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Solar‐driven interfacial evaporation is a promising technology for desalination. The photothermal conversion materials are at the core and play a key role in this field. Design of photothermal conversion materials based on organic dyes for desalination is still a challenge due to lack of efficient guiding strategy. Herein, a new D (donor)‐A (acceptor) type conjugated tetraphenylpyrazine (TPP) luminophore (namely TPP‐2IND) was prepared as a photothermal conversion molecule. It exhibited a broad absorption spectrum and strong π–π stacking in the solid state, resulting in efficient sunlight harvesting and boosting nonradiative decay. TPP‐2IND powder exhibited high photothermal efficiency upon 660 nm laser irradiation (0.9 W cm−2), and the surface temperature can reach to 200°C. Then, an interfacial heating system based on TPP‐2IND is established successfully. The water evaporation rate and the solar‐driven water evaporation efficiency were evaluated up to 1.04 kg m−2 h−1 and 65.8% under 1 sunlight, respectively. Thus, this novel solar‐driven heating system shows high potential for desalination and stimulates the development of advanced photothermal conversion materials. [ABSTRACT FROM AUTHOR]

The search for deep-blue dyes with high luminescence efficiency in the aggregate state and high brightness is particularly important in optoelectronic application. Herein, based on a typical aggregation-induced emission (AIE) unit of tetraphenylpyrazine (TPP), four dyes were prepared by connecting it with chiral binaphthyl units via an acetylenic bond. The use of the TPP unit is critical to aggregation-enhanced emission (AEE) and deep-blue emission, whereas the merging of the binaphthyl unit is beneficial for molecular conjugation to remarkably improve absorption, photoluminescence (PL) quantum efficiency and brightness. Besides, the binaphthyl unit can serve as an axially chiral source to endow the deep-blue dyes with chirality. It was revealed that attaching a longer alkoxy chain to the dyes facilitates the formation of helical self-assemblies determined by chiral transfer but leads to an aggregation-caused emission (ACQ) effect. Moreover, using these deep-blue dyes as energy donors for energy delivery, other emissions and pure white light emission can be generated effectively via an energy transfer process based on a rational mixture of donors and acceptors in PMMA films. The device fabricated by coating this film onto a blue LED also emitted distinct and stable white light. This work provides a flexible way to design high-performance blue materials for potential applications. [ABSTRACT FROM AUTHOR]

Hypochlorite (ClO−), as a kind of essential reactive oxygen species, plays a crucial role in vitro and in vivo. Here, a ratiometric fluorescent probe (TPAM) was designed and constructed for sensing ClO− based on substituted triphenylamine and malononitrile, which exhibited obvious colour transfer from orange to colourless under daylight accompanied by noticeable fluorescence change from red to green in response to ClO−. TPAM could effectively monitor ClO− with the merits of fast response, excellent selectivity, high sensitivity and a low detection limit of 0.1014 μM. 1H NMR, mass spectra and theoretical calculations proved that ClO− caused the oxidation of the carbon–carbon double bond in TPAM, resulting in compound 1 and marked changes in colour and fluorescence. In addition, TPAM was utilized for imaging ClO− in living cells successfully with good photostability and biocompatibility. [ABSTRACT FROM AUTHOR]

The detection of nitrophenolic explosives is important in counterterrorism and environmental protection, but it is still a challenge to identify the nitroaromatic compounds among those with a similar structure. Herein, a simple tetraphenylethene (TPE) derivative with aggregation-induced emission (AIE) characteristics was synthesized and used as a fluorescent sensor for the detection of nitrophenolic explosives (2, 4, 6-trinitrophenol, TNP and 2, 4-dinitrophenol, DNP) in water solution and in a solid state with a high selectivity. Meanwhile, it was found that only hydroxyl containing nitrophenolic explosives caused obvious fluorescence quenching. The sensing mechanism was investigated by using fluorescence titration and 1H NMR spectra. This simple AIE-active probe can potentially be applied to the construction of portable detection devices for explosives. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) fluorescence imaging with the merits of deep tissue penetration and high signal to background ratio is widely adopted in disease diagnosis, controlled drug delivery and the in situ and real time monitoring of biological procedures. In particular, the use of aggregation-induced emission luminogens (AIEgens), which feature a large Stokes shift, superior photostability and high brightness, has further expanded the practical application of fluorescence imaging. Here in this article, we utilized 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (IC) as the electron acceptor (A) and aromatic aldehydes as the electron donor (D) to fabricate NIR AIEgens. Accordingly, six AIEgens, namely, NIC, 6-MNIC, 6-HNIC, 4-MNIC, DMPIC and DMNIC, were obtained. The photophysical properties plus theoretical calculation results verified that the introduction of D–A interactions successfully redshifted the emission maxima of the obtained AIEgens. DMNIC, with a 4-(dimethylamino)naphthalen-1-yl group as the electron donor moiety, exhibited the longest emission maximum at 694 nm in pure DMSO. The low cytotoxicity and good cell imaging ability toward HeLa cells further guaranteed that DMNIC would provide good prospects for future applications in chemo/biosensing, disease theranostics or diagnosis, controlled drug delivery and release, and deep tissue imaging. [ABSTRACT FROM AUTHOR]

Novel chiral AIEgens bearing optically pure amino groups were synthesized and showed excellent discrimination for a series of chiral acidic compounds and amino acids. Interestingly, after supramolecular assembly with 4-sulfocalix[4]arene, the obtained complexes showed enhanced enantioselectivity for chiral acids. [ABSTRACT FROM AUTHOR]

A pair of chiral R/S-TPE-BINOL derivatives with dark resonance energy transfer was facilely synthesized by coupling of a tetraphenylethylene (TPE) derivative, BODIPY dye and R/S-1,1′-bi-2-binaphthol (BINOL), where TPE not only was selected as a dark energy donor, but also can endow the target molecules with aggregation-induced emission (AIE) characteristics; BODIPY served as an energy acceptor; BINOL, one of the most popular axially chiral compounds, was employed as a chiral source. Due to the chiral feature of R/S-TPE-BINOL, obvious CD and CPL signals were observed in the solution and aggregated states. Generally, for organic dyes, high dissymmetric factor (gem) values are often accompanied by low emission efficiencies. To improve emission efficiency, an effective strategy of dark through-bond energy transfer was adopted. This method makes it possible to avoid fluorescence leakage originating from donor emission. The energy of TPE can be completely transferred to the BODIPY unit before non-radiative relaxation with an energy transfer efficiency of up to 99% and a high quantum yield of 91%. Remarkably, these enantiomers could self-assemble into bowl-like hollow microspheres in a mixed solvent of THF/water to give a stable fluorescent suspension with tunable emission from the green to yellow region. Moreover, TPE-BOD was selected as the fluorescent probe for specific staining of lipid droplets in living cells. [ABSTRACT FROM AUTHOR]

Abstract: Tetraphenylethylene (TPE) foldamers with double hairpin‐turn linkers showing an aggregation‐induced emission (AIE) effect have been synthesized for the first time. A crystal structure of a foldamer–TNT complex has been obtained, enabling unprecedented direct observation of the interactions between TNT molecules and the chromophores of the foldamer. Instead of π–π stacking interactions, which have often been considered to be the key mechanism in the binding of TNT by chromophoric receptors, strong n–π interactions between the nitro groups of TNT and the aromatic rings of the foldamer have been found. Exceptionally, by addition of 1 % NaF to a suspension of the foldamer in H2O/THF (95:5), the fluorescence quenching efficiency by TNT vapor significantly increased from about 20 % to more than 90 %. Even after diluting TNT‐saturated air at 25 °C by a factor of 2×104, an obvious quenching response was observed, indicating that ultratrace TNT vapor (down to 3.4 fg per mL of air) could be detected. [ABSTRACT FROM AUTHOR]

Tetraphenylethylene (TPE) and its derivatives are the most typical and most widely studied organic compounds showing aggregation-induced emission (AIE). Due to their propeller-like structures, V-like clefts exist between the aryl rings, which make them promising host compounds. However, such a possibility is seldom explored. Herein, it is reported that TPE derivatives bearing two or four pyridine rings at the para positions of the phenyl rings (TPE-Pys) can selectively include triangular (Δ-like) m-phthalic acid from a mixture of o-, m-, and p-phthalic acids due to their shape complementary to form host-guest co-crystals, which showed redder emission than the TPE-Pys themselves. The emission of co-crystals 1- 5 could be reversibly switched between yellow and red by alternating exposure to HCl and ammonia vapor. The host-guest co-crystals not only exhibited great potential for selectively recognizing and separating m-phthalic acid and as multicolor emission materials, but are also suitable for use as secret ink due to their reversible color change on varying the host-guest interactions. [ABSTRACT FROM AUTHOR]

The structures, stabilities and magnetic properties of CrXn(X= Na, Rb and Cs;nup to 9) clusters are studied using density functional theory to search for the stable magnetic superatoms. The geometrical optimisations indicate the ground-state structures of CrXnevolve toward a close packed structure with an interior Cr atom surrounded byXatoms as the cluster size increase. Their stabilities are analysed by the relative energy, gain in energy (ΔE(n)) and the highest unoccupied molecular orbital and lowest unoccupied molecular orbital gaps. Furthermore, the magnetic moments of CrXnclusters show an odd–even oscillation. Here, we mainly focus on the CrX7(X= Na, Rb and Cs) clusters due to the same valence count as the known stable magnetic superatoms VNa8, VCs8and TiNa9. Although these clusters all have a filled electronic configuration 1S21P6and large magnetic moment 5 μB, our studies indicate that only CrNa7is highly stable compared to its nearest neighbours, while CrRb7and CrCs7clusters are less stable. This suggests that Cr-doped Na7is most appropriate for filled electronic configuration and CrNa7is shown to be a stable magnetic superatom. More interesting, we find CrRb8and CrCs8with the filled electronic configuration 1S21P6have higher stability and large magnetic moment 6 μBin their respective series. [ABSTRACT FROM AUTHOR]

A tetraphenylethylene (TPE) Schiff base macrocycle with an aggregation-induced emission (AIE) effect was synthesized by the condensation reaction of the TPE dialdehyde and 1,2-benzenediamine. The macrocycle could aggregate into nanofibers in an aqueous solution to give a stable and fluorescent suspension. The fluorescent nanofibers showed a highly selective response to copper ions in an aqueous solution with the detection sensitivity up to a nanomolar level. Meanwhile, the emission of the nanofibers displayed a very large Stokes shift up to 260 nm because of the AIE effect, which brought the emission into the red area and avoided background interference. Therefore, the macrocycle probe showed great potential for the detection of Cu(ii) in real water samples including pork juice-containing water. In addition, the macrocycle reacted with Cu(ii) to give a color change and so the copper ion can be detected at the 10 μM level by the naked eye. [ABSTRACT FROM AUTHOR]

A tetraphenylethylene (TPE) Schiff-base macrocycle showing an aggregation-induced emission (AIE) effect has been synthesized, which could aggregate into nanospheres and emit yellow fluorescence in aqueous media. By virtue of its AIE effect, the macrocycle showed a sensitive and selective response to 2,4,6-trinitrophenol (TNP) and 2,4-dinitrophenol (DNP) among a number of nitroaromatic compounds, which could be used to detect TNP and DNP at nanomolar levels. Moreover, it exhibited a superamplified quenching effect with DNP but not with TNP, providing a possible means of discriminating these two compounds. In comparison with open-chain TPE Schiff-bases, the cavity of the macrocycle is essential for the selectivity for DNP over TNP. In addition, quantitative analyses of both DNP and TNP in real water samples and qualitative detection of these two analytes in the solid state by the macrocycle have been tested. The reliability of the quantitative analysis has been confirmed by HPLC. Our findings demonstrate that the TPE Schiff-base macrocycle has great potential as an excellent sensor for DNP and TNP. [ABSTRACT FROM AUTHOR]

