Squaramide-based receptors in anion supramolecular chemistry: insights into anion binding, sensing, transport and extraction

Over the last 15 years, squaramide-based receptors have attracted the attention of supramolecular chemists working in the field of anion recognition. Herein, we highlight examples of squaramide-based receptors that are able to bind, sense, extract and transport anions.

Organic Donor-Acceptor Complexes As Potential Semiconducting Materials

In this review article, the synthesis, characterization and physico-chemical properties of the organic donor-acceptor complexes are highlighted and a special emphasis has been placed on developing them as semiconducting materials. The electron-rich molecules, i. e., donors have been broadly grouped in three categories, namely polycyclic aromatic hydrocarbons, nitrogen heterocycles and sulphur containing aromatic donors. The reactions of these classes of the donors with the acceptors, namely tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), tetracyanobenzene (TCNB), benzoquinone, pyromellitic dianhydride and pyromellitic diimides, fullerenes, phenazine, benzothiadiazole, naphthalimide, DMAD, maleic anhydride, viologens and naphthalene diimide are described. The potential applications of the resulting DA complexes for physico-electronic purposes are also included. The theoretical investigation of many of these products with a view to rationalise their observed physico-chemical properties is also discussed.

Aminoguanidine-based bioactive proligand as AIEE probe for anticancer and anticovid studies

The emission features of a novel bioactive compound, 1,3-bis(2-hydroxy-3,5-diiodophenyl-methylideneamino)guanidine is found impressive with aggregation induced emission enhancement. The nitrogen and iodine rich multidentate proligand was characterized physicochemically. SCXRD and Hirshfeld surface investigation have revealed the presence of significant triangular iodine bonding apart from hydrogen bonding, weak C-H⋯π and π⋯π intermolecular interactions. These interactions collectively contribute to the solid-state packing arrangement of the molecules within the crystal lattice. The band gap of the compound was estimated experimentally and is supported with theoretical calculations. The solid-state fluorescence quantum yield of Φ = 0.36 emphasizes the utility of the proligand and the AIEE characteristics is attributed to restricted intramolecular motions as indicated by fluorescence lifetime decay studies. Strong interaction of the compound with calf thymus DNA was explored experimentally and found to align with in silico docking results. Notably, in vitro anticancer assessment on MCF-7 breast cancer cells show an IC50 value of 181.05 μg mL-1 and signifying its potent cytotoxic properties. Also, the compound is found to have lesser cytotoxicity against L929 normal cell line with an IC50 value of 356.54 μg mL-1. Computational studies further underscore the exceptional binding affinity with active sites in the SARS-CoV-2 main protease 3CLpro, surpassing established repurposed drugs. Furthermore, the proligand demonstrates excellent putative affinity towards the SARS-CoV-2 spike glycoprotein, accompanied by its distinctive AIEE attributes, drug likeness and DNA binding capability rendering it a valuable tool for prospective research investigations.

Flexible molecular crystals for optoelectronic applications

The cornerstones of the advancement of flexible optoelectronics are the design, preparation, and utilization of novel materials with favorable mechanical and advanced optoelectronic properties. Molecular crystalline materials have emerged as a class of underexplored yet promising materials due to the reduced grain boundaries and defects anticipated to provide enhanced photoelectric characteristics. An inherent drawback that has precluded wider implementation of molecular crystals thus far, however, has been their brittleness, which renders them incapable of ensuring mechanical compliance required for even simple elastic or plastic deformation of the device. It is perplexing that despite a plethora of reports that have in the meantime become available underpinning the flexibility of molecular crystals, the "discovery" of elastically or plastically deformable crystals remains limited to cases of serendipitous and laborious trial-and-error approaches, a situation that calls for a systematic and thorough assessment of these properties and their correlation with the structure. This review provides a comprehensive and concise overview of the current understanding of the origins of crystal flexibility, the working mechanisms of deformations such as plastic and elastic bending behaviors, and insights into the examples of flexible molecular crystals, specifically concerning photoelectronic changes that occur in deformed crystals. We hope this summary will provide a reference for future experimental and computational efforts with flexible molecular crystals aimed towards improving their mechanical behavior and optoelectronic properties, ultimately intending to advance the flexible optoelectronic technology.

