The title compound ethyl 2-(6-(1,3-dioxo-4,5,6,7-tetrahydro-lH-isoindol-2(3H)- yl)-7-fluoro-3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl) butanoate 3 was synthesized by the reaction of ethyl 2-(6-amino-7-fluoro-3-ox...The title compound ethyl 2-(6-(1,3-dioxo-4,5,6,7-tetrahydro-lH-isoindol-2(3H)- yl)-7-fluoro-3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl) butanoate 3 was synthesized by the reaction of ethyl 2-(6-amino-7-fluoro-3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl) butanoate with 4,5,6,7- tetraydrophthalic anhydride, and its structure was determined by X-ray single-crystal diffraction. The crystal belongs to the monoclinic system, space group P2 1/n with a = 9.3469(2), b = 16.7715(5), c = 13.7153(4) A, β= 104.9680(10)°, μ = 0.107 mm^-1, Mr = 430.42, V= 2077.08(10) ,A3, Z= 4, Dc = 1.376 g/cm3, F(000) = 904, T= 296(2) K, R = 0.0508 and wR = 0.1478.展开更多
Graphitic carbon nitride(g-C_(3)N_(4)) is a fascinating photocatalyst for solar energy utilization in photo-catalysis.Nevertheless,it often suffers from moderate photo-catalytic activity due to its low specific surfac...Graphitic carbon nitride(g-C_(3)N_(4)) is a fascinating photocatalyst for solar energy utilization in photo-catalysis.Nevertheless,it often suffers from moderate photo-catalytic activity due to its low specific surface area and fast recombination rate of photogenerated electrons upon photo-excitation.Herein,we overcome the bottlenecks by constructing a porous g-C_(3)N_(4) nanosheet(PCNS)through a simple thermal oxidation etching method.Benefited from its porous layer structure,the obtained PCNS exhibits large specific surface area,efficient separation of photogenerated charge carriers,as well as high exposure of active sites.As a result,it is robust and universal in visible light-driven dehydrogenation of alcohols in water under oxidant-free condition.Almost quantitative yields(>99%)of various valuable carbonyl compounds were obtained over PCNS,while bulk g-C_(3)N_(4) was far less efficient.Moreover,the photo-catalyst was highly stable and could be facilely recovered from the aqueous system for efficient reuse.The easy preparation and excellent performance made PCNS a promising and competitive photocatalyst for the solar applications.展开更多
A mild and simple process for the effective oxidation of 5-hydroxymethylfurfural(HMF) into 2,5-diformylfuran(DFF) has been developed using Na NO2 as the oxidant. Some important reaction parameters were investigate...A mild and simple process for the effective oxidation of 5-hydroxymethylfurfural(HMF) into 2,5-diformylfuran(DFF) has been developed using Na NO2 as the oxidant. Some important reaction parameters were investigated to optimize the oxidation of HMF into DFF. It was found that the reaction solvent was very crucial for this reaction. Trifluoroacetic acid was the best solvent for the oxidation of HMF into DFF by Na NO2.Under the optimal reaction condition, almost quantitative HMF conversion and high DFF yield of 90.4% were obtained after 1 h at room temperature.展开更多
Silicon-based(Si)materials are promising anodes for lithium-ion batteries(LIBs)because of their ultrahigh theoretical capacity of 4200 mA h g^(−1).However,commercial applications of Si anodes have been hindered by the...Silicon-based(Si)materials are promising anodes for lithium-ion batteries(LIBs)because of their ultrahigh theoretical capacity of 4200 mA h g^(−1).However,commercial applications of Si anodes have been hindered by their drastic volume variation(∼300%)and low electrical conductivity.Here,to tackle the drawbacks,a hierarchical Si anode with double-layer coatings of a SiOx inner layer and a nitrogen(N),boron(B)co-doped carbon(C-NB)outer layer is elaborately designed by copyrolysis of Si-OH structures and a H3BO_(3)-doped polyaniline polymer on the Si surface.Compared with the pristine Si anodes(7mA h g^(−1) at 0.5 A g^(−1) after 340 cycles and 340 mA h g^(−1) at 5 A g^(−1)),the modified Si-based materials(Si@SiOx@C-NB nanospheres)present su perior cycling stability(reversible 1301 mA h g^(−1) at 0.5 A g^(−1) after 340 cycles)as well as excellent rate capability(690mA h g^(−1) at 5 A g^(−1))when used as anodes in LIBs.The unique double-layer coating structure,in which the inner amorphous SiOx layer acts as a buffer matrix and the outer defect-rich carbon enhances the electron diffusion of the whole anode,makes it possible to de liver excellent electrochemical properties.These results indicate that our double-layer coating strategy is a promising approach not only for the devel opment of sustainable Si anodes but also for the design of multielement-doped carbon nanomaterials.展开更多
In water, N,N′-diarylpyridinium thiazolo[5,4-d]thiazole guests(G1–G3) were encapsulated by cucurbit[8]uril(Q[8]) to construct Q[8]_(3)/G_(2) complexes, in which the encapsulated G molecules exist as an exact face-to...In water, N,N′-diarylpyridinium thiazolo[5,4-d]thiazole guests(G1–G3) were encapsulated by cucurbit[8]uril(Q[8]) to construct Q[8]_(3)/G_(2) complexes, in which the encapsulated G molecules exist as an exact face-to-face dimer. These complexation behaviors have been indicated by proton nuclear magnetic resonance(~1H NMR) spectroscopy and isothermal titration calorimetry(ITC),and have been confirmed by X-ray single crystal structural analysis of Q[8]_(3)/G2_(2). While free guests G1–G3 have no ability to sensitize singlet oxygen, they all become effective singlet oxygen sensitizers when complexed with Q[8]. By irradiation of white light, Q[8]_(3)/G_(2) complexes induced selective oxidation of aryl sulfide to aryl sulfoxide in good yields and selective oxidation of dimethyl sulfide(DMS) to dimethyl sulfoxide(DMSO) in excellent yields without over-oxidation to dimethyl sulfone(DMSO_(2))even for elongated irradiation. High-yield photo-oxidation of DMS to DMSO_(2) was only achieved by irradiation of blue light in the presence of Q[8]_(3)/G1_(2), which was also effective in photobleaching of Rhodamine B in water. The higher photo-oxidation power of Q[8]_(3)/G1_(2) has been ascribed to an additional generation of reactive oxygen species besides singlet oxygen.展开更多
