Emission Enhancement Characteristics Research Articles

Triphenylamine-Based Solid-State Emissive Fluorene Derivative with Aggregation-Induced Emission Enhancement Characteristics

Aggregation-induced emission (AIE) has garnered considerable attention in recent years. Understanding the mechanisms underlying AIE phenomena is crucial. Here, we present the design and synthesis of a novel fluorene derivative (4) based on triphenylamine, which exhibits typical AIE properties. The structure of it was totally characterized using FT-IR, MALDI-TOF mass analysis, elemental analysis, 1H, and 13C NMR spectroscopy. It displayed strong solid-state emission with diverse fluorescence characteristics. The AIE property of the compound was systematically studied using photoluminescence spectroscopy, revealing a distinct yellow light-emitting phenomenon. The solid-state luminescence showed a red shift of 148 nm compared to its luminescence in dilute dimethylformamide (DMF) solutions. Moreover, photophysical characteristics, including absorption and emission spectra, as well as fluorescence lifetime, were examined using UV–vis absorption and fluorescence emission spectroscopy. Compound (4) exhibited superior photosensitization abilities in both solid and solution states, with a notably enhanced effect observed in the solid state compared to the solution state.

A Novel Fluorogenic Probe Reveals Lipid Droplet Dynamics in ME/CFS Fibroblasts

AbstractLipid droplets (LDs) are dynamic cellular organelles that play an essential role in lipid metabolism and storage. LD dysregulation has been implicated in various diseases. However, investigations into the cellular LD dynamics under disease conditions have been rarely reported, possibly due to the absence of high performing LD imaging agents. Here a novel fluorogenic probe, AM‐QTPA, is reported for specific LD imaging. AM‐QTPA demonstrates viscosity sensitivity and aggregation‐induced emission enhancement characteristics. It is live cell permeable and can specifically light up LDs in cells, with low background noise and superior signals that can be quantified. After validation in cell model with LD accumulation induced by oleic acid treatment, AM‐QTPA is applied in a small proof‐of‐concept number of human fibroblast samples derived from people diagnosed with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a complex and debilitating disease with unknown cause. The results indicate the presence of larger but fewer LDs in ME/CFS fibroblasts compared to the healthy counterparts, accompanying with frequent LD‐mitochondria contacts, suggesting potential upregulation of lipolysis in ME/CFS connective tissue like fibroblasts. Overall, AM‐QTPA provides new understanding of the anomalous LD dynamics in disease status, which, potentially, will facilitate in‐depth investigation of the pathogenesis of ME/CFS.

Tetraphenylethylene fused pyrrolo[3,2-b]pyrrole derivatives with reversible mechanofluorochromic and aggregation-induced emission enhancement characteristics

Modification on typical of molecular unit with aggregation-induced emission (AIE)/aggregation-induced emission enhancement (AIEE) can play a important role in obtaining solid-state fluorescence materials and mechanofluorochromic (MFC) materials. We utilize the multicomponent reaction of TPE-containing aldehyde, arylamine and butane-2,3-dione in the presence of iron(III) perchlorate to design and synthesize two novel MFC materials by combination of the tetraphenylethylene (TPE) and pyrrolo [3,2-b]pyrrole core units. Investigation of CHW-1 and CHW-2 aggregation-induced emission behaviors indicated that these materials all exhibited AIEE properties. Subsequent mechanochromic luminescence tests exhibited reversible mechanochromism natures that involve fluorescent color change from green to yellow (Grinding-induced spectral shift (△λ): 35 nm and 38 nm, respectively). Then the datas (including SEM, PXRD and DSC) revealed that this mechanofluorochromism was ascribed to the transformation of crystal state to the amorphous form. Moreover, CHW-1 and CHW-2 could be applied for optical recording devices and security printing.