C3-Symmetric Luminescent Diketone with Amido-Linkage as a Polymorphic Fluorescence Emitter

The study introduces a novel C3-symmetric β-diketone compound, BTA-D3, and its monomeric counterpart, D, with a focus on their synthetic procedure, photophysical properties and aggregation behavior. Both compounds exhibit characteristic absorption and weak fluorescence in solution, with BTA-D3 displaying higher absorption coefficients due to its larger number of diketone units. Density Functional Theory (DFT) calculations suggest increased co-planarity of diketone groups in BTA-D3. A significant finding is the Aggregation-Induced Emission (AIE) property of BTA-D3, as its fluorescence intensity increases dramatically when exposed to specific solvent ratios. The AIE behavior is attributed to intermolecular excitonic interaction between BTA-D3 molecules in self-organized aggregates. We also studied fluorescence anisotropy of BTA-D3 and D. Despite its larger size, BTA-D3 showed reduced anisotropy values because of efficient intramolecular energy migration among three diketone units. Furthermore, BTA-D3 demonstrates unique polymorphism, yielding different emission colors and structures depending on the solvent used. A unique approach is presented for promoting the growth of self-organized aggregate structures via solvent evaporation, leading to distinct fluorescence properties. This research contributes to the understanding of C3-symmetric structural molecules and provides insights into strategies for controlling molecular alignment to achieve diverse fluorescence coloration in molecular materials.

Ultrafast restricted intramolecular rotation in molecules with aggregation induced emission

In this work, the ultrafast intramolecular rotation behavior of 1,1,2,3,4,5-hexaphenylsilole has been investigated in several solutions with different viscosities using femtosecond transient absorption spectroscopy combined with density functional theory and time-dependent density functional theory calculations. It is demonstrated that the nonradiative process, which competes with radiative decay, involves two main stages, namely the restricted intramolecular rotation and internal conversion processes. The intramolecular rotation depends on viscosity and presents a significant restriction. The restricted rotational rate is determined to be dozens of picoseconds. The following nonradiative process is strongly dominated by intramolecular rotation. The nonradiative decay rate will decrease with the increase in viscosity, leading to a rise in the radiative probability and photoluminous yield. These results have borne out the mechanism of ultrafast restricted intramolecular rotation of aggregation induced emission and provided a detailed photophysical picture of nonradiative processes.

Multi-step FRET systems based on discrete supramolecular assemblies

Fluorescence resonance energy transfer (FRET) from the excited state of the donor to the ground state of the acceptor is one of the most important fluorescence mechanisms and has wide applications in light-harvesting systems, light-mediated therapy, bioimaging, optoelectronic devices, and information security fields. The phenomenon of sequential energy transfer in natural photosynthetic systems provides great inspiration for scientists to make full use of light energy. In recent years, discrete supramolecular assemblies (DSAs) have been successively constructed to incorporate donor and multiple acceptors, and to achieve multi-step FRET between them. This perspective describes recent advances in the fabrication and application of DSAs with multi-step FRET. These DSAs are categorized based on the non-covalent scaffolds, such as amphiphilic nanoparticles, host-guest assemblies, metal-coordination scaffolds, and biomolecular scaffolds. This perspective will also outline opportunities and future challenges in this research area.

Aggregation/Crystallization-Induced Emission in Naphthyridine-Based Carbazolyl-Modified Donor-Acceptor Boron Dyes Tunable by Fluorine Atoms

Four donor-acceptor boron difluoride complexes based on the carbazole electron donor and the [1,3,5,2]oxadiazaborinino[3,4-a][1,8]naphthyridine acceptor were designed, synthesized, and systematically spectroscopically investigated in solutions, in dye-doped polymer films, and in the solid states. The dyes exhibit an intense blue to red solid-state emission with photoluminescence quantum yields of up to 59 % in pure dye samples and 86 % in poly(methyl methacrylate) films. All boron complexes show aggregation-induced emission and reversible mechanofluorochromism. The optical properties of these dyes and their solid state luminescence can be tuned by substitution pattern, i. e., the substituents at the naphthyridine unit. Exchange of CH3- for CF3-groups does not only increase the intramolecular charge transfer character, but also provides a crystallization-induced emission enhancement.

Charge-Reversal NaCl/G-Quartets for Aggregation-Induced Mitochondrial MicroRNA Imaging and Ion-Interference Therapy

Mitochondrial therapy is a promising new strategy that offers the potential to achieve precise disease diagnosis or maximum therapeutic response. However, versatile mitochondrial theranostic platforms that integrate biomarker detection and therapy have rarely been exploited. Here, we report a charge-reversal nanomedicine activated by an acidic microenvironment for mitochondrial microRNA (mitomiR) detection and ion-interference therapy. The transporter liposome (DD-DC) was constructed from a pH-responsive polymer and a positively charged phospholipid, encapsulating NaCl nanoparticles with coloading of the aggregation-induced emission (AIE) fluorogens AIEgen-DNA/G-quadruplexes precursor and brequinar (NAB@DD-DC). The negatively charged nanomedicine ensured good blood stability and high tumor accumulation, while the charge-reversal to positive in response to the acidic pH in the tumor microenvironment (TME) and lysosomes enhanced the uptake by tumor cells and lysosome escape, achieving accumulation in mitochondria. The subsequently released Na+ in mitochondria not only contributed to the formation of mitomiR-494 induced G-quadruplexes for AIE imaging diagnosis but also led to an osmolarity surge that was enhanced by brequinar to achieve effective ion-interference therapy.

