AIE-active Tetraphenylethylene Research Articles

Aggregation-Induced Enhanced Electrochemiluminescence Resonance Energy Transfer Biosensor for Ultrasensitive Detection of Carcinoembryonic Antigen Based on Donor-Acceptor Organic Nanoparticles.

Aggregation-induced electrochemiluminescence (AIECL) combines the merits of aggregation-induced emission (AIE) and electrochemiluminescence (ECL), which has become a research hot spot in recent years. Therefore, we synthesized a novel AIE compound (Z)-3-(4-(2-butyl-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)phenyl)-2-(4-(1,2,2-triphenylvinyl)phenyl)acrylonitrile (TPENI) with a donor-acceptor (D-A) structure, that is, a simple peripheral modification of 4-(2-butyl-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl) benzaldehyde (NI-CHO) with AIE-active tetraphenylethylene (TPE) to achieve the transition of NI-CHO from aggregation-caused quenching (ACQ) to an AIE molecule. When TPENI was in the aggregated state, the luminescence intensity was significantly enhanced due to the TPE structural unit restricting the free rotation of the intramolecular benzene ring, as well as the π-π stacking interactions of the molecules, which was conducive to the preparation of TPENI NPs as ECL materials. Satisfactorily, we found that the ECL intensity of TPENI NPs was increased by about 4.8-fold compared with that of the molecules dispersed in organic solution, and the stability reached about 1000 s. Based on the excellent ECL properties of TPENI NPs, an "on-off-on" ECL biosensor with a wider detection range (1 fg/mL to 100 ng/mL) and a lower detection limit of 0.20 fg/mL (S/N = 3) was proposed for sensitive analysis of a carcinoembryonic antigen (CEA). Overall, this work provided a new approach to the realization of AIECL and laid the foundation for the application of naphthalimide derivatives in ECL.

Theranostic FRET Gate to Visualize and Quantify Bacterial Membrane Breaching.

Designing new antimicrobial-cum-probes to study real-time bacterial membrane breaching and concurrently developing inquisitorial image-based analytical tools is essential for the treatment of infectious diseases. An array of aggregation-induced emission (AIE) polymers (donor) consisting of neutral, anionic, and cationic charges were designed and employed as antimicrobial theranostic gatekeepers for the permeabilization of the peptidoglycan layer-adherable crystal violet (CV, acceptor). An AIE-active tetraphenylethylene (TPE)-tagged polycaprolactone biodegradable platform was chosen, and their self-assembled tiny amphiphilic nanoparticles were employed as a gatekeeper in the construction of bacterial membrane-reinforced fluorescent resonance energy transfer (FRET) probes. Electrostatic adhering of the cationic AIE polymer and subsequent gate opening aided fluorescent FRET probe activation on the membrane of Gram-negative bacteria, Escherichia coli. The selective photoexcitation energy transfer process in confocal microscopy experiments facilitated the building of a visualization-based FRET assay for the quantification of bactericidal activity. Nonantimicrobial AIE polymers (neutral and anionic) did not breach the bacterial membrane, resulting in no FRET signal. Detailed photophysical studies were done to establish the FRET probe mechanism, and a proof of concept was established.

Amplification of AIE-effect of tetraphenylethylene on solid support: Formation of a sensitive fluorescent nanosensor for turn-on detection of Cu2+ and successive sensing of ascorbate ions