Targeted protein degradation(TPD)is an emerging tool for degrading proteins of interest,which affords an attractive modality for cancer therapy.However,the present TPD technologies must engage a proteolysis-specific a...Targeted protein degradation(TPD)is an emerging tool for degrading proteins of interest,which affords an attractive modality for cancer therapy.However,the present TPD technologies must engage a proteolysis-specific actuator to initiate degradation of targeted proteins in the proteasome or lysosome.Herein,we report an artificial tractor that can induce endocytosis-mediated protein depletion without hijacking a proteolysis-specific actuator.In this design,bispecific aptamer chimeras(BSACs)are established,which can bridge human epidermal growth factor receptor 2(ErbB-2),an important biomarker in a common important biomarker in cancer,with membrane proteins of interest.Taking advantage of the property of aptamer-induced endocytosis and digestion of ErbB-2,another membrane protein is translocated into the lysosome in a hitchhike-like manner,resulting in lysosomal proteolysis along with ErbB-2.This strategy frees the TPD from the fundamental limitation of proteolysis-specific actuator and allows simultaneous regulation of the quantity and function of two oncogenic receptors in a cell-type-specific manner,expanding the application scope of TPD-based therapeutics.展开更多
Surface structures and electronic properties of hypophosphite H2PO2^- on Ni(111) and Ag(111) surfaces were investigated by means of density functional theory at B3LYP/6-31 + +G(d,p) level. The most stable stru...Surface structures and electronic properties of hypophosphite H2PO2^- on Ni(111) and Ag(111) surfaces were investigated by means of density functional theory at B3LYP/6-31 + +G(d,p) level. The most stable structure was that in which the H2PO2^- adsorbs with its two P--O bonds faced to the substrate surface. The results of the Mulliken population analysis showed that because of the subtle difference of electron configuration, the adsorption energy was larger on the Ni surface than on the Ag surface, and the amounts of both donation and back donation were larger on the Ni(111) surface than on the Ag(111) surface. There were more negative Mulliken charge transfer from H2PO2^- to substrate clusters on Ni surface than on Ag surface and more positive Mulliken charges on P atom in Ni4H2PO2^- than in Ag4H2PO2^-, which means that P atom in Ni4H2PO2^- is easily attacked by a nucleophile such as OH . Thus, H2PO2^- is more easily oxidated on Ni(111) surface than on Ag(111) suface. These results indicated that the silver surface is inactive for the oxidation reaction of the hypophosphite anion.展开更多
Bioorthogonal cleavage reaction-triggered prodrug activation by the pretargeted methods can achieve accurate cancer therapy.However,the click and release efficiency of these methods in vivo is limited by the space-tim...Bioorthogonal cleavage reaction-triggered prodrug activation by the pretargeted methods can achieve accurate cancer therapy.However,the click and release efficiency of these methods in vivo is limited by the space-time dislocation of bioorthogonal prodrug-trigger pairs within the tumor area,caused by their asynchronous administration and inconsistent accumulation for most delivery systems.We herein created a nanovoid-confinement and click-activated(NCCA)core–shell nanoreactor by incorporating prodrugs within zeolitic imidazolate framework-90(ZIF-90)as core and coating tetrazine-based covalent organic framework(COF)as shell.After surface modification of aptamer polymer,the NCCA nanoreactor enabled the sufficient delivery of photodynamic prodrugs within tumor.Notably,the core of ZIF-90 was decomposed by tumor acidic environment,inducing the high-efficiency activation of photodynamic prodrugs via nanoconfined bioorthogonal reaction with tetrazine-based COF shell.As a result,such photodynamic agents are efficiently and safely accumulated into tumor and specifically activated for precise photodynamic therapy of cancer cells and tumor bearing mice with minimizing toxic side effect.Taken together,such NCCA nanoreactor clearly demonstrates the critical feasibility to realize the synchronous delivery of both prodrugs and triggers for precise treatment,which most of delivery systems are not able to afford.展开更多
Thirteen novel N-(2-fluoro-5-(3-methyl-2,6-dioxo-4-(trifluoromethy)-2,3-dihydropyrimidin-1(6H)-yl)phenyl)- 2-phenoxy)acetamides were designed and synthesized utilizing 4-fluoro-aniline and ethyl 3-amino-4,4,4...Thirteen novel N-(2-fluoro-5-(3-methyl-2,6-dioxo-4-(trifluoromethy)-2,3-dihydropyrimidin-1(6H)-yl)phenyl)- 2-phenoxy)acetamides were designed and synthesized utilizing 4-fluoro-aniline and ethyl 3-amino-4,4,4-trifluoro-but-2-enoate as starting materials. The chemical structures of all compounds were confirmed by IH NMR, IR, mass spectrum and elemental analyses. Subsequently, the herbicidal activities of the as-prepared compounds were evalu-ated in the greenhouse. Bioassay results indicated that most of compounds had better herbicidal activities against dicotyledonous weeds. Among all the tested compounds, compounds 4a--4i showed good herbicidal activities at both pre-emergence and post-emergence treatment against two or three kinds of dicotyledonous weeds, such as Abutilon theophrasti Medic, Amaranthus ascendens L, and Chenopodium album L at the dosage of 75 g ai/ha.展开更多
A two-channel electrochemical quartz crystal microbalance (EQCM) was used to investigate the cyclic voltammetric behavior of two Prussian blue (PB) film-modified Au electrodes in a two-electrode con-figuration in aque...A two-channel electrochemical quartz crystal microbalance (EQCM) was used to investigate the cyclic voltammetric behavior of two Prussian blue (PB) film-modified Au electrodes in a two-electrode con-figuration in aqueous solution. The redox peaks observed in the two-electrode cyclic voltammogram (CV) are assigned to the intrinsic redox transitions among the Everitt's salt, PB, and Prussian yellow for the film itself, the redox process of the Au substrate and the redox process of small-quantity ferri-/ferrocyanide impurities entrapped in the PB film, as also supported by ultraviolet-visible (UV-Vis) spectroelectrochemical data. The profile of the two-electrode solid-state CV for the PB powder sand-wiched between two gold-coated indium-tin oxide (ITO) electrodes is similar to that for two PB-modified Au electrodes in aqueous solution, implying similar origins for the corresponding redox peaks. The two-channel EQCM method is expected to become a highly effective technique for the studies of the two-electrode electrochemical behaviors of many other species/materials.展开更多