The molar heat capacities of three different concentrations of aqueous SrCl2 solutions, 0.1212, 0.4615 and 1.878 mol⋅kg−1, were measured, using a precision automated adiabatic calorimeter in the temperature range from 80 to 320 K. Solid–liquid phase transitions were observed at 272.83, 270.18 and 255.15 K, respectively, for these three solutions. The molar enthalpies and entropies of the phase transitions were evaluated. The experimental heat capacity data were fitted to polynomial equations, and based on the polynomial equations and thermodynamic relationship, the thermodynamic functions relative to 298.15 K, [ H T− H298.15 K] and [ S T− S298.15 K], of the three solutions were derived in the range of 80 to 320 K with an interval of 5 K. [ABSTRACT FROM AUTHOR]

In recent years, aggregation-induced emission luminogens (AIEgens) have been widely developed for bio-imaging, theranostics, organic photoelectronics, and chemo/biosensors. While, the existing AIEgens are almost all obtained by organic synthesis, experiencing complicated synthesis routes, high cost, environmentally unfriendly, and poor biocompatibility. Therefore, exploration of AIEgens from natural products is an attractive alternative approach. In this contribution, two natural AIE-active materials, Tangeretin and Nobiletin, were found, which can be extracted from orange peel. Single crystal structure, fluorescence spectra and viscosity analyses verified that restriction of intramolecular rotation was responsible for the AIE phenomenon of Tangeretin and Nobiletin. The theoretical calculation results indicated that the intermolecular charge transfer (ICT) was related with the bathochromic-shift in the solid-state. Moreover, Tangeretin and Nobiletin were biocompatible and could selectively target lysosomes. In short, these natural products provided a new approach for obtaining new kinds of AIEgens, and showing great potential in bioimaging. • Two poly(methoxy)flavone (tangeretin and nobiletin) were extracted from orange peel. • Tangeretin and nobiletin have excellent aggregation-induced emission properties. • The results show that both tangeretin and nobiletin can effectively locate in lysosomes. [ABSTRACT FROM AUTHOR]

Designing molecules with donor-acceptor-donor (D-A-D) architecture plays an important role in obtaining second near-infrared region (NIR-II, 1000-1700 nm) fluorescent dyes for biomedical applications; however, this always comes with a challenge due to very limited electronic acceptors. On the other hand, to endow NIR-II fluorescent dyes with combined therapeutic applications, trivial molecular design is indispensable. Herein, we propose a pyrazine-based planar electronic acceptor with a strong electron affinity, which can be used to develop NIR-II fluorescent dyes. By structurally attaching two classical triphenylamine electronic donors to it, a basic D-A-D module, namely Py-NIR, can be generated. The planarity of the electronic acceptor is crucial to induce a distinct NIR-II emission peaking at ∼1100 nm. The unique construction of the electronic acceptor can cause a twisted and flexible molecular conformation by the repulsive effect between the donors, which is essential to the aggregation-induced emission (AIE) property. The tuned intramolecular motions and twisted D-A pair brought by the electronic acceptor can lead to a remarkable photothermal conversion with an efficiency of 56.1% and induce a type I photosensitization with a favorable hydroxyl radical (OH˙) formation. Note that no additional measures are adopted in the molecular design, providing an ideal platform to realize NIR-II fluorescent probes with synergetic functions based on such an acceptor. Besides, the nanoparticles of Py-NIR can exhibit excellent NIR-II fluorescence imaging towards orthotopic 4T1 breast tumors in living mice with a high sensitivity and contrast. Combined with photothermal imaging and photoacoustic imaging caused by the thermal effect, the imaging-guided photoablation of tumors can be well performed. Our work has created a new opportunity to develop NIR-II fluorescent probes for accelerating biomedical applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Photodynamic therapy as a burgeoning and non-invasive theranostic technique has drawn great attention in the field of antibacterial treatment but often encounters undesired phototoxicity of photosensitizers during systemic circulation. Herein, a supramolecular substitution strategy is proposed for phototherapy of drug-resistant bacteria and skin flap repair by using macrocyclic p-sulfonatocalix(4)arene (SC4A) as a host, and two cationic aggregation-induced emission luminogens (AIEgens), namely TPE-QAS and TPE-2QAS, bearing quaternary ammonium group(s) as guests. Through host-guest assembly, the obtained complex exhibits obvious blue fluorescence in the solution due to the restriction of free motion of AIEgens and drastically inhibits efficient type I ROS generation. Then, upon the addition of another guest 4,4'-benzidine dihydrochloride, TPE-QAS can be competitively replaced from the cavity of SC4A to restore its pristine ROS efficiency and photoactivity in aqueous solution. The dissociative TPE-QAS shows a high bacterial binding ability with an efficient treatment for methicillin-resistant Staphylococcus aureus (MRSA) in dark and light irradiation. Meanwhile, it also exhibits an improved survival rate for MRSA-infected skin flap transplantation and largely accelerates the healing process. Thus, such cascaded host-guest assembly is an ideal platform for phototheranostics research., (© 2024 Wiley‐VCH GmbH.)

