基于AIE效应的内源性硫化氢荧光探针的研究进展

合理设计监测内源性硫化氢的荧光探针分子有助于充分了解其生理和病理功能.目前,在研的检测硫化氢的小分子荧光探针多存在聚集诱导猝灭效应,因此克服此缺陷的聚集诱导发光效应荧光探针的研究受到越来越多的关注.本文结合研究实践简要综述了近几年具有聚集诱导发光效应的化学反应型硫化氢活体成像荧光探针的研究进展及设计思想并进行展望,以期对该领域研究提供一些借鉴和思考.

Novel strategy of multidimensional information encryption via multi-color carbon dots aggregation-induced emission

Carbon dots(CDs)with aggregation-induced emission(AIE)have sparked significant interest in multidimensional anti-counterfeiting due to their exceptional fluorescence properties.However,the preparation of AIE CDs with multicolor solid-state fluorescence remains a formidable challenge due to its complicated construction.In the present work,a novel class of multicolor AIE CDs(M-CDs)were fabricated using selected precursor(salicylic acid,thiosalicylic acid,and 2,2'-dithiodibenzoic acid),with an eco-friendly,low-cost one-pot solvothermal method.In the dilute organic solution,M-CDs manifested blue emission,but upon aggregation in the presence of water,the red,yellow,green,and blue emissions were displayed due to the AIE effect.Structural analysis,coupled with theoretical calculations,revealed that the increase in the size of sp2 domains would lower the Eg and cause a red-shift emission wavelength.Significantly,the continuous emission of M-CDs from blue to red can be utilized as ink for multimode printing,enabling the creation of a variety of school badges and quick response codes.These findings hold promising implications for multi-information encryption applications.

Confinement fluorescence effect of an aggregation-induced emission luminogen in crystalline polymer

Despite the impressive progress of stimuli-responsive fluorescent materials,little is known about the influence of confinement created by crystalline polymer over the fluorescence properties of fluorescent molecules.The effects of confinement on the fluorescence of an aggregation-induced emission luminogen(AIEgen)are investigated using computational simulations,which reveal that the confined space induces the AIEgens to take a more planar conformation,resulting in a red-shifted emission spectrum.With this property,the study is extended to explore the confinement generated by various polymer crystalline forms,and it is shown that different fluorescence colors are activated.This confinement fluorescence effect is attributed to the different spatial dimensions of the polymer amorphous layer between lamellar crystals where the AIEgens are located.These results indicate the immediate association between crystalline structure and fluorescence signals,activating unprecedented photophysical properties of luminescent materials,and also providing the possibility for crystalline structure visualization,it is important for the many polymer crystallization processes occurring in the materials processing.

Synthesis and ultraviolet/aggregation-induced emission investigation of novel tetraphenylvinyl hydrazone derivatives: efficient multimodal chemosensors for fluoride ion

Herein,three novel tetraphenylethylene hydrazone chemosensors TC12,SC16,and TC16 are prepared for the selective detection of F−.Two NH and one C=N units are incorporated into the sensors for better colorimetric responses,whereas the tetraphenyl unit is in charge of the aggregation-induced emission effect.Among them,compounds SC16 and TC16 form stable gels with some organic solvents.All the tetrahydrofuran/H2O solutions of the three compounds exhibit aggregation-induced emission effect,whereby the fluorescence emission increases by varying degrees with the volume of poor solvent water.Moreover,good aggregation-induced emission effects are observed in the self-assembly of SC16 and TC16.As a sample chemosensor,TC12 in tetrahydrofuran responds to F−selectively with high sensitivity,with the colorimetric and fluorometric detection limits of 8.25×10^(−7) mol·L^(-1) and 2.69×10^(−7) mol·L^(-1),respectively.The reversible gel-sol-gel phase transition and color changes indicate that both SC16-dimethyl sulfoxide and TC16-ethyl acetate gels specifically respond to F-with good sensitivity.The detection results are well supported by ultraviolet-visible spectroscopy,fluorescent spectroscopy,and 1H nuclear magnetic resonance.More importantly,the driving forces of gelation are visually clarified through the single crystal X-ray analysis of compound TOMe.