Macrocyclization-induce emission enhancement characteristics of benzothiadiazole-based macrocycles: A theoretical study

We present a comprehensive investigation into the molecular structures in the ground state and the first singlet excited state, intramolecular and intermolecular interactions, as well as the emission properties of monomers, dimers and macrocycles using density functional theory and time-dependent density functional theory. Our study aims to unveil the macrocyclization-induce emission enhancement principle for benzothiadiazole-based macrocycles. Compared with the typical π-π stacking of monomers, macrocycles exhibit the tighter stacking arrangement due to the presence of strong intramolecular and intermolecular hydrogen bond interactions and the rigid triangular geometry of macrocycle, which is conducive to the enhancement of emissions efficiency. The calculated oscillator strength of macrocycles in the first excited state is much higher than that of dimers composed of two monomers. Meanwhile, the large transition electric dipole moment is beneficial for enhancing the emission efficiency. Additionally, our study reveals an emission wavelength red-shift for macrocycles after “CH”/N substitution in the acceptor moiety, and the transition mode from LUMO to HOMO can be mainly attributed to intramolecular charge transition characters from acceptor to donor fragments. Our theoretical study might provide valuable insights for the design of innovative luminescent macrocycles with high emission efficiency.

Naturally Occurring Chalcones with Aggregation-Induced Emission Enhancement Characteristics.

In this paper, the natural chalcones: 2'-hydroxy-4,4',6'-trimethoxychalcone (HCH), cardamonin (CA), xanthohumol (XN), isobavachalcone (IBC) and licochalcone A (LIC) are studied using spectroscopic techniques such as UV-vis, fluorescence spectroscopy, scanning electron microscopy (SEM) and single-crystal X-ray diffraction (XRD). For the first time, the spectroscopic and structural features of naturally occurring chalcones with varying numbers and positions of hydroxyl groups in rings A and B were investigated to prove the presence of the aggregation-induced emission enhancement (AIEE) effect. The fluorescence studies were carried out in the aggregate form in a solution and in a solid state. As to the results of spectroscopic analyses conducted in the solvent media, the selected mixtures (CH3OH:H2O and CH3OH:ethylene glycol), as well as the fluorescence quantum yield (ϕF) and SEM, confirmed that two of the tested chalcones (CA and HCH) exhibited effective AIEE behaviour. On the other hand, LIC showed a large fluorescence quantum yield and Stokes shift in the polar solvents and in the solid state. Moreover, all studied compounds were tested for their promising antioxidant activities via the utilisation of 1,1- diphenyl-2-picrylhydrazyl as a free-radical scavenging reagent as well as potential anti-neurodegenerative agents via their ability to act as acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitors. Finally, the results demonstrated that licochalcone A, with the most desirable emission properties, showed the most effective antioxidant (DPPH IC50 29%) and neuroprotective properties (AChE IC50 23.41 ± 0.02 μM, BuChE IC50 42.28 ± 0.06 μM). The substitution pattern and the biological assay findings establish some relation between photophysical properties and biological activity that might apply in designing AIEE molecules with the specified characteristics for biological application.

A water-stable Schiff base fluorophore: AIEE behavior, reversible mechanofluorochromism, detection of water content and viscosity of automobile brake fluid, and cell imaging

Imine compounds (Schiff base) have been reported with aggregation-induced emission (AIE)/aggregation-induced emission enhancement (AIEE) characteristics: they were weakly or non-emissive when dissolved well in organic solvents while the fluorescence emission turned on drastically in the presence of water. However, for some of the Schiff bases, the enhanced emission upon aggregation is derived from their parent aldehydes rather than the Schiff base molecule themselves due to the hydrolysis. The susceptibility to hydrolysis has thus limited the wide application of Schiff bases in aqueous media. In this work, a water-stable Schiff base fluorophore DBSFCN was synthesized in which the triphenylamine (TPA) electron donor and benzonitrile electron acceptor were joined together by the imine structure. The hydrolytic stability of DBSFCN was confirmed by structural and spectral analysis. Meanwhile, DBSFCN displayed significant fluorescence emission enhancement in a water/tetrahydrofuran (THF) mixture with high water content and relatively good fluorescence quantum yield at the solid state (0.48), which exhibited a typical AIEE feature. Based on the water stability and AIEE characteristic of DBSFCN, a quantitative method for the determination of water content and kinematic viscosity of the automobile brake fluid was established. In addition, DBSFCN was available in living cell imaging and reversible mechanofluorochromism.

Flexible HSA-interactive phenolphthalein based probe proficient at selective turn-on sensing for Zn2+ & Al3+

A phenolphthalein based fluorescent probe, 3, 3-Bis-[4-hydroxy-3-(pyridine-2-yliminomethyl)-phenyl]-3H-isobenzofu ran-1-one (PHPA), has been synthesized. It exhibits high sensitivity and selectivity towards Zn2+ and Al3+over other relevant water soluble metal ions and also display novel aggregation-induced emission enhancement (AIEE) characteristics. Both complexes followed 2:1 metal to ligand stoichiometry calculated from Job's plot. A significant fluorescence enhancement with a turn-on ratio of ∼94-fold was triggered via chelation-enhanced fluorescence through sensor complex (Zn2+-PHPA) and∼245-fold increase for sensor complex Al3+-PHPA. In addition, the binding sites of both sensor complexes (PHPA-Zn2+ & PHPA-Al3+) have been confirmed through 1H NMR, 13C NMR, FT-IR and ESI-MS spectroscopy. The detection limits is found to be 8.5 × 10−8 M for complex PHPA-Zn2+ and 1.88 × 10−7 M for complex PHPA-Al3+, respectively. The reversible detection of Zn2+ and Al3+ complexes in methanol are also ascertained in the presence of Na2EDTA, enabling the construction of a molecular Logic gate. An advanced-level NOT-AND-OR logic gate has been constructed from a different chemical combinational input and emission output. Human serum albumin (HSA) binding studies were performed by various spectroscopic methods to expound possible bioactivity of PHPA. Interestingly; the AIEE properties of PHPA may advance its impact as studied in methanol-water mixtures with high water contents. To gain the knowledge into the AIEE mechanism of the PHPA, the size and growth process of particles in different volume percentage of water and methanol mixture were studied using time-resolved photoluminescence, dynamic light scattering, and optical microscopic image. The probe PHPA has also been used to detect intracellular Zn2+ ion in A549 cells.

AIE-active non-planar phenothiazine-based derivatives with mechanical-induced emission enhancement characteristics

Two new AIE-active non-planar phenothiazine-based derivatives EPMMBS and EPMBS, with subtly different electron-withdrawing moieties were synthesized, showing mechanical-induced emission enhancement characteristics.

Janus-Type AIE Fluorophores: Synthesis and Properties of π-Extended Coumarin-Bearing Triskelions.

Janus-type triskelion-shaped fluorophores comprising coumarins bearing various electron-donating substituents (1aad, 1add, 1ccd, and 1cdd) were successfully synthesized via an intramolecular Ullmann coupling. Density functional theory (DFT) calculations indicated that all the compounds presented two different molecular surfaces, similar to Janus-type molecules. The absorption and fluorescence spectra of asymmetrical derivatives 1aad, 1add, 1ccd, and 1cdd exhibited a bathochromic shift due to their narrow highest occupied molecular orbital (HOMO) -lowest unoccupied molecular orbital (LUMO) gap. Natural transition orbital (NTO) analysis indicated that the excited state orbital overlaps differ among the C3 symmetrical and asymmetrical dyes. These triskelion-shaped fluorophores were found to form molecular nanoaggregates in THF/H2O mixtures and demonstrated aggregation-induced emission (AIE) enhancement characteristics as a result of restricting their molecular inversion. These results indicate that Janus-type AIE fluorophores are potentially applicable as solid-state fluorescent chiral materials, which can be optimized by controlling their molecular rearrangement in the solid state.

D-A-D type cyclohexyl and cycloheptyl-modified benzo[d]imidazole derivatives with different aggregation-induced emission enhancement (AIEE) and mechanofluorochromic properties

Four tetraphenylethylene or triphenylamine-functionalized donor-acceptor-donor type benzo[d]imidazole derivatives 1–4 with different cycloalkyl substituents were successfully developed and characterized. All of these fluorogenic compounds showed remarkable aggregation-induced emission enhancement characteristics, and these luminogens emitted high brightness orange or green fluorescence in the aggregation state. Furthermore, these cyclohexyl or cycloheptyl-modified benzo[d]imidazole molecules exhibited tunable solid-state fluorescence effect, and their solids demonstrated contrasting mechanically triggered fluorescence responses. More specifically, luminogens 1–3 showed no observable fluorescence changes under mechanical stimulation, while tetraphenylethylene-based cycloheptyl-modified benzo[d]imidazole luminogen 4 displayed reversible mechanochromic fluorescence conversion between green and yellowish-green emission colors. The mechanofluorochromic mechanism of solid 4 was revealed by the powder X-ray diffraction measurements, and the experimental results proved that the phase interconversion between crystalline and amorphous states was responsible for the noticed switchable mechanoresponsive fluorescence. In addition, the mechanical force-sensitive emission of fluorogenic molecule 4 afforded its promising application in ink-free writing.