In Situ Monitoring and Tuning Multilayer Stacking of Polymer Lamellar Crystals in Solution with Aggregation-Induced Emission

Many types of self-assembled 2D materials with fascinating morphologies and novel properties have been prepared and used in solution. However, it is still a challenge to monitor their in situ growth in solution and to control the number of layers in these materials. Here, we demonstrate that the aggregation-induced emission (AIE) effect can be applied for the in situ decoupled tracing of the lateral growth and multilayer stacking of polymer lamellar crystals in solution. Multilayer stacking considerably enhances the photoluminescence intensity of the AIE molecules sandwiched between two layers of lamellar crystals, which is 2.4 times that on the surface of monolayer crystals. Both variation of the self-seeding temperature of crystal seeds and addition of a trace amount of long polymer chains during growth can control multilayer lamellar stacking, which are applied to produce tunable fluorescent patterns for functional applications.

Highly Efficient Blue Fluorescent Organic Light-Emitting Devices Based on λ5-Phosphinine Derivatives

Although λ5-phosphinine derivatives are known as a promising class of blue fluorescent emitters, those photoluminescent quantum yield (PLQY) values have been reached up to 92 %, however, only a few examples have been explored as an emitter for blue organic light-emitting device (OLED), and the external quantum efficiency (EQE) has been below 2.4 % so far. In this study, we newly developed two types of blue λ5-phosphinine derivatives namely CN-COCF3 and CO2Me-CHO, and investigated the photophysical properties in the solid states. The photophysical analyses in solid state films suggested that the strong electron-accepting nature of these λ5-phosphinine derivatives caused the inferior PLQY values, and the exciplex formation with the host and neighboring materials should be avoided to improve the device efficiency. By choosing suitable host and neighboring materials with deep ionization potentials, we successfully realized efficient blue fluorescent OLEDs with EQE of over 4 % and CIE (0.14, 0.18). This is among the best in λ5-phosphinine-based blue OLEDs so far.

Lasing in Low-Dimensional Crystals of a Fumaronitrile-Based Luminogen

Low-dimensional structures are ideal for organic laser media because of their efficient waveguide, photon confinement, and stimulated emission. Control of the structure and alignment of luminescent molecules is very important for realizing laser media. Here, we fabricate low-dimensional crystals of bis(biphenyl)fumaronitrile (BPFN), which is an aggregation-induced emission luminogen. The BPFN molecule contains fumaronitrile, which displays solid-state luminescence, and biphenyl, which forms low-dimensional structures through dipole-dipole interactions. Solvent diffusion yielded two-dimensional platelet crystals of BPFN with strong dipole-dipole CH-π interactions. The high photoluminescence quantum efficiency of 0.46 and uniaxially aligned molecular π-electronic transition dipole moment in the two-dimensional crystals of BPFN resulted in optically pumped lasing even when using an optical excitation source with a long pulse duration (∼5 ns). One-dimensional BPFN crystals obtained via epitaxial growth on the cleaved surface of a KBr single crystal also displayed lasing behavior.

Unlocking Diverse π-Bond Enrichment Frameworks by the Synthesis and Conversion of Boronated Phenyldiethynylethylenes

The π-bond enrichment frameworks not only serve as a crucial building block in organic synthesis but also assume a pivotal role in the fields of materials science, biomedicine, photochemistry, and other related disciplines owing to their distinctive structural characteristics. The incorporation of various substituents into the C═C double bonds of tetrasubstituted alkenes is currently a highly significant research area. However, the synthesis of tetrasubstituted alkenes with diverse substituents on double bonds poses a significant challenge in achieving stereoselectivity. Here, we reported an efficient and convergent route of Cu-catalyzed borylalkynylation of both symmetrical and unsymmetrical 1,3-diynes, B2pin2, and acetylene bromide to the construction of boronated phenyldiethynylethylene (BPDEE) derivatives with excellent chemo-, stereo-, and regioselectivities. BPDEