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Display devices with circularly polarized luminescence (CPL) can realize sophisticated functions. However, the generation of mesoscopic chirality and CPL is usually very difficult, especially for those devices fabricated from achiral molecules. Herein, a very simple device is fabricated by achiral twisted nematic liquid crystals (LCs) doped with achiral aggregation‐induced emission luminogens, which exerts high‐performance CPL through molecular assembly. Full‐colored CPL with relatively high luminescence dissymmetry factor of 10−2 is achieved. This study thus not only provides new insights in constructing high‐performance CPL‐emitting devices but also promotes the development of LC display techniques.

Acid-base homeostasis is crucial for normal physiology, metabolism, and functions of living organisms. Thus, the development of effective techniques to monitor it either in vitro or in vivo is in great demand. Herein, a series of multifunctional oxazine-containing polyheterocycles with aggregation-induced emission characteristics are in situ generated by metal-free one-pot A3 polymerizations of terminal diynes, dialdehydes, and ureas. Most of the polymers are synthesized with high molecular weights (Mw up to 49 900) in nearly quantitative yields and display intense solid-state emission and remarkable fluorescence response to protonation and deprotonation. Based on the unique photophysical properties, a fast responsive and reversible fluorescent sensor for ammonia with a detection limit of 960 ppb is achieved and applied for detecting biogenic amines and seafood spoilage. Besides, the polymeric nanoparticles show excellent lysosome-targeting specificity in cell imaging. The polyheterocycles show ratiometric pH sensing behavior with a broad acid-base response window from pH 1 to 9, which shed light on visualizing physiologic pH in gastrointestinal tract. Taking freshwater Cladocera Moina macrocopa as a model organism, in vivo mapping of its intestinal pH shows an increased pH gradient approximately from 4.2 to 7.8 along the foregut, midgut, and hindgut. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

The utilization of luminogens with aggregation-induced emission (AIE) characteristics has recently been developed at a tremendous pace in the area of theranostics, mainly because AIE luminogens (AIEgens) hold various distinct advantages, such as good biocompatibility, excellent fluorescence properties, simple preparation and modification, perfect size of nano-aggregation for enhanced permeability and retention effect, promoted efficiencies of photodynamic and photothermal therapies, efficient photoacoustic imaging, and ready constructions of multimodal imaging and therapy. Significant breakthroughs and developments of theranostics based on AIEgens have been achieved in the past few years, and great progress has been witnessed in many theranostic modalities, indicating that AIEgens remarkably complement conventional theranostic materials and promote the development of theranostics. This review provides theoretical insights into the advantages of AIEgens in theranostics, and systematically summarizes the basic concepts, seminal studies, recent trends and perspectives in theranostics based on AIEgens. We believe that AIEgens would be promising multifunctional theranostic platforms in clinical fields and facilitate significant advancements in this research-active area.

The increasing impact of bacteria on cancer progression and treatments has been witnessed in recent years. Insufficient attention to cancer-related bacteria may lead to distant metastasis, poor therapeutic efficiency and low survival rates for cancers. Exploiting new approaches that enable selective imaging and effective killing of cancer cells and bacteria are thus of great value for the battle against cancers. Herein, we report an aggregation-induced emission (AIE) luminogen, namely TPPCN, with intense emission and efficient reactive oxygen species production for fluorescence imaging and killing cancer cells and Gram-positive bacteria. This work not only demonstrates the potential of AIE luminogens in comprehensive cancer treatments but also stimulates the enthusiasm of scientists to design more multifunctional AIE systems for both cancer and bacteria theranostics. © 2018 The Royal Society of Chemistry.

This work provides the finding of aggregation-induced circular dichroism (AICD), optical properties and helical assemblies of pi-pi conjugated molecule hexaphenylsilole (HPS). As an achiral molecule, HPS was found to exhibit unusual AICD and circular polarized luminescence (CPL). Upon aggregation, it self-assembled into fluorescent helical nanofiber and nanotubes. Theoretical modeling suggests that van der Waals interaction between HPS monomers plays an essential role in the formation of helical nanofibers. These kinds of molecules have important applications given the increasing demand of miniaturized optics and electronic devices.