A cyanostilbene-based molecule with aggregation-induced emission properties: amplified spontaneous emission, protonation effect and electroluminescence

A terpyridine-substituted cyanostilbene derivative(Z)-2-(4′-([2,2′:6′,2″-terpyridin]-4′-yl)-[1,1′-biphenyl]-4-yl)-3-phenylacrylonitrile(CNSTPy) was synthesized and characterized. The compound exhibits remarkable aggregation-induced emission phenomenon and its single crystal shows a blue emission with fluorescent efficiency as high as 45%. Based on its aggregation state behavior, multiple applications towards exploring its lasing, fluorescence switching and electroluminescence properties were realized. Amplified spontaneous emission(ASE) was observed from the crystal and verified by the variable pump strip method, with a threshold value of ～1.5 m J cm^(-2). The protonation/deprotonation processes accompanied by the formation of different molecular aggregation structure result in the distinct blue and yellow emissions. Additionally, the molecule also shows a moderate electroluminescence performance.

A supramolecular self-assembly material based on cucurbituril and cationic TPE as ultra-sensitive probe of energetic pentazolate salts

The successful synthesis of the pentazolate anion(cyclo-N-5)has been a great breakthrough in the field of energetic materials.However,the detection methods for these energetic materials based on the pentazolate anion are quite rare.Herein,two fluorescent probes for cyclo-N-5anion were designed.Sensor 1(TPE2N)was synthesized with a tetraphenylethylene functionalized by two cationic groups which can generate strong electrostatic interactions with pentazolate anion and result in specific fluorescent changes.Sensor 2 was designed based on sensor 1 and supramolecular cucurbit[7]uril(CB[7]).The unique structural features of CB[7]provide sites for the interaction between the cations and N-5anion in its cavity,which would generate a platform for the detection and enhance the recognition performance.Isothermal titration calorimetry(ITC)experiment and fluorescence titration experiment indicate the binding molar ratio between sensor 1 with CB[7]is 1:2.Both sensors display typical aggregation-induced emission(AIE)features and good water-solubility.The sensors demonstrate excellent sensitivity to pentazole hydrazine salt with high enhancement constant(sensor 1:1.34×10^(6);sensor 2:3.78×10^(6))and low limit of detection(LOD:sensor 1=4.33μM;sensor 2=1.54μM).The formation of an AIE-based supramolecular sensor effectively improves the sensitivity to N-5anion.In addition,the probes also have good selectivity of N-5anion salts.The research would shed some light on the design of novel fluorescent sensors to detect pentazolate-based molecules and provides an example of supramolecular chemistry combined with fluorescent probes.

Topological effect on fluorescence emission of tetraphenylethylene-based metallacages

Herein,we describe the selective formation of a barrel-shaped or a ball-shaped fluorescent metallacage by controlling the shape and stoichiometry of the building blocks.Specifically,the tetraphenylethylene-based donor and two acceptors with different numbers of Pt(Ⅱ)centers were combined via coordination-driven self-assembly.Owing to the differences in the shapes of the assemblies,the resultant ball-shaped metallacage displayed stronger and blue-shifted fluorescence compared to the barrel-shaped one in dilute solutions,while a reversal of fluorescence intensities was observed in the aggregation process.Overall,this work demonstrates that the photophysical properties of supramolecular coordination complexes can be affected by subtle geometrical factors,which can be controlled precisely at the molecular level.

New Quinoxaline-Based Blue Emitters: Molecular Structures, Aggregation-Induced Enhanced Emission Characteristics and OLED Application

Three new deep blue light emitters,bearing quinoxaline with different substituents(biphenyl/pyrene)at the 1-or 2-position,were synthesized by a Pd-catalysed coupling reaction in high yields,and were fully characterized by 1H/13C NMR spectroscopy,single crystal X-ray diffraction,and high-resolution mass spectrometry(HRMS).

