Changing the behavior of chromophores from aggregation-caused quenching to aggregation-induced emission: development of highly efficient light emitters in the solid state

Tetraphenylethene-based mononuclear aggregation-induced emission (AIE)-active mechanofluorochromism gold(I) complexes with different auxiliary ligands

In this study, a series of tetraphenylethene-containing gold(I) complexes with different auxiliary ligands have been synthesized. These complexes were characterized using a variety of techniques including nuclear magnetic resonance spectroscopy, mass spectrometry, and single crystal X-ray diffraction. Their aggregation-induced emission (AIE) behaviors were investigated through ultraviolet/visible and photoluminescence spectrum analyses, and dynamic light scattering measurements. Meanwhile, their mechanofluorochromic properties were also studied via solid-state photoluminescence spectroscopy. Intriguingly, all these mononuclear gold(I) molecules functionalized by tetraphenylethene group demonstrated AIE phenomena. Furthermore, five gold(I) complexes possessing diverse auxiliary ligands exhibited distinct fluorescence changes in response to mechanical grinding. For luminogens 2-5, their solids showed reversible mechanofluorochromic behaviors triggered by the mutual transformation of crystalline and amorphous states, while for luminogen 1, blue-green-cyan three-color solid fluorescence conversion was realized by sequential mechanical grinding and solvent fumigation. Based on this stimuli-responsive tricolored fluorescence feature of 1, an information encryption system was successfully constructed.

Phototherapeutic applications of benzophenone-containing NIR-emitting photosensitizers based on different receptor modulations

Photodynamic therapy (PDT) plays a crucial role in treating cancer and major infectious diseases. However, the hypoxic microenvironment and deep-seated tumors often compromise the effectiveness of photosensitizers (PSs). PSs primarily generate type-II reactive oxygen species (ROS), which are limited under hypoxic conditions. Pyridinium salts frequently exhibit critical dark toxicity in vitro. Moreover, PDT alone often fails to achieve optimal anti-tumor effects compared to its combined application with photothermal therapy (PTT). To address these issues, we replaced pyridinium with quinolinium, significantly reducing dark toxicity. Additionally, the incorporation of benzophenone enhanced ROS generation, achieving a synergistic effect of type-I and type-II PDT. Fine-tuning the conjugated structure enhanced the donor-acceptor (D-A) intensity, while the stretching vibrations of carbon-carbon double bonds and carbon-nitrogen triple bonds red-shifted the excitation wavelength to the near-infrared (NIR) region and improved the photothermal conversion efficiency (PCE). This strategy provides a molecular design approach for achieving synergy between PDT and PTT. The synthesized four NIR-emitting aggregation-induced emission quinolinium salts exhibited mitochondrial targeting ability and low dark toxicity. Among them, FCN-TPAQ-BP showed excellent ROS generation capability, a PCE of 39.2%, good biocompatibility, and low dark toxicity, making it an ideal candidate for enhancing PDT's antitumor efficacy.

Tumor targeting pH-triggered fluorescence-switchable hyaluronic acid-based micelles with aggregation-induced emission activity for tracing drug release and intelligent drug delivery

In this study, an amphiphilic polymer (Bio-HA(TPE-CN)-mPEG) was designed and synthesized, which was fabricated by introducing hydrophobic aggregation-induced emission (AIE) fluorophore, acid-labile imine bond, methoxy poly (ethylene glycol) (mPEG) and tumor targeting ligand biotin to the backbone of hyaluronic acid. The polymer could self-assemble into micelles and solubilize hydrophobic anticancer drugs. In vitro drug release study indicated that the micelles could disassemble rapidly under acidic environment. The involvement of biotin and HA could enhance the cellular uptake of micelles by tumor cells. Modification of micelles by mPEG could minimize non-specific protein adsorption. Fluorescence studies indicated that the micelles exhibited excellent AIE features and emitted intense long-wavelength fluorescence. More excitingly, the micelles were red emissive in the normal physiological environment, but switched to blue fluorescence in the acidic tumor environment, which could be further applied for real-time monitoring and quantification of the drug release. The in vivo antitumor efficacy study demonstrated the superior antitumor activity of the PTX-loaded micelles. The Bio-HA(TPE-CN)-mPEG micelles were promising drug carriers for chemotherapy and bioimaging.

ROF-2 as an Aggregation-Induced Emission (AIE) Probe for Multi-Target Amyloid Detection and Screening of Amyloid Inhibitors

Misfolding and aggregation of amyloid peptides into β-structure-rich fibrils represent pivotal pathological features in various neurodegenerative diseases, including Alzheimer's disease (AD), type II diabetes (T2D), and medullary thyroid carcinoma (MTC). The development of effective amyloid detectors and inhibitors for probing and preventing amyloid aggregation is crucial for diagnosing and treating debilitating diseases, yet it poses significant challenges. Here, an aggregation-induced emission (AIE) molecule of ROF2 with multifaceted functionalities as an amyloid probe and a screening tool for amyloid inhibitors using different biophysical, cellular, and worm assays, are reported. As an amyloid probe, ROF2 outperformed ThT, demonstrating its superior sensing capability in monitoring, detecting, and distinguishing amyloid aggregates of different sequences (Amyloid-β, human islet amyloid polypeptide, or human calcitonin) and sizes (monomers, oligomers, or fibrils). More importantly, the utilization of ROF2 as a screening molecule to identify and repurpose cardiovascular drugs as amyloid inhibitors is introduced. These drugs exhibit potent amyloid inhibition properties, effectively preventing amyloid aggregation and reducing amyloid-induced cytotoxicity both in cells and nematode. The findings present a novel strategy to discovery AIE-based amyloid probes and to be used to repurpose amyloid inhibitors, expanding diagnostic and therapeutic options for neurodegenerative diseases while addressing vascular congestion and amyloid aggregation risks.

Time-Encoded Information Encryption with pH Clock Guided Broad-Spectrum Emission by Dynamic Assemblies

With growing threats from counterfeiting-based security breaches, multi-level and specific stimuli-responsive anti-counterfeiting devices and message encryption methods have attracted immense research interest. Fluorescence-based encryption from aggregation-induced emission (AIE)-based materials solves the problems to a considerable extent. However, the development of smarter patterns with hierarchical security levels alongside dynamic display is still challenging. To screen out this complication, we bring forward a pH-switchable fluorescent assembly of an AIEgen and an aliphatic acid. We later temporally direct the molecular assembly with the aid of a chemical trigger-regulated pH clock, generating a transitory multicolor emission, including transient white light generation. The pH-dependent emissions were further implemented in constructing smart multi-input fluorescent chemical AND gates. Subsequently, we integrate the time-gated emissive system to develop an advanced multi-dimensionally secure data encryption strategy. This novel approach enhances anti-counterfeiting measures by introducing an additional layer of security based on temporal characteristics.

Fast and Efficient Sensing of Drugs in Water Using Self-Assembling D-Glucamine-Functionalized Naphthalenediimide and 1,8-Naphthalimide Fluorophores

Fast and sensitive quantification of drugs as emerging pollutants in water bodies is a pressing need in contemporary society, to prevent serious environmental concerns that could negatively impact on human health. This explains the surge of interest in this field, and the need to identify highly selective sensing systems. Addressing this issue, in this work we synthesized two D-glucamine functionalized fluorophores bearing self-assembling cores, as 1,8-naphthalimide and naphthalene diimide. We studied their self-assembly in water solution, and characterized the aggregated formed by determining their stability constant, their morphology and size by scanning electron microscopy, resonance light scattering and dynamic light scattering, as well their solid-state emission ability. Then, we studied their sensing ability, in water, towards pharmaceutically active compounds such as ciprofloxacin, nalidixic acid, carbamazepine and diclofenac sodium salt, by fluorescence investigation. Data collected show that the self-assembling ability is significantly affected by the fluorophore structure, which in turn also determines sensing ability. In particular, the naphtalene diimide-based probe was the most sensitive, with LOD as low as 0.01 μM in the presence of nalidixic acid, which is in line and competitive with more complex sensing systems, recently reported in the literature.

Structural modulation of aggregation-induced emission luminogens for NIR-II fluorescence imaging/photoacoustic imaging of tumors

Concurrent near-infrared-II (NIR-II) fluorescence imaging (FLI) and photoacoustic imaging (PAI) holds tremendous potential for effective disease diagnosis owing to their combined benefits and complementary features, in particular on the basis of a single molecule. However, the simultaneous guarantee of high-quality NIR-II FLI and PAI is recognized to be challenging impeded by the competitive photophysical processes at the molecular level. Herein, a simple organic fluorophore, namely T-NSD, is finely engineered with facile synthetic procedures through delicately modulating the rigidity and electron-withdrawing ability of the molecular acceptor. The notable advantages of fabricated T-NSD nanoparticles include a large Stokes shift, intense fluorescence emission in the NIR-II region, and anti-quenching properties in the aggregated states, which eventually enable the implementation of dual-modal NIR-II FLI/PAI in a 4T1 tumor-xenografted mouse model with reliable performance and good biocompatibility. Overall, these findings present a simple strategy for the construction of NIR-II optical agents to allow multimodal disease diagnosis.

Research progress of fluorescent composites based on cyclodextrins: Preparation strategies, fluorescence properties and applications in sensing and bioimaging

Fluorescence analysis has been regarded as one of the commonly used analytical methods because of its advantages of simple operation, fast response, low cost and high sensitivity. So far, various fluorescent probes, with noble metal nanoclusters, quantum dots, organic dyes and metal organic frameworks as representatives, have been widely reported. However, single fluorescent probe often suffers from some deficiencies, such as low quantum yield, poor chemical stability, low water solubility and toxicity. To overcome these disadvantages, the introduction of cyclodextrins into fluorescent probes has become a fascinating approach. This review (with 218 references) systematically covers the research progress of fluorescent composites based on cyclodextrins in recent years. Preparation strategies, fluorescence properties, response mechanisms and applications in sensing (ions, organic pollutants, bio-related molecules, temperature, pH) and bioimaging of fluorescent composites based on cyclodextrins are summarized in detail. Finally, the current challenges and future perspectives of these composites in relative research fields are discussed.

Intramolecular Charge Transfer and Stimuli-Responsive Emission in Cholesterol-Appended Phenothiazine-Cyanostyryl-Based Donor-Acceptor Systems

Organic fluorescent molecules have received considerable attention owing to their various optoelectronic applications. Herein, we report the design and synthesis of two cholesterol-functionalized cyanostyrene-phenothiazine-based D-π-A systems that are emissive in both the solution and solid states. The newly synthesized cholesterol-appended phenothiazine-cyanostyrene diads PTCS-1 and PTCS-2 vary in the N-alkylation of phenothiazine, respectively, with─octyl and─hexyl chains. Both molecules are highly fluorescent and show reasonably good quantum yields in nonpolar solvents because of twisted intramolecular charge transfer (TICT). The molecules exhibit aggregation-induced emission in the solid state. Due to the presence of flexible alkyl chains in the phenothiazine and cholesterol moieties, PTCS-1 and PTCS-2 show mechanochromic luminescence switching in response to external shear stress and emission recovery under methanol vapor. Powder X-ray diffraction studies prove that the emission switching on the applied stimuli in both PTCS-1 and PTCS-2 is attributed to the reversible transformation between the crystalline and amorphous states. Time-dependent density functional theory (TD-DFT) studies are carried out to gain insight into the ICT interactions. TD-DFT analysis at the TD-M06-2X/def2-TZVP level further revealed that in both molecules, the lowest unoccupied molecular orbital (LUMO) + 2, LUMO, highest occupied molecular orbital (HOMO), and HOMO - 1 orbitals are responsible for the charge transfer interactions. These ICT interactions are identified as π-π* type interactions.

Novel BODIPY-based nano-biomaterials with enhanced D-A-D structure for NIR-triggered photodynamic and photothermal therapy

Near-infrared (NIR) responsive nanoparticles are an important platform for multimodal phototherapy. Importantly, the simultaneous NIR-triggered photodynamic (PDT) and photothermal (PTT) therapy is a powerful approach to increase the antitumor efficiency of phototherapic nanoparticles due to the synergistic effect. Herein, a boron dipyrromethene (BODIPY)-based amphiphilic dye with enhanced electron donor-acceptor-donor (D-A-D) structure (BDP-AP) was designed and synthesized, which could self-assemble into stable nanoparticles (BDP-AP NPs) for the synergistic NIR-triggered PDT/PTT therapy. BDP-AP NPs synchronously generated singlet oxygen (1O2) and achieved preeminent photothermal conversion efficiency (61.42%). The in vitro and in vivo experiments showed that BDP-AP NPs possessed negligible dark cytotoxicity and infusive anticancer performance. BDP-AP NPs provide valuable guidance for the construction of PDT/PTT-synergistic NIR nanoagents to improve the efficiency of photoinduced cancer therapy in the future.

Extensive optical and DFT studies on novel AIE active fluorescent sensor for Colorimetric and fluorometric detection of nitrobenzene in Solid, solution and vapor phase

An electron rich isophthalamide based sensor IPA has been synthesized through a simple two-step reaction, containing noteworthy aggregation induced emission (AIE) properties. Considering the significant emission with λmax at 438 nm, sensor IPA has been employed for the sensing of nitrobenzene (NB) in solid, solution and vapor state with high sensitivity and selectivity. Sensor IPA showed noteworthy colorimetric and fluorometric quenching in fluorescence emission when exposed to NB. Small size of NB and involvement of photoinduced electron transfer (PET) lead to detection of NB down to 60 nM. IPA-NB interaction was studied through UV-Vis. spectroscopic studies along with fluorescence spectroscopy. Moreover, 1H and 13C NMR titration experiments provided additional support for determination of interaction type. Furthermore, by using density functional theory (DFT) calculations, thermodynamic stability was studied. Additionally, non-covalent interactions (NCI), frontier molecular orbitals (FMO), density of states (DOS), were investigated for providing further evidence of nitrobenzene sensing and its interaction with sensor. Natural bond orbital (NBO) analysis was carried out for charge transfer studies. Quantum theory of atom in molecule (QTAIM) and SAPT0 studies provided information about interaction points and binding energy. Additionally, IPA was investigated for NB sensing in real water samples, and its effective participation in solid state on-site detection as well as in solution phase was brought to light along with logic gate construction.

Critical Assessment of Micellar Surface Charge-Dependent Disaggregation and Reaggregation of a Bis-Indole Self-Aggregate: What Should Be Our Case-Dependent Choice?

"Aggregation-caused quenching" is a deep-seated mechanism and has been widely used by the researchers as the possible basis for new sensor development. Contrast to aggregation, its turn around process, disaggregation, has gained much less consideration so far. Unfortunately, study of the further scope for reaggregation of the disaggregated probe assembly in the same solution, as and when required, is still under the rare category. The central theme of the current study is focused on this aspect. For this purpose, the effects of headgroup charge (cationic, anionic, and nonionic) and polarity of the micelles on the degree of disaggregation and subsequent emission amelioration of a synthesized bis-indole derivative, 3,3'-bisindolyl(phenyl)methane (BIPM), are studied using steady-state and time-resolved spectroscopic techniques. The relative emission yield of BIPM (φf = 0.01) is significantly enhanced in the presence of cetyltrimethylammonium bromide (φf = 0.21) and polyoxyethylene (20) sorbitan monolaurate (φf = 0.24), whereas comparatively less emission enhancement is recorded within the sodium dodecyl sulfate system (φf = 0.07). In contrast, addition of an external biophilic agent, uric acid, causes requenching of the enhanced emission because of the reaggregation of the disaggregated probes. Detailed microscopic and calorimetric studies are also adopted to investigate the disaggregation-reaggregation mechanism of BIPM associations. The study will provide prior insights about the use of suitable micellar systems for the required degree of disaggregation as well as for the modulation of emission efficiency by controlled tuning of the disaggregation-reaggregation equilibrium for similar probe associations in pure aqueous medium avoiding any chemical transformation.

Cystine-cored diphenylalanine appended peptide-based self-assembled fluorescent nanostructures direct redox-responsive drug delivery

Fabrication of stimuli-responsive superstructure capable of delivering chemotherapeutics directly to the cancer cell by sparing healthy cells is crucial. Herein, we developed redox-responsive hollow spherical assemblies through self-assembly of disulfide-linked cysteine-diphenylalanine (SN). These fluorescent hollow spheres display intrinsic green fluorescence, are proteolytically stable and biocompatible, and allow for real-time monitoring of their intracellular entry. The disulfide bond facilitates selective degradation in the presence of high glutathione (GSH) concentrations, prevalent in cancer cells. We achieved efficient encapsulation (68.72%) of the anticancer drug doxorubicin (Dox) and demonstrated GSH-dependent, redox-responsive drug release within cancerous cells. SN-Dox exhibited a 20-fold lower effective concentration (2.5 μM) for compromising breast cancer cell viability compared to non-malignant cells (50 μM). The ability of SN-Dox to initiate DNA damage signaling and trigger apoptosis was comparable to that of the unencapsulated drug. Our findings highlight the potential of SN for creating site-specific drug delivery vehicles for sustained therapeutic release.

Construction of glutathione-responsive paclitaxel prodrug nanoparticles for image-guided targeted delivery and breast cancer therapy

Paclitaxel (PTX) remains an essential drug in the treatment of breast cancer. To improve metabolic stability and real-time monitoring of drug location, we develop a visualized nano-prodrug. Novel hyaluronic acid (HA)-coated glutathione (GSH)-sensitive chitosan (CS)-based nano-prodrug (HA/TPE-CS-SS-PTX NPs) with aggregation-induced emission effects (AIE) were accomplished. The prodrug NPs (drug loading 29.32%, particle size 105 nm, regular sphericity) exhibit excellent fluorescence stability. The prodrug NPs could target tumor cells with high expression of CD44 and decompose in the presence of high concentrations of glutathione. In vitro evaluations revealed that the prodrug NPs have significant cytotoxicity on 4T1 cells, and due to their excellent AIE characteristics, their position in cells can be tracked. Moreover, the prodrug NPs also shown superior anti-tumor effects in vivo experimental. Overall, the HA/TPE-CS-SS-PTX NPs we constructed have excellent bio-imaging capabilities and can be served as a potential nanomedicine for PTX delivery against breast cancer.

Machine Learning Prediction of Quantum Yields and Wavelengths of Aggregation-Induced Emission Molecules

The aggregation-induced emission (AIE) effect exhibits a significant influence on the development of luminescent materials and has made remarkable progress over the past decades. The advancement of high-performance AIE materials requires fast and accurate predictions of their photophysical properties, which is impeded by the inherent limitations of quantum chemical calculations. In this work, we present an accurate machine learning approach for the fast predictions of quantum yields and wavelengths to screen out AIE molecules. A database of about 563 organic luminescent molecules with quantum yields and wavelengths in the monomeric/aggregated states was established. Individual/combined molecular fingerprints were selected and compared elaborately to attain appropriate molecular descriptors. Different machine learning algorithms combined with favorable molecular fingerprints were further screened to achieve more accurate prediction models. The simulation results indicate that combined molecular fingerprints yield more accurate predictions in the aggregated states, and random forest and gradient boosting regression algorithms show the best predictions in quantum yields and wavelengths, respectively. Given the successful applications of machine learning in quantum yields and wavelengths, it is reasonable to anticipate that machine learning can serve as a complementary strategy to traditional experimental/theoretical methods in the investigation of aggregation-induced luminescent molecules to facilitate the discovery of luminescent materials.

Synthesis of Regioregular and Random Boron-Fused Azomethine Conjugated Polymers for Film Morphology Control

Regioregular and random conjugated polymers based on a boron-fused azomethine unit were synthesized by Sonogashira-Hagihara cross coupling reaction. Although these polymers exhibited similar optical properties in the solution states, a distinct difference was observed in the aggregation forming ability in the film states; scanning electron microscope (SEM) observation indicated the existence of fiber-like aggregates in the spin-coated film of the regioregular polymer, while regiorandom polymer showed no aggregate in the film state. Accordingly, the UV-vis absorption spectrum of the regioregular polymer showed an increased shoulder peak due to the aggregate formation, whereas the random one showed no change. Furthermore, an absolute fluorescence quantum efficiency of the regioregular polymer was enhanced in response to the aggregate disassembly via thermal annealing treatment. In this study, we demonstrate that controlling regioregularity of the conjugated polymers can induce the different morphological structures and thermal-responsive behaviors. These findings could be beneficial for the design strategy and potential applications of thin-film optoelectronic devices with stimuli-responsive properties.

Reductive prodrug and AIE copolymer nanoparticle for monitoring and chemotherapy

Polymeric micelle systems for drug delivery, monitor and chemotherapy have gained significant attention, and reductive polymeric micelle systems have become particularly attractive due to their controlled release behavior without additional assistance. However, there are challenges in accurately controlling drug and probe release from the nanoparticles and determining the loading content of drug and probe. To address these issues, we have developed a reduction-responsive Pt(IV) prodrug-based polymeric delivery system that can be dynamically monitored using aggregation-induced emission luminogens (AIE) based bioprobes. These polymeric micelle can self-assemble into nanoparticles and release both bio-active Pt(II) drug and bio-probe upon reduction activation. TPE molecules released in the inner endo/lysosomal microenvironment aggregate and fluoresce upon irradiation, thus allowing real-time tracking of drug biodistribution without additional contrast agents. Advantages of this system include position-specific chemical bond cleavage, control of platinum content, and monitoring of drug reduction and biodistribution.

The role of interfacial donor-acceptor percolation in efficient and stable all-polymer solar cells

Polymerization of Y6-type acceptor molecules leads to bulk-heterojunction organic solar cells with both high power-conversion efficiency and device stability, but the underlying mechanism remains unclear. Here we show that the exciton recombination dynamics of polymerized Y6-type acceptors (Y6-PAs) strongly depends on the degree of aggregation. While the fast exciton recombination rate in aggregated Y6-PA competes with electron-hole separation at the donor-acceptor (D-A) interface, the much-suppressed exciton recombination rate in dispersed Y6-PA is sufficient to allow efficient free charge generation. Indeed, our experimental results and theoretical simulations reveal that Y6-PAs have larger miscibility with the donor polymer than Y6-type small molecular acceptors, leading to D-A percolation that effectively prevents the formation of Y6-PA aggregates at the interface. Besides enabling high charge generation efficiency, the interfacial D-A percolation also improves the thermodynamic stability of the blend morphology, as evident by the reduced device "burn-in" loss upon solar illumination.

Metallaaromatic Complexes as Candidates for Future Molecular Materials and Electronic Devices: Recent Advancements

In recent years, the field of organometallic chemistry has made a great progress and diverse types of metallaaromatics have successively been reported. In those studies, incorporation of ligated osmium centers into metallaaromatic systems played a prominent role. The reviewed literature documents that certain metallaaromatics with unconventional photophysical properties, redox and electronic transport properties and magnetism, have potential to be widely used in diverse practical applications, with selected examples of amino acid and fluoride anion identification, photothermal effects, functional materials, photodynamic therapy (PDT) in biomedicine, single-molecule junction conductors, and electron-transport layer materials (ETLs) in solar cells.

Mechanofluorochromic Properties of 1,4-Diphenylanthracene Derivatives with Hypsochromic Shift

Several types of 1,4-diphenylanthracene derivatives 1-4 were prepared, and their photophysical properties were observed in the solid and solution states. Interestingly, the CN-group-substituted 1,4-diphenylanthracene derivative 2 was found to exhibit a higher fluorescence quantum yield (ϕf = 0.71) in the solid state than in the solution state, probably due to the formation of an intermolecular Ar-CN⋯H-Ar hydrogen bond and antiparallel type locked packing structure in the solid state. Furthermore, for some derivatives, an increase in the fluorescence quantum yield was observed in the PMMA film (1 wt%) over both the solid state and the solution state. More interestingly, some of the 1,4-diphenylanthracene derivatives exhibited unusual mechanofluorochromic properties with a "hypsochromic shift" in luminous color depending on the substituents of the phenyl group, and with the derivatives having CF3, OMe, CN, and two F substituents (1d-1f, 2-4) showing a significant luminous color change with a "hypsochromic shift" after grinding. However, no change in the luminous color was observed for the derivatives having H, Me, and one F substituent (1a-1c), and especially for some of the CN-substituted derivatives, a reversible luminous color change with a "hypsochromic shift" was observed, probably due to the formation of an antiparallel type packing structure. These "hypsochromic" anthracene derivatives could probably be utilized as new mechanofluorochromic materials.

Enabling nonconjugated polyesters emit full-spectrum fluorescence from blue to near-infrared

Near-infrared luminophores have many advantages in advanced applications, especially for structures without π-conjugation aromatic rings. However, the fabrication of red clusteroluminogens from nonconjugated polymers is still a big challenge, let alone the near-infrared clusteroluminogens. Here, we develop nonconjugated luminophores with full-spectrum from blue to near-infrared light (470 ~ 780 nm), based on color phenomenon of nonconjugated polyesters synthesized from the amine-initiated copolymerization of epoxides and cyclic anhydrides. We reveal that amines act as initiators attached to polymer chain ends. The formation of various amine-ester complexes in polyesters induces red to near-infrared light, conceptually, amine-ester complexed clusteroluminescence via intra/inter-chain charge transfer. Significantly, emission colors can be easily tuned by the contents and types of amines, microstructures of polyesters, and their concentration. This work provides a low-cost, scalable platform and strategy for the production of high-efficiency, multicolor luminescent materials.

Progress and Perspectives on Promising Covalent-Organic Frameworks (COFs) Materials for Energy Storage Capacity

In recent years, a new class of highly crystalline advanced permeable materials covalent-organic frameworks (COFs) have garnered a great deal of attention thanks to their remarkable properties, such as their large surface area, highly ordered pores and channels, and controllable crystalline structures. The lower physical stability and electrical conductivity, however, prevent them from being widely used in applications like photocatalytic activities and innovative energy storage and conversion devices. For this reason, many studies have focused on finding ways to improve upon these interesting materials while also minimizing their drawbacks. This review article begins with a brief introduction to the history and major milestones of COFs development before moving on to a comprehensive exploration of the various synthesis methods and recent successes and signposts of their potential applications in carbon dioxide (CO2 ) sequestration, supercapacitors (SCs), lithium-ion batteries (LIBs), and hydrogen production (H2 -energy). In conclusion, the difficulties and potential of future developing with highly efficient COFs ideas for photocatalytic as well as electrochemical energy storage applications are highlighted.

Polarity-Induced Morphological Transformation with Tunable Optical Output of Terpyridine-Phenanthro[9,10-d]imidazole-Based Ligand and Its Zn(II) Complexes with I-V Characteristics

Self-assembled nanostructures obtained from various functional π-conjugated organic molecules have been able to draw substantial interest due to their inherent optical properties, which are imperative for developing optoelectronic devices, multiple-color-emitting devices with color-tunable displays, and optical sensors. These π-conjugated molecules have proven their potential employment in various organic electronic applications. Therefore, the stimuli-responsive fabrication of these π-conjugated systems into a well-ordered assembly is extremely crucial to tuning their inherent optical properties for improved performance in organic electronic applications. To this end, herein, we have designed and synthesized a functional π-conjugated molecule (TP) having phenanthro[9,10-d]imidazole with terpyridine substitution at the 2 position and its corresponding metal complexes (TPZn and (TP)2Zn). By varying the polarity of the self-assembly medium, TP, TPZn, and (TP)2Zn are fabricated into well-ordered superstructures with morphological individualities. However, this medium polarity-induced self-assembly can tune the inherent optical properties of TP, TPZn, and (TP)2Zn and generate multiple fluorescence colors. Particularly, this property makes them useful for organic electronic applications, which require adjustable luminescence output. More importantly, in 10% aqueous-THF medium, TPZn exhibited H-type aggregation-induced white light emission and behaved as a single-component white light emitter. The experimentally obtained results of the solvent polarity-induced variation in optical properties as well as self-assembly patterns were further confirmed by theoretical investigation using density functional theory calculations. Furthermore, we investigated the I-V characteristics, both vertical and horizontal, using ITO and glass surfaces coated with TP, TPZn, and (TP)2Zn, respectively, and displayed maximum current density for the TPZn-coated surface with the order of measured current density TPZn > TP > (TP)2Zn. This observed order of current density measurements was also supported by a direct band gap calculation associated with the frontier molecular orbitals using the Tauc plot. Hence, solvent polarity-induced self-assembly behavior with adjustable luminescence output and superior I-V characteristics of TPZn make it an exceptional candidate for organic electronic applications and electronic device fabrication.

Quantum-sized topological insulators/semimetals enable ultrahigh and broadband saturable absorption

Two-dimensional topological insulators/semimetals have recently attracted much attention. However, quantum-sized topological insulators/semimetals with intrinsic characteristics have never been reported before. Herein, we report the high-yield production of topological insulator (i.e., Bi2Se3 and Sb2Te3) and semimetal (i.e., TiS2) quantum sheets (QSs) with monolayer structures and sub-4 nm lateral sizes. Both linear and nonlinear optical performances of the QSs are investigated. The QS dispersions present remarkable photoluminescence with excitation wavelength-, concentration-, and solvent-dependence. The solution-processed QSs-poly(methyl methacrylate) (PMMA) hybrid thin films demonstrate exceptional nonlinear saturation absorption (NSA). Particularly, Bi2Se3 QSs-PMMA enables record-high NSA performance with a broadband feature. Specifically, the (absolute) modulation depths up to 71.6 and 72.4% and saturation intensities down to 1.52 and 0.49 MW cm-2 are achieved at 532 and 800 nm, respectively. Such a phenomenal NSA performance would greatly facilitate their applications in mode-locked lasers and related fields.