A novel AIEE active anti-B18H22 derivative-based Cu2+ and Fe3+ fluorescence off-on-off sensor

A novel fluorescence sensor for successive detection of Cu2+ and Fe3+ based on anti-B18H22 derivative which possesses 5-hydroxyisoquinoline as an ionophore was synthesized via a one-pot and its structure and photophysical properties were characterized by NMR, HRMS, FTIR, UV–vis, PL and theoretical calculation. The fluorophore displays two emission peaks at 460 nm and 670 nm in THF solution coming from the emission of the locally excited state and intramolecular charge transfer fluorescence, respectively. The complex exhibited obvious aggregation-induced emission enhancement (AIEE) characteristics in THF/H2O solution by increasing the aqueous concentration from 70% to 95%. The AIEE molecules showed a high selectivity towards Cu2+ over other metal ions by forming a 2:1 metal-to-ligand complex in THF/H2O (fw = 20%) solution, the fluorescence intensity increased as a linear function of the Cu2+ concentration at 460 nm due to the inhibition of PET effect. The fluorescent emission was quenched linearly by the addition of Fe3+, which provides a method for successive determination of Cu2+ and Fe3+ based on ‘off-on-off’ fluorescence of the fluorescent. The detection limit of Cu2+ and Fe3+ was 5.7 × 10−6 M and 7.2 × 10−5 M respectively. Morever, a rapid identification of Cu2+ in the aqueous solution by naked eyes can be realized. In addition, the molecules were pH-sensitive, the fluorescence quenching can be observed in strongly alkaline environment. The method has been applied to the determination of copper ions in water samples with satisfactory results.

A novel optical fiber sensor based on AIEgens for highly selective and sensitive detection of Fe 3+

A novel optical fiber sensor for the detection of Fe3+ based on AIEgens was reported for the first time. A new anti-B18H22 derivative ((5-NH2C9H6N)2B18H20, Referred as to S1) bearing 5-aminoisoquinoline was synthesized via a one-pot and its structure was verified by 1H NMR and HRMS, photophysical properties were characterized by UV–Vis, fluorescence spectrum and theoretical calculation. The fluorophore exhibits obvious aggregation-induced emission enhancement (AIEE) characteristics in THF/H2O solution by increasing the aqueous concentration from 70% to 90%. The aggregation-induced emission (AIE) molecule in THF/H2O (ƒw = 90%) solution shows high selectivity for detecting Fe3+ over other metal ions by forming a 1:1 metal-to-ligand complex, and the detection limit is 5.25 × 10−5 M. The optical fiber sensor based on S1 for the detection of Fe3+ was fabricated, and the detection limit of Fe3+ can reach to be 0.137 nM. The sensor can be used to detect Fe3+ in chemical, environmental and biological fields.

Fluorinated tolane-based fluorophores bearing a branched flexible unit with aggregation-induced emission enhancement characteristics

Precise molecular design of fluorinated tolane-based fluorophores can control both the electron density and molecular aggregated structures.

Y-shaped novel AIEE active push-pull quinoxaline derivatives displaying acidochromism and use towards white light emission by controlled protonation

A series of novel Y-shaped push-pull quinoxaline derivatives 2a-2f with quadrupolar and tripodal arrangement having quinoxaline as an electron acceptor (A) and biphenyl and phenyl as an electron donor (D), was designed, synthesized and characterized. Single crystal XRD studies depicted the twisted conformation for quadrupolar quinoxaline derivative 2a. All compounds displayed positive solvatochromism upon increasing solvent polarity from toluene to DMSO. Further, the aggregation studies confirmed the presence of aggregation induced emission enhancement (AIEE) characteristics. Quadrupolar derivatives 2a and 2f displayed nearly five-fold emission enhancement while tripodal derivatives 2b-2e displayed much lesser emission enhancement on aggregation in THF-water mixture. The photophysical studies were also explored in the presence of acid. Visual colour changes from colourless to light yellow or red under day light, and emission change from violet or indigo to green were observed in solution upon addition of TFA. The spectral and visible colour changes were reversed upon addition of TEA. A controlled protonation of tripodal derivative 2c in chloroform solution caused white photoluminescence and thus may have potential application in white light emitting diodes.

Dramatically Enhanced and Red-shifted Photoluminescence Achieved by Introducing an Electron-withdrawing Group into a Non-traditional Luminescent Small Organic Compound.