The combination of reflectance UV-Vis spec- troelectrochemistry with electrochemical quartz crystal microbalance (EQCM) and separate reflectance FTIR char- acterization were used to investigate the structural intercon...The combination of reflectance UV-Vis spec- troelectrochemistry with electrochemical quartz crystal microbalance (EQCM) and separate reflectance FTIR char- acterization were used to investigate the structural intercon- version for poly(o-phenylenediamine) (PoPD) between its ladder structure with phenazine units and polyaniline-like linear chains. The poly(o-phenylenediamine) films potentio- statically (0.8 V vs. SCE) grew on Au electrodes from 0.20 mol·L?1 H2SO4 (PoPD1) or 0.40 mol·L?1 NaOH (PoPD2) aque- ous solution containing 0.20 mol·L?1 Na2SO4 + 0.10 mol·L?1 o-phenylenediamine. By considering the mass of deposited PoPD2 film obtained from the EQCM data and the charge consumed under the current peak at ca. 0.6 V vs. SCE for oxidation of -NH2 groups in as-prepared PoPD2 during po- tential cycling in 0.10 mol·L-1 aqueous H2SO4, the molar per- centage of the polyaniline-like chains was estimated to be 19% (relative to total phenylenediamine units), being in agreement with the result obtained from a formaldehyde- combination experiment through the aminocarbonyl reaction. After 40-cycle potential sweeps between 0.2 and 0.8 V vs. SCE the polyaniline-like chains in PoPD2 could be com- pletely converted via intramolecular cyclization into the lad- der structure with phenazine units. However, PoPD1 was found to be perfectly composed of the ladder structure with phenazine units, and after 40-cycle potential sweeps between ?0.4 and 0.1 V vs. SCE only 2.5% in molar percentage of PoPD’s ladder structure could be converted into polyani line-like chains, suggesting that the ladder structure with phenazine units is thermodynamically more stable due to its possessing higher conjugation.展开更多
Homocysteine(Hcy), cysteine(Cys) and glutathione(GSH) play crucial roles in redox homeostasis during mitochondria functions. Simultaneous differentiation and visualization of mitochondrial biothiols dynamics are signi...Homocysteine(Hcy), cysteine(Cys) and glutathione(GSH) play crucial roles in redox homeostasis during mitochondria functions. Simultaneous differentiation and visualization of mitochondrial biothiols dynamics are significant for understanding cell metabolism and their related diseases. Herein, a multisitebinding fluorescent probe(MCP) was developed for simultaneous sensing of mitochondrial Cys, GSH and Hcy from three fluorescence channels for the first time. This novel probe exhibited rapid fluorescence turn-on, good water-solubility, high selectivity and large spectral separation for discriminating Cys, GSH and Hcy with 131-, 96-, 748-fold fluorescence increasement at 471, 520, 567 nm through different excitation wavelengths, respectively. Importantly, this probe was successfully applied to simultaneous monitoring of mitochondrial Cys, GSH, and Hcy in live cells and zebrafish from three fluorescence channels,promoting the understanding of the functions of Hcy, Cys and GSH.展开更多
Underpotential deposition(UPD) of Cu on an Au electrode followed by redox replacement reaction(RRR) of CuUPD with a Pt source(H2PtCl6 or K2PtCl4) yielded Au-supported Pt adlayers(for short,Pt(CuUPD-Pt4+)n/Au for H2PtC...Underpotential deposition(UPD) of Cu on an Au electrode followed by redox replacement reaction(RRR) of CuUPD with a Pt source(H2PtCl6 or K2PtCl4) yielded Au-supported Pt adlayers(for short,Pt(CuUPD-Pt4+)n/Au for H2PtCl6,or Pt(CuUPD-Pt2+)n/Au for K2PtCl4,where n denotes the number of UPD-redox replacement cycles).The electrochemical quartz crystal microbalance(EQCM) technique was used for the first time to quantitatively study the fabricated electrodes and estimate their mass-normalized specific electrocatalytic activity(SECA) for methanol oxidation in alkaline solution.In comparison with Pt(CuUPD-Pt2+)n/Au,Pt(CuUPD-Pt4+)n/Au exhibited a higher electrocatalytic activity,and the maximum SECA was obtained to be as high as 35.7 mA ?g?1 at Pt(CuUPD-Pt4+)3/Au.The layer-by-layer architecture of Pt atoms on Au is briefly discussed based on the EQCM-revealed redox replacement efficiency,and the calculated distribution percentages of bare Au sites agree with the experimental results deduced from the charge under the AuOx-reduction peaks.The EQCM is highly recommended as an efficient technique to quantitatively examine various electrode-supported catalyst adlayers,and the highly efficient catalyst adlayers of noble metals are promising in electrocatalysis relevant to biological,energy and environmental sciences and technologies.展开更多
A simultaneous C2-H arylation and C8-H alkylation of naphthalene ring has been achieved by palladiumcatalyzed cascade reaction of N-(2-halophenyl)-2-(naphthalen-1-yl)acrylamides with aryl iodides,which provides an eff...A simultaneous C2-H arylation and C8-H alkylation of naphthalene ring has been achieved by palladiumcatalyzed cascade reaction of N-(2-halophenyl)-2-(naphthalen-1-yl)acrylamides with aryl iodides,which provides an efficient method for synthesizing various aryl-substituted spirocyclic oxindoles.The protocol enables three C-C bonds formation via an intramolecular Heck reaction and sequentially regioselective C-H bond activation.展开更多
In this work, an efficient copper-catalyzed three-component reaction for the synthesis of sulfenylimidazo [1,2-a]pyridines using elemental sulfur as the sulfenylating agents has been developed. The reaction could proc...In this work, an efficient copper-catalyzed three-component reaction for the synthesis of sulfenylimidazo [1,2-a]pyridines using elemental sulfur as the sulfenylating agents has been developed. The reaction could proceed smoothly with a high degree of functional group tolerance and provide the desired products in moderate to good yield.展开更多
Due to the fact that most microRNAs are small in size,low abundance in biological samples,homologous sequence among family members,and protein enzymes-based strategies display limited practical applications,therefore,...Due to the fact that most microRNAs are small in size,low abundance in biological samples,homologous sequence among family members,and protein enzymes-based strategies display limited practical applications,therefore,we reported a simple enzyme-free DNA sensor for microRNA detection utilizing a multiple signal amplification strategy.The sensing system termed as C-CHA-HCR includes six hairpin DNA reactants that are metastable on account of intramolecular hybridization.The DNA hairpin reactants are opened and hybridized with the corresponding complementary DNA strand in the presence of miR-21 via toehold-mediated CHA,HCR reaction,and circulation between CHA and HCR,resulting in a hugely amplifying signal output.Without introducing external protein enzymes,this sensing system showed highly sensitive and selective on the detection of miR-21.A linear response range of miR-21 from 25 pmol/L to 1 nmol/L with a limit of detection(LOD)of 1.8 pmol/L was obtained.This promising biosensor was successfully applied to the detection of microRNA in human serum samples with acceptable recovery rates,suggesting the potential applications in disease diagnosis,treatment,and prognosis.展开更多
Acid phosphatase(ACP)is a ubiquitous phosphatase in living organisms.The abnormal variation of ACP is related to various diseases.Herein,we propose a colorimetric method based on CeO_(2)-modified gold core shell nanop...Acid phosphatase(ACP)is a ubiquitous phosphatase in living organisms.The abnormal variation of ACP is related to various diseases.Herein,we propose a colorimetric method based on CeO_(2)-modified gold core shell nanoparticles(Au@CeO_(2)NPs)to analyze ACP activity with high sensitivity and specificity.In this design,2-phospho-L-ascorbic acid trisodium salt(AAP)is dephosphorylated by ACP and produces reductive ascorbic acid(AA),which makes the CeO_(2)shell decomposition.A remarkable blue shift of localized surface plasmon resonance peak(LSPR,from yellow to green)along with the scattering intensity ratio changes from individual Au@CeO_(2)NPs are observed.ACP activity can be quantified by calculating the ratio changes of individual Au@CeO_(2)NPs.This assay reveals limit of detection(LOD)of 0.044 mU/mL and the linear range of 0.05–5.0 mU/mL,which are much lower than most of spectroscopic measurements in bulk solution.Furthermore,the recovery measurements in real samples are satisfactory and the capacity for practical application is demonstrated.As a consequence,Au@CeO_(2)NPs used in this assay will find new applications for the ultrasensitive detection of enzyme activity.展开更多
Blinking fluorophore perovskite nanocrystals (NCs) were employed to image the fine structure of the polystyrene (PS) electrospun fibers. The conditions of CsPbBr3 NCs embedded and dispersed into PS were investigated a...Blinking fluorophore perovskite nanocrystals (NCs) were employed to image the fine structure of the polystyrene (PS) electrospun fibers. The conditions of CsPbBr3 NCs embedded and dispersed into PS were investigated and optimized. The stochastic optical reconstruction microscopy is employed to visualize the fine structure of the resulted CsPbBr3@PS electrospun fibers at sub-diffraction limit. The determined resolution in the reconstructed nanoscopic image is around 25.5 nm, which is much narrower than that of conventional fluorescence image. The complex reticulation and multicompartment in bead sub-diffraction-limited structures of CsPbBr3@PS electrospun fibers were successfully mapped with the help of the stochastic blinking properties of CsPbBr3 NCs. This work demonstrated the potential applications of CsPbBr3 perovskite NCs in super-resolution fluorescence imaging to reconstruct the sub-diffraction-limited features of polymeric material.展开更多
New lanthanide metal-organic framework(MOF) nano/microrods, [C4mim]Cl-Eu-MOF, [C8mim]Cl-Eu- MOF and [C12mim]Cl-Eu-MOF, were conveniently synthesized via an ionic liquid-assisted hydrothermal method and characterized...New lanthanide metal-organic framework(MOF) nano/microrods, [C4mim]Cl-Eu-MOF, [C8mim]Cl-Eu- MOF and [C12mim]Cl-Eu-MOF, were conveniently synthesized via an ionic liquid-assisted hydrothermal method and characterized by means of powder X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), thermo- gravimetric analysis(TG) and transmission electron microscopy(TEM). The obtained nano/microrods with low sur- face areas were efficient for the removal of Congo red(CR) from aqueous solutions. Under the optimum conditions, [C4mim]Cl-Eu-MOF with a specific surface area of 5.1 m^2/g exhibited an ultrahigh adsorption capacity of 2606 mg/g toward CR. Notably, the adsorption efficiency of [C4mim]Cl-Eu-MOF for CR via nano/microscale stacking can be directly demonstrated by TEM. In-depth understanding of CR removal by [C4mim]Cl-Eu-MOF nano/microrods was also supported by FTIR, Raman spectroscopy and zeta potential analyses.展开更多
基金Supported by the National Natural Science Foundation of China (20872033, 20575019)Natural Science Foundation of Hunan Province (07JJ1003)+1 种基金Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China) (KLCBTCMR2008-14)Scientific Research Fund of Science and Technology Department of Hunan Province (No. 2006GK3067)
文摘The title compound ethyl 2-(6-(1,3-dioxo-4,5,6,7-tetrahydro-lH-isoindol-2(3H)- yl)-7-fluoro-3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl) butanoate 3 was synthesized by the reaction of ethyl 2-(6-amino-7-fluoro-3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl) butanoate with 4,5,6,7- tetraydrophthalic anhydride, and its structure was determined by X-ray single-crystal diffraction. The crystal belongs to the monoclinic system, space group P2 1/n with a = 9.3469(2), b = 16.7715(5), c = 13.7153(4) A, β= 104.9680(10)°, μ = 0.107 mm^-1, Mr = 430.42, V= 2077.08(10) ,A3, Z= 4, Dc = 1.376 g/cm3, F(000) = 904, T= 296(2) K, R = 0.0508 and wR = 0.1478.
基金financial support provided by the National Natural Science Foundation of China(21676078)the Natural Science Foundation of Hunan Province for Distinguished Young Scholar(2016JJ1013)+1 种基金Scientific Research Fund of Hunan Provincial Education Department(19A323)Science and Technology Planning Project of Hunan Province(2018TP1017)。
文摘Graphitic carbon nitride(g-C_(3)N_(4)) is a fascinating photocatalyst for solar energy utilization in photo-catalysis.Nevertheless,it often suffers from moderate photo-catalytic activity due to its low specific surface area and fast recombination rate of photogenerated electrons upon photo-excitation.Herein,we overcome the bottlenecks by constructing a porous g-C_(3)N_(4) nanosheet(PCNS)through a simple thermal oxidation etching method.Benefited from its porous layer structure,the obtained PCNS exhibits large specific surface area,efficient separation of photogenerated charge carriers,as well as high exposure of active sites.As a result,it is robust and universal in visible light-driven dehydrogenation of alcohols in water under oxidant-free condition.Almost quantitative yields(>99%)of various valuable carbonyl compounds were obtained over PCNS,while bulk g-C_(3)N_(4) was far less efficient.Moreover,the photo-catalyst was highly stable and could be facilely recovered from the aqueous system for efficient reuse.The easy preparation and excellent performance made PCNS a promising and competitive photocatalyst for the solar applications.
基金supported by the National Natural Science Foundation of China(21272065)Scientific Research Fund of Hunan Provincial Education Department(13C562+2 种基金15C0816)Outstanding Youth Project of Hunan Provincial Education Department(15B134)the funding offered by China Scholarship Council(201506720018)
文摘A mild and simple process for the effective oxidation of 5-hydroxymethylfurfural(HMF) into 2,5-diformylfuran(DFF) has been developed using Na NO2 as the oxidant. Some important reaction parameters were investigated to optimize the oxidation of HMF into DFF. It was found that the reaction solvent was very crucial for this reaction. Trifluoroacetic acid was the best solvent for the oxidation of HMF into DFF by Na NO2.Under the optimal reaction condition, almost quantitative HMF conversion and high DFF yield of 90.4% were obtained after 1 h at room temperature.
基金supported by Joint Funds of the National Natural Science Foundation of China(U20A20280)the National Natural Science Foundation of China(21805083,52074119)+3 种基金the Academy of Sciences large apparatus United Fund of China(U1832187)the Scientific Research Fund of Hunan Provincial Education Department(19K058)the Science and Technology Planning Project of Hunan Province(2018TP1017)the High-Tech Leading Plan of Hunan Province(2020GK2072).
文摘Silicon-based(Si)materials are promising anodes for lithium-ion batteries(LIBs)because of their ultrahigh theoretical capacity of 4200 mA h g^(−1).However,commercial applications of Si anodes have been hindered by their drastic volume variation(∼300%)and low electrical conductivity.Here,to tackle the drawbacks,a hierarchical Si anode with double-layer coatings of a SiOx inner layer and a nitrogen(N),boron(B)co-doped carbon(C-NB)outer layer is elaborately designed by copyrolysis of Si-OH structures and a H3BO_(3)-doped polyaniline polymer on the Si surface.Compared with the pristine Si anodes(7mA h g^(−1) at 0.5 A g^(−1) after 340 cycles and 340 mA h g^(−1) at 5 A g^(−1)),the modified Si-based materials(Si@SiOx@C-NB nanospheres)present su perior cycling stability(reversible 1301 mA h g^(−1) at 0.5 A g^(−1) after 340 cycles)as well as excellent rate capability(690mA h g^(−1) at 5 A g^(−1))when used as anodes in LIBs.The unique double-layer coating structure,in which the inner amorphous SiOx layer acts as a buffer matrix and the outer defect-rich carbon enhances the electron diffusion of the whole anode,makes it possible to de liver excellent electrochemical properties.These results indicate that our double-layer coating strategy is a promising approach not only for the devel opment of sustainable Si anodes but also for the design of multielement-doped carbon nanomaterials.
基金supported by the National Natural Science Foundation of China (22271090, 12204167)。
文摘In water, N,N′-diarylpyridinium thiazolo[5,4-d]thiazole guests(G1–G3) were encapsulated by cucurbit[8]uril(Q[8]) to construct Q[8]_(3)/G_(2) complexes, in which the encapsulated G molecules exist as an exact face-to-face dimer. These complexation behaviors have been indicated by proton nuclear magnetic resonance(~1H NMR) spectroscopy and isothermal titration calorimetry(ITC),and have been confirmed by X-ray single crystal structural analysis of Q[8]_(3)/G2_(2). While free guests G1–G3 have no ability to sensitize singlet oxygen, they all become effective singlet oxygen sensitizers when complexed with Q[8]. By irradiation of white light, Q[8]_(3)/G_(2) complexes induced selective oxidation of aryl sulfide to aryl sulfoxide in good yields and selective oxidation of dimethyl sulfide(DMS) to dimethyl sulfoxide(DMSO) in excellent yields without over-oxidation to dimethyl sulfone(DMSO_(2))even for elongated irradiation. High-yield photo-oxidation of DMS to DMSO_(2) was only achieved by irradiation of blue light in the presence of Q[8]_(3)/G1_(2), which was also effective in photobleaching of Rhodamine B in water. The higher photo-oxidation power of Q[8]_(3)/G1_(2) has been ascribed to an additional generation of reactive oxygen species besides singlet oxygen.
