查看更多>>摘要：The development of n-type semiconductor is still far behind that of p-type semiconductor on account of the challenges in enhancing carrier mobility and environmental stability.Herein,by blending with the polymers,n-type ultrathin crystalline thin film was successfully prepared by the method of meniscus-guided coating.Remarkably,the n-type crystalline films exhibit ultrathin thickness as low as 5nm and excellent mobility of 1.58 cm2 V-1 s-1,which is outstanding in currently reported organic n-type tran-sistors.Moreover,the PS layer provides a high-quality interface with ultralow defect which has strong resistance to external interference with excellent long-term stability,paving the way for the application of n-type transistors in logic circuits.
查看更多>>摘要：The recent advances in accelerated polymerization of N-carboxyanhydrides(NCAs)offer an effective strat-egy to simplify the preparation of polypeptide materials.However,the fine-tuning of polymerization ki-netics,which is critical to differentiate the main polymerization and the side reactions,remains largely unexplored.Herein we report the modulation of polymerization rate of NCA in a water/oil biphasic sys-tem.By altering the aqueous pH,the initial location of the initiators,and the pKa of initiating amines,we observed the change in polymerization time from several minutes to a few hours.Due to the high in-terfacial activity and low pKa value,controlled polymerization was observed from multi-amine initiators even if they were initially located in the aqueous phase.This work not only improves our understand-ing on the biphasic polymerization mechanism,but also facilitates preparation of versatile polypeptide materials.
查看更多>>摘要：The chemoselective hydrogenation of structurally diverse nitroaromatics is a challenging process.Gen-erally,catalyst activity tends to decrease when excellent selectivity is guaranteed.We here present a novel photocatalyst combining amino-functionalized carbon dots(N-CDs)with copper selenite nanoparti-cles(N-CDs@CuSeO3)for simultaneously improving selectivity and activity.Under visible light irradiation,the prepared N-CDs@CuSeO3 exhibits 100％catalytic selectivity for the formation of 4-aminostyrene at full conversion of 4-nitrostyrene in aqueous solvent within a few minutes.Such excellent photocatalytic performance is mainly attributed to the precise control of the hydrogen species released from the am-monia borane by means of light-converted electrons upon N-CDs@CuSeO3.Besides,the defect states at the interface of N-CDs and CuSeO3 enable holes to be trapped for promoting separation and transfer of photogenerated charges,allowing more hydrogen species to participate in catalytic reaction.
查看更多>>摘要：Carbon dots(CDs)have been attracted much attention and widely studied due to their excellent fluo-rescence(FL)properties,better biocompatibility and outstanding photo/chemical stability.However,the disadvantage of lower quantum yield(QY)still limits its wide application.Herein,we reported a novel and convenient strategy to prepare photo-induced Ag/CDs(p-Ag/CDs)by irradiating the mixed Ag+and hydrophobic CDs(h-CDs)acetone solution with ultraviolet(UV)light.The obtained p-Ag/CDs exhibit a greatly enhanced FL emission together with a blue shift(460 nm)than h-CDs(520 nm).The QY of p-Ag/CDs is measured to be 51.1％,which is 10.4 times higher than that of h-CDs(4.9％),indicating that photo-induced Ag modulation can effectively improve the optical properties of CDs.The mechanisms for the FL enhancement and blue shift of h-CDs are studied in detail.The results prove that the greatly en-hanced FL emission is from the generated Ag nanoparticles(AgNPs)by UV light irradiation based on metal-enhanced fluorescence(MEF),and the increased oxygen-contained groups in this process lead to the blue shift in CDs fluorescence.Interestingly,the p-Ag/CDs exhibit higher sensitivity and selectivity for sulfide ions(S2-)detection than that of h-CDs,which have a lower response to S2-.This work not only offers a novel strategy to improve the FL properties of materials but also endows them with new functions and broadens their application fields.
查看更多>>摘要：Carbon dots(CDs)with superior fluorescence properties have attracted a growing number of research interests in anti-counterfeiting.However,the preparation of CDs with thermally turn-on fluorescence and full-color-emitting in visible spectrum is still a big challenge due to the complicated reaction mechanism in the formation of CDs.Here,a simple precursor-oriented strategy for the preparation of multicolor CDs with heat-stimuli turn-on fluorescence is reported.Comprehensive experimental characterizations and theoretical calculations revealed that the emission wavelength of CDs can be readily tuned from 460 nm to 654nm with selected precursors,which was ascribed to the extent of conjugated sp2-domains(core states)and the amount of oxygen-and nitrogen-containing groups bound to sp2-domains(surface states).After simply mixing two or three kinds of CDs,a full-color range of fluorescence emission was realized,and the CDs-based fluorescence inks were successfully fabricated.Particularly,all the printed patterns from the inkjet exhibited a thermal-induced enhancement in fluorescence.On this basis,combining CDs with heating-induced"turn-off"fluorescence materials can lead to multidimensional and multistage en-cryption.These results demonstrate that the thermochromic and photochromic CDs with much more en-hanced security exhibit promising application in data storage and encryption.
