a variety of human diseases including acute lymphoblastic leukemia.After entry into cells,6TG is metabolically converted into 6-thioguanos...6-Thioguanine(6TG)is a widely used chemotherapeutic agent for the treatment of a variety of human diseases including acute lymphoblastic leukemia.After entry into cells,6TG is metabolically converted into 6-thioguanosine(^(S)G)nucleotide that can be incorporated into the genome during DNA replication.^(S)G in genomic DNA could induce cell death by triggering the post-replicative mismatch repair(MMR)pathway.Meanwhile,incorporation of 6TG into the Cp G sites could perturb the global DNA methylation and gene regulation.However,the effect of 6TG on RNA modifications is still unknown.Adenosine-toinosine(A-to-I)editing in RNA is one of the most common post-transcriptional modifications in mammals and there is growing evidence showing the significant alteration of A-to-I RNA editing in tumor tissues compared to normal tissues.In the current study,we examined the incorporation of 6TG into RNA and investigated its effect on A-to-I editing of bladder cancer-associated protein(BLCAP)transcript in acute lymphoblastic leukemia cells.The results demonstrated that ^(S)G could be incorporated into various RNA species,with m RNA having the most abundant ^(S)G.In addition,the results showed 6TG treatment elevated A-to-I editing in BLCAP transcript through upregulating adenosine deaminase 2 acting on RNA(ADAR2),which eventually contributes to the decreased cell viability.This study highlights a new mechanism of the cytotoxicity of 6TG in inducing cell death.展开更多
文摘Covalent organic frameworks(COFs)with photoactive units have attracted significant interest in visible light photocatalysis and can present a metal‐free scenario for activating O_(2).As a typical photoactive unit,thiazolo[5,4‐d]thiazole(TzTz)has rarely been added to COFs.However,circumventing the low reversibility of TzTz,it could be embedded into the building blocks beforehand,along with other bonds likeβ‐ketoenamine in forming COFs.TzTz was embedded into 1,1′‐biphenyl‐4,4′‐diamine(BD)using this approach to produce 4,4′‐(TzTz‐2,5‐diyl)dianiline(DTz).Under organobase‐modulated solvothermal conditions,combining 1,3,5‐triformylphloroglucinol(Tp)with BD and DTz resulted in the production ofβ‐ketoenamine‐linked TpBD‐COF and TpDTz‐COF.Both TpDTz‐COF and TpBD‐COF are microspheres.TpDTz‐COF possessed more adequate separation and charge migration than TpBD‐COF.This resulted in superior performance for the blue light photocatalytic selective oxidation of benzylamine with O_(2).Furthermore,with O_(2) as the main oxidant,a wealth of benzylamines could be converted into imines over TpDTz‐COF.Mechanistic investigations substantiate that oxidation of benzylamines obeys an electron transfer pathway,in which superoxide anion(O_(2)•–)is the crucial reactive oxygen species.This study highlights the superiority of TzTz‐embedded COFs in developing effective photocatalytic systems for organic transformations.
文摘Herein,we report an asymmetric two-component alkenyl Catellani reaction for the construction of C—N axial chirality through a palladium/chiral norbornene cooperative catalysis and an axial-to-axial chirality transfer process.Various partially aromatic iodinated 2-pyridones,quinolones,coumarin and uracil substrates react with 2,6-disubstituted aryl bromides with a tethered amide group,to afford a wide variety of polycyclic C—N atropisomers(38 examples,up to 97%e.e.).The obtained C—N axial chirality originates from the preformed transient C—C axial chirality with high fidelity.The synthetic utility of this chemistry is demonstrated by facile prepa-ration of complex quinoline and pyridine based C—N atropisomers through a N-deprotection and aromatization sequence.In addi-tion,a remote axial-to-central diastereoinduction process dictated by C—N axial chirality is observed with excellent diastereocontrol.