Lysosomes are involved in a multitude of cellular processes and their dysfunction is associated with various diseases. They are the most acidic organelles (pH 3.8-6.6, size 0.1-1.2 mu m) with the highest viscosity (47190 cP at 25 degrees C) in the cell. Because of their acidity, pH dependent non-AIE active fluorescent lysosomal probes have been developed that rely on protonation inhibited photoinduced electron transfer (PET). In this work, an acidic pH independent lysosome targetable piperazine-TPE (PIP-TPE) AIEgen has been designed with unique photophysical properties making it a suitable probe for quantifying viscosity. In a non-aggregated state PIP-TPE shows deep-blue emission as opposed to its yellowish-green emission in the bulk. It possesses high specificity for lysosomes with negligible cytotoxicity and good tracing ability due to its better photostability compared to LysoTracker Red. In contrast to most known lysosome probes that rely solely on PET, restriction of intramolecular motion (RIM) due to the larger viscosity inside the lysosomes is the mechanism responsible for PIP-TPE's fluorescence. PIP-TPE's high selectivity is attributed to its unique molecular design that features piperazine fragments providing a perfect balance between lipophilicity and polarity.

A new polymerization route for the preparation of functional heterocyclic polymers was developed from diphenol derivatives and unactivated internal diynes. The alkyne polyannulations of 4,4′-sulfonyldiphenol and 4,4′-(α,ω-alkylenedioxy)bis(diphenylacetylene)s or 1,2-bis[4-(2-phenylethynyl)phenyl]-1,2-diphenylethene were catalyzed by Pd2(dba)3 in the presence of bathophenanthroline, silver acetate and copper(ii) acetate monohydrate in 1,4-dioxane at 130 °C, affording polymers with benzofuran moieties in satisfactory yields and high molecular weights (Mw up to 34-000). All the polymers were thermally stable, losing merely 5% of their weight at high temperatures of up to 376 °C. They showed a good film-forming ability and their thin solid films showed high refractive indices (RI = 1.900-1.611) in a wide wavelength region of 400-1000 nm. The polymer carrying tetraphenylethene units in the backbone was photosensitive and could be utilized to generate a fluorescent pattern by the photolithography process. © The Royal Society of Chemistry 2016.

The rapid acquisition of antibiotic resistance poses difficulties in the development of effective methods to eliminate pathogenic bacteria. New bactericides, especially those do not induce the emergence of resistance, are thus in great demand. In this work, we report an aggregation-induced emission fluorogen, TPE-Bac, for bacterial imaging and elimination. TPE-Bac can be readily dissolved in aqueous solution with weak emission. The presence of bacteria can turn on its emission, and thus no washing step is required in the imaging process. Meanwhile, TPE-Bac can be applied as a bactericide for elimination of bacteria. The amphiphilic TPE-Bac bearing two long alkyl chains and two positively charged amines can intercalate into the membrane of bacteria, increase membrane permeability and lead to dark toxicity. The efficiency of bacteria killing is greatly enhanced under light irradiation. TPE-Bac can serve as a photosensitizer to induce reactive oxygen species (ROS) generation, which ensures the efficient killing of bacteria. The TPE-Bac-containing agar plates can be continuously used for bacteria killing by applying light to induce ROS generation.

Reported herein is a new class of pure polycyclic hydrocarbon molecules, designed through a novel aggregation-induced emission (AIE) strategy, with unexpected photochromic properties. The restriction of intramolecular motion was found as a comprehensive mechanism for the AIE effect. The photochromism mechanism study revealed that the photocyclization reaction of cis-stilbene, the molecular conformation in the single crystal and the tetracene backbone should contribute to the unique photo behavior. In particular, the fast responsive, photo-reversible and thermo-irreversible photochromic effect facilitated in the solid state opens a new field of aggregation-promoted photochromism.

The facile synthesis of a tetraphenylethene-based macrocycle having aggregation-induced emission characteristics and that expresses illusory topology of the Penrose stairs is presented. As a result of the twisted chirality (P or M) of the tetraphenylethene unit and the axial chirality of the macrocyclic linkage (R or S), the macrocycle exhibits two absolute configurations whose interconversion is energetically favorable as revealed by theoretical calculations.