In a novel strategy, MCM-41 was used as a solid support for amplifying the aggregation-induced emission (AIE) effect of tetraphenylethylene (TPE) in order to develop a selective and sensitive fluorescent nanosensor for the detection of Cu2+ and subsequent sensing of ascorbate ions. A O-propargyl derivative of TPE (TPE-OPrg) was appended on to azide-functionalized MCM-41 (AzP-MCM-41) by click-reactions catalyzed by a combination of Cu(II)-PPh3. As the AIE-active TPE sits on the solid surface of MCM-41, it starts emitting bluish fluorescence. The fluorescence response borne a linear relationship with the increasing concentration of Cu2+ (R2 = 0.99335), leading to a turn-on chemodosimeter with the limit of detection (LOD) of 1 × 10-8 M (0.6 ppb), which is much lower than the standard set by US-EPA (1.5–2.5 10-5 M) in drinking water. Subsequently, the same strategy was utilized in the sensitive detection of ascorbate ions (AA), keeping in mind that they can spontaneously convert Cu(II) to Cu(I), the active catalyst for click-reactions. Again, a high regression coefficient (R2 = 0.99776) was obtained for AA in a linear range of 0.01–1.0 μM (LOD of 1.8 ppb). The mesoporous material, AzP-MCM-41, was characterized by XRD, FT-IR, TGA, BET, etc. The formation of TPE-MCM-41 conjugate was confirmed by solid-state NMR spectroscopy. A new strategy, cost-effective single-step synthesis of AIE-probe, high selectivity and sensitivity, dual-sensing option, low LOD for both Cu2+ and AA are some of the merits of this analytical tool.

Aminoglycoside antibiotic kanamycin functionalized tetraphenylethylene molecular probe for highly selective detection of bovine serum albumin protein

A novel tetraphenylethylene (TPE) functionalized aminoglycoside antibiotic kanamycin (TPE-kana 1) has been successfully synthesized and characterized by means of modern analytical and spectroscopic techniques. The probe TPE-kana 1 showed strong affinity towards bovine serum albumin (BSA) compared to its other biological competitors. The recognition of BSA have been investigated employing UV–Vis absorption and fluorescence emission spectroscopy. The significant color change of TPE-kana 1 with BSA can be observed by necked eye, where the role of AIE-active TPE molecule is handle in both optical and colorimetric changes. The quenching of fluorescence of TPE-kana 1 with BSA was characterized by fluorescence spectroscopy, with 71.16% of quenching efficiency. Moreover, the Stern–Volmer quenching constant was calculated and found to be 2.46 × 107 M−1. Probe TPE-kana 1 showed detection limit of 2.87 nM (nM) towards BSA with binding constant 7.56 × 107 M. A molecular docking study is also performed to investigate the detail interactions between TPE-kana 1 with the sites of BSA via non-covalent i.e., H-bonding, π-cation interactions, π-donor hydrogen bonds and π-π interactions. The lowest binding energy conformation was found at − 10.42 kcal/mol.

Novel AIE-active tetraphenylethylene derivatives as multitask smart materials for turn-on mechanofluorochromism, quantitative sensing of pressure and picric acid detection

Developing multitask smart materials is in high demand and remains challenging in the organic fluorophore research field. In this work, we designed and synthesized a series of tetraphenylethylene modified fluorophores (TPEN, TPEH, TPEF, TPEIZ, TPECN) with D-π-A configuration and various terminal substituents, whose packing structures in the solid state were finely manipulated and revealed by single-crystal structure analysis. These materials showed excellent aggregation-induced emission (AIE) and mechanofluorochromism (MFC) properties. The fluorescence peaks of TPEH, TPEF, TPEIZ and TPECN were gradually red-shifted with the change of solid fluorescence quantum yields (ΦF) under grinding, derived by the different molecular conformation and packing between crystalline and amorphous states. Notably, thanks to the high sensitivity to force, TPEH and TPEF exhibited high-contrast turn-on MFC property with obviously increase of ΦF. Meanwhile, TPEF achieved the quantitative detection of pressure in turn-on modal due to the special molecular packing induced by the F atom. Additionally, TPEH, TPEF, TPEIZ and TPECN were applied for the detection of picric acid (PA) and the limit of detection for the four materials was 7.58 μM, 458 nM, 634 nM and 4.62 μM, respectively. The mechanism was attributed to the synergistic effects of coulombic forces and protonation/hydrogen bonding interactions and the photoinduced electron transfer (PET) process. This work provides a new scope for rational design of highly sensitive multitask smart materials for low-pressure and PA detection.

Precise modulation of the triplet state distribution for high-efficiency non-doped standard saturated red OLEDs

AIE-active tetraphenylethylene precisely regulates triplet state energy level distribution to induce spontaneous upper reversed intersystem crossing to produce a desirable standard saturated red organic light-emitting diode.

Stepwise Increase of NdIII -Based Phosphorescence by AIE-Active Sensitizer: Broadening the AIPE Family from Transition Metals to Discrete Near-Infrared Lanthanide Complexes*.

We designed two near-infrared (NIR) lanthanide complexes [(L)2 -Nd(NO3 )3 ] (L=TPE2 -BPY for 1, TPE-BPY for 2) by employing aggregation-induced emission (AIE)-active tetraphenylethylene (TPE) derivatives as sensitizers, which possessed matched energy to NdIII , prevented competitive deactivation under aggregation, even shifted the excitation window toward 600 nm by twisted intramolecular charge transfer. Furthermore, benefiting from the 4 f electron shielding effect and antenna effect, the enhanced excitation energies of the AIE-active sensitizers by structural rigidification transferred into the inert NdIII excited state through 3 LMCT, affording the first aggregation-induced phosphorescence enhancement (AIPE)-active discrete NIR-emitting lanthanide complexes. As 1 equipped with more AIE-active TPE than 2, L→Nd energy transfer efficiency in the former was higher than that in the latter under the same conditions. Consequently, the crystal of 1 exhibited one of the longest lifetimes (9.69 μs) among NdIII -based complexes containing C-H bonds.

An aggregation-induced emission (AIE)-active fluorescent chemodosimeter for selective sensing of hypochlorite in water and solid state: Endogenous detection of hypochlorite in live cells

Hypochlorite (ClO−) being an important reactive oxygen species plays a crucial role in the oxidative damage to tissue and other various diseases. Highly selective, sensitive, and quick detection of aberrant ClO− is vital for the protection of living organisms and the environment. Accordingly, fluorescent molecules are most effective sensor system for ClO−. Herein, we have synthesized and characterized a water soluble AIE-active tetraphenylethylene (TPE)-based fluorescent molecule TPE−Py+ (TPP) for rapid (10 s) and selective detection of ClO− based on ClO− induced oxidation of N-alkylpyridinium to N-methyl-2-pyridone. ClO− mediated aggregation-induced emission (AIE) enhancement corresponds to turn-on response. Scanning electron microscopic (SEM) study supports AIE behavior of the probe upon treatment with ClO−. The detection limit of TPP for ClO− was found to be 8.89 nM and exhibited high selectivity among other possibly interfering analytes (ROS, RNS, other ions). TPP-based handy test kits were developed for the solid-state detection of ClO− in environmental samples. Furthermore, our probe was effective in detecting ClO− in real water samples, fetal bovine serum and able to detect endogenous ClO− in live cell.

Phthalimide conjugation turns the AIE-active tetraphenylethylene unit non-emissive: its use in turn-on sensing of hydrazine in solution and the solid- and vapour-phase.

Hydrazine is a vital precursor used in several pharmaceuticals and pesticide industries and upon exposure can cause severe health hazards. Herein, a new AIEgen, tetraphenylethylene phthalimide (TPE-PMI), is synthesized in a one-step solvent-free mechanochemical approach exploiting the simple condensation between TPE-NH2 and phthalic anhydride and used for the selective and sensitive detection of hydrazine. TPE-PMI with an AIE-active TPE-moiety is non-emissive in the solid phase by design. Hydrazine performs the cleavage of TPE-PMI in a typical “Gabriel synthesis” pathway to release AIE-active TPE-NH2 in an aqueous solution to emit blue fluorescence. A gradual rise in fluorescence intensity at 462 nm was due to the increasing hydrazine concentration and TPE-PMI showed a linear relationship with hydrazine in the concentration range from 0.2 to 3 μM. The selectivity study confirmed that the probe is inert to amines, amino acids, metal anions, anions and even common oxidants and reductants. The detection limit is 6.4 ppb which is lower than the US Environmental Protection Agency standard (10 ppb). The practical utilities of TPE-PMI were successfully demonstrated through quantitative detection of hydrazine vapour on solid platforms like paper strips and TLC plates. Furthermore, on-site detection of hydrazine in the solid phase was demonstrated by spiking the soil samples with measured quantities of hydrazine and quantitation through image analysis. This cost-effective sensing tool was successfully utilized in in vitro detection of hydrazine in live HeLa cells.