文摘This work presents the visible-light photocatalytic selective oxidation of thiols to disulfides with molecular oxygen(O2) on anatase TiO2. The high specific surface area of anatase TiO2 proved to be especially critical in conferring high photocatalytic activity. Herein, surface complexation between thiol and TiO2 gives rise to photocatalytic activity under irradiation with 520 nm green light-emitting diodes(LEDs), resulting in excellent reaction activity, substrate scope, and functional group tolerance. The transformation was extremely efficient for the selective oxidation of various thiols, particularly with substrates bearing electron-withdrawing groups(reaction times of less than 10 min). To date, the longest wavelength of visible light that this system can utilize is 520 nm by the surface complex of substrate-TiO2. Importantly, O2 was found to act as the electron and proton acceptor, rather than to incorporate into the substrates. Our findings regarding this surface complex-based photocatalytic system can allow one to understand the interaction between the conduction band electrons and O2.
文摘Electrocatalytic CO_(2) reduction has attracted growing attention as a promising route to realize artificial carbon recycling.Proton transfer plays an essential role in CO_(2) reduction and dramatically impacts product distribution.However,the precise control of proton transfer during CO_(2) reduction remains challenging.In this study,we present a well-controlled proton transfer through the modification of several purines with similar molecular structures,and reveal a direct correlation between surface proton transfer capability and CO_(2) reduction selectivity over Cu electrode.With a moderate proton transfer capability,the guanine modification can remarkably boost CH_(4) production and suppress C2 products formation.In-situ ATR-SEIRAS suggests a weakened^(*)CO intermediate adsorption and a relatively low local pH environment after the guanine modification,which facilitates the^(*)CO protonation and detachment for CH_(4) generation.
基金supported by the National Natural Science Foundation of China (22072108)。
文摘Visible light photocatalysis of covalent organic frameworks(COFs) has made significant progress in recent years. Benzotrithiophene(BTT), a planar, electron-rich building block, turns out to be foundational in assembling COFs in which the fullπ-conjugation of BTT is essential to facilitate electron transfer. Herein, a sp~2 carbon-conjugated COF, namely BTT-sp~2c-COF, is assembled from benzo[1,2-b:3,4-b′:5,6-b′′]trithiophene-2,5,8-tricarbaldehyde and [1,1′:4′,1′′-terphenyl]-4,4′′-dicarbonitrile towards photocatalysis. More importantly, TEMPO(2,2,6,6-tetramethylpiperidin-1-yl)oxyl, 1 mol%) could considerably accelerate the selective oxidation of organic sulfides with O_(2) over BTT-sp~2c-COF. TEMPO mediates hole transfer between BTT-sp~2c-COF and organic sulfides, and O-atoms are incorporated into sulfoxides via an electron transfer pathway. Merging BTT-sp~2c-COF photocatalysis with TEMPO generally applies to transforming organic sulfides into sulfoxides. This work implies the full π-conjugation of electron-rich building blocks into COFs is a viable strategy for selective visible light photocatalysis.
基金financial support from the National Natural Science Foundation of China(21975188,21905211,U21A20285)B.G.is thankful to Wuhan University for start-up funds(600460062).
文摘Tuning F?rster resonance energy transfer(FRET)in metal-organic frameworks for fluorescence turn on sensing is rarely reported.Herein,we designed and synthesized several FRET-based metal-organic frameworks(MOFs)with different donor/acceptor ratios.Through the oxidation of the acceptor,the FRET process in MOFs can be efficiently modulated so as to turn-on the fluorescence of the framework in a controlled manner.Interestingly,the MOF with an optimized donor/acceptor ratio of 7.0 was used as an efficient fluorescence turn on sensor for Hg(Ⅱ)ions with good sensitivity and selectivity.We believe our present study will not only give a useful method to construct fluorescence turn-on sensors but also trigger the construction of novel FRET-based MOFs for the fluo-rescence turn-on sensing of target analytes in the future.
基金the fnancial support from the National Natural Science Foundation of China(Grant Nos.51873159 and 62175189)GX acknowledged the funding support from the Open Project Program of Wuhan National Laboratory for Optoelectronics(No.2019WNLOKF015).