Mechanochromic (MC) luminogens have found promising applications in mechanosensors, security papers, and optical storage for their change in emission behaviors in response to mechanical stimuli. Examples on MC luminescent materials are rare before the discovery of MC luminescence in aggregation-induced emission (AIE) luminogens. The twisted conformations of AIE luminogens (AIEgens) with appropriate crystallization capability afford loosely packing patterns, which facilitates their phase transformation in the solid state. The amorphous films of AIEgens exhibit enhanced emission intensity upon pressurization due to the increased molecular interactions, whereas crystals of AIEgens exhibit MC luminescence due to their amorphization by mechanical stimuli. AIEgens enrich the type of MC luminogens but those showing high emission contrast and multicolor emission switching and those working in a turn-on emission mode are seldom reported. Disclosure of the design strategy of high performance MC luminogens and exploration of their high-tech applications may be the future research directions for MC luminogens. © 2015 American Chemical Society.

Tetraphenylethene-functionalized acetylenes [(C6H5)(2)C=C(C6H5)(C6H4C equivalent to CR), R = C8H17 and C6H5] were synthesized, and their polymerizations were effected by WCl6Ph4Sn at elevated temperatures in toluene under nitrogen, furnishing polymers P1 and P2. The polymers possessed good solubility and degraded at high temperatures of up to similar to 400 degrees C under nitrogen. Both polymers emitted weakly in the solution state. Whereas the emission of P1 was enhanced when aggregated, that of P2 was quenched, demonstrating that the light emission of polyacetylenes could be varied readily by changing their molecular structure. The polymers could serve as fluorescent chemosensors for explosive detection with an amplification effect. UV irradiation of their films in air photo-oxidized and bleached the fluorescence of the exposed parts, generating fluorescent photopatterns. The polymers exhibited optical nonlinearity and could limit laser pulses.

In this paper, a new aggregation-induced emission (AIE)-active compound, 1,2-bis(4-(3,6-bis(dimesitylboranyl)-9H-carbazol-9-yl) phenyl)-1,2-diphenylethene (BBDCZPD), has been successfully synthesized. The building block of BBDCZPD comprises tetraphenylethene as the skeleton, carbazole as the hole-transporting moiety and dimesitylboron as the electron-transporting moiety. Its structure is fully characterized using elemental analysis, mass spectrometry and proton nuclear magnetic resonance spectroscopy. The thermal, electrochemical and photophysical properties of BBDCZPD are studied using thermal analysis, electrochemical methods, UV-vis absorption spectroscopy and fluorescence spectroscopy, respectively. The results show that BBDCZPD exhibits excellent thermal stability and electrochemical stability as well as AIE properties. Moreover, a multilayer organic light-emitting diode (OLED) device is fabricated by using BBDCZPD as the non-doped emitter which displays good electroluminescence performances with a turn-on voltage of 5.2 V, a maximum luminance of 5406 cd m(-2) and a maximum luminance efficiency of 5.34 cd A(-1). The electroluminescence properties of BBDCZPD demonstrate its potential application in OLEDs.

A luminogen with aggregation-induced emission characteristics is reported for bacterial imaging and antibiotics screening studies. The luminogen can light up bacteria in a wash-free manner, which simplifies the imaging process and increases its accuracy in bacterial detection. It can also be applied to high-throughput screening of antibiotics and fast evaluation of bacterial susceptibility, giving reliable results in less than 5 h. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Phase structures and transitions of a series of biphenyl containing side chain liquid crystalline polyacetylenes (SCLCPAS) with different length of spacer and alkyl tail, poly((m + 2)-{[(4'-alkyloxy-4-biphenylyl)carbonyl]oxy}-1-yne) [P-m,7 (m = 4, 5, 8), P-m,5 (m = 9), P-m,5(L) (m = 3, 9), m is the number of methylene units in the spacer], were studied by differential scanning calorimeter, polarized light microscopy, one- and two- 9 dimensional wide-angle X-ray diffraction. It is revealed that phase structures of the samples.-are strongly dependent on the lengths of spacer and alkyl tail. The samples with short spacer (m <= 4) render the molecular shape of sheet-like due to the strong coupling between the backbone and the biphenyl groups on side-chains. They from highly ordered smectic phase with an additional ordering on the subnanometer scale (SmX degrees) at low temperatures. For m > 5, P-m,7 exhibits the low-temperature phase of smectic B (SmB), While P-9,5 and 139,5(L) form smectic E (SmE). As the long spacers adopt more gauche conformations to satisfy the ordered packing of biphenyl groups, the coupling of main and side chain is relieved. Among the samples studied, P-5,7 is unique, which can retain the sheet-like shape but form the SmB, structure based on a fully interdigitated packing manner. Therefore, the spacer length of m = 5 sets the boundary between coupling and decoupling of the backbone and side-chains. Phase transition sequences of the SCLCPAs studied are also found to be influenced clearly by varying the spacer and tail lengths.

In this contribution, we finely tuned the singlet-triplet energy gap (Delta E-ST) of AIE-active materials to modulate their fluorescence, phosphorescence and delay fluorescence via rational molecular design and investigated the possible ways to harvest their triplet energy in OLEDs. Noteworthily, two molecules o-TPA-3TPE-o-PhCN and o-TPA-3TPE-p-PhCN with larger Delta E-ST values (0.59 eV and 0.45 eV, respectively) emitted efficient long-lived low temperature phosphorescence in their glassy solutions and exhibited efficient crystallization-induced room temperature phosphorescence (RTP). Meanwhile, it was the first time to observe a novel crystallization-induced delay fluorescence phenomenon in another AIE-active molecule p-TPA-3TPE-p-PhCN owing to its very small Delta E-ST value (0.21 eV). It was also found that molecules with various Delta E-ST values showed significantly different temperature sensitivity. Non-doped electroluminescent (EL) devices using these molecules as light-emitting layers were fabricated, exhibiting external quantum efficiencies (EQE) higher than theoretical values of purely singlet emitter type devices. Particularly, p-TPA-3TPE-p-PhCN showed outstanding device performances with high luminance and efficiencies up to 36900 cd m(-2), 11.2 lm W-1, 12.8 cd A(-1) and 4.37%, respectively, considering that its solid-state quantum yield was only 42%. All the above observations suggested that tuning the Delta E-ST values of AIE materials is a powerful methodology to generate many more interesting and meaningful optoelectronic properties.

Deep blue emitters are crucial for full color displays and organic white lighting. Thanks to the research efforts by scientists, many efficient light emitters with aggregation-induced emission (AIE) characteristics have been synthesized and found promising applications in organic light-emitting diodes (OLEDs). However, few AIE emitters with deep blue emissions and excellent electroluminescence (EL) performance have been reported. The contribution here reports a simple but successful molecular design strategy for synthesizing efficient solid-state emitters for nondoped OLEDs with both deep blue and white emissions. This strategy utilizes triphenylethene, a weakly conjugated AIE luminogen, as building block for constructing deep blue emitter, involving no complicated control of emission color through adjustment of the steric hindrance of chromophores, and enables a wide selection of partnered functional units. The synthesized AIE luminogen, abbreviated as BTPE-PI, is thermally stable and exhibits high fluorescence quantum efficiency as well as good charge injection capability in the solid state. Nondoped deep blue OLED fabricated from BTPE-PI shows a very high external quantum efficiency of 4.4% with a small roll-off, whose performance is the best among deep blue AIE materials reported so far. An efficient white OLED with Commission Internationale de l'Eclairage (CIE) coordinates of (0.33, 0.33) at theoretical white point was first achieved by using AIE luminogen BTPE-PI as deep blue emitter. Such molecular design strategy opens a new avenue in the development of efficient solid-state deep blue emitters for nondoped OLED applications. © 2015 American Chemical Society.