Solid-State Solvent-Independent Excited-State Intramolecular Proton Transfer in a Coordination Polymer and Its Temperature Dependence

Increasing demand for futuristic switches and sensors around the world has created an intense interest in smart materials, which can show a rapid but feature-dependent change in the physical properties in the presence of external stimuli. Hitherto such changes in the photophysical property of materials, specifically in the solid state, are projected for the use of smart on-off switches. Materials having an external-stimuli-responsive change in the photophysical properties like excited-state intramolecular proton transfer (ESIPT) can also be utilized for these purposes. Although the event of solid-state ESIPT is not new in the domain of material chemistry, especially for organic molecules, it was never observed for coordination polymers (CPs). Previous instances of ESIPT in CPs have necessitated the presence of a solvent as a suspension medium, driving a solvent-assisted ESIPT phenomenon. However, the emergence of a solvent-independent ESIPT-enabled CP presents unique advantages. The well-defined periodic arrangement ensures reliable property variations, while the robust coordination bonds between the metal nodes and ligands provide durability in harsh environments. Addressing this gap, we present the first ever solid-state, solvent-free, and solvent-independent ESIPT-active CP. Remarkably, this CP exhibits temperature-dependent ESIPT on-off behavior, demonstrating its potential as a cutting-edge material in the field of smart switches and sensors.

A High-Efficiency Deep Blue Emitter for OLEDs with a New Dual-Core Structure Incorporating ETL Characteristics

In this study, we introduced the weak electron-accepting oxazole derivative 4,5-diphenyl-2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)oxazole (TPO) into both anthracene and pyrene moieties of a dual core structure. Ultimately, we developed 2-(4-(6-(anthracen-9-yl)pyren-1-yl)phenyl)-4,5-diphenyloxazole (AP-TPO) as the substitution on the second core, pyrene, and 4,5-diphenyl-2-(4-(10-(pyren-1-yl)anthracen-9-yl)phenyl)oxazole (TPO-AP) as the substitution on the first core, anthracene. Both materials exhibited maximum photoluminescence wavelengths at 433 and 443 nm in solution and emitted deep blue light with high photoluminescence quantum yields of 82% and 88%, respectively. When used as the emitting layer in non-doped devices, TPO-AP outperformed AP-TPO, achieving a current efficiency of 5.49 cd/A and an external quantum efficiency of 4.26% in electroluminescence. These materials introduce a new category of deep blue emitters in the organic light-emitting diodes field, combining characteristics related to the electron transport layer.

Naphthalene Diimide-Based Orange Emitting Luminogen: A Fluorometric Probe for Thiol Sensing through the Click Reaction

Fluorometric sensors have gained considerable attention in various fields, including environmental monitoring, biomedical research, and clinical diagnostics. This article delineates the fabrication of an orange emitting naphthalene diimide (NDI) derivative consisting of maleimide moiety (NDI-mal) for fluorometric sensing of thiols. Spherical shaped organic nanoparticles (∼100-150 nm) were constructed by NDI-mal in dimethyl sulfoxide (DMSO)/dimethylformamide (DMF)-water through J-type aggregation. NDI-mal displayed self-assembly driven aggregation-induced emission (AIE) through excimer formation at λem= 588 nm at fw = 99 vol % DMSO/DMF-water. Naphthyl residue at both terminals of NDI-mal facilitates intramolecular charge transfer (ICT) from the donor naphthyl residue to the acceptor NDI core. The fluorescence intensity of NDI-mal fluorescent organic nanoparticles (FONPs) got quenched in the presence of thiols due to thiol-maleimide adduct formation (Michael addition). NDI-mal FONPs selectively probed thiol functionalized small molecules (4-aminothiophenol), biomolecules (glutathione (GSH)), and proteins (reduced BSA) with high sensitivity having a limit of detection of 15.3 nM, 6.0 nM, and 9.2 ng/mL, respectively. Importantly, thiol sensing was selective against analogous small molecules, biomolecules, and proteins devoid of thiol moieties. Cellular imaging demonstrated selective diagnosis of cancer cells by NDI-mal FONPs through quenching of its emission upon interaction with thiols in B16F10 cells due to the high abundance of GSH in cancer cells compared to NIH3T3 cells. NDI-mal FONPs emitted their native fluorescence inside cells subjected to reactive oxygen species mediated thiol oxidation via Fenton's reaction. Notably, GSH-maleimide adduct formation by NDI-mal FONPs displayed notable therapeutic efficacy against cancer cells having ∼2.4-fold higher killing of B16F10 in comparison to NIH3T3 cells possibly through oxidative stress induced apoptosis owing to the depletion in the GSH level. Thus, NDI-mal AIE-gen successfully emerged as a selective and sensitive probe toward thiols through thiol-maleimide click chemistry with therapeutic ability against cancer cells in the absence of systematic intervention.

Substituent-Controlled Photophysical Responses in Dihydropyridine Derivatives and Their Application in the Detection of Volatile Organic Contaminants

In the ever-expanding realm of organic fluorophores, structurally simple and synthetically straightforward molecules with unique photophysical properties have received special attention. Among these, 1,4-dihydropyridine (DHP) is an important scaffold that permits fine-tuning of their photophysical properties through substituents on the periphery. Herein, we describe a series of solid-emissive N-substituted 2,6-dimethyl-4-methylene-1,4-dihydropyridine derivatives appended with electron-withdrawing substituents (dicyanomethylene or 2-dicyanomethylene-3-cyano-2,5-dihydrofuran) at the C-4 position and alkyl or alkylaryl groups on the DHP nitrogen. Electronic and steric tuning exerted by these substituents resulted in interesting photophysical properties such as negative solvatochromism, solidstate, and aggregation-induced emission (AIE). Theoretical calculations were carried out to explain the solvatochromic properties. Insight into the AIE properties was obtained through variable-temperature nuclear magnetic resonance and viscosity- and temperature-dependent emission studies. The variations in molecular packing in the crystal lattice with changes in the N-substituents contributed to the tuning of solid state emission properties. Detection of aromatic volatile organic compounds (VOCs) was achieved using the aggregates of the DHP derivatives. Among the VOCs, p-xylene elicited a significant enhancement in emission, allowing its detection at submicromolar levels.

Cobalt-doped hollow polydopamine for oxygen generation and GSH consumption enhanced chemo-PTT combined cancer therapy

Nanotechnology has revolutionized the field of therapeutics by introducing a plethora of nanomaterials capable of enhancing traditional drug efficacy or paving the way for innovative treatment methods. Within this domain, we propose a novel Cobalt-doped hollow polydopamine nanosphere system. This system, incorporating Doxorubicin loading and hyaluronic acid (HA) surface coating (CoHPDA@DOX-HA), is designed for combined tumor therapy. The overarching aim is to diminish the administration dosage, mitigate the cytotoxic side effects of chemotherapy drugs, augment chemosensitivity within neoplastic tissues, and attain superior results in tumor treatment via combined therapeutic strategies. The targeted molecule, hyaluronic acid (HA), amplifies the biocompatibility of CoHPDA@DOX-HA throughout circulation and fosters endocytosis of the nanoparticle system within cancer cells. This nanosphere system possesses pH sensitivity properties, allowing for a meticulous drug release within the acidic microenvironment of tumor cells. Concurrently, Polydopamine (PDA) facilitates proficient photothermal therapy upon exposure to 808 nm laser irradiation. This process further amplifies the Glutathione (GSH) depletion, and when coupled with the oxygen production capabilities of the Cobalt-doped hollow PDA, significantly enhances the chemo-photothermal therapeutic efficiency. Findings from the treatment of tumor-bearing mice substantiate that even at dosages equivalent to a singular DOX administration, the CoHPDA@DOX-HA can provide efficacious synergistic therapy. Therefore, it is anticipated that multifunctional nanomaterials with Photoacoustic Tomography (PAT) imaging capabilities, targeted delivery, and a controlled collaborative therapeutic framework may serve as promising alternatives for accurate diagnostics and efficacious treatment strategies.

