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Aggregation-induced emission (AIE) smart materials with multiple stimulus responses have a wide range of applications. Here, a series of tetraphenylethylene (TPE) derivatives, TPEN 1 S 3 , TPEN 2 S 2 , TPEN 3 S 1 were synthesized. The sensitivity of molecules to pH, UV light, and metal ions could be effectively tuned by modulating the ratio of amino to sulfonic acid groups. These TPE derivatives exhibited yellow emissions in aggregated state due to the AIE characteristics. Acidification conversion of the NH 2 groups to NH 3 + for three molecules induced the suppression of intramolecular charge transfer (ICT), which resulted in a 72–102 nm blue shift in the fluorescence emission. Solid powders of these compounds exhibited reversible protonation-deprotonation process induced by HCl/NH 3 ·H 2 O vapor. TPEN 1 S 3 , TPEN 2 S 2 and TPEN 3 S 1 in solution could be photoactivated and emit blue fluorescence (ca. 482 nm, 475 nm, and 480 nm). Photocyclo-dehydrogenation reactions of compounds were triggered by the UV irradiation and the maximum cyclization ratios could reach 12%, 66%, and 50%, respectively. Protonation of NH 2 group significantly enhanced the rate of the photocyclo-dehydrogenation reaction. Furthermore, the solid powders of protonated compounds displayed pronounced reversible photochromic properties due to the generation of cyclization intermediate. In addition, TPEN 1 S 3 , TPEN 2 S 2 , and TPEN 3 S 1 exhibited responsiveness to a diverse range of metal ions. Specifically, the TPEN 2 S 2 molecule functioned as a photo sensor for Li + ions with a blue shift in fluorescence emission. The limit of detection (LOD) value was 0.679 μM. These multiple stimuli-responsive AIE molecules hold significant potential for use in advanced photo-controlled patterning, encryption applications, and the detection of metal ions. [Display omitted] • Novel AIE compounds TPEN 1 S 3 , TPEN 2 S 2 , TPEN 3 S 1 based on tetraphenylethylene (TPE) for photoluminescence (PL) sensors are fabricated. • Multi-stimuli responsive fluorescence of AIE compounds are investigated under acid, UV light and metal ions. • Amino group protonation can induce reversible fluorescence conversion and accelerate photocyclo-dehydrogenation reactions. • Probe TPEN 2 S 2 is good selectivity and sensitivity for Li + detection. • Three paper-based application scenarios are designed for information encryption and anti-counterfeiting. [ABSTRACT FROM AUTHOR]

In this study, six tetraphenylethene (TPE) derivatives had been designed and synthesized, named as TPEH , TPEOMe , TPEtBu , TPEOH , TPECN and TPEPy , which exhibited intramolecular charge transfer (ICT) character and aggregation-induced emission (AIE) performance. Based on the electron-donating ability originated from the highly localized π electrons, electrons could be transferred from these TPE derivatives to electron-deficient nitroaromatic explosive picric acid (PA) resulting in quenched fluorescence emission. Thus, they had excellent sensitivity and selectivity for PA detection in aggregate states. The limits of detection (LOD) were 1.64, 0.50, 0.93, 1.48, 0.49 and 0.35 μM for them, respectively, captured from fluorescence signal. Moreover, a semi-quantitative detection method based on smartphone digital image was developed to detect PA with LOD of 490, 26.6, 69.1, 74.1, 3.57 and 100 μM, respectively. The dual-mode sensors had excellent detection character improving the accuracy of the detection result. The fluorescence quenching mechanism was explored as photoinduced electron transfer (PET) and energy transfer. This study provided a new strategy for the design of AIE active materials, expanded the application of smartphones in explosive detection which had practical potential in effective sensing. • Six compounds (TPEH , TPEOMe , TPEtBu , TPEOH , TPECN and TPEPy) had been synthesized. • These compounds exhibited significant aggregation-induced emission properties. • PA was detected by fluorescence sensing and smartphone colorimetry. • The dual-mode sensors improved the accuracy of the detection result. • The fluorescence quenching mechanism between TPE derivatives and PA was studied. [ABSTRACT FROM AUTHOR]

A series of novel fluorinated tetraphenylethylene (TPE)-based 8–10 membered medium ring compounds with photochromic characters and mechanofluorochromic (MFC) features were concisely synthesized. These solid powder of 8, 9 and 10 members fluorinated TPE-based medium ring, 441F , 461F and 481F all exhibited photochromic character, comparing with their alkyl analogues. Notably, the solid powder of 441F displayed an intuitively evident crimson after ultraviolet (UV) irradiation and then reversed identical to its original white color within 42 s. Furthermore, the various photochromic abilities and stimuli responsive fluorescence of these compounds could be regulated by fluorinated loops' size. Such fast responsive and high-contrasted of photo switchable color of 441F promise candidate for photochromic materials. A series of novel fluorinated cyclic TPE with integration of AIE properties, reversed MFC features and conspicuous photochromic behaviors were synthesized. The various photochromic and MFC behaviors of these compounds could be regulated by the fluorinated loop's sizes. Remarkably, solid powder of the fluorinated mesocyclic TPE, 441F , showed intuitional color change, switching from white to a visually recognizable crimson after UV irradiation, and then it reversed to its original color within 42 s. [Display omitted] • A series of novel fluorinated mesocyclic TPE compounds with conspicuous photochromic behaviors were synthesized. • The photochromic and MFC behaviors of these mesocyclic compounds could be regulated by the fluorinated loop's sizes. • 441F powder switched from white to intuitional crimson color after UV irradiation, then reversed to white within 42 s. • Comparing the previous photocyclization in TPE, this is the first example of photocyclization on benzene ring of TPE. [ABSTRACT FROM AUTHOR]

A series of position and conjugation–dependent donor–acceptor naphthalimide–tetraphenylethylene isomeric conjugates (NTPEs 1 – 6), possessing single–bond (C–C), vinyl linkage, and acetylene linkage between naphthalimide and tetraphenylethylene moieties, were designed and synthesized. NTPEs 1 – 6 were fully characterized by 1H NMR, 13C NMR, and mass spectroscopy. The effects of the position and conjugation in NTPEs 1 – 6 on the absorption, fluorescence, and aggregation–induced emission enhancement were explored. Among the NTPEs 1 – 6 , the 4–substituted NTPEs show the most prominent electronic communication. Furthermore, the 3–substituted NTPEs and 4–substituted NTPEs with single–bond linkage exhibit aggregation–induced emission enhancement, whereas 4–substituted NTPEs with vinyl linkage, and acetylene linkage show small aggregation–caused quenching. The NTPEs 1 – 3 and 5 show enhanced fluorescence and long fluorescent lifetimes in aggregated state, exhibiting aggregation induced emission. The nanoaggregates of NTPEs 1 – 6 formed in tetrahydrofuran/water (1:9, v/v) solutions are observed by scanning electron microscopy (SEM), fluorescence microscopy, and dynamic light scattering (DLS). Image 1 • Donor–acceptor based naphthalimide–tetraphenylethylene isomeric conjugates (NTPEs) were designed and synthesized. • The nature of conjugation and position perturbs the absorption, emission, and AIE properties of the NTPEs. • The 4-substituted NTPEs show the most prominent electronic communication. • The fluorescence time–decay profiles further supports aggregation induced emission of NTPEs. [ABSTRACT FROM AUTHOR]