Polyhydroaminations for the synthesis of stable nitrogen-substituted conjugated polymers with well-defined structures remain a great challenge and the control of the regio- and stereochemistry of the enamine product of the hydroamination is non-trivial. Herein we report an efficient tandem polymerization of alkynes, carbonyl chlorides and primary amines to afford regio- and stereoregular conjugated poly(enaminone)s. The atom-economical one-pot sequential polycoupling-hydroamination polymerization catalyzed by Pd(PPh3)(2)Cl-2/CuI proceeded smoothly under mild conditions, furnishing nitrogen-substituted conjugated polymers with high molecular weights (up to 46 100) and high regio-/stereoregularities (100%) in nearly quantitative yields (up to 99%). The single crystal structure of the model compound, together with the NMR spectra comparison of the model compound and polymers provided direct insight into the stereoselectivity of the polymerization, verifying the sole Z-vinylene isomer of the polymers. Through the exquisite structural design strategy of the intramolecular hydrogen bond of the resulting hydroamination product, the tautomerization between enamine and imine as well as E/Z isomerization was successfully avoided, providing products with high chemical stability and sole Z-vinylene isomers. The conjugated polymers display excellent solubility in common organic solvents, good film-forming ability, and high thermal stability. The hydrogen bond formation of the polymer helps to block the potential photo-induced electron transfer process and the polymer shows a unique aggregation-enhanced emission phenomenon: their solutions are weakly emissive, while their nanoaggregates or thin films are brightly emissive. Furthermore, thin films of the polymers enjoy high refractive indices (1.9103-1.6582) in a wide wavelength region of 400-1000 nm, which can be further modulated by UV irradiation. Meanwhile, well-resolved fluorescent photopatterns of the polymers can be fabrica

The development of efficient multicomponent polymerization (MCP) to prepare heteroatom-rich macromolecules, especially those with complicated structures and multifunctionality, is gathering increasing research interest from chemists. In this work, we report a facile one-pot three-component polymerization method to prepare multifunctional polymers. The Cu-catalyzed polycoupling reactions of aromatic diynes, disulfonyl azide, and optically active amino esters proceeded in a mild manner under room temperature, furnishing regular poly(N-sulfonylamidine)s with high molecular weights (Mw up to 35 900) and in satisfactory yields (up to 87%). The model compound was synthesized to verify the complete transformation from monomers to the desired polymeric products. All the polymers possess excellent solubility in common organic solvents, good film-forming ability, and high thermal stability. The backbones of the polymers are induced to helically rotate by the optically active chiral amino esters, resulting in the circular dichroism (CD) absorption in the solutions and cast films. The polymers are almost nonemissive in solutions, whereas their nanoaggregates or thin films fluoresce intensely upon photoexcitation, showing a unique phenomenon of aggregation-induced emission (AIE). The thin films of these polymers possess high refractive indices (RI = 1.7327-1.6419) in a wide wavelength region of 400-893 nm and low optical dispersions (D down to 0.0247). Well-resolved two-dimensional fluorescent photopatterns can be generated by UV irradiation of these thin films via a copper photomask in air. This work provides an efficient approach toward synthesizing multifunctional heteroatom-rich polymeric materials, overcoming the drawbacks of conventional polymerizations. © 2015 American Chemical Society.

Organic luminescent materials carrying no phenyl rings have attracted much interest from researchers due to their excellent biocompatibility and good biodegradability, which make them available for potential applications in a variety of biomedical areas, such as fluorescent bioprobe, drug delivery and gene carrier, and provide a new insight into the photophysical process of light emission. In this work, we studied the optical properties of poly[(maleic anhydride)-alt-(vinyl acetate)] (PMV), a pure oxygenic nonconjugated polymer and proved that the origin of its emission was associated with the clustering of the locked carbonyl groups. PMV exhibits solvatochromism: after interaction with electron-rich solvents, its absorption and emission shift to the longer wavelength region due to the formation of polymer/solvent complexes. This enables fine-tuning of its optical property by varying the solvent without the need of changing the chromophore.

Two bifunctional red AIE luminogens with efficient solid-state emission and good hole-transporting characteristics are reported. Efficient non-doped OLEDs are fabricated with high external quantum efficiencies of up to 3.9%. Bilayer EL devices using them as both EMLs and HTLs are fabricated with good performances.

Luminogens with the feature of aggregation-induced emission (AIE) are a class of 'heterodox' molecules, whose emissions are brightened by aggregate formation. The restriction of their intramolecular motions in an aggregate state is the main cause of the AIE process. In this account, we summarize recent progress in exploring high-tech applications of AIE luminogens (AIEgens) as biological sensors, chemical probes, optoelectronic devices, and intelligent materials. Our discussion is focused on mechanistic analysis, classifying the electronic interactions involved into three categories: (a) through-bond, (b) through-space, and (c) through-bond and -space conjugations. Such a mechanistic understanding will help guide further development of new AIEgens and their applications.