文摘Thermally activated delayed fuorescence(TADF)small molecule bis-[3-(9,9-dimethyl-9,10-dihydroacridine)-phenyl]-sulfone(m-ACSO2)was used as a universal host to sensitize three conventional fuorescent polymers for maximizing the electroluminescent performance.The excitons were utilized via inter-molecular energy transfer and the non-radiative decays were successfully refrained in the condensed states.Therefore,the signifcant enhancement of the electroluminescent efciencies was demonstrated.For instance,after doping poly(9,9-dioctylfuorene-co-benzothiadiazole)(F8BT)into m-ACSO2,the external quantum efciency(EQE)was improved by a factor of 17.0 in the solution-processed organic light-emitting device(OLED),as compared with the device with neat F8BT.In terms of the other well-known fuorescent polymers,i.e.,poly(para-phenylene vinylene)copolymer(Super Yellow,SY)and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene](MEH-PPV),their EQEs in the devices were respectively enhanced by 70%and 270%,compared with the reference devices based on the conventional host 1,3-di(9H-carbazol-9-yl)benzene(mCP).Besides the improved charge balance in the bipolar TADF host,these were partially ascribed to reduced fuorescence quenching in the mixed flms.
基金financially supported by the National Natural Science Foundation of China(No.62175189)the Program for Promoting Academic Collaboration and Senior Talent Fostering between China and Canada,Australia,New Zealand,and Latin America(2021-109)the joint China-Sweden Mobility programme(No.52211530052).
文摘Lewis acid−base adducts resulting from instantaneous interactions provide a cost-effective strategy for color tuning and anticounterfeiting information.Herein,we report the construction of luminescent Lewis acid−base adducts via inkjet printing.Due to the unique weak coordination bond of B→N,it is feasible to construct anticounterfeiting information that is easy to erase.The in situ postsynthesis of the luminescent quick response codes via inkjet printing facilitates precision chemistry control to change the emission ranging from deep-blue(peaking at 407 nm)to orange-red(peaking at 597 nm).The encrypted information can be quickly erased either by modulating the temperature to dissociate the weak coordination or strong Lewis base to promote a neutralization reaction.
基金the National Natural Science Foundation of China (51673151)Natural Science Foundation of Hubei Province (2017CFA002)the Fundamental Research Funds for the Central Universities (2042017kf0247 and 2042018kf0014) for financial support
文摘“Union is strength”.In the realm of organic molecules,the macroscopic performance of molecular aggregates is not just the simple overlay of single molecules,and in many cases,new properties can be created by molecular uniting with particular packing modes[1–4].As to the organic emissive materials,various changes can be rea-lized from single molecules to aggregates(Fig.1),in-cluding the emerged bright emission,the varied emission color,the different emission forms,and the arisen new excitation processes.
基金Wearegrateful to the National Natural Science Foundationof China(Nos.21734007,51973162,21875174)Excellent Youth Foundation of Hubei Scientific Committee(2020CFA084).
文摘Researchers investigated the organic optoelectronic materials and facilitated their development in organic light-emitting diodes(OLEDs),chemo-and biosensors,organic solar cells,data storage,and anticounterfeiting devices.Atoms make up molecules through chemical bonds,and molecular aggregates are formed through weak intermolecular interactions.The opto-electronic performance of these materials depends on not only the properties of the well-designed molecules with specific function groups,but also their aggregate states.The molecular aggregates in the form of nanoparticles can be applied in biological imaging,and films can be applied to photovoltaic and photodeformable devices,in which,the alignment of optoelectronic molecules can be either an ordered crystalline or an amorphous state.Generally,the crystalline materials could be deeply investigated by single crystal/powder X-ray diffraction analysis,which could provide the accurate information about molecular conformations,interactions and packing characteristics.It afforded a convenient way to investigate the possible relationship between molecular aggregates and opto-electronic properties.Among various opto-electronic materials,organic room temperature phosphorescence(RTP)materials exhibit the extremely sensitive luminescence property to molecular aggregates,even the dynamic properties can be detected by the tiny change of molecular aggregates.Thus,we selected the organic RTP emission as the output information of molecular aggregates,and afforded typical examples to find the possible relation between RTP effect and molecular packing.Accordingly,molecular packing can be adjusted by the external force as light,mechanical force,temperature,electric field,and so on,as well as the molecular structures as the building blocks,and the systematic investigation in the dynamic and static aggregation structures is of great value to the design of various optoelectronic materials.This review discusses the relationship among molecular structures,aggregation behaviors and corresponding optoelectronic properties by a comprehensive summary of recent research in our group,and the concept of molecular uniting set identified characteristic(MUSIC)is afforded.