Abstract The influence of different states of AIE derivative with columnar liquid crystalline phase on circularly polarized luminescence (CPL) was investigated in this work. Two novel tetraphenylethylene derivatives with multiple cholesterol units (TPE-C and TPE-SC) were prepared. They exhibited enantiotropic liquid crystalline behaviours with the ordered hexagonal columnar mesophase. They possessed excellent AIE properties in H 2 O-THF system. The fluorescence quantum yields of TPE-C and TPE-SC at solid state were as high as 28.8% and 22.6%, respectively. The chiral transfer from cholesterol units to TPE cores was confirmed by CD spectra. The studies on CPL spectra suggested that their CPL behaviors were tuned by the different states. They showed weak CPL properties at solid and isotropic state but strong CPL luminescence at liquid crystalline phase based on the orderly columnar self-assembly. The g lum of TPE-SC at liquid crystalline phase reached 8.83 × 10−2. Highlights • Novel tetraphenylethylene AIE derivatives (TPE-C and TPE-SC) with columnar liquid crystalline mesophases were prepared. • They possess hexagonal columnar mesophases. • The chirality of cholesterol units was transferred to TPE cores. • The CPL properties varied with different states of liquid crystalline AIE materials were firstly studied. • The g lum of TPE-SC at mesophase is as high as 8.83 × 10−2. [ABSTRACT FROM AUTHOR]

Abstract Efficient production and flexible surface functionalization are important developing directions for the synthesis of polymeric nanomaterials. In this work, aggregation-induced emission (AIE) polymeric nanoparticles (PNPs) were efficiently synthesized by encapsulating a model AIE luminogen, tetraphenylethylene (TPE), within a polymeric matrix via miniemulsion polymerization. The AIE PNPs with similar emission and particle properties were synthesized in a wide solid content range of 8–40 wt%. The particle size and photoluminescence intensity of AIE PNPs could be flexibly tuned by synthetic parameters including the surfactant content and TPE content. Furthermore, the surface carboxyl- and amino-functionalization of AIE PNPs were conveniently achieved through copolymerization of styrene and functional monomers methacrylic acid and 2-aminoethyl methacrylate hydrochloride, respectively, in miniemulsions. The surface functionalization extent could be facilely tuned by the content of functional monomers. This miniemulsion polymerization based technique could be a feasible and efficient method to prepare AIE PNPs with versatile surface functionalization, tunable brightness, and controllable particle properties for the applications in biodetection, bioimaging, etc. Graphical abstract Image 1 Highlights • AIE PNPs can be efficiently made via high solid content miniemulsion polymerization. • Surface functionalization of AIE PNPs can be directly performed during polymerization. • Brightness, particle properties, and surface functionalization of AIE PNPs can be facilely tuned. [ABSTRACT FROM AUTHOR]

Abstract Aggregation-induced emission (AIE) should be a unique and abnormal fluorescence phenomenon that has attracted increasing research interest over the past decades. Since its discovery by Tang et al., a number of AIE-active molecules with different structure, functional groups and optical properties have been reported. These AIE-active molecules can be further utilized to fabricate various functional materials, which have exhibited great potential for different applications. By taking advantage of this AIE feature (quenching in solution but emission in aggregation state), various bio-/chemosensors have been constructed for detection of relation biological and chemical species. Although some review items on these aspects have been summarized previously, some recent advances and development about targeted biosensor are not included. In this review article, the recent advances and progress in the construction of AIE-active luminogens based fluorescent bio-/chemosensors has been summarized. The challenge and further development of the construction of AIE-active molecules based bio-/chemosensors are also highlighted. Graphical abstract Image 1 Highlights • Design and fabrication of sensors based on AIEgens. • AIEgens could be used for chemosensor. • AIEgens could be used for biomosensor • The utilization of AIEgens for various biomedical applications. [ABSTRACT FROM AUTHOR]

Abstract Deep-blue organic light-emitting diodes (OLEDs) with low efficiency roll-off and high color purity are critical for the tetraphenylethylene-based AIEgens derivative. In this work, the novel blue emitter, 3-(1-phenyl-1 H -phenanthro[9,10-d]imidazol-2-yl)-10-(4-(1,2,2-triphenylvinyl)phenyl)-10H-phenothiazine (TPEPPI), was designed and synthesized to develop a new material possessing aggregation-induced emission (AIE) characteristics and deep-blue emission. The TPEPPI hardly emits fluorescence in tetrahydrofuran (THF), the luminescence intensity increased by 5.5 times when the water content reaches 95%, showing strong fluorescence in aggregated state. Three different non-doped device structures were fabricated, all of the OLEDs showed deep-blue emission (∼460 nm). The optimized device Ⅲ exhibited an emission peak at 467 nm, a maximum current efficiency of 4.25 cd A−1, a maximum power efficiency of 3.35 lm W−1, a maximum luminance of 16750 cd m−2, a maximum external quantum efficiency of 2.36%, and the essentially negligible efficiency roll-off of 3.3%, which is the first observation of deep-blue emission using a tetraphenylethylene-substituted phenothiazine-based AIEgens derivative in OLEDs. Graphical abstract Image 1 Highlights • A new AIE-active phenothiazine-based substituted TPE blue emitter was designed. • Non-doped device with essentially negligible efficiency roll-off of 3.3%. • Deep-blue emission with TPE-substituted phenothiazine-based AIEgens derivative. [ABSTRACT FROM AUTHOR]

Abstract Encapsulating fluorogens into polymeric nanoparticles is proven an effective method to shield the fluorogens from the outer environment and improve the biocompatibility as well. Conventionally, the fluorogens are firstly conjugated to the monomers and then polymerized into macromolecules, where tedious molecular design and synthesis was unavoidable. Herein, we present a facile method to prepare the fluorogen-functionalized polymer, and then use the polymer as build blocks to fabricate nano-probes aiming at cell-imaging. Unlike the conventional ways, we prepared a homopolymer with active esters on the repeating units and used the polymer as matrix to graft fluorogens and hydrophilic groups. Note that the fluorogen and hydrophilic groups selected in our study were tetraphenylethylene (TPE) and polyethylene glycol (PEG), respectively. The resulting amphiphilic random copolymer self-assembled into spherical nanoparticles with size around 225 nm in aqueous solution. With comparable amount of TPE moieties, the polymeric nanoparticles demonstrated much stronger emission than the nanoparticles formed by small molecules of TPE derivatives. The polymeric nanoparticles showed very good stability and biocompatibility, and were employed to label Hela cells and gave high-contrast fluorescent images. We anticipate that the methodology presented in this study might be developed into a general avenue to encapsulating fluorogens into nanoparticles. Graphical abstract Image 1 Highlights • Post-polymerization modification was employed to prepare amphiphilic copolymers. • The copolymer contains TPE and PEG groups on the side chain. • The nanoparticles formed by the copolymers showed strong fluorescent emission. • The nanoparticles were applied to label Hela cells with high-contrast images. [ABSTRACT FROM AUTHOR]