Small organic compounds without any traditional fluorescent chromophores are generally non-emissive, and only very few are reported to emit weak blue fluorescence. Here we synthesized a non-traditional luminescent small organic compound N-(2,2,2-trifluoroethyl)acrylamide (TFAM) with dramatically enhanced and red-shifted photoluminescence by introducing a strong electron-withdrawing group into acrylamide (AM). Very impressively, TFAM emits cyan (472 nm) and yellow-green (560 nm) fluorescence in solutions and solid state, respectively. TFAM also shows aggregation-induced emission enhancement (AIEE) and excitation-dependent fluorescence (EDF) characteristics, as well as temperature and metal cations-responsive fluorescence. Theoretical calculations show that the introduction of electron-withdrawing group leads to a lower energy gap between the HOMO-LUMO energy levels in TFAM than in AM. And strong cooperative hydrogen bonds are formed in TFAM molecules, resulting in rigidification of molecular conformations. The study provides a strategy for preparing non-traditional luminescent compounds with enhanced and red-shifted photoluminescence.

Polymerizable AEE-active Dye with Optical Activity for Fluorescent Nanoparticles Based on Phenothiazine: Synthesis, Self-assembly and Biological Imaging

In consideration of various advantages such as less harmful, higher sensitivity, and deeper imaging depth, etc, AIE materials with long-wave emission are attracting extensive attention in many fields of vascular visualization, organelle imaging, cells tracker, forensic detection, bioprobe and chemosensor, etc. In this paper, a novel fluorescent (R)-PVHMA monomer with chirality and aggregation-induced emission enhancement (AEE) characteristics was acquired through enzymatic transesterification reaction basing on phenothiazine, and its〖 [α]〗_D^(25 ℃) value was about -6.39° with 3.08eV energy level of HOMO and LUMO situations by the quantum calculations. Afterwards, a series of PEG-PVH1 and PEG-PVH2 copolymers with chirality feature were achieved through RAFT polymerization of the obtained (R)-PVHMA and PEGMA with various feed ratios. When the feed molar ratio of (R)-PVHMA increased to 29.6% from 21.5%, its actual molar fractions in the PEG-PVH1 and PEG-PVH2 copolymers accordingly increased to 25.7% from 18.1%. The molecular weight of PEG-PVH1 was about 2.2×104 with narrow PDI, and their kinetics estimation showed a first-order quasilinear procedure. In aqueous solution, the amphiphilic copolymers PEG-PVH could self-assembles into about 100 nm nano-particles. In a 90% water solution of H2O and THF mixture, the fluorescence intensity had the maximum value, and the emission wavelength presented at 580 and 630 nm. The investigation of cytotoxicity and cells uptake showed that PEG-PVH FONs had outstanding biocompatibility and excellent cells absorption effects, which have great potential in bioimaging application.

Indolo[3,2-b]carbazole derivatives with high fluorescent emission both in solution and aggregated states and mechanical-induced emission enhancement characteristic

Four novel indolo[3,2-b]carbazole derivatives (F-ICZ, 2F-ICZ, F-ICZ-Ben and 2F-ICZ-Ben) with A-π-D-π-A structure were designed and synthesized via Knoevenagel and Suzuki-Miyaura reactions. The photophysical properties of indolo[3,2-b]carbazole derivatives in different solvents, aggregates emission behaviors and solid state were investigated systematically. The compounds exhibited an obvious solvatochromic effect. Compounds F-ICZ and 2F-ICZ showed AIEE property in tetrahydrofuran-water mixture solution, and compounds F-ICZ-Ben and 2F-ICZ-Ben exhibited high fluorescent emission both in solution and aggregated states. The significant reasons may be the increase of conjugate degree in solution and no obviously π-π stacking in aggregated state. Furthermore, compound F-ICZ possessed mechanofluorochromic property, and F-ICZ-Ben exhibited mechanical-induced emission enhancement characteristics. The reasons for mechanofluorochromic property are the changes in molecular packing patterns. This work further provided an efficient strategy for designing more mechanofluorochromic materials with high fluorescent emission both in solution and aggregated states.

Chiral Pentaphenylpyrrole Derivatives with Aggregation-Induced Emission Enhancement and Aggregation Induced Circular Dichroism and Their Helical Self-assembly

A pair of enantiomers (S)-P5PdiAM and (R)-P5PdiAM containing two chiral substituents, and their raceme rac-P5PdiAM were synthesized by introducing (R)-/(S)- or racemic 1-phenylethylamine into 1-biphenyl-2,3,4,5-tetraphenylpyrrole. The target compounds all show weak aggregation-induced emission enhancement (AIEE) characteristics in the DMSO/H2O mixed system, indicating that the introduction of chirality hardly affect the photophysical properties of the compound. In addition, the chiral compounds (S)-P5PdiAM and (R)-P5PdiAM show strong circular dichroism (CD) signals in THF/H2O mixed solution with a water fraction of 70%, that is, they exhibit aggregation-induced circular dichroism characteristics (AICD). Because the aggregates of (S)-P5PdiAM and (R)-P5PdiAM emit weakly, there is no circularly polarized luminescence (CPL) signals upon aggregation. The chiral compounds (S)-P5PdiAM and (R)-P5PdiAM can self-assemble to form helical nanofibers in a THF/H2O mixture with a water fraction of 70%, while the racemic rac-P5PdiAM assembled to form nano-particles, indicating that chiral substituents have a great influence on the self-assembly and the morphologies of the nano-aggregates.

Rational design of coumarin fluorophore with solvatochromism, AIE and mechanofluorochromic enhancement properties

A new fluorophore 7-(diphenylamino)coumarin-4-yl pivalate (DPACP) with solvatochromism, aggregation-induced emission (AIE) and mechanofluorochromic (MFC) enhancement characteristics was rationally designed and synthesized by attaching bulky diphenylamine electron-donor and pivalate ester electron-acceptor to coumarin. With solvent polarity increase from n-hexane to acetonitrile, this molecular displayed a bathochromic shift in the emission wavelength (from 436 nm to 553 nm) and a decrease in the quantum yield (from 81.1% to 2.8%), indicating solvatochromic effect. Also, the AIE behaviors were observed in CH3CN/water and THF/water mixture systems. For example, the PL intensity increased 6 times in mixed solvent (CH3CN: water = 10 : 90) compared to that in pure CH3CN. Moreover, the emission of original powder samples was red-shifted (from 438 nm to 483 nm) with fluorescence enhancement (the solid-state quantum yield increase from 19% to 28%) upon grinding, and the emission behaviors of grinding powder samples could be reverted to original state by wetting with n-hexane. Furthermore, the relationship among the molecular structure, intermolecular interactions and emission properties was investigated by single-crystal diffraction analysis. DPACP had a twisted conformation because of steric hindrance from diphenylamine and pivalate ester groups, which played a decisive role in realizing AIE and MFC enhancement behaviors. The absence of π-π stacking observed in single-crystal structure was the main reason for the AIE property. The MFC enhancement property could be ascribed to the disturbance of weak electrostatic interaction of adjacent molecules upon grinding. The bulky group of pivalate ester was first used to construct MFC molecule, and this work provided insights for developing AIE and MFC materials based on conventional planar fluorophore which was always subject to ACQ effect.

Flavanone-Based Fluorophores with Aggregation-Induced Emission Enhancement Characteristics for Mitochondria-Imaging and Zebrafish-Imaging.

Fluorophores with aggregation-induced emission enhancement (AIEE) characteristics applied in bioimaging have attracted more and more attention in recent years. In this work, a series of flavanone compounds with AIEE characteristics was developed and applied to fluorescence imaging of mitochondria and zebrafish. The compounds were readily prepared by the thermal dehydration of chalcone that was obtained by the reaction of o-hydroxyacetophenone and benzaldehyde. Two of these compounds showed significant AIEE characteristics by fluorescence performance experiments, including optical spectra, fluorescence spectra, fluorescence quantum yield (φF), fluorescence lifetime, and scanning electron microscopy (SEM). Compared with traditional organic fluorescent dyes, these compounds have high fluorescence emission and high fluorescence quantum yield in solid or aggregated state, which overcomes the shortcoming of aggregation-caused quenching (ACQ). More importantly, the two compounds exhibited low cytotoxicity and good cytocompatibility in A549 lung cells at the experimental concentration range and they specifically targeted mitochondria, which make it of great potential use in mitochondria labeling. In addition, they were embryonic membrane permeable and had different affinities for different tissues and organs of zebrafish, but mainly distributed in the digestive system, providing a basis for the application of such compounds in bioimaging. These AIEE compounds with superior properties could be of great potential use in mitochondria imaging and other in vivo studies.