基金supported in part by the National Natural Science Foundation of China(grant nos.21705010,21735001,22274046,and 91853104)Hunan Provincial Natural Science Foundation of China(grant nos.2022JJ20038 and 2020JJ4409)+1 种基金the Scientific Research Fund of Hunan Provincial Education Department(grant no.20B032)Natural Science Foundation of Changsha City(grant no.kq2202189).
文摘Targeted protein degradation(TPD)is an emerging tool for degrading proteins of interest,which affords an attractive modality for cancer therapy.However,the present TPD technologies must engage a proteolysis-specific actuator to initiate degradation of targeted proteins in the proteasome or lysosome.Herein,we report an artificial tractor that can induce endocytosis-mediated protein depletion without hijacking a proteolysis-specific actuator.In this design,bispecific aptamer chimeras(BSACs)are established,which can bridge human epidermal growth factor receptor 2(ErbB-2),an important biomarker in a common important biomarker in cancer,with membrane proteins of interest.Taking advantage of the property of aptamer-induced endocytosis and digestion of ErbB-2,another membrane protein is translocated into the lysosome in a hitchhike-like manner,resulting in lysosomal proteolysis along with ErbB-2.This strategy frees the TPD from the fundamental limitation of proteolysis-specific actuator and allows simultaneous regulation of the quantity and function of two oncogenic receptors in a cell-type-specific manner,expanding the application scope of TPD-based therapeutics.
文摘Surface structures and electronic properties of hypophosphite H2PO2^- on Ni(111) and Ag(111) surfaces were investigated by means of density functional theory at B3LYP/6-31 + +G(d,p) level. The most stable structure was that in which the H2PO2^- adsorbs with its two P--O bonds faced to the substrate surface. The results of the Mulliken population analysis showed that because of the subtle difference of electron configuration, the adsorption energy was larger on the Ni surface than on the Ag surface, and the amounts of both donation and back donation were larger on the Ni(111) surface than on the Ag(111) surface. There were more negative Mulliken charge transfer from H2PO2^- to substrate clusters on Ni surface than on Ag surface and more positive Mulliken charges on P atom in Ni4H2PO2^- than in Ag4H2PO2^-, which means that P atom in Ni4H2PO2^- is easily attacked by a nucleophile such as OH . Thus, H2PO2^- is more easily oxidated on Ni(111) surface than on Ag(111) suface. These results indicated that the silver surface is inactive for the oxidation reaction of the hypophosphite anion.
基金supported by the National Key R&D Program of China(No.2019YFA0210103)the National Natural Science Foundation of China(No.21974039)+3 种基金China Postdoctoral Science Foundation(Nos.2020TQ0092 and 2020M682537)the Science and Technology Innovation Program of Hunan Province(No.2020RC2019)the Special Funds for the Construction of Innovative Provinces in Hunan Province(No.2019RS1031)the Opening Fund of Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research(Hunan Normal University),the Ministry of Education.
文摘Bioorthogonal cleavage reaction-triggered prodrug activation by the pretargeted methods can achieve accurate cancer therapy.However,the click and release efficiency of these methods in vivo is limited by the space-time dislocation of bioorthogonal prodrug-trigger pairs within the tumor area,caused by their asynchronous administration and inconsistent accumulation for most delivery systems.We herein created a nanovoid-confinement and click-activated(NCCA)core–shell nanoreactor by incorporating prodrugs within zeolitic imidazolate framework-90(ZIF-90)as core and coating tetrazine-based covalent organic framework(COF)as shell.After surface modification of aptamer polymer,the NCCA nanoreactor enabled the sufficient delivery of photodynamic prodrugs within tumor.Notably,the core of ZIF-90 was decomposed by tumor acidic environment,inducing the high-efficiency activation of photodynamic prodrugs via nanoconfined bioorthogonal reaction with tetrazine-based COF shell.As a result,such photodynamic agents are efficiently and safely accumulated into tumor and specifically activated for precise photodynamic therapy of cancer cells and tumor bearing mice with minimizing toxic side effect.Taken together,such NCCA nanoreactor clearly demonstrates the critical feasibility to realize the synchronous delivery of both prodrugs and triggers for precise treatment,which most of delivery systems are not able to afford.
基金Project supported by the National Natural Science Foundation of China (No. 20872033), Hunan Provincial Natural Science Foundation of China (No. 07JJ1003) and Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China) (No. KLCBTCMR2008-14).
文摘Thirteen novel N-(2-fluoro-5-(3-methyl-2,6-dioxo-4-(trifluoromethy)-2,3-dihydropyrimidin-1(6H)-yl)phenyl)- 2-phenoxy)acetamides were designed and synthesized utilizing 4-fluoro-aniline and ethyl 3-amino-4,4,4-trifluoro-but-2-enoate as starting materials. The chemical structures of all compounds were confirmed by IH NMR, IR, mass spectrum and elemental analyses. Subsequently, the herbicidal activities of the as-prepared compounds were evalu-ated in the greenhouse. Bioassay results indicated that most of compounds had better herbicidal activities against dicotyledonous weeds. Among all the tested compounds, compounds 4a--4i showed good herbicidal activities at both pre-emergence and post-emergence treatment against two or three kinds of dicotyledonous weeds, such as Abutilon theophrasti Medic, Amaranthus ascendens L, and Chenopodium album L at the dosage of 75 g ai/ha.