Triphenylamine-Based N,O-Bidentate BF2 -Enolimine Initiator for Three-Arm Star Polymethacrylates with Dual-State Fluorescent Emission

Three-arm star polymethacrylates with dual-phase (solution and solid-state) fluorescent emission have been synthesized via atom transfer radical polymerization (ATRP) using a triphenylamine-derived organboron complex (TAPA-BKI-3Br) as initiator. The as-synthesized three-arm star polymethacrylates exhibited bright emission in both solution and the solid states due to the highly twisted structure and intramolecular charge transfer (ICT) effect of TAPA-BKI core, as well as the steric effect and restriction of intramolecular motions from the polymer arms. And the polymer chains have an important influence on the photophysical behavior of the as-synthesized three-arm star polymethacrylates in the aggregated state.

Dibenzothiophene Sulfone-Based Ambipolar-Transporting Blue-Emissive Organic Semiconductors Towards Simple-Structured Organic Light-Emitting Transistors

The development of blue-emissive ambipolar organic semiconductor is an arduous target due to the large energy gap, but is an indispensable part for electroluminescent device, especially for the transformative display technology of simple-structured organic light-emitting transistor (SS-OLET). Herein, we designed and synthesized two new dibenzothiophene sulfone-based high mobility blue-emissive organic semiconductors (DNaDBSOs), which demonstrate superior optical property with solid-state photoluminescent quantum yield of 46-67 % and typical ambipolar-transporting properties in SS-OLETs with symmetric gold electrodes. Comprehensive experimental and theoretical characterizations reveal the natural of ambipolar property for such blue-emissive DNaDBSOs-based materials is ascribed to a synergistic effect on lowering LUMO level and reduced electron injection barrier induced by the interfacial dipoles effect on gold electrodes due to the incorporation of appropriate DBSO unit. Finally, efficient electroluminescence properties with high-quality blue emission (CIE (0.179, 0.119)) and a narrow full-width at half-maximum of 48 nm are achieved for DNaDBSO-based SS-OLET, showing good spatial control of the recombination zone in conducting channel. This work provides a new avenue for designing ambipolar emissive organic semiconductors by incorporating the synergistic effect of energy level regulation and molecular-metal interaction, which would advance the development of superior optoelectronic materials and their high-density integrated optoelectronic devices and circuits.

Naphthalimide-Based AIEgens for Sensing Protein Disulfide Isomerase through Thiol-Disulfide Redox Exchange

Aggregation-induced emission (AIE)-based fluorescent organic nanoparticles (FONPs) with distinctive characteristics are emerging as superior sensors due to their facile fabrication, high signal-to-noise ratio, and good biocompatibility. The present article delineates the detection and analysis of the redox behavior of the protein disulfide isomerase (PDI) enzyme by exploitation of the AIE of novel naphthalimide (NI) derivatives having thiol (-SH) and disulfide (-S-S-) moieties. Self-aggregated spherical-shaped organic nanoparticles were prepared by synthesized NI-based amphiphiles (NISH, NISS, NINSS, and TNINSH) through J-type aggregation in DMSO-water (fw = 99 vol %). Naphthyl residue containing NI-derived amphiphiles (NINSS and TNINSH) exhibited AIE (blue and yellow) at 470 and 550 nm, respectively, in DMSO-water (fw = 99 vol %). NINSS and TNINSH FONPs were suitably utilized in sensing PDI through their redox nature of thiol-disulfide exchange. Fluorescence quenching of NINSS FONPs was observed due to reduction of disulfide to thiol by PDI, whereas emission intensity was progressively red-shifted and enhanced ("Dual-AIE") for TNINSH (containing ER-targeting N-tosylethylenediamine), owing to oxidation of thiol to disulfide by PDI. NINSS and TNINSH FONPs were found to be highly efficient in sensing PDI through the AIE-based "fluorescence off/on" mechanism having limits of detection of ∼12.6-17.7 and ∼11.7-16.5 ng/mL, respectively. In vitro cell imaging for NIH3T3 (noncancer) and B16F10 (melanoma) cells with NINSS and TNINSH FONPs displayed excellent diagnosis of eukaryotic cells upon interaction with indigenous PDI. Notably, detection of cancer cells was more sensitive over the noncancerous cells by these FONPs due to overexpression of PDI within cancer cells.

Peptide-triggered self-assembly of collagen mimetic peptides into nanospheres by electrostatic interaction and π-π stacking

Collagen is the most abundant protein in various connective tissues, providing mechanical integrity as well as regulating cellular activities. Self-assembled peptides have been extensively explored to develop collagen mimetic materials, due to their attractive features such as easy synthesis, selective sequences and low immunogenicity. Metal ion-triggered self-assembly of collagen mimetic peptides has recently received increasing interests, since the addition of external stimuli offers programmable control of the self-assembly process. We have for the first time reported a peptide-stimulated self-assembly of collagen mimetic peptides into nanospheres by electrostatic interaction and π-π stacking. We have accidentally discovered that FAM-modified positively-charged triple helical peptide FAM-PRG was highly soluble, while the addition of a single-stranded negatively-charged peptide EOG-10 efficiently drove its self-assembly into well-ordered spherical nanomaterials. Peptide EOG-10 has been shown to mediate similar self-assembly of TPE-modified triple-helical peptide TPE-PRG into luminescent exquisite nanospheres, consistently demonstrating the robustness of this peptide-triggered strategy. Fluorescence monitoring of the interaction of EOG-10 and TPE-PRG at different ratios indicated that EOG-10 specifically binds to TPE-PRG to form a 3 : 1 complex. High salt concentration was shown to inhibit the self-assembly of TPE-PRG with EOG-10, suggesting that their self-assembly was controlled by electrostatic interaction. The self-assembly of TPE-PRG with EOG-10 has been further revealed to require the exact lengths of both peptides as well as complementary sequences without mutations, indicating a pairwise "side-by-side" binding mode. Notably, the identity of the N-terminal residues of X-PRG has been found to play a determinant role in the self-assembly, while non-aromatic residues lost the self-assembling capability, suggesting that π-π stacking and electrostatic interactions collectively modulate the self-assembly of X-PRG and EOG-10. To conclude, we have developed a highly biocompatible and programmably controlled peptide-triggered self-assembly approach to create novel collagen mimetic nanomaterials, which may have great potential in advanced functional materials.

Design and synthesis of photostable triphenylamine based neutral AIE nano luminogens: specific and long-term tracking of mitochondria in cells

With the increasing dependence on fluorescence bioimaging, luminogens with aggregation-induced emission (AIE) properties have gained significant attention due to their excellent photostabilization, minimal photobleaching, high reliability, and superior biocompatibility. Since mitochondria are crucial subcellular organelles in eukaryotic cells with important biological functions, organelle-specific AIE emitters with distinct functions have been highly sought after, but with limited success using simple synthetic methods. Here, we describe a strategy for synthesizing two triphenylamine (TPA) based acrylonitriles, tethered to different donor groups, TPA and phenothiazine (PTZ), respectively, with superior AIE properties using Suzuki coupling. We conducted a systematic and detailed experimental analysis of the structural characteristics of both AIE luminogens, which exhibited excellent photostability, a large Stokes shift, and bright solid-state emission. A cell viability study carried out with F1 and F2 dyes revealed that both luminogens exhibited excellent biocompatibility. Based on fluorescence experiments, F2 displayed excellent AIE characteristics, permeability, biocompatibility, and photostability compared to rhodamine 123, allowing it to selectively stain and track mitochondria in cancer cells over an extended period of time. The Pearson correlation coefficient of F2 and rhodamine 123 was estimated to have an r-value of 0.99. Our findings are expected to provide insight into the synthesis of an extensive archive of AIE-based acrylonitriles with fascinating properties for mitochondrial staining.