Three novel gold(I) complexes based on triphenylamine, carbazole or tetraphenylethylene moiety have been successfully designed and synthesized. Meanwhile, their structures were characterized by nuclear magnetic resonance spectroscopy and elemental analysis. Their solid-state luminescence characteristics were surveyed by photoluminescence spectroscopy, and their distinct mechanical stimulus-responsive behaviors in the solid state were also investigated by photoluminescence spectroscopy. Interestingly, the solid-state phosphorescence and emission lifetimes of these mononuclear gold(I) complexes 1 – 3 could be tuned by introducing different fluorophores involving triphenylamine, carbazole or tetraphenylethylene. Furthermore, luminogen 1 exhibited switchable mechanochromic luminescence behavior with color change from yellow to colorless, and the solid-state luminescence on-off mechanochromism between yellow-green and colorless of luminogen 2 could also be observed. However, no mechanochromism phenomenon was observed for tetraphenylethene-containing luminogen 3 . The powder X-ray diffraction results suggested that the unusual high-contrast mechanochromism characteristics of luminogens 1 and 2 could be attributed to a crystalline-to- amorphous morphology transition. [ABSTRACT FROM AUTHOR]

A series of novel tetraphenylethylene aromatic acylhydrazone derivatives 11 , 12 and 13 with 4, 8 or 12 alkyl chains were designed and synthesized in yields of 82–85%. Studies on the mesomorphic properties suggested the ordered hexagonal columnar mesophase for compounds 11 , 12 and 13 . The increase in the number of alkyl chains was favourable for decreasing the phase-transition temperatures and extending the mesophase temperature range. Further, samples 11 , 12 and 13 presented an excellent AIE effect. The fluorescence intensities increased by 70, 84 and 43 times for samples 11 , 12 and 13 , respectively. The absolute fluorescence quantum yields were 18.7%, 27.4% and 23.8% in solid films at room temperature and 6.7%, 24.2% and 17.3% in the mesophase. These results suggested that the number of alkyl chains greatly influenced the fluorescence emission and sample 12 with 8 alkyl chains exhibited the strongest fluorescence emission. Sample 12 also displayed the electroluminescence performance on OLED device. [ABSTRACT FROM AUTHOR]

A tetraphenylethylene fluorophore based on D-π-A structure was employed to design and synthesize the TPE-Py-FP probe for selective detection of ATP. TPE-Py-FP had the advantages of large Stokes shift, great hydrophilicity and good selectivity. Especially, the pyridine portion and quaternary ammonium structure of TPE-Py-FP had positively charged sites, which could be used as recognition groups to interact with the negatively charged triphosphate structure of ATP. Then the fluorescence emission of TPE-Py-FP at 580 nm showed a "turn-on" response after adding ATP. Moreover, this probe could rapidly respond to ATP over a wide linear range of 10–120 μM and the limit of detection (LOD) was 2.76 μM. The zeta potential and dynamic light scattering experiments revealed that the detection mechanism was mainly the electrostatic adsorption interaction between the dual positively charged sites of TPE-Py-FP and the negatively charged triphosphate structure of ATP. Additionally, TPE-Py-FP could localize in mitochondria specifically with a Pearson's coefficient of 0.81, and show great utility in monitoring the fluctuation of mitochondrial ATP level. [Display omitted] • TPE-Py-FP has the advantages of large Stokes shift, great hydrophilicity and low fluorescence background. • TPE-Py-FP with the dual positively charged sites shows high selectivity and sensitivity for ATP detection. • TPE-Py-FP has excellent mitochondrial targeting ability with a Pearson's coefficient of 0.81 • TPE-Py-FP is successfully applied to monitor the fluctuation of mitochondrial ATP in cells under drug induction. [ABSTRACT FROM AUTHOR]

Herein, a new water soluble Ca 2+ fluorescence chemosensor based on aggregation-induced emission (AIE) characteristics has been developed, combining the AIE effect of tetraphenylethylene (TPE) and the complexation capability of bidentate pyridine carboxylate. The bidentate pyridine carboxylate group provides the chemosensor with good water-solubility which is important for detection in biological systems. This chemosensor L showed high selectivity for Ca 2+ by a turn-on response in almost pure aqueous solution with a detection limit of 51.2 nM. L can be used as a recyclable Ca 2+ fluorescent chemosensor in the presence of EDTA. Moreover, the chemosensor L was successfully applied to imaging detection and real-time monitoring of Ca 2+ in living cells with low toxicity and good membrane permeability. [ABSTRACT FROM AUTHOR]

In this work, we report a simple strategy by mixing a naphthyl-substituted tetraphenylethylene derivative ( TPE ) and cucurbit[8]uril (CB[8]) in aqueous solution, based on the host-guest complexation between CB[8] and TPE , to construct supramolecular hyperbranched polymers. The host-guest interaction between CB[8] and TPE efficiently restricted the intramolecular rotation and the non-radiative relaxation channel, thereby resulting in the strong emission of TPE in dilute solution. We further investigate the self-assembly behaviors of the obtained supramolecular hyperbranched polymers in aqueous solution, which exhibited individual spherical aggregates with the diameter of ∼60 nm. By using the spherical aggregates as energy donors and eosin Y disodium salt (EY) as energy acceptors, we have constructed highly efficient aqueous light-harvesting systems in aqueous solution. [ABSTRACT FROM AUTHOR]

A series of tetraphenylethylenes (TPE) derivatives in which one or more of the phenyl rings have been replaced by a fused fluorine containing 2,3,4,5-tetrahydrobenzo[b][1,4]dioxocane unit have been synthesized. The analysis of the photoluminescence emission under application of mechanical grinding and thermal treatment show that in addition to the expected aggregation induced emission behavior observed in solution, these simple modifications of the TPE system confer mechanofluorochromic properties to the corresponding materials. The results of X-ray diffraction and theoretical calculations suggest that the introduction of tetrafluorobutylenedioxy “loops” control the balance between weak intermolecular interactions and thus the interconversion between “macro” and “micro-aggregates” which is proposed as the basic mechanism for the observed MFC properties. [ABSTRACT FROM AUTHOR]

New tri- or tetraphenylethylene-substituted phenylcarbazole derivatives exhibiting aggregation-induced emission were synthesized by the synthetic route including Pd-catalyzed Suzuki or Buchwald-Hartwig coupling and Heck reactions. The results of evaluation of the thermal, optical, electrochemical, photophysical, and charge-transporting properties of the synthesized derivatives are presented. The compounds possess high thermal stabilities with 5% weight loss temperatures exceeding 350 °C. Some of the synthesized compounds form glasses with glass transition temperature ranging from 77 to 114 °C. Their maximum fluorescence intensity wavelengths are in the range of 472–498 nm. The highest photoluminescence quantum yield of 43.9% was observed for the solid sample of 2-(4-(4-(1,2,2-triphenylvinyl)phenylethenyl)phenyl)-9-ethylcarbazole. The electron photoemission spectra of the films of the synthesized compounds revealed ionization potentials of 5.49–5.74 eV. Hole drift mobilities in the layers of 9-phenylcarbazole para- substituted with tri- or tetraphenylethylene moities reached 10 −3 cm 2 V −1 s −1 at moderate electric fields, as established by the time-of-flight technique. [ABSTRACT FROM AUTHOR]

A series of new diarylethene compounds with both photochromism and aggregation-induced emission have been synthesized by connecting tetraphenylethene and triphenylethene to the bisthienylethene. All the four compounds exhibit good photochromism upon irradiation with alternative UV and visible light. And they are all provided with aggregation-induced emission properties in tetrahydrofuran solution with different fraction of water, non-emissive in the pure tetrahydrofuran solution but yellowish green fluorescence in the aggregate or solid state. Furthermore, the compounds connecting tetraphenylethene to the bisthienylethene were found to exhibit the stronger fluorescence emission in the aggregate or solid state than the ones connecting triphenylethene to the bisthienylethene. [ABSTRACT FROM AUTHOR]

Two novel aggregation-induced emission compounds harnessing Excited-State Intramolecular Proton Transfer process based on salicylideneaniline derived from tetraphenylethylene and cholesterol moieties were synthesized and characterized. One of the compounds could gelate in cyclohexane exhibiting gelation-induced enhanced emission and the emission intensities can be reversibly changed with the gel-solution transition by alternate cooling and heating. Moreover, this compound showed photochromic behavior both in gel and solid states under UV light irradiation due to the loose packing of the molecules and permitting the molecule to rotate, which may be a potential candidate for external stimuli-responsive materials through tuning the self-assembly process of the functional gelator. [ABSTRACT FROM AUTHOR]

A mechanically interlocked host rotaxane was synthesized by incorporation of tetraphenylethylene and phenanthroimidazole units in the axle to exhibit significant emission bands and demonstrate host-guest interactions via its topologically constrained cavity, and thus to induce a significant and selective fluorescence quenching of rotaxane towards ferric ion (Fe 3+ ). The quenching efficiencies of rotaxane with both ferric ion (Fe 3+ ) and bio-molecular Hemin (containing ferric ion) were investigated to compare the sensitivities of rotaxane for ferric ion and bio-molecular Hemin. The present study could probe host-guest interactions of rotaxane with ferric ion (Fe 3+ ) and Hemin as well as monitoring the biological conversion of Hemin to Heme in presence of sodium ascorbate (as a reducing agent), where the reduced non-toxic Heme could be generated from the toxic form of Hemin. [ABSTRACT FROM AUTHOR]

As a very important noble metal, palladium has extensive application in alloy materials, catalysts, jewelry, and so on. Due to concern for the effect of the palladium ion on environment and human being health, the detection of the palladium is necessary. However, the analysis of the palladium ions with high selectivity and sensitivity is very rare. Here, we synthesized sulfur-containing tetraphenylethylene (TPE) tetracycle tetrathioether in high yield, which displayed aggregation-induced emission enhancement (AIEE) and 100% fluorescence quantum yield (Φ F) in the aggregation state. Exceptionally, when 21 kinds of metal ions were added into the TPE tetrathioether in THF solution, only palladium ions could quench the bright fluorescence of the TPE tetrathioether, displaying extremely high selectivity of the probe. Meanwhile, the interaction between palladium and TPE tetrathioether produced a white to black precipitate, enabling visual detection of the palladium ion. The limit of detection (LOD) was as low as 3.85 × 10−7 M, indicating a high sensitivity of probe. By the X-ray crystallographic analysis and NMR spectra, it was found that palladium ions could coordinate with four sulfur atoms in the caves of TPE tetrathioether at gem sites. The design of TPE macrocyclic thioether with quantitative Φ F provided a new approach to very high selective and sensitive probe, and even visual detection for palladium ions. [Display omitted] • New tetraphenylethylene macrocycle thioether with quantitative fluorescence quantum yield is synthesized. • The TPE macrocycle could include palladium ion in its cavity, showing highly selective and sensitive detection of palladium. • The detection of palladium ion can be visualized by naked eye because of color change besides fluorescence quenching. [ABSTRACT FROM AUTHOR]

The development of effective detectors for volatile organic vapor detection has attracted extensive attention. Through solid-state oxidative coupling polymerization, poly(tetraphenylethylene-co-phenylene)s were prepared by mechanical grinding of tetraphenylethylene and 1,4-dipentoxybenzene with FeCl 3 as the oxidative catalyzer. The FT-IR and NMR spectra confirmed the main chain to be composed of segments of dipentoxybenzenes, segments of tetraphenylethylenes, and segments of fused ring structures, which were formed via the intermolecular coupling reaction and intramolecular coupling reaction. With the increased ratios of TPE monomers, the copolymers displayed a concentration-induced discoloration behavior from blue-emitting red-shifting to green-emitting. Although the formation of planar fused rings led to an ACQ phenomenon of the copolymers, the polymer conformations, and the polymer stacking could be adjusted by solvent molecules absorbed by the TLC plates, thereby the copolymers could be used as fluorescent probes for various violate organic vapors. The multicolor fluorescent could be observed by the naked eye to distinguish a variety of organic molecules with similar structures, for example, methanol and other alcohols, pentane and other alkanes, the dimethyl benzenes with different substitution positions, and so on. Therefore, multicolor fluorescent probes have a potential application in the detection of volatile organic vapors. [Display omitted] • Through the solid-state oxidative coupling polymerization, PTP was synthesized. • The concentration-induced discoloration property could be observed from PTP. • Multicolor fluorescence response of PTP to various volatile organic vapors. [ABSTRACT FROM AUTHOR]

At present, organic small molecule-based hole transporting materials (HTMs) are extensively investigated in perovskite solar cells (PSCs), and a variety of structures have been developed. Most of the studies in HTMs focus on the central scaffolds, while little attention is paid to the periphery groups. In this work, two small organic molecules (TPE-2Cz and TPE-3Cz) are designed and synthesized, with tetraphenylethylene as the core structure, N -ethylcarbazole and methoxyphenyl as the peripheral groups. The C 2 or C 3 position on N -ethylcarbazole is connected to the arylamine N atom in TPE-2Cz and TPE-3Cz, respectively. We systematically investigate how the N -ethylcarbazole modified at different positions (C 2 or C 3) affect the property of HTMs and finally the performance of PSC devices. Compared with TPE-2Cz, TPE-3Cz shows a higher hole mobility, better hole extraction and hole transport ability. The device based on TPE-3Cz as the hole transport material achieves a decent power conversion efficiency of 20.94%. Therefore, our work reveals that the periphery group engineering should be taken into consideration when designing organic HTMs. [Display omitted] • Two small organic molecules were designed and synthesized, with N -ethylcarbazole as the peripheral groups. • In TPE-2Cz and TPE-3Cz, the effect of substitution position was systematically discussed. • The TPE-3Cz-based device shows a decent power conversion efficiency of 20.94%. [ABSTRACT FROM AUTHOR]

By incorporating tetraphenylethene (TPE) into the platform of polyphenylbenzene through different linkage modes and adjustment of conjugation, four highly twisted luminogens were synthesized, of which showed good thermal stability verified by thermogravimetric and differential scanning calorimetry analysis. All these luminogens exhibited typical aggregation induced emission phenomenon. Utilizing them as emitting layers, nondoped fluorescent organic light-emitting diodes were fabricated. Thanks to their well-designed highly twisted structures, all devices showed blue to deep-blue emission. The deep-blue emission devices based on emitter containing meta -tetraphenylethene exhibited maximum current efficiency of 1.32 cd A −1 , while the Commission Internationale de l'Éclairage (CIE) coordinates were (0.16, 0.12), close to our previous report of deep-blue emission. Combined with our previous results, it might be predicted that perhaps, the CIE coordinates limit of TPE-based luminogens should be around (0.15, 0.11), and the CIE y is hard to break through 0.10, unless other building blocks with shorter conjugation used instead of TPE. [ABSTRACT FROM AUTHOR]