Naphthalene diimide based near-infrared luminogens with aggregation-induced emission characteristics for biological imaging and high mobility ambipolar transistors

Organic conjugated materials combining high conductivity with strong solid-state emission are highly desired for organic electronic applications,yet still rather rare.Herein,a novel luminogen(TEN)comprised by linking naphthalene diimides and triphenyl ethylene with vinyl bridges is reported.TEN exhibits aggregation-induced emission(AIE)behavior of a strong nearinfrared fluorescence over 700 nm and the efficiency above 60.5%in the solid state,while also shows promising application in vivo bio-imaging with good permeability and extremely low background.Single crystal of TEN reveals intra-and intermolecular C–H…O hydrogen bonds,contributing to an inclined molecular stacking along the a-axis of the cell,creating a 1 D charge carrier transporting channel under a shortπ-πinteraction distance of 3.42?,which might benefit the solid emission and charge transport ability simultaneously.Solution processed bottom contact,top gate organic field effect transistors based on TEN reveal a high ambipolar charge transport ability with the hole mobility up to 0.13 cm2 V-1 s-1 and electron mobility up to0.010 cm2 V-1 s-1.Further atomic force microscopy and X-ray diffraction analysis on TEN thin film confirm the existence of the1 Dπ-πstacking channel,suggesting the stacking geometry revealed in crystal crucial for facilitating high charge carrier mobility while preserving the strong solid emission at the same time.

High-performance nano-splitters containing aggregation-induced emission luminogens for stereoselective crystallization obtained via polymerization-induced self-assembly

Collecting both enantiomorphs with high optical purity and yield in a single crystallization process can be achieved by adding aggregated polymeric“tailor-made”additives,known as nano-splitters.Inefficient preparation and large addition amount have hindered the practical application of such amazing nanoparticles.Herein,we report the first nano-splitters containing aggregation-induced emission luminogens prepared via polymerization-induced self-assembly of block copolymer,poly[(S)-2-(tert-butoxycarbonylamino)-6-(methacrylamido)hexanoic acid]-b-polystyrene,followed by the removal of tert-butoxycarbonyl groups.When added into the supersaturated solution of racemic amino acids(a.a.)with seeds,the fluorescent labeled nano-assemblies enantioselectivity dyed the crystals of S-a.a.and enabled the separation from colorless R-a.a.crystals in terms of fluorescent difference.Both enantiomers were obtained with high optical purity and yield(e.g.,R-asparagine monohydrate,>99 ee%;S-asparagine monohydrate,∼94 ee%;88%total yield).Owing to a low detection limit of fluorescence,the addition amount was reduced to 0.03 wt%without remarkably compromising the ee values of both enantiomorphs.Due to the low addition amount and efficient synthesis,the output–input ratio was increased greatly.

A historical review of aggregation-induced emission from 2001 to 2020:A bibliometric analysis

Aggregation-induced emission(AIE)is a photophysical phenomenon that a certain group of luminescent materials that become highly luminous when aggregated in a bad solvent or solid state.This year is the 20th anniversary since the AIE concept firstly proposed in 2001.Many advanced applications were gradually being explored,covering optics,electronics,energy,and bioscience and so on.At present,bibliometrics can enlighten the researchers with comprehensive sights of the achievements and trends of a specific field,which is critical for academic investigations.Herein,we presented a general bibliometric overview of AIE covering 20 years of evolution.With the assistance of Web of Science Core Collection database and several bibliometric software tools,the annual publication and citation,most influential countries/regions,most contributing authors,journals and institutions,second near-infrared(NIR-Ⅱ)related hotspots,as well as the forecast of frontiers were demonstrated and systematically analyzed.This study summarizes the current research status in AIE research field and provides a reference for future research directions.

Photosensitizers with Aggregation-induced Emission and Their Biomedical Applications

Microorganisms and cancer have always been the fierce enemies of human beings,but the traditional methods of treating them still have many defects.Therefore,it is extremely important to develop rapid,effective and safe treatments.Photodynamic Therapy(PDT)has attracted much attention because of its advantages of non-invasive,non-drug tolerance,high selectivity and low toxicity.As a result,more and more scientists are committed to developing better photosensitizers to enhance the efficiency of PDT in the therapy of microorganisms as well as tumors.The discovery of aggregation-induced emission(AIE)phenomenon provides a novel research direction for the progress of photosensitizer and brings a broader prospect for PDT.This review focuses on the recent progress of photosensitizers(PSs)with AIE properties in PDT from two aspects of anti-microbial and anti-cancer.Among them,anti-microbial aspects were introduced from the perspectives of anti-bacterial,anti-fungal and anti-viral aspects,while anti-cancer aspects were first introduced from the perspective of different target sites of photosensitizers,and then based on the modification of their own structures.Finally,the current limitations,challenges and future development of AIE photosensitizer(AIE-PSs)are clarified in view of the existing strategies and obstacles,so as to promote the development of AIE-PSs in the future clinical applications.