Fluorescent Dye-Doped Brightening Polymer-Stabilized Bistable Cholesteric Liquid Crystal Films

Brightening polymer-stabilized bistable cholesteric liquid crystal (PSBCLC) films with doped fluorescent dyes were prepared using the polymerization-induced phase separation (PIPS) method. The transmittance performance behavior of these films in both states (focal conic and planar) and absorbance change in multiple dye concentrations were studied using a UV/VIS/NIR spectrophotometer. The change occurring in dye dispersion morphology with different concentrations was obtained by means of the polarizing optical microscope. The maximum fluorescence intensity of different dye-doped PSBCLC films was measured using a fluorescence spectrophotometer. Moreover, the contrast ratios and driving voltages of these films were calculated and recorded to demonstrate film performance. Finally, the optimal concentration of dye-doped PSBCLC films with a high contrast ratio and a relatively low drive voltage was found. This is expected to have great potential applications in cholesteric liquid crystal reflective displays.

Theoretical and experimental studies on mechanochromic triphenylamine based fluorescent "ON-OFF-ON" sensor for sequential detection of Fe3+ and deferasirox

A novel triphenylamine (TPA) based sensor TTU was rationally designed and synthesized that exhibited reversible mechanochromic and aggregation induced emission enhancement (AIEE) properties. The AIEE active sensor was employed for fluorometric detection of Fe³⁺ in aqueous medium, with distinguished selectivity. The sensor showed a highly selective quenching response towards Fe³⁺ that is ascribed to complex formation with paramagnetic Fe³⁺. Subsequently, TTU-Fe³⁺ complex acted as a fluorescence sensor for the detection of deferasirox (DFX). The subsequent addition of DFX to TTU-Fe³⁺ complex led to the recovery of fluorescence emission intensity of sensor TTU that was attributed to the displacement of Fe³⁺ by DFX and release of sensor TTU. The proposed sensing mechanisms for Fe³⁺ and DFX was confirmed through ¹H NMR titration experiment and DFT calculations. Frontier molecular orbitals (FMO), density of states (DOS), natural bond orbital (NBO), non-covalent interaction (NCI) and electron density difference (EDD) analysis were performed using DFT calculations to support the experimental results. Moreover, sensor TTU displayed colorimetric detection of Fe³⁺. Further, the sensor was employed for the detection of Fe³⁺ and DFX in real water samples. Finally, logic gate was fabricated by using sequential detection strategy.

A biocompatible polyurethane fluorescent emulsion with aggregation-induced emission for targeted tumor imaging

The applications of fluorescence imaging in tumor detection and assistance in tumor resection have become progressively more widespread. Biocompatible fluorescent nanoparticles with high sensitivity and selectivity are a challenge for biological fluorescence imaging. Ligand-mediated targeting of nanoparticles to tumors is an appealing tactic for improving imaging efficiency. Herein, tetraphenyl ethylene (TPE) and phenylboronic acid (PBA) were introduced into polyurethane to synthesize a PU-TPE-PBA (PTP) fluorescent emulsion with aggregation-induced emission (AIE) for targeted tumor imaging. The PTP emulsion with a size of less than 50 nm shows excellent stability and high fluorescence sensitivity (extremely low TPE concentrations of 0.31 μg mL^-1). Since PBA can selectively recognize and bind to sialic acid (SA) which is widely overexpressed in tumor cells, such PTP nanoparticles can be enriched in tumors and retained for longer periods due to enhanced permeability and retention (EPR) as well as active targeting effects. In addition, the PTP emulsion exhibits good biocompatibility and biosafety. Therefore, the novel PTP emulsion is promising for tumor cell imaging.

Inclusion Complexes of Photosensitizers with Cyclodextrins for Enhancing the Fabrication of Volume Grating

A supramolecule photosensitizer (supra-photosensitizer) based on the host-guest complexation of cyclodextrins and a bis-chalcone dye (BDEA) was prepared. Methyl-β-cyclodextrin (Me-β-CD), with the highest inclusion rate, was confirmed as the best host among the four cyclodextrins. The host-guest properties of Me-β-CD and BDEA were characterized by FTIR, XRD, ¹H NMR, PLQY, SEM, Job's plot, Benesi-Hildebrand plot, and others. Compared to the conventional photosensitizers, the supra-photosensitizers showed higher fluorescence emission and longer fluorescence lifetime whether as a powder or distributed in a film. The improvement in fluorescence coincided with improvement in photoinitiation efficiency and was proven to enhance the generation of volume grating. It is expected that the supra-photosensitizer may open a new avenue for the design of high-performance photoinitiation systems.

Introduction of Multicomponent Dyes into 2D MOFs: A Strategy to Fabricate White Light-Emitting MOF Composite Nanosheets

Metal-organic frameworks (MOFs) have been extensively studied in host-guest chemistry by means of ultrahigh porosities, tunable channels, and component diversities. As the host matrix, MOFs exhibit immense potential in the preparation of single-phase white light-emitting (SPWLE) materials. Nonetheless, it is a great challenge that the size of the introduced guest molecules is limited by MOF pores, which affects the WLE optimization. In this work, two-dimensional (2D) MOFs are first utilized as the host matrices to simultaneously encapsulate red-green-blue fluorescent dyes for SPWLE. Various dyes@2D MOF composites with high-quality WLE performances and ultrathin nanosheet morphologies are directly assembled from 2D MOF precursors and dyes in high yields. Owing to the flexible interlamellar space of 2D MOFs, different types and sizes of guests can be easily introduced, which greatly expands the range of available MOF hosts and guests, making the WLE much more tunable. The strategy of employing 2D MOFs as the host matrices to introduce multicomponent dyes for SPWLE nanosheets resolves the restriction of MOF pores on the guest molecule size and opens a new avenue to rationally design and prepare SPWLE nanosheets that are highly solution-processable.

An aggregation induced emission active bis-heteroleptic ruthenium(II) complex for luminescence light-up detection of pyrophosphate ions

A red emissive ruthenium(II) complex 1[PF6]2 of an amino ethanol substituted 1,10-phenanthroline-based ligand (L1) has been developed and characterized by spectroscopic analysis and single-crystal X-ray diffraction. Complex 1 shows an aggregation-induced emission (AIE) enhancement and forms nano-aggregates in the poor solvent water and highly dense polyethylene glycol (PEG) media. The possible reason behind the AIE properties may be the rigidity gained through weak supramolecular interactions between neighbouring phenanthroline ligands and PF₆^- counterions. The AIE properties were supported by UV-vis and photoluminescence (PL) spectroscopy and dynamic light scattering (DLS) studies to substantiate the formation of nano-aggregates and to understand the morphology of the aggregated particles, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies were performed. Compound 1[PF6]2 was highly selective towards pyrophosphate ions (PPi) over other phosphates such as ATP, ADP, AMP and H₂PO₄^- ions and other competitive anions in the PL spectroscopic channel in acetonitrile. The PL titrations of 1[PF6]2 with PPi in CH₃CN furnished the association constant K_a = 1.08 × 10⁴ M^-1 and the detection limit was calculated as low as 1.54 μM. The PPi detection has been established through the unique H-bonding interaction, supported by ¹H NMR titration. Finally, the cytotoxicity study and bioimaging were carried out for biological application. The complex shows very low cytotoxicity and good biocompatibility and is suitable for intracellular PPi imaging.