基金the financial support from the National Key Research and Development Program of China(2016YFB0401002)the National Natural Science Foundation of China(51873159)+2 种基金the National Natural Science Foundation of China(51773045,21772030,51922032 and 21961160720)the Fundamental Research Funds for the Central Universities of China(2042019kf0234)the financial support from the National Key Research and Development Program of China(2017YFA0206600)。
文摘The excitons in organic semiconductors undergo either radiative or non-radiative decay after excitation.Unlike the singlets in the fluorescence counterparts,the triplets in the heavy-metal based phosphorescent emitter,thermally activated delayed fluorescence emitter with a small singlet-triplet gap,and metal-free room-temperature phosphorescence emitter with strong spinorbital coupling,respectively,could be feasibly harvested for photon generation, which are responsible for the theoretical 100% internal quantum efficiency.
基金funded by the National Natural Science Foundation of China(Nos.22072108 and 21773173)。
文摘Designing visible light photocatalysts with a metal oxide semiconductor as the starting material could expand a new horizon for the conversion and storage of solar energy.Here,the benchmark photocatalyst TiO_(2) was used to pursue this goal by anchoring aromatic acids.Extending the aromatic acid was strategically deployed to design TiO_(2) complexes with violet light-induced selective aerobic oxidation of sulfide as the probe reaction.With benzoic acid(BA)as the initial molecule,horizontally extending one or two benzene rings furnishes 2-naphthoic acid(2-NA)and 2-anthracene acid(2-AA).Moreover,triethylamine(TEA),an electron transfer mediator,was introduced to maintain the integrity of the anchored aromatic acids.Notably,there was a direct correlation between theπ-conjugation of aromatic acid ligand and the selective aerobic oxidation of sulfides.Among the three aromatic acids,2-AA delivered the best result over TiO_(2) due to the most extensiveπ-conjugated system.Ultimately,violet light-induced selective aerobic oxidation of sulfides into corresponding sulfoxides was conveniently realized by cooperative photocatalysis of 2-AA-TiO_(2) with 10 mol%of TEA.This work affords an extending strategy for designing the next-generation ligands for semiconductors to expand visible light-induced selective reactions.
基金the financial support from NSFC(Nos.21971198 and 21772148)Large-scale Instrument and Equipment Sharing Foundation of Wuhan University and the Natural Science Foundation of Hubei Province(Grant No.2020CFA036)。
文摘Main observation and conclusion A redox-neutral Fe-catalyzed intramolecular C-H amidation of N-benzoyloxyureas is described.This methodology employs a simple iron complex in situ generated from Fe(OTf)2 and bipyridine as the catalyst and N-benzoyloxyureas as the nitrene precursors without using exogenous oxidants.An array of cyclic ureas were synthesized via aliphatic C(sp^(3))-H amidation in excellent yields.In addition,this catalytic system is also amenable to aryl C(sp^(2))-H nitrene insertion to provide benzimidazolones in moderate yields.
基金support from the National Natural Science Foundation of China(Nos.21974101 and 22174102).
文摘Carbon dots(CDs)have gradually become a widely favored type of fluorescent nanomaterials with unlimited and promising applications.This work reports a means of breaking the shackle of method to develop new red and white CDs by introducing free radicals.The resulting white emissive CDs in this strategy are employed to demonstrate electroluminescent white-light-emitting diodes(WLEDs)and achieve a record-high external quantum efficiency(0.95%)of one-step-produced white CDs(WCD)-LEDs,which dramatically simplifies the whole fabrication processes of WLEDs.With additional passivation treatment,the red CDs(RCD2)with excellent properties such as N and S co-doping,bright(quantum yield=49%)and stable photoluminescence(PL),large positive zeta potential(+20.5 mV),and two-photon fluorescence are obtained.Such RCD2 are used for rapid staining(5 min)of yeast cells.The two CDs synthesized via this method have outstanding performance in different aspects,which provides new promise of CDs for further functionalization and applications.
基金financially supported by the National Natural Science Foundation of China (Nos.22172116 and 21773176)。
文摘Li-rich manganese-based oxides (LRMO) with high capacities are attractive cathode materials for next-generation lithium-ion batteries.However,poor cycling stability is one of the key issues impeding their commercialization.Here,for the first time,we employed trimethoxy(3,3,3-trifluoropropyl)silane (TMTFS) as a multifunctional electrolyte additive to stabilize the LRMO cathode interphase and elevate its cycling performance.The LRMO electrode delivered a high reversible capacity of 250.4 mAh·g^(-1) with a stable capacity retention of 91% after 200 cycles.
基金The work is supported by the National Key R&D Program of China(2017YFC0906800)the National Natural Science Foundation of China(21672166,21635006,and 21721005).
文摘Active demethylation of 5-methylcytosine(5mC)can be realized through ten-eleven translocation(TET)dioxygenase-mediated oxidation of 5mC to 5-hydroxymethylcytosine(5hmC),5-formylcytosine(5fC),and 5-carboxylcytosine(5caC),followed by thymine DNA glycosylase(TDG)-initiated base excision repair(BER).The TDG-BER pathwaymay lead to the generation of DNA strand breaks,potentially compromising genome integrity.Alternatively,direct decarboxylation of TET-produced 5caC is highly attractive because this mechanism allows for conversion of 5mC to cytosine without the formation of DNA strand breaks.However,cleavage of the C–C bond in 5caC in human cells remains an open question.We examined this reaction in cell extract and live cells using 5caC-carrying hairpin DNA substrate.After incubation with whole-cell protein extract or transfection into human cells,we monitored the transformation of 5caC to cytosine through direct decarboxylation or BER using liquid chromatography–tandem mass spectrometry(LCMS/MS)analyses at both the mononucleotide and oligodeoxynucleotide levels.Our results clearly showed the direct conversion of 5caC to cytosine in human cells,providing evidence to support a novel pathway for active DNA demethylation.
基金This work was supported by the National Natural Science Foundation of China(21704042,21604039,61875090,51873159,91833306,21674049)the Six Talent Plan of Jiangsu Province(XCL-049)+4 种基金1311 Talents Program of Nanjing University of Posts and Telecommunications(Dingfeng)the Natural Science Fund for Colleges and Universities in Jiangsu Province(17KJB150017)China Postdoctoral Science Foundation Funded Project(2018M642284)the Nanjing University of Posts and Telecommunications Start-up Fund(NUPTSF)(NY219007,NY217140)the Science and Technology Innovation Project for Overseas Students in Nanjing.
文摘The exploration of high-performance solution-processible host materials for blue and white electrophosphorescent devices is a key and fundamental challenge in the ongoing development of organic semiconductors.Herein,two solution-processible resonance host materials with self-adaptive characteristics are delicately designed and constructed.Because of the dynamic tautomerization upon resonance variation,these smart hosts show self-adaptive and selectively enhanced charge carrier flux at high triplet energy levels.Conferred by the resonance molecules,solution-processed blue and white devices exhibit excellent maximum current efficiencies(CEs)of 29.8 and 57.3 cd A−1,and external quantum efficiencies(EQEs)up to 14.5%and 23.5%,respectively.Our works highlight the significant progress of the solution-processed phosphorescent organic light-emitting diodes(PhOLEDs)using resonance host molecules,potentially furnishing a leap forward in constructing advanced organic semiconductors for next-generation optoelectronic devices.
基金supported by the National Natural Science Foundation of China(21772095,91833306,61875090,and 21674049)the 1311 Talents Program of Nanjing University of Posts and Telecommunications(Dingshan),the Six Talent Plan(2016XCL050)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(46030CX17761).