Organo-soluble tetraphenylethylene derived monolayer-protected gold nanorods were prepared and characterized. The prepared gold nanorods covered with tetraphenylethylene thiol via the strong covalent Au–S linkage were found to be soluble and stable in organic solvents. The successful thiol exchange and modification of tetraphenylethylene derivative molecules on gold nanorods were confirmed from UV–Vis, Raman and FT-IR spectra. The gold nanorods were found to have a quenching effect on the aggregation-induced emission of the tetraphenylethylene thiol molecule modified on their surfaces. [ABSTRACT FROM AUTHOR]

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 (Φ F) 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 Φ F. 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. • A series of tetraphenylethylene modified D-π-A fluorophores were designed and synthesized. • The compounds showed excellent aggregation-induced emission (AIE) and mechanofluorochromism (MFC) properties. • TPEF exhibited high-contrast turn-on MFC property and quantitative detection of pressure in turn-on modal. • The materials were applied for the detection of picric acid (PA) with low limit of detection. [ABSTRACT FROM AUTHOR]

Chiroptical functional materials with circularly polarized luminescence (CPL) properties have drawn increasing interest for their potential applications in optoelectronics and chiral sensing. However, the development of CPL materials with both large luminescence dissymmetry (g lum) factors and high quantum yields (Φ F) in solid state is still a challenging task. In this work, organic–inorganic hybrid silica films have been prepared by the in-situ polycondensation of a cholesteric liquid-crystalline organosilane with the addition of a chiral dopant and an aggregation-induced emission (AIE)-active tetraphenylethene (TPE) derivative under an acidic condition. The resulting films emit bright CPL with the absolute g lum values about 0.15, which were mainly caused by the long-range ordered supramolecular helical structure. It is found that the handedness of the CPL was dominated by the selective reflection of the cholesteric liquid crystal films. • Hybrid silica films were prepared by polycondensation of cholesteric liquid-crystalline organosilanes with AIE organosilanes. • The silica films showed good circularly polarized luminescence activity and enhanced fluorescence efficiency. • It was found that the handedness of the CPL was dominated by the selective reflection of cholesteric liquid crystal films. [ABSTRACT FROM AUTHOR]

Various aggregation-induced emission luminogen (AIEgen) derivatives based on TPE (tetraphenylethylene) containing the electron-donating moiety (–NMe 2 , –OMe) and bromine (–Br) moiety were prepared, which are key intermediates for tuning the emission wavelength of TPE; Type 1: dimethylamine (NMe 2)-substituted derivatives, Type 2: methoxy (OMe)-substituted derivatives, Type 3: bromine (Br)-substituted derivatives, and Type 4: mixed formulation derivatives. We systematically analyzed the synthesis, AIE properties, photophysical properties, and biological applicability of 16 types of TPE-based AIEgen. We expect that our investigation, especially the donor-substitution effect of TPE, could serve as a guide to developing a new TPE-based AIEgen series as well as fluorescent probes. [Display omitted] • Donor-substitution effect of tetraphenylethylene (TPE) AIEgens was systematically identified. • Synthesis and photophysical property of 16 derivatives of TPE was disclosed. • CLSM imaging of cells using the TPE derivatives was demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: Two novel aggregation-induced emission compounds derived from tetraphenylethylene and gallic acid were synthesized and characterized. Both of the emission compounds possessed mesomorphic properties and exhibited mesomorphic phases over a wide temperature range and the thermal-induced mesomorphic transition from metastable to stable phases accompanied by a change of the luminescent color. The mesomorphic transition may be ascribed to liquid crystalline phase transition. The emission compounds possess different gelation behavior in organic solvents. The emission intensities of the emission compounds can be reversibly changed with the gel–solution transition by alternate cooling and heating. Moreover, the color and emission of these organogelators can be repeatedly switched by various external stimuli including pressing, heating and solvent-fuming. These new compounds may offer potential as external stimuli-responsive materials. [Copyright &y& Elsevier]

Abstract: Four new gem-tetraphenylethylene-based oligomers were synthesized by Suzuki coupling reaction in good yields (62–80%) and characterized by NMR, mass spectrometer and elemental analysis. The absorption maxima of the synthesized oligomers in the solution possess similar absorption bands located at 328–332 nm. They are shown to be thermally stable and emit light in blue region (404–485 nm). All the oligomers are AIE-active, emit weakly in solutions with Φ f values not exceeding 4%, become strong emitters in the aggregated states and the PL intensity values increase up to 18-fold. The results of CV measurements of the oligomers showed good reversibility, indicating that the compounds have good electrochemical stability. The HOMO values of the oligomers are in the range of −5.63 to −5.61 eV. The photoluminescence properties in aggregate-state and the high HOMO energy levels of these oligomers make them applicable as an active material for a light-emitting device. [Copyright &y& Elsevier]

Luminescent Down-Shifting (LDS) is an optical approach applied in several photovoltaic (PV) technologies in which high energy solar radiation is converted to a wavelength region where the response of the photovoltaic devices is better. The use of LDS layers on organic photovoltaics (OPV) could serve two purposes: to prevent cell degradation by filtering the incident ultraviolet (UV) radiation and to improve the spectral response of PV cells at short-wavelength. This work reports, the design and synthesis of a series of tetraphenylethylene (TPE) derivatives based on TPE-A or A-π-TPE-π-A molecular structure featuring various electron-acceptor (A) groups. The photophysical properties of the new LDS compounds were systematically studied in 1,4-dioxane solution and film (Zeonex) by UV–visible absorption and fluorescence spectroscopy, and electrochemical properties studied by cyclic voltammetry. Thermal stability of the new LDS compounds was evaluated by Thermogravimetric analysis (TGA). Theoretical computational studies provided evidence of existence of intramolecular charge-transfer (ICT) between frontier orbitals of donor and acceptor moieties. The good photophysical and thermal properties of the synthesized TPE derivatives, associated with high molar absorption coefficients in UV spectrum and emission maximum in the range of 476–531 nm, make them promising candidates for LDS layers in OPV application. [Display omitted] • TPE dyes with different acceptor structures were synthesized and characterized. • Photophysical properties were investigated by theoretical/experimental studies. • Electrochemical properties were investigated by DFT and VC studies. • ICT mechanism between donor and acceptor moieties was evidenced by DFT method. • They showed good optical and thermal properties to be used as LDS layer in OPV cell. [ABSTRACT FROM AUTHOR]

Aggregation-induced fluorescent materials are of great importance in optoelectronics and bioelectronics in solid-state devices. Herein, functionalized oligothiophenes were designed and synthesized with the tetraphenylethylene (TPE) groups to explore the length effect and color tuning for the effective detection of explosives. Remarkably, compounds 2TPE1T and 2TPE2T show an aggregation-induced emission phenomenon, while longer π –conjugated molecules 2TPE3T , 2TPE4T , TPE5T and 2TPE6T show aggregation-caused quenching character, where the reason has been explained based on UV – Vis spectra ranging from 378 to 446 nm. Furthermore, fluorescent titration experiments demonstrate that dye 2TPE1T has a better response than dye 2TPE2T for nitroaromatics. The visual detection limit of 2,6-DNT is 18.2 ng/cm2 in the test strip of 2TPE1T. In addition, there is an exquisitely linear curve between the theoretical and experimental energy levels for TPE functionalized oligothiophenes. The influence of introducing TPE end-capped on the energy gap convergence has also been discussed, showing the energy level correlation of linear fitting combined with a theoretical and experimental perspective. This result not only paves the way toward π –functional materials but also expands their applications. [Display omitted] • A family of TPE functionalized oligothiophenes has been prepared. • Dyes 2TPE1T and 2TPE2T show an AIE phenomenon. • Dye 2TPE1T has a better response than dye 2TPE2T for nitroaromatics. • Naked-eye detection limit of 2,6-DNT is 18.2 ng/cm2 in the test strip of 2TPE1T. • An exquisitely linear curve is observed between theoretical and experimental. [ABSTRACT FROM AUTHOR]

Abstract: Two novel red fluorescent thieno-[3,4-b]-pyrazine-cored molecules containing tetraphenylethylene as peripheral groups, T-TP and T-TP1, are designed and synthesized. Their photophysical, electrochemical and electroluminescent properties are investigated. They are characterized by large Stokes shifts of over 100 nm. The bulky peripheral groups enable these molecules to be well soluble and provide the site-isolation effect on the planar emissive core. These novel materials are used as non-doped emitting layer to fabricate organic light-emitting diodes (OLEDs) by vacuum evaporation technique. Saturated red emission is obtained with a maximum brightness of 1385 cd m−2 and a luminance efficiency of 0.66 cd A−1. [Copyright &y& Elsevier]

Sensitive detection of explosives has always been a frontier research for scientists. In this work, two [3 + 2] imine organic cages (1 and 2) stemmed from distinct TPE-based dialdehydes (TPE-2CHO/TPE-2PCHO) and common tri(2-aminoethyl)amine were obtained. Both of them are fluorescence silence in solution and high-efficient AIE could be observed, which is different from all known TPE-based organic cages with AIEE properties. Because of the cage skeleton encircled by multiple benzene rings, the two cages can effectively detect various explosives including nitrobenzene, 2-nitrotoluene, 3-nitrotoluene, 4-nitrotoluene and 2,6-dinitrotoluene both in solution and in the solid state, in which cage 1 displays higher detection ability due to its nine encircling benzene donors [Display omitted] • Partial benzene ring modified TPE-based dialdehydes were used to construct imine organic cages. • Cages 1 and 2 show typical AIE characteristics. • The two cages can effectively detect various explosives both in water phase and solid state. [ABSTRACT FROM AUTHOR]

This work develops a facile synthesis for aggregation-induced emission (AIE)-active hyperbranched polyglycidols (HPGs) to design a solid-state sensor for detecting nitroaromatic explosives. The tetraphenylethylene moieties were conjugated onto the periphery of the HPGs in a single step using dynamic boronate ester cross-linkers. The resulting AIE-active HPGs exhibited excellent AIE characteristics in tetrahydrofuran (THF)/H 2 O mixtures, emitting a strong blue fluorescence under UV irradiation. Dynamic light scattering and transmission electron microscopic analyses demonstrated that the self-assembled nanosized aggregates were stable in the THF/H 2 O mixture. The fluorescence of the aggregates was dramatically quenched by various nitro compounds, including 2,4,6-trinitrophenol (or picric acid; PA), 2,6-dinitrophenol, 4-nitrophenol, 4-nitrotoluene, and nitromethane. The nano-aggregates exhibited extraordinary sensitivity towards PA, with a Stern‒Volmer constant (K sv) of 2.27 × 104 M−1 and a limit of detection of 40 ppb. Paper strips encapsulating the aggregates exhibited a vivid visual quenching, promising the practical applicability of these polymers as solid-state sensors for the detection of nitroaromatic explosives. [Display omitted] [ABSTRACT FROM AUTHOR]

The elegant electroswitchable color/emission properties of electrochromic/electrofluorochromic dual-functional materials motivates the exploration of their new applications. In this work, a new poly (urea-urethane) was synthesized via nucleophilic copolymerization of electroactive oligoaniline derivative, solid-emissive tetraphenylethylene groups, and alkyl isocyanate. The resultant poly (urea-urethane) exhibited good electroactivity and desirable aggregation-induced emission properties. High-performance electrochromic/electrofluorochromic behavior had been disclosed with a high optical contrast ratio of ΔT = 50.4%, a moderate fluorescence on/off ratio of 10.5, and high coloration efficiency of 503 cm2/C at 768 nm. A reflective/emissive dual-mode display device had also been manufactured based on the resultant poly (urea-urethane) and charge-balancing V 2 O 5 , exhibiting a reversible color change and tunable fluorescence conversion upon the electric stimulus. Furthermore, this polymer showed an interesting color/fluorescence response to H 2 O 2 , due to the linkage mechanism between its redox states and optical properties. The spray-coated poly (urea-urethane) test strips were employed in visualized dual-determination of H 2 O 2 with gradual color change from gray to dark green, along with an obvious fluorescence change from light blue to dark, which displays easy operation and rapid detection. This work reports the synthesis of an electrochromic/electrofluorochromic poly (urea-urethane) bearing AIE-active groups and electroactive oligoaniline segments, which shows great potentials in reflective/emissive dual-mode display and colorimetric/fluorometric dual-determination of H 2 O 2. [Display omitted] • A new poly (urea-urethane) (PUU) bearing AIE and oligoaniline groups was synthesized. •PUU displays electrochromic/electrofluorochromic dual-functional performance. •A reflective/emissive dual-mode display device was fabricated based on PUU and V 2 O 5. •Spray-coated PUU test strips were employed in visualized dual-determination of H 2 O 2. [ABSTRACT FROM AUTHOR]

A novel tetraphenylethylene derivative tethered with polyhedral oligosilsesquioxane nanocages (TPE-POSS) was designed and synthesized as turn-on fluorescent sensor for detection of F−. The aggregation-induced emission (AIE) property, self-assembly behavior and detection mechanism of the complex were then elucidated by UV–vis absorption spectra, photoluminescence spectra and dynamic light scattering experiments. The results reveal that POSS nanocages can collapse due to the Si–O bond cleavage with the present of F−. The POSS nanocages collapse then trigger the AIE activity of TPE luminogens, endowing TPE-POSS with excellent turn-on detecting ability, high selectivity and sensitivity to F−, with a detection limit as low as 1.66 × 10−7 M. [Display omitted] • A novel TPE derivative tethered with polyhedral oligosilsesquioxane nanocages (TPE-POSS) was synthesized. • The TPE-POSS possesses aggregation-induced emission (AIE) characteristic and large Stokes shift. • The TPE-POSS displays turn-on detecting ability to fluoride ions. [ABSTRACT FROM AUTHOR]

Since the discovery of aggregation induced emission (AIE) phenomenon, various stimuli-responsive materials have been rapidly developed. However, the development of self-assembled amphiphilic light-responsive materials in aqueous solution needs to be solved urgently. In this work, three new amphiphilic tetraphenylethylene (TPE) derivatives (TPE-1 , TPE-2 and TPE-3) with AIE properties and photochromism were synthesized and investigated. Owing to the different electron-donating abilities of the three groups attached to TPE units, the TPE-1 , TPE-2 and TPE-3 displayed blue-green, yellow-green, and orange fluorescence emission in the aggregation state respectively. Furthermore, ordered nanoparticles formed via self-assembly in aqueous solution showed interesting photocyclization behaviors, which lead to fluorescence quenching under ultraviolet light irradiation (λ = 365 nm). Therefore, the compounds can be used as anti-counterfeiting ink in the information encryption due to their amphiphilicity and photo-responsiveness. This work contributes new members to the amphiphilic light-responsive materials family and demonstrates the potential for applications in the fields of optical information storage, information security protection, and erase/rewrite systems. [Display omitted] • Three tetraphenylethylene derivatives with AIE properties and photochromism were synthesized and investigated. • The designed compounds displayed different fluorescence emission in the aggregation state. • The ordered nanoparticles formed via self-assembly in aqueous solution showed interesting photocyclization behaviors. • The compounds were successfully used as anti-counterfeiting ink in the information encryption. [ABSTRACT FROM AUTHOR]

A novel aggregation-induced emission (AIE) structure containing a tetraphenylethene (TPE) unit covalently linked with a spiropyran (SP) unit was synthesized and investigated in semi-aqueous solutions with 90% water fraction. The open-form structure of red-emissive merocyanine (MC) unit combined with TPE unit was utilized as a bi-fluorophoric sensor to detect lead(II) ion, which could be transformed from the close-form structure of non-emissive SP unit upon UV exposure. Moreover, the TPE unit as an energy donor with the blue-green photoluminescence (PL) emission at 480 nm was combined with the MC unit as an energy acceptor with the red PL emission at 635 nm. Due to the Förster resonance energy transfer (FRET) processes, the bi-fluorophoric sensor produced more efficient ratiometric PL behavior to induce a stronger red PL emission than that of the mono-fluorophoric MC unit. Hence, the PL sensor responses of the AIE bi-fluorophoric structure toward lead(II) ion could be further amplified via the FRET-OFF processes to turn off red PL emission of the coordinated MC acceptor and to recover blue-green PL emission of the TPE donor. Accordingly, the best LOD value for the AIE sensor detection toward Pb2+ was 0.27 μM. The highest red MC emission with the optimum FRET process of AIE sensor could be utilized in cell viability tests to prove the non-toxic and remarkable bio-marker of AIE sensor to detect lead(II) ion in live cells. The developed FRET-OFF processes with ratiometric PL behavior of the bi-fluorophoric AIE sensor can be utilized for future chemo- and bio-sensor applications. [Display omitted] • A novel AIE structure containing a tetraphenylethene unit covalently linked with a spiropyran (SP) unit was synthesized. • Upon UV exposure, red emissive merocyanine (MC) acceptor combined with TPE donor was used as a FRET sensor to detect Pb2+. • Due to FRET processes, the bi-fluorophoric sensor showed stronger red PL than that of the mono-fluorophoric MC analogue. • The ratiometric PL responses of the FRET sensor toward lead(II) ion could be further amplified via FRET-OFF processes. • The FRET sensor possessing the best limit of detection (LOD: 0.27 μM) toward Pb2+ could be used as a remarkable bio-marker. [ABSTRACT FROM AUTHOR]

Herein an aqueous-phase artificial light-harvesting platform has been constructed based on the self-assembly of three small organic molecules: a rigid acetal-based spirocyclic skeleton bridged tetraphenylethylene dimer as donor, a hydrophobic dye molecule Nile Red as acceptor, and the surfactant cetyltrimethyl ammonium bromide as amphiphile to enwrap the donor and acceptor and disperse them in water. Due to the rigid skeleton of the tetraphenylethylene dimer that can well accommodate and distribute Nile Red inside the self-assembled nanospheres, the system shows ultrahigh light-harvesting antenna effects. Moreover, by simply tuning the donor/acceptor molar ratio, tunable emission including a bright white-light emission could be realized. Image 1 • An efficient artificial light-harvesting system in water has been constructed by employing small organic molecules. • An ultrahigh antenna effect of 66 could be achieved under a higher donor/acceptor ratio of 250/1. • By simply adjusting the D/A ratio in the NPs, tunable emission including a white-light emission was achieved. • The system is also stable in the solid state and can be used as security inks for anti-counterfeiting techniques. [ABSTRACT FROM AUTHOR]

Two novel tetraphenylethylene derivatives (denoted as A12-TPE and T12-TPE) were prepared by incorporating different chiral d -gluconic acid substituents into the achiral TPE core. Their aggregation-induced emission (AIE) activity, self-assembly structure and circularly polarized luminescent (CPL) performance were then investigated using various techniques. The results reveal that both A12-TPE and T12-TPE exhibit AIE properties with quantum yields as high as 74.3% and 74.0% respectively. Moreover, due to the synergy effect of steric hindrance of the acetal group and chiral induction of d -gluconic acid, A12-TPE possesses a helical supermolecular structure, which endowed the material with distinct CPL properties. On the contrary, T12-TPE without the acetal group exhibits a lamellar structure rather than a helical structure, and no CPL signal can be observed. The helical supermolecular structure, in combination with the AIE activity and CPL performance of A12-TPE , make it a promising material for fabrication of chiral luminescent devices. Image 1 • Two novel TPE derivatives with different chiral substituents (A12-TPE and T12-TPE) were synthesized. • A12-TPE and T12-TPE possesses lamellar and helical supramolecular structures, respectively. • The unique helical supermolecular structure endowed A12-TPE with distinct CPL property. [ABSTRACT FROM AUTHOR]

The ethylene fused PDI oligomers, especially for the dimer (PDI2), have emerged as alternative building blocks to the parent PDI in constructing NFAs owing to their outstanding optoelectronic properties, twisted configurations as well as concise gram-scale synthesis. In this work, a non-fullerene acceptor (NFA) based on tetraphenylethylene (TPE) core flanked with four PDI2 units, coded as TPE-4PDI2 , was designed and synthesized. The analogue (TriPE-3PDI2) which consists of triphenylethylene (TriPE) and three PDI2 panels was synthesized for comparison. OSCs based on TPE-4PDI2 show a best PCE of 7.10%, which is much higher than that of TriPE-3PDI2 based ones. Moreover, this PCE is also higher than that of TPE-4PDI based devices (5.53%). To the best of our knowledge, the PCE of 7.10% is among the highest values for TPE-cored NFAs based OSCs. These results indicate that PDI2 is a promising building block for constructing high performance NFAs. And this work provides a facile and effective molecule-designing method to promote the PCE of PDI based non-fullerene OSCs. Image 1 • Two PDI2 based non-fullerene acceptors were designed and synthesized. • TPE-4PDI2 based devices obtained a much higher PCE of 7.10% than did TriPE-3PDI2 based OSCs. • PDI2 is a promising building block for constructing high performance NFAs. [ABSTRACT FROM AUTHOR]

Far-red and "turn-on" fluorescence sensors were paid much attention due to their outstanding merits, but this kind of fluorescence probe for Y3+ was not presented up to date. In this work, a Schiff-base bridged m -aminobenzoic acid-decorating tetraphenylethylene was designed and synthesized in yield of 89%. It exhibited the far-red fluorescence at 550–670 nm in aqueous media based on AIE effect. It showed high selective sensing ability for Y3+ among all kinds of metal ions with the obvious "turn-on" fluorescence, which was observed for the first time for fluorescence sensor of Y3+. The detection limit for Y3+ was as low as 2.23 × 10−7 M. The sensor mechanism of 1:1 stoichiometric ratio was clarified by fluorescence titration, FT-IR spectra, 1H NMR and MS spectra. The selective sensing of Y3+ was further successfully applied on detecting Y3+ for tested paper, simulated water sample and bio-imaging of live cells, suggesting the good practical application potential of this fluorescence sensor on detecting Y3+ in complicated water media and living body environment. • First "turn-on" fluorescence sensor for Y3+ in water media was presented. • The high selective sensing ability for Y3+ among various metal ions was observed. • The detection limit for Y3+ was as low as 2.23 × 10−7 M. • The Y3+ sensor was applied for tested paper, simulated water sample and bio-imaging. • The sensor mechanism of 1:1 stoichiometric ratio was clarified. [ABSTRACT FROM AUTHOR]

Subtle modification of molecular structure can play a crucial role in determining photophysical properties and stimuli-responsive behavior. Herein, four aggregation-induced emission (AIE)-active tetraphenylethylene-based positional isomers S1 , S2 , S3 and S4 have been designed and synthesized. S2 and S4 exhibit higher fluorescence quantum yield (Φ FL) as compared to S1 and S3 , respectively, which was due to the positional isomerism. In addition, all four isomers exhibit reversible mechanofluorochromic (MFC) behavior with mechanical-induced emission enhancement (MIEE), which was studied using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). S1 and S2 display better MFC activities, compared with S3 and S4 , due to opened phenylimidazole presenting a more twisted conformation. Moreover, they can detect picric acid (PA) in a highly selective and sensitive manner in aqueous media, due to the excellent proton-binding property of the imidazole group, which was verified by 1 H NMR spectra and supported by theoretical calculations. Overall, tetraphenylethylene containing arylimidazole derivatives described herein will efficiently expand the development of design principles to supply diverse multifunctional tools for material science and material engineering. Image 1 • A series of isomers were synthesized by combination of TPE and arylimidazole units. • Isomers exhibit MFC behavior with mechanical-induced emission enhancement. • Isomers can detect PA in a highly sensitive manner in aqueous medium. [ABSTRACT FROM AUTHOR]

Three furan-based diketopyrrolopyrrole (DPP) chromophores have the same D−A−D structure and various tetraphenylethylene, pyrene and dibenzothiophene tails with intramolecular donor-acceptor spacers. Different π -extended chromophores show different intramolecular charge transfer properties. Furthermore, according to UV–Vis and emission spectral studies, dyes F1 – F3 exhibit aggregation-caused quenching (ACQ) in tetrahydrofuran aqueous solutions. Interestingly, dyes F1 and F3 show aggregation-induced emission (AIE) behaviors in DMSO/toluene mixtures, while pyrene-functionalized DPP dye F2 still has ACQ character. It is noted that a contour plot is firstly carried out to be better understood the AIE and ACQ phenomena. Moreover, the energy gaps for the methyl counterpart of dyes F1 – F3 are 2.30, 2.29 and 2.35 eV, respectively, which indicate that introducing asymmetrical D−A−D− π furan-containing DPP structures can reduce the HOMO–LUMO gaps easily and rapidly. In addition, a computational and experimental investigation has been provided, including theoretical and optical energy gaps for full comparison. Image 1 • A contour plot is firstly demonstrated to be understood AIE and ACQ phenomena. • Three asymmetrical D−A−D− π furan-based DPPs have been constructed. • The fluorescence quantum yield of dye F1 is 49%, showing the strong peaks. • A computational and experimental investigation has been provided. [ABSTRACT FROM AUTHOR]

Supramolecular interactions and molecular conformations play significant role on producing fluorescent polymorphs with tunable emission in the solid state from single fluorophore. External stimuli-induced structural transformation from one polymorph to another polymorph without losing single crystalline character (single-crystal-to-single-crystal transition (SC-SC)) provides perfect model to understand the structure-property of molecules in the solid state and designing new functional fluorescent materials. Herein we have tailored the substituent groups in the aggregation-induced-emissive (AIE) tetraphenylethylene (TPE) based donor (D)-acceptor (A) fluorophores (TPPA-1-6) and explored fluorescent polymorphs formation and SC-SC transition in the solid state. TPPA-1 showed conformational fluorescent polymorphs via twisted and co-planar conformation between TPE phenyl group and cyanophenyl acceptor phenyl ring. However, single crystal analysis of other derivatives revealed that substituent groups and supramolecular interactions control the molecular conformation and SC-SC transition. Fluorophore with same substituent but positional change also show drastic effect on the fluorescent polymorphs formation and SC-SC transition. Substituents that can form strong intermolecular interactions stabilize the less stable co-planar structure whereas bulky substituents with weak intermolecular interactions produced twisted or both conformers. Photophysical, powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and thermogravimteric (TG) analysis were performed to substantiate and get insight on the structural transformation. The formation of fluorescent polymorphs and SC-SC transition exhibited tunable and switchable solid state fluorescence. The non-planar TPE core has been made use to demonstrate high contrast stimuli induced reversible fluorescence switching. Overall, the present studies attempted to gain information on the structural design for developing SC-SC transforming functional organic fluorescent materials that could be of potential interests for optoelectronic and display devices. Mechanofluorochromic TPE based aggregation induced emissive fluorophores displayed substituent group dependent polymorphism, tunable emission and rare single crystal-single crystal structural transformation. Image 1 • Fluorescent polymorphs with tunable solid state fluorescence. • A rare solvent vapour induced single crystal to single crystal transformation. • High contrast mechanofluorochromism. • Structure-property studies. [ABSTRACT FROM AUTHOR]

Tetraphenylethylene (TPE) based aggregation-induced emission (AIE) polymers containing different degrees of functionalization of photobleachable azo chromophores were developed and their photophysical properties were explored. The synthesized epoxy monomer derived from TPE core reacted with aniline to give the precursor polymer, which confirmed typical AIE characteristics. Then through a post-polymerization azo-coupling scheme, various contents of 2-phenylazo-4, 5-dicyanoimidazole groups were readily introduced into the TPE based epoxy precusor polymer. Experimental results suggested that only a small amount of such imidazole-type azo component could totally cage the intense AIE fluorescence of the whole polymer due to the fluorescence resonance energy transfer process. By exposure to visible light (450 nm), azo units could be photo bleached notably, thus resulting in dramatic recovery of the blue fluorescence. Depending on this, visible light induced fluorescent patterns were easily fabricated and erased, indicating that the prepared azo caged AIE Polymers could be promising candidates for anti-counterfeiting and optical information storage. Visible light activated fluorescence of imidazole-type azo caged aggregation-induced emission polymers was reported. The effect of azo contents on fluorescence intensity was studied, which revealed that only a small amount of imidazole-type azo groups could totally cage the strong AIE fluorescence of the polymers. Irradiated with visible light, azo chromophores could be photo bleached, leading to remarkable recovery of the blue fluorescence. Fluorescent patterns have been easily fabricated. Image 1 • Only a small amount of imidazole-type azo chromophores could totally cage the strong AIE fluorescence of the polymers. • Imidazole-type azo chromophores could be photo bleached with visible light. • Visible light induced fluorescent patterns have been easily fabricated and erased. [ABSTRACT FROM AUTHOR]