Hypochlorite (ClO - ), as a kind of essential reactive oxygen species, plays a crucial role in vitro and in vivo. Here, a ratiometric fluorescent probe (TPAM) was designed and constructed for sensing ClO - based on substituted triphenylamine and malononitrile, which exhibited obvious colour transfer from orange to colourless under daylight accompanied by noticeable fluorescence change from red to green in response to ClO - . TPAM could effectively monitor ClO - with the merits of fast response, excellent selectivity, high sensitivity and a low detection limit of 0.1014 μM. 1 H NMR, mass spectra and theoretical calculations proved that ClO - caused the oxidation of the carbon-carbon double bond in TPAM, resulting in compound 1 and marked changes in colour and fluorescence. In addition, TPAM was utilized for imaging ClO - in living cells successfully with good photostability and biocompatibility., (© 2023 John Wiley & Sons Ltd.)

The detection of nitrophenolic explosives is important in counterterrorism and environmental protection, but it is still a challenge to identify the nitroaromatic compounds among those with a similar structure. Herein, a simple tetraphenylethene (TPE) derivative with aggregation-induced emission (AIE) characteristics was synthesized and used as a fluorescent sensor for the detection of nitrophenolic explosives (2, 4, 6-trinitrophenol, TNP and 2, 4-dinitrophenol, DNP) in water solution and in a solid state with a high selectivity. Meanwhile, it was found that only hydroxyl containing nitrophenolic explosives caused obvious fluorescence quenching. The sensing mechanism was investigated by using fluorescence titration and 1 H NMR spectra. This simple AIE-active probe can potentially be applied to the construction of portable detection devices for explosives.

Mechanochromic (MC) luminescence of organic molecules has been emerging as a promising smart material for optical recording and memory devices. At the same time, pressure-induced blue-shifted and enhanced luminescence are rarely reported now. Herein, a series of cyanostilbene-based AIEgens with different substituents were synthesized to evaluate the influence of morphology transformation and push-pull electronic effect on the MC luminescence. Among these luminophores, compound 1 with one cyano group and diethylamino group was more susceptible to mechanical stimuli and obtained blue-shifted and enhanced fluorescence in response to anisotropic grinding. Powder X-ray diffraction patterns indicated that the MC behaviors were ascribed to the solid-state morphology transition from crystal-to-crystal. Analysis of crystal structures revealed that loose molecular packing is a key factor for high high-contrast MC luminescence. The smart molecular design, together with the excellent performance, verified that luminophores with twisted structures are ideal candidates for MC luminogens.