Functionalized Fluorescent Nanostructures Generated from Self-Assembly of a Cationic Tripeptide Direct Cell-Selective Chemotherapeutic Drug Delivery

Nanodrug delivery systems (NDDs) capable of conveying chemotherapeutics directly into malignant cells without harming healthy ones are of significant interest in the field of cancer therapy. However, the development of nanostructures with the requisite biocompatibility, inherent optical properties, cellular penetration ability, encapsulation capability, and target selectivity has remained elusive. In an effort to develop cell-selective NDDs, we have synthesized a cationic tripeptide Boc-Arg-Trp-Phe-OMe (PA1), which self-assembles into well-ordered spheres in 100% aqueous medium. The inherent fluorescence properties of the peptide PA1 were shifted from the ultraviolet to the visible region by the self-assembly. These fluorescent nanostructures are proteolytically stable, photostable, and biocompatible, with characteristic blue fluorescence signals that permit us to monitor their intracellular entry in real time. We also demonstrate that these tripeptide spherical structures (TPSS) have the capacity to entrap the chemotherapeutic drug doxorubicin (Dox), shuttle the encapsulated drug within cancerous cells, and initiate the DNA damage signaling cascade, which culminates in apoptosis. Next, we functionalized the TPSS with an epithelial-cell-specific epithelial cell adhesion molecule aptamer. Aptamer-conjugated PA1 (PA1-Apt) facilitated efficient Dox delivery into the breast cancer epithelial cell line MCF7, resulting in cell death. However, cells of the human cardiomyocyte cell line AC16 were resistant to the cell killing actions of PA1-Apt. Together, these data demonstrate that not only can the self-assembly of cationic tripeptides like PA1 be exploited for efficient drug encapsulation and delivery but their unique chemistry also allows for functional modifications, which can improve the selectivity of these versatile NDDs.

Tuning the Solid Phase Fluorescence Emission from Long Wavelength Visible to Near-Infrared in Oxazol-5-One Derivatives: Structure-Property Relationship, Theoretical and Experimental Studies

Most of the fluorescent molecules among organic [Formula: see text]-conjugated materials show blue or green emission in the solid phase but few of them emit red-shifted visible and near-infrared light in the material science. To create molecules emitting for this feature, two π-conjugated oxazol-5-one derivatives containing donor (OCH₃) and acceptor groups (NO₂) were synthesized. Their optical and charge-transport properties were investigated through experimental and theoretical methods including the single crystal X-ray crystallography, Hirshfeld Surface Analysis, photophysical studies and Density Functional Theory (DFT), respectively. In addition, FT-IR, ¹H-NMR, ¹³C-NMR spectroscopy, cyclic voltammetry (CV) measurements were performed. According to our results, both molecules may provide the significant pathway of development of long wavelength visible and red emissive features in solid phase with the aggregation induced enhanced emission (AIEE) properties particularly in the fields of OLEDs, optical communication, defence and bioimaging.

Novel biocompatible and sensitive visual sensor based on aggregation-induced emission for on-site detection of radioactive uranium in water and live cell imaging

In consideration of the severe hazards of radioactive uranium pollution, the rapid assessment of uranium in field and in vivo are urgently needed. In this work a novel biocompatible and sensitive visual fluorescent sensor based on aggregation-induced emission (AIE) was designed for onsite detection of UO₂²⁺ in complex environmental samples, including wastewater from Uranium Plant, river water and living cell. The AIE-active sensor (named as TPA-SP) was prepared with a "bottom-up" strategy by introducing a trianiline group (TPA) with a single-bond rotatable helix structure into the salicylaldehyde Schiff-base molecule. The photophysical properties, cytotoxicity test, recognition mechanism and the analytical performance for the detection of UO₂²⁺ in actual water samples and cell imaging were systematically investigated. TPA-SP exhibited high sensitivity and selectivity toward UO₂²⁺ as well as outstanding anti-interference ability against large equivalent of different ions in a wide effective pH range. A good linear relationship in the UO₂²⁺ concentration range of 0.05-1 μM was obtained with a low limit of detection (LOD) of 39.4 nM (9.38 ppb) for uranium detection. The prepared visual sensor showed great potential for fast risk assessment of uranium pollution in environmental systems. In addition, our results also indicated that the TPA-SP exhibited very low cytotoxicity in cells and demonstrated great potential for uranium detection in vivo.

Solid-State Luminescent Materials with Multiple Emission Colors and Near-Unity Quantum Yield

Developing solid luminescent materials with a unity quantum yield and tunable emission color is promising, although it is still a difficult task. A straightforward heat-treatment method has been developed to load 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) into the matrix of boric acid (BA) to produce powders with a near-unity quantum yield and tunable emission color from yellow to green. Our results suggest that the emission of the powders originates from PTCDA, and the tunability of the emission color is caused by the hydrolysis of PTCDA in the alkaline environment. The near-unity quantum yield is attributed to the BA matrix, which confines PTCDA. In addition, the powder also shows excellent thermal stability that allows its application in light-emitting diodes. The above results are important for the development of solid-state luminescent materials for various applications, and also provide a clue for studying the emission properties of luminescent materials.

An oxygen-generating metal organic framework nanoplatform as a “synergy motor” for extricating dilemma over photodynamic therapy

Photodynamic therapy (PDT) combined with metal organic frameworks (MOFs) addresses current obstacles.

Pentacyclic and Hexacyclic Osmaarynes and Their Derivatives

Although osmabenzyne, osmanaphthalyne, osmaphenanthryne, and osmaanthracyne have been previously reported, the synthesis of polycyclic osmaarynes is still a challenge. Herein, we report the successful synthesis of the first pentacyclic osmaarynes (pyreno[b]osmabenzynes 1 a and 2 a) and hexacyclic osmaaryne (peryleno[b]osmabenzyne 3 a). Nucleophilic reaction of osmaarynes was used to obtain the corresponding pyreno[b]osmium complexes (1 and 2) and peryleno[b] osmium complex (3), which exhibited near-infrared luminescence and aggregation-induced emission (AIE) properties. Complexes 2 and 3 are resistant to photodegradation, and complex 2 has better photothermal conversion properties than 3.

Chromatographic methods for rapid aflatoxin B1 analysis in food: a review

Aflatoxin B1 (AFB1) is a mycotoxin and is the most carcinogenic of all known chemicals. In view of the AFB1 characteristics of widespread distribution, serious pollution, great harm to humans, and animals and difficult to remove, it is urgent to develop a convenient and sensitive detection method. Moreover, chromatographic test strips (CTSs) are a rapid detection technology that combines labeling technology with chromatography technology. CTSs have been widely used in the fields of environmental monitoring, medical diagnosis, and food safety analysis in recent years. Different from other immune assays, they have the advantages of short measuring time, low cost, high efficiency and no need for professionals to operate. In addition, the introduction of nanomaterials has laid a good foundation for the detection of high sensitivity, high specificity and high efficiency via CTSs. Herein, we tend to comprehensively introduce the applications of chromatographic methods in AFB1 detection and pay attention to the signal detection modes based on nanomaterials in antibody-based immunochromatographic strips (ICSs), such as colorimetric, fluorescent, chemiluminescent, and Raman scattering sensing. Some typical examples are also listed in this review. In the end, we make a summary and put forward prospects for the development of CTSs.