Conformational sensitivity of tetraphenyl-1,3-butadiene derivatives with aggregation-induced emission characteristics

Organic dyes with conformational sensitivity can be used to probe weak interactions at the molecular level.Here,three molecules based on tetraphenyl-1,3-butadienes(TPBs)were synthesized and studied with respect to their synthesis,structural characterization and potential application.All TPBs showed aggregation-induced emission(AIE)characteristics and sensitive conformational properties,in which the emission wavelengths could be changed in different states.The TPBs single crystals revealed that the phenyl groups at the 4-position of the 1,3-butadienes contributed to their conformational sensitivity.Furthermore,the potential application for monitoring the interactions among polyelectrolyte complexes and metal ions was explored,and the results showed that TPBs could be used for sensitively probing some weak interactions by changing the emission wavelengths due to their conformation-sensitive properties.TPBs may become a new star in AIE research fields.

Aggregation-induced Emission Fluorogen as Mammalian Cell Cytoplasmic Tracker with Long Retention Time and High Photo-stability

Fluorescent probes used for cell imaging are powerful tools in cell-based assays and research.In this study,we exhibited a water-soluble aggregation-induced emission fluorogen(AIEgen),BSPO-TPE,specifically stained cytoplasm in live cells and had an excellent photostability when compared to that of two widely used commercial fluorescent dyes.The long cytoplasm retention time of BSPO-TPE demonstrated its suitability as a live cell cytoplasm tracker.

Recent Process of Photo-responsive Materials with Aggregation-induced Emission

The research of photo-responsive materials,with changed absorption and emission under light stimulus,has drawn more and more attention due to their wide applications.However,most of them suffered from the notorious aggregation-caused quenching(ACQ)effect,which often led to the unconspicuous luminescent change in photo-responsive process.To solve this problem,the strategy of combining aggregation-induced emission(AIE)and photochromic properties was utilized,which largely enriched the phenomenon and application of photo-responsive materials.This short review summarized the recent progress of photo-responsive AIE materials with changed UV absorbance or PL phenomenon under UV-irradiation,including the types of molecular structures,internal mechanisms and the practical applications.Also,some outlooks were given on the further exploration of this field at the end of this paper.

Blue fluorophores comprised of tetraphenylethene and imidazole： aggregation-induced emission and electroluminescence

By melting tetraphenylethene （TPE） and 1,2,4,5-tetraphenyl-lH-imidazole （TPI） units together through different linking positions, three new fluorophores are synthesized, and their optical, electronic and electro- luminescence （EL） properties are fully studied. Owing to the presence of TPE unit（s）, these fluorophores are weak emitters in solutions, but are induced to emit strongly in the aggregated state, presenting typical aggregation-induced emission characteristics. The experimental and computational results reveal that different connection patterns between TPE and TPI could impact the molecular conjugation greatly, leading to varied emission wavelength, fluorescence quantum yield and EL performance in organic light emitting diodes （OLEDs）. The fluorophore built by attaching TPE unit to the 1-position of imidazole ring shows bluest fluorescence, and its EL device emits at deep blue region （445 nm; CIE= （0.16, 0.15））. And the device based on the fluorophore by linking TPE to the 2- position of imidazole ring shows EL at 467 nm （CIE= （0.17, 0.22）） with good efficiencies of 3.17 cd.A ^-1, and 1.77%.

Aggregation-induced emission shining in the biomedical field:From bench to bedside

Fluorogens with aggregation-induced emission characteristics(AIEgens)have been developed in an unprece-dented manner in the biomedical field over the past decade,which is ascribable to their superior fluorescence quantum yields,photosensitivities,as well as their“turn-on”characteristics in their aggregate states.By delib-erately engineering their molecular structures and nanocarriers,the input energies of AIEgens can be channeled into specific forms,thereby enabling bioimaging,phototherapy,and even synergetic therapy.Moreover,multiple targeting strategies have been tailored for nidus and pathogen localization that subsequently guide therapeutic processes.This review integrates application-oriented design strategies for AIEgens,demonstrating how microscopic imaging,bioimaging,and theranostics can be developed to combat tumors,pathogens,and other diseases,and critically discusses challenges and perspectives for clinical translation.

Recent advances in chiral aggregation-induced emission fluorogens

Over the past decade,aggregation-induced emission(AIE)molecules have played a pivotal role in bioimaging,anti-microbial,and photodynamic therapy,and have been at the forefront of several disciplines worldwide.When combined with chiral moieties,they can easily collide with dazzling sparks and exhibit exceptional and unique advantages.In the application of chiral recognition and measurement of enantiomeric excess,it can identify chi-ral molecules visually based on color change and precipitation reaction,quantitatively analyze chiral molecules while determining the enantiomeric composition based on the fluorescence intensity change at different wave-lengths,and obtain two parameters about chiral molecules from one measurement,thereby demonstrating its high selectivity,sensitivity and accuracy in chiral identification.In the field of organic circularly polarized lu-minescent(CPL)materials,the asymmetry(g lum)of common organic light emitting elements is usually between 10−5 and 10−2,whereas the CPL asymmetry factor(g lum)of chiral AIE fluorogens(AIEgens)can reach 1.42,which is very close to the theoretical value of 2.Therefore,the combination of chiral elements and luminescent groups promotes their adoption in the field of organic CPL materials.Herein we have summarized the recent applications of chiral AIEgens in both chiral molecule recognition and circularly polarized organic light-emitting diode(CP-OLED)in order to provide future researchers with a more comprehensive and detailed understanding of chiral AIEgens and to encourage more scientists to contribute to the development of AIEgens.

Donor-Acceptor Typed AIE Luminogens with Near-infrared Emission for Super-resolution Imaging

Aggregation-induced emission(AIE)luminogens(AIEgens)with high brightness in aggregates exhibit great potentials in biological imaging,but these AIEgens are seldom applied in super-resolution biological imaging,especially in the imaging by using the structural illumination microscope(SIM).Based on this consideration,we synthesized the donor-acceptor typed AIEgen of DTPA-BTN,which not only owns high brightness in the near-infrared(NIR)emission region from 600 nm to 1000 nm(photoluminescence quantum yield,PLQYs=11.35%),but also displays excellent photo-stability.In addition,AIE nanoparticles based on 4,7-ditriphenylamine-[1,2,5]-thiadiazolo[3,4-c]pyridine(DTPA-BTN)were also prepared with highly emissive features and excellent biocompatibility.Finally,the developed DTPA-BTN-based AIE nanoparticles were applied in the super-resolution cellular imaging via SIM,where much smaller full width at half-maximum values and high signal to noise ratios were obtained,indicating the superior imaging resolution.The results here imply that highly emissive AIEgens or AIE nanoparticles can be promising imaging agents for super-resolution imaging via SIM.

Organic Nanocrystals Based on a Solid-emission-tunable AIEgen for Cell Imaging

The development of fluorescent nanocrystals based on organic small molecules is of great importance in bioimaging due to the merits of easy modification,high brightness and excellent photostability,however suffering from the emission-detrimental aggregation-caused quenching(ACQ)effect.Herein,we successfully designed and synthesized an AIE-active di(N,N-dimethylaniline)-dibenzofulvene(named as NFTPE),which exhibits the crystallization-induced emission enhancement(CIEE)effect.Interestingly,two types of yellow-and orange-emissive crystals for NFTPE were obtained,exhibiting aggregation microenvironment-dependent emission tuning in the solid state.Single-crystal analysis and density functional theory(DFT)calculations reveal that different aggregation microenvironments result in the distinct molecular conformation for various emission.Excitingly,the crystallization of NFTPE in an aqueous solution under the assistance of amphiphilic PEG polymer matrices could be monitored in situ by the fluorescence changes,facilitating the preparation of NFTPE nanocrystals(NFTPE-NCs)by adjusting the aggregation microenvironment.The obtained NFTPE-NCs exhibit the superior performance in cell imaging in respect to high brightness,photostability,and biocompatibility,thus demonstrating the potential in bioimaging applications.