查看更多>>摘要：A dimesitylboryl-ended oligothiophene with tetrazine as core(BTz)was synthesized and its reactivity and spectral changes toward trans-cyclooctene((4E)-TCO-OH),cis-cyclooctene and bicyclo[6.1.0]non-4-yn-9-ylmethanol were comprehensively studied.The fluorescence intensity of BTz was enhanced up to more than 100 times upon bioorthogonal reaction with(4E)-TCO-OH.In addition,the first crystal structure of isolated product of tetrazine derivative with cyclooctene was determined,which clearly confirmed a dehydrogenation occurred after Diels-Alder reaction under ambient conditions.
查看更多>>摘要：Mitochondrial damage is closely related to the occurrence of many diseases.However,accurate moni-toring and reporting of mitochondrial damage are not easy.Here,we developed a small molecule fluo-rescent probe named CB-C1,which has splendid spectral properties(large Stokes shift,strong affinity for RNA,etc.)and excellent targeting ability to intracellular mitochondria.After mitochondria were damaged by external stimuli,CB-C1 would light up the nucleolus as a signal reporter.The cascade imaging of mi-tochondria and nucleolus using CB-C1 can monitor and visualize the mitochondrial status in living cells in real-time.Based on the above advantages,the probe CB-C1 has reference significance for the related research of mitochondrial damage and the prevention and treatment of related diseases.
查看更多>>摘要：While nickel(Ⅱ)complexes have been widely used as catalysts for carbon-carbon coupling reactions,the exploration of their photophysical and photochemical properties is still in the infancy.Here,a series of square-planar Ni(Ⅱ)complexes[(diNHC)NiX2]bearing chelating benzimidazole-based bis(N-heterocyclic carbene)ligands and varying anionic coligands(1,X=Cl;2,X=Br;3,X=I)are synthesized and struc-turally characterized.In solid state,both 1 and 2 exhibit orange-red photoluminescence under ambient conditions.The photophysical and electrochemical measurements along with density functional theory(DFT)calculations reveal that the low-energy emissions can be attributed to singlet excited states with ligand-to-ligand charge-transfer(LLCT)character.This work suggests that strong-field N-heterocyclic car-bene ligands play a crucial role to achieve the luminescence of Ni(Ⅱ)complexes.
查看更多>>摘要：White light emitting systems of pure organic materials have attracted extensive research interest due to their better compatibility and functional scalability.The reported organic white light materials are mainly based on the multi-channel emission regulation of the compound itself or the mixing of multicolor lu-minescence materials,but studies on the dependence between multicolor luminescence and the external environment are lacking,which limits the application of these materials in areas such as identification and sensing.This paper reports that the 4-or 3-hydroxyl-substituted naphthalimides NapH1 and NapH2 form intermolecular hydrogen bonds with adjacent molecules in the environment,and undergo excited-state intermolecular proton transfer under irradiation,resulting in blue-yellow or blue-red dual fluores-cence emission,respectively.Since the two compounds have different two-color luminescence channels and the two-color intensity ratio is affected by the environment,and the intermolecular hydrogen bond is determined by the hydrogen bond receptor,polarity,and temperature in the environment,the full spec-trum from blue to red light and white light emission can be obtained by adjusting the mixing ratio of the two dyes and the solvent polarity and the ambient temperature.This environmentally sensitive white emission is used to detect the alkalinity of different papers,and the dyed paper can be used as a test strip for acid-base vapor detection.
查看更多>>摘要：While enol-keto tautomerism has attracted great interest in Schiff bases and related compounds in solution and crystal states,the self-assembly of energy-unfavored keto form were scarcely investi-gated.Here,we report a keto-form directed self-assembly of a naphthalene-attached enantiomeric N-salicylideneanil analog L/DGG-Nap accompanied with a significantly amplified circularly polarized lumi-nescence(CPL).It was found that LGG-Nap exists as a mixture of enol and keto form in monomer at a di-luted toluene solution.The increment of the concentrations leads to the formation of predominated keto form,which subsequently triggers the self-assembly.Cryo-transmission electron microscopy(Cryo-TEM)revealed that a hierarchical assembly process happened upon increasing the concentration of LGG-Nap in toluene.Individual nanofibers formed at 1 × 10-4 mol/L and transferred into helical nanofiber bundles in 5 × 10-3 mol/L.Interestingly,while these is nearly no circular dichroism(CD)or CPL in the monomeric solution,the assembly showed strong CD and CPL.Remarkably,the dissymmetry factor(glum)was sig-nificantly amplified from zero in solution through the 0.005 in individual nanofiber to 0.1 in nanofiber bundles.This work demonstrates that the enol-keto tautomerism can be broken and trigger the self-assembly upon increasing the concentration,which can subsequently direct the chiral self-assembly and significantly amplify the dissymmetry factor of assembled CPL materials.
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