基金the National Natural Science Foundation of China (Grant Nos. 20675029, 90713018 & 20335020)the Foundation of the Ministry of Education of China (jiaorensi[2000]26, jiaojisi[2000]65)+1 种基金Hunan Provincial Educational Department (05K009, 05A036)State Key Laboratory of Electroanalytical Chemistry
文摘A two-channel electrochemical quartz crystal microbalance (EQCM) was used to investigate the cyclic voltammetric behavior of two Prussian blue (PB) film-modified Au electrodes in a two-electrode con-figuration in aqueous solution. The redox peaks observed in the two-electrode cyclic voltammogram (CV) are assigned to the intrinsic redox transitions among the Everitt's salt, PB, and Prussian yellow for the film itself, the redox process of the Au substrate and the redox process of small-quantity ferri-/ferrocyanide impurities entrapped in the PB film, as also supported by ultraviolet-visible (UV-Vis) spectroelectrochemical data. The profile of the two-electrode solid-state CV for the PB powder sand-wiched between two gold-coated indium-tin oxide (ITO) electrodes is similar to that for two PB-modified Au electrodes in aqueous solution, implying similar origins for the corresponding redox peaks. The two-channel EQCM method is expected to become a highly effective technique for the studies of the two-electrode electrochemical behaviors of many other species/materials.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.20275010,20335020)Hunan Province(Grant No.02JJY4054)+1 种基金the Basic Research Special Program of the Ministry of Science and Technology of China(Grant No.2003CCC00700)the Foundation of the Ministry of Education(MOE)of China(Grant Nos.jiaorensi[2000]26,jiaojisi[2000]65).
文摘The combination of reflectance UV-Vis spec- troelectrochemistry with electrochemical quartz crystal microbalance (EQCM) and separate reflectance FTIR char- acterization were used to investigate the structural intercon- version for poly(o-phenylenediamine) (PoPD) between its ladder structure with phenazine units and polyaniline-like linear chains. The poly(o-phenylenediamine) films potentio- statically (0.8 V vs. SCE) grew on Au electrodes from 0.20 mol·L?1 H2SO4 (PoPD1) or 0.40 mol·L?1 NaOH (PoPD2) aque- ous solution containing 0.20 mol·L?1 Na2SO4 + 0.10 mol·L?1 o-phenylenediamine. By considering the mass of deposited PoPD2 film obtained from the EQCM data and the charge consumed under the current peak at ca. 0.6 V vs. SCE for oxidation of -NH2 groups in as-prepared PoPD2 during po- tential cycling in 0.10 mol·L-1 aqueous H2SO4, the molar per- centage of the polyaniline-like chains was estimated to be 19% (relative to total phenylenediamine units), being in agreement with the result obtained from a formaldehyde- combination experiment through the aminocarbonyl reaction. After 40-cycle potential sweeps between 0.2 and 0.8 V vs. SCE the polyaniline-like chains in PoPD2 could be com- pletely converted via intramolecular cyclization into the lad- der structure with phenazine units. However, PoPD1 was found to be perfectly composed of the ladder structure with phenazine units, and after 40-cycle potential sweeps between ?0.4 and 0.1 V vs. SCE only 2.5% in molar percentage of PoPD’s ladder structure could be converted into polyani line-like chains, suggesting that the ladder structure with phenazine units is thermodynamically more stable due to its possessing higher conjugation.
基金supported by the National Natural Science Foundation of China (Nos. 21877035 and 21977028)Research Foundation of Education Bureau of Hunan Province (No. 18B004)。
文摘Homocysteine(Hcy), cysteine(Cys) and glutathione(GSH) play crucial roles in redox homeostasis during mitochondria functions. Simultaneous differentiation and visualization of mitochondrial biothiols dynamics are significant for understanding cell metabolism and their related diseases. Herein, a multisitebinding fluorescent probe(MCP) was developed for simultaneous sensing of mitochondrial Cys, GSH and Hcy from three fluorescence channels for the first time. This novel probe exhibited rapid fluorescence turn-on, good water-solubility, high selectivity and large spectral separation for discriminating Cys, GSH and Hcy with 131-, 96-, 748-fold fluorescence increasement at 471, 520, 567 nm through different excitation wavelengths, respectively. Importantly, this probe was successfully applied to simultaneous monitoring of mitochondrial Cys, GSH, and Hcy in live cells and zebrafish from three fluorescence channels,promoting the understanding of the functions of Hcy, Cys and GSH.
基金supported by NSFC(No.20602010)Scientific Research Fund of Hunan Provincial Education Department(No.10B061) and Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province
基金supported by the National Natural Science Foundation of China (20675029 & 90713018)the State Special Scientific Project on Water Treatment (2009ZX07212-001-06)
文摘Underpotential deposition(UPD) of Cu on an Au electrode followed by redox replacement reaction(RRR) of CuUPD with a Pt source(H2PtCl6 or K2PtCl4) yielded Au-supported Pt adlayers(for short,Pt(CuUPD-Pt4+)n/Au for H2PtCl6,or Pt(CuUPD-Pt2+)n/Au for K2PtCl4,where n denotes the number of UPD-redox replacement cycles).The electrochemical quartz crystal microbalance(EQCM) technique was used for the first time to quantitatively study the fabricated electrodes and estimate their mass-normalized specific electrocatalytic activity(SECA) for methanol oxidation in alkaline solution.In comparison with Pt(CuUPD-Pt2+)n/Au,Pt(CuUPD-Pt4+)n/Au exhibited a higher electrocatalytic activity,and the maximum SECA was obtained to be as high as 35.7 mA ?g?1 at Pt(CuUPD-Pt4+)3/Au.The layer-by-layer architecture of Pt atoms on Au is briefly discussed based on the EQCM-revealed redox replacement efficiency,and the calculated distribution percentages of bare Au sites agree with the experimental results deduced from the charge under the AuOx-reduction peaks.The EQCM is highly recommended as an efficient technique to quantitatively examine various electrode-supported catalyst adlayers,and the highly efficient catalyst adlayers of noble metals are promising in electrocatalysis relevant to biological,energy and environmental sciences and technologies.