Correction: Spermine-directed supramolecular self-assembly of water-soluble AIE-active tetraphenylethylene: nanobelt, nanosheet, globular and nanotubular structures

Correction for ‘Spermine-directed supramolecular self-assembly of water-soluble AIE-active tetraphenylethylene: nanobelt, nanosheet, globular and nanotubular structures’ by Duong Duc La et al., New J. Chem., 2018, 42, 15379–15386, DOI: 10.1039/C8NJ02636J.

The electrosynthesis of highly photofunctional porous polymer PTCPE and the effect of BFEE on its electrochemical polymerization and fluorescence property

The development of porous polymer films with high emission efficiency simultaneously overcomes the unprocessable and poor photofunctionality limitations faced in the conjugated porous polymers (CPPs) field, and therefore has attracted more and more attentions. In this work, monomer 1,1,2,2-tetrakis(4-(9H-carbazol-9-yl)phenyl)ethene that contained AIE-active tetraphenylethylene and carbazole units had been synthesized via McMurry reaction. And its corresponding CPP (PTCPE) films were easily obtained using the electropolymerization method in CH2Cl2-BFEE mixtures without adding any supporting electrolyte. These CPPs films exhibited high fluorescence in the solid state because of AIE-active TPE. Their electrochemical polymerization and fluorescence properties could be changed by adjusting the polymerization conditions.

AIE active TPE mesogens with p6mm columnar and Im3m cubic mesophases and white light emission property

The discotic tetraphenylethylene (TPE) mesogens composing of a TPE core surrounded by four flexible 1,2,3-triazole dendritic paddles were synthesized efficiently via CuAAC click reaction. Interesting such TPE mesogens can self-assemble into not only the hexagonal columnar phase but also the rarely observed 3D micellar Im3¯m cubic phase in their bulk states, as well as organogels with spherulitic or porous morphologies in organic solvents. AIE effects are observed in different aggregation states of such TPE mesogens. When such TPE mesogens are dispersed in nematic LC 5CB, dichroic ratio values up to 6.34 are obtained. Furthermore the emission colors of both pure TPE mesogens and the doped gel formed by doping TPE mesogen with DPP dye are tunable. Remarkably, TPE/12+DPP/2C8 complex can exhibit stable white light emission (WLE) in gel state and poly(ethylene glycol) (PEG) film.

Synergistic effect between electroactive tetraphenyl-p-phenylenediamine and AIE-active tetraphenylethylene for highly integrated electrochromic/electrofluorochromic performances

A new design concept combines conjugated TPPA and AIE-active TPE units in an electroactive/fluorescent polymer with excellent properties: high fluorescence and on/off rates, superior cycling and long-term switching stability and fast response speed.

Facile fabrication of cross-linked fluorescent organic nanoparticles with aggregation-induced emission characteristic via the thiol-ene click reaction and their potential for biological imaging

Over the past several years, the biomedical applications of fluorescent organic nanoparticles (FONs) with aggregation-induced emission (AIE) feature have been extensively explored because the AIE-active FONs could effectively overcome the aggregation caused quenching (ACQ) effect of FONs based on conventional organic dyes. The development of novel methods for synthesis of AIE-active FONs plays a centre role for their biomedical applications. In this work, we reported a facile one-step thiol-ene click reaction for fabrication of AIE-active FONs through conjugation of acrylated PEG and AIE-active tetraphenylethylene (TPE) with two ene bonds using pentaerythritol tetra(3-mercaptopropionate) as the linkage. The successful synthesis of TPE containing AIE-active copolymers was evidenced by various characterization techniques. The particle size and fluorescence properties of the resultant TPE-S-PEG copolymers were evaluated by transmission electronic microscopy and fluorescence spectroscopy. Moreover, the cell viability and cell uptake behavior was also examined to evaluate their potential for biological imaging. We demonstrated that the cross-linked TPE-S-PEG show small size, high water dispersibility, low cytotoxicity and strong fluorescence for tracing. All of these advantages endow the TPE-S-PEG FONs great potential for biological imaging applications. Furthermore, this novel click reaction can take place under mild experimental conditions with high efficiency. It could be also further expanded for preparation of multifunctional AIE-active materials due to the universality of the thiol-ene click reaction and good precursor applicapability. Taken together, we have developed a novel and effective thiol-ene click reaction to fabricate the cross-linked AIE-active FONs, which display excellent physicochemical and biological properties and are promising for biomedical applications.