文摘Organic semiconductors with bipolar transporting character are highly attractive as they offer the possibility to achieve high optoelectronic performance in simple device structures.However,the continual efforts in preparing bipolar materials are focusing on donor-acceptor(D-A)architectures by introducing both electron-donating and electron-withdrawing units into one molecule in static molecular design principles.Here,we report a dynamic approach to construct bipolar materials using only electron-donating carbazoles connected by N-P=X resonance linkages in a donor-resonance-donor(D-r-D)structure.By facilitating the stimuli-responsive resonance variation,these D-r-D molecules exhibit extraordinary bipolar properties by positively charging one donor of carbazole in enantiotropic N^(+)=P-X-canonical forms for electron transport without the involvement of any acceptors.With thus realized efficient and balanced charge transport,blue and deep-blue phosphorescent organic light emitting diodes hosted by these D-r-D molecules show high external quantum efficiencies up to 16.2%and 18.3%in vacuum-deposited and spin-coated devices,respectively.These results via the D-r-D molecular design strategy represent an important concept advance in constructing bipolar organic optoelectronic semiconductors dynamically for high-performance device applications.
基金supported by the Fundamental Research Funds for the Central Universities(No.2042021kf0212)the National Natural Science Foundation of China(Nos.22074110 and 21721005)。
文摘Ribosomal RNAs(rRNAs) provide the structural framework of ribosomes and play critical roles in protein translation.In ribosome biogenesis,rRNAs acquire various modifications that can influence the structure and catalytic activity of ribosomes.However,rRNA modifications in plants have yet to be fully defined.Herein,we proposed a method to purify rRNAs by a successive isolation with different strategies,including poly A-based m RNA depletion and agarose gel electrophoresis-based purification,with which highly pure rRNAs could be obtained.In addition,we developed a liquid chromatography-electrospray ionization-tandem mass spectrometry(LC-ESI-MS/MS) method to systematically profile and characterize modifications from the isolated highly pure plant 18S rRNA and 25S rRNA.LC-ESI-MS/MS analysis showed that 10 and 12 kinds of modifications were present in plant 18S rRNA and 25S rRNA,respectively.Notably,among these identified modifications,2 kinds of modifications of N^(2),N^(2)-dimethylguanosine(m^(2,2)G)and N^(6),N^(6)-dimethyladenosine(m^(6,6)A) in 18S rRNA,and 4 kinds of modifications of m^(2,2)G,m^(6,6)A,N7-methylguanosine(m^(7)G) and 3-methyluridin(m^(3)U) in 25S rRNA,were first reported to be present in plants.Moreover,exposure of Arabidopsis thaliana to cadmium(Cd) led to significant changes of modifications in both 18S rRNA and 25S rRNA of plants,indicating that rRNA modifications play important roles in response to environmental stress.The discovery of new modifications in plant rRNAs improves the spectra of plant rRNA modifications and may promote the investigation of the functional roles of plant ribosomes in regulating gene expression.
基金supported by the National Natural Science Foundation of China(Nos.22074110,21635006,21721005)。
文摘6-Thioguanine(6TG)is a widely used chemotherapeutic agent for the treatment of a variety of human diseases including acute lymphoblastic leukemia.After entry into cells,6TG is metabolically converted into 6-thioguanosine(^(S)G)nucleotide that can be incorporated into the genome during DNA replication.^(S)G in genomic DNA could induce cell death by triggering the post-replicative mismatch repair(MMR)pathway.Meanwhile,incorporation of 6TG into the Cp G sites could perturb the global DNA methylation and gene regulation.However,the effect of 6TG on RNA modifications is still unknown.Adenosine-toinosine(A-to-I)editing in RNA is one of the most common post-transcriptional modifications in mammals and there is growing evidence showing the significant alteration of A-to-I RNA editing in tumor tissues compared to normal tissues.In the current study,we examined the incorporation of 6TG into RNA and investigated its effect on A-to-I editing of bladder cancer-associated protein(BLCAP)transcript in acute lymphoblastic leukemia cells.The results demonstrated that ^(S)G could be incorporated into various RNA species,with m RNA having the most abundant ^(S)G.In addition,the results showed 6TG treatment elevated A-to-I editing in BLCAP transcript through upregulating adenosine deaminase 2 acting on RNA(ADAR2),which eventually contributes to the decreased cell viability.This study highlights a new mechanism of the cytotoxicity of 6TG in inducing cell death.