基金the National Natural Science Foundation of China (Nos.21572051,21602057,21901071,and 21971061)Natural Science Foundation of Hunan Province (Nos.2020JJ5350 and 2020JJ5347)+1 种基金Scientific Research Fund of Hunan ProvincialEducation Department (Nos.18A002,19B359 and 17C1137)Science and Technology Planning Project of Hunan Province (No. 2018TP1017) for financial support。
文摘A simultaneous C2-H arylation and C8-H alkylation of naphthalene ring has been achieved by palladiumcatalyzed cascade reaction of N-(2-halophenyl)-2-(naphthalen-1-yl)acrylamides with aryl iodides,which provides an efficient method for synthesizing various aryl-substituted spirocyclic oxindoles.The protocol enables three C-C bonds formation via an intramolecular Heck reaction and sequentially regioselective C-H bond activation.
基金supported by the National Natural Science Foundation of China(Nos.21072054,21572051,21602057)the Ministry of Education of China(No.213027A)the Scientific Research Fund of Hunan Provincial Education Department(No.15A109)
文摘In this work, an efficient copper-catalyzed three-component reaction for the synthesis of sulfenylimidazo [1,2-a]pyridines using elemental sulfur as the sulfenylating agents has been developed. The reaction could proceed smoothly with a high degree of functional group tolerance and provide the desired products in moderate to good yield.
基金supported by the National Natural Science Foundation of China(21874042,21974042).
文摘Due to the fact that most microRNAs are small in size,low abundance in biological samples,homologous sequence among family members,and protein enzymes-based strategies display limited practical applications,therefore,we reported a simple enzyme-free DNA sensor for microRNA detection utilizing a multiple signal amplification strategy.The sensing system termed as C-CHA-HCR includes six hairpin DNA reactants that are metastable on account of intramolecular hybridization.The DNA hairpin reactants are opened and hybridized with the corresponding complementary DNA strand in the presence of miR-21 via toehold-mediated CHA,HCR reaction,and circulation between CHA and HCR,resulting in a hugely amplifying signal output.Without introducing external protein enzymes,this sensing system showed highly sensitive and selective on the detection of miR-21.A linear response range of miR-21 from 25 pmol/L to 1 nmol/L with a limit of detection(LOD)of 1.8 pmol/L was obtained.This promising biosensor was successfully applied to the detection of microRNA in human serum samples with acceptable recovery rates,suggesting the potential applications in disease diagnosis,treatment,and prognosis.
基金supported by the Natural Science Foundation of Hunan Province,China(No.2022JJ40266)the Open Research Fund of School of Chemistry and Chemical Engineering,Henan Normal University,China(No.2022A04).
文摘Acid phosphatase(ACP)is a ubiquitous phosphatase in living organisms.The abnormal variation of ACP is related to various diseases.Herein,we propose a colorimetric method based on CeO_(2)-modified gold core shell nanoparticles(Au@CeO_(2)NPs)to analyze ACP activity with high sensitivity and specificity.In this design,2-phospho-L-ascorbic acid trisodium salt(AAP)is dephosphorylated by ACP and produces reductive ascorbic acid(AA),which makes the CeO_(2)shell decomposition.A remarkable blue shift of localized surface plasmon resonance peak(LSPR,from yellow to green)along with the scattering intensity ratio changes from individual Au@CeO_(2)NPs are observed.ACP activity can be quantified by calculating the ratio changes of individual Au@CeO_(2)NPs.This assay reveals limit of detection(LOD)of 0.044 mU/mL and the linear range of 0.05–5.0 mU/mL,which are much lower than most of spectroscopic measurements in bulk solution.Furthermore,the recovery measurements in real samples are satisfactory and the capacity for practical application is demonstrated.As a consequence,Au@CeO_(2)NPs used in this assay will find new applications for the ultrasensitive detection of enzyme activity.
基金This work was supported by the National Natural Science Foundation of China(No.21974073).
文摘Blinking fluorophore perovskite nanocrystals (NCs) were employed to image the fine structure of the polystyrene (PS) electrospun fibers. The conditions of CsPbBr3 NCs embedded and dispersed into PS were investigated and optimized. The stochastic optical reconstruction microscopy is employed to visualize the fine structure of the resulted CsPbBr3@PS electrospun fibers at sub-diffraction limit. The determined resolution in the reconstructed nanoscopic image is around 25.5 nm, which is much narrower than that of conventional fluorescence image. The complex reticulation and multicompartment in bead sub-diffraction-limited structures of CsPbBr3@PS electrospun fibers were successfully mapped with the help of the stochastic blinking properties of CsPbBr3 NCs. This work demonstrated the potential applications of CsPbBr3 perovskite NCs in super-resolution fluorescence imaging to reconstruct the sub-diffraction-limited features of polymeric material.
基金Supported by the National Natural Science Foundation of China(No.21475042), the Scientific Research Fund of Hunan Pro- vincial Education Department, China(No.12B077), the Open Fund Project of State Key Laboratory of Chemo/Biosensing and Chemometrics in Hunan University, China(No.201103) and the Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province, China.
文摘New lanthanide metal-organic framework(MOF) nano/microrods, [C4mim]Cl-Eu-MOF, [C8mim]Cl-Eu- MOF and [C12mim]Cl-Eu-MOF, were conveniently synthesized via an ionic liquid-assisted hydrothermal method and characterized by means of powder X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), thermo- gravimetric analysis(TG) and transmission electron microscopy(TEM). The obtained nano/microrods with low sur- face areas were efficient for the removal of Congo red(CR) from aqueous solutions. Under the optimum conditions, [C4mim]Cl-Eu-MOF with a specific surface area of 5.1 m^2/g exhibited an ultrahigh adsorption capacity of 2606 mg/g toward CR. Notably, the adsorption efficiency of [C4mim]Cl-Eu-MOF for CR via nano/microscale stacking can be directly demonstrated by TEM. In-depth understanding of CR removal by [C4mim]Cl-Eu-MOF nano/microrods was also supported by FTIR, Raman spectroscopy and zeta potential analyses.