Spermine-directed supramolecular self-assembly of water-soluble AIE-active tetraphenylethylene: nanobelt, nanosheet, globular and nanotubular structures

Tetrasulfonate-tetraphenylethylene (Su-TPE) is non-emissive in water and upon addition of a good solvent such as THF (fTHF = 95%) it displays strong fluorescence emission with a quantum yield of 6.33%.

Tetraphenylethylene-Based AIE-Active Probes for Sensing Applications.

This Review provides a comprehensive analysis of recent development in the field of aggregation-induced emission (AIE)-active tetraphenylethylene (TPE) luminophores and their applications in biomolecular science. It begins with a discussion of the diverse range of structural motifs that have found particular applications in sensing, and demonstrates that TPE structures and their derivatives have been used for a diverse range of analytes such as such as H+, anions, cations, heavy metals, organic volatiles, and toxic gases. Advances are discussed in depth where TPE is utilized as a mechanoluminescent material in bioinspired receptor units with specificity for analytes for such as glucose or RNA. The rapid advances in sensor research make this summary of recent developments in AIE-active TPE luminophores timely, in order to disseminate the advantages of these materials for sensing of analytes in solution, as well as the importance of solid and aggregated states in controlling sensing behavior.

Dual-Stimuli-Responsive Fluorescent Supramolecular Polymer Based on a Diselenium-Bridged Pillar[5]arene Dimer and an AIE-Active Tetraphenylethylene Guest

We report a new strategy to construct a multi-stimuli-responsive fluorescent supramolecular polymer by the strong host–guest interactions between a diselenium bond-bridged pillar[5]arene dimer and an AIE-active tetraphenylethylene (TPE)-containing neutral guest bearing two imidazole terminal binding sites. The resulting supramolecular polymer shows a remarkable fluorescence emission decrease at low concentration. Significantly, the diselenium bonds introduced into the supramolecular polymer serve as redox-responsive building blocks. Upon addition of reductants, the supramolecular polymer depolymerized owing to the cleavage of the covalent diselenium bonds in the system. On the other hand, competitive guests such as adiponitrile, which bind strongly with pillar[5]arenes, could lead the disassembly of the polymer to oligomers without breaking any covalent bonds in the system. These two types of depolymerization approaches can both result in the fluorescence intensity recovery of the system to a certain exte...

Flower-like superstructures of AIE-active tetraphenylethylene through solvophobic controlled self-assembly

The development of well-organized structures with high luminescent properties in the solid and aggregated states is of both scientific and technological interest due to their applications in nanotechnology. In this paper we described the synthesis of amphiphilic and dumbbell shaped AIE-active tetraphenylethylene (TPE) derivatives and studied their self-assembly with solvophobic control. Interestingly, both TPE derivatives form a 3D flower-shape supramolecular structure from THF/water solutions at varying water fractions. SEM microscopy was used to visualise step-wise growth of flower-shape assembly. TPE derivatives also show good mechanochromic properties which can be observed in the process of grinding, fuming and heating. These TPE derivative self-assemblies are formed due to two main important properties: (i) the TPE-core along with alkyl chains, optimizing the dispersive interactions within a construct, and (ii) amide-linkage through molecular recognition. We believe such arrangements prevent crystallization and favour the directional growth of flower-shape nanostructures in a 3D fashion.

Solvophobic control aggregation-induced emission of tetraphenylethene-substituted naphthalene diimide via intramolecular charge transfer

Tuning non-emissive NDIs into highly fluorescent material in aggregated by employing AIE-active tetraphenylethylene to the core via ICT effect.