pH values play an important role in various cell biological processes. Abnormal pH values in living systems are frequently associated with the development of diseases such as cancers, infection, and other diseases. Real-time monitoring of the changes of pH values in vivo will give us the significant indication for these diseases' progression. Within those pH-sensitive imaging probes, aggregation-induced emission (AIE) molecules exhibit great potential in aqueous imaging environment due to their high fluorescence quantum yield and stability. However, the modulation of the AIE probe with pH sensitivity and light-up property face challenges. Here, we introduced a new glycopeptide-modified AIE probe ( TGO ) based on the optimized solid-phase peptide synthesis approach. The response to pH of the peptide: DDDD progression changed hydrophobicity and hydrophilicity, resulting in the change of the amphipathicity balance. When modulating the pH from 5.5 to 8.0, the adverse protonation of the peptide induced assembled nanostructure transformation from nanolamellae to nanomicelles. Meanwhile, the pH-induced charge change in peptides can greatly influence the microenvironment of the AIEgen, resulting in the increase of fluorescence intensity.

Chirality is important to chemistry, biology and optoelectronic materials. The study on chirality has lasted for more than 170 years since its discovery. Recently, chiral materials with aggregation-induced emission (AIE) have attracted increasing interest because of their fascinating photophysical properties. In this review, we discussed the recent development of chiral materials with AIE properties, including their molecular structures, self-assembly and functions. Generally, the most effective strategy to design a chiral AIE luminogen (AIEgen) is to attach a chiral scaffold to an AIE-active fluorophore through covalent bonds. Moreover, some propeller-like or shell-like AIEgens without chiral units exhibit latent chirality upon mirror image symmetry breaking. The chirality of achiral AIEgens can also be induced by some optically active molecules through non-covalent interactions. The introduction of an AIE unit into chiral materials can enhance the efficiency of their circularly polarized luminescence (CPL) in the solid state and the dissymmetric factors of their helical architectures formed through self-assembly. Thus, highly efficient circularly polarized organic light-emitting diodes (CPOLEDs) with AIE characteristics are developed and show great potential in 3D displays. Chiral AIEgens are also widely utilized as "turn on" sensors for rapid enantioselective determination of chiral reagents. It is anticipated that the present review can entice readers to realize the importance of chirality and attract much more chemists to contribute their efforts to chirality and AIE study., Competing Interests: The authors declare no competing financial interests., (This journal is © The Royal Society of Chemistry.)

Organic molecules with an aggregation-induced emission (AIE) effect have recently been attracting more and more attention due to their colossal potential in solid emitters and chemo/biosensors. The number and variety of AIEgen compounds are expanding very rapidly to obtain better application performance and a wider area of application. Among AIEgen systems, tetraphenylethylene (TPE) and its derivatives are the class that have received the most extensive study and the most rapid development because of their facile synthesis. Due to its C2 symmetry and at least tetratopic reaction positions, the TPE unit is also an ideal building block for constructing macrocycles and cages. The resultant cyclic TPE compounds have exhibited many exceptional performances that are difficult to access in their open chain counterparts, such as AIE enhancement, improvement in selectivity and sensitivity as sensors, emission tuning by guests, supramolecular catalysis, further disclosure of the AIE mechanism, molecular adsorption, storage and release, the propeller-like conformation exploitation of the TPE unit in chiral materials and so on. Recently, therefore, a large variety of studies about the synthesis, properties and application research of TPE macrocycles and cages have been reported. These TPE macrocycles and cages significantly expand the research area for the AIE phenomenon and its applications, and represent a development of the AIE area. However, up to now, no review of TPE macrocycles and cages has been available. Thus, this review serves as a summary of the designs, synthesis, photophysical properties, self-assembly, applications and prospects of TPE macrocycles and cages.

The propeller-like conformation of tetraphenylethylene (TPE) with aggregation-induced emission (AIE) effect was partially and completely fixed by intramolecular cyclization for the first time. The immobilization of propeller-like conformation was found to show great advantages in determining the enantiomer purity, identifying the chiral amines. The completely fixed conformers are resolved into M- and P-enantiomer, which showed mirror imaged CD and almost quantitative fluorescence quantum yield. Furthermore, it also showed a mirror and large circularly polarized luminescence dissymmetric factor, depending on the helicity of the enantiomer. The result provides the most direct and persuasive evidence for AIE via the restriction of intramolecular rotation and finds the new insight of the compounds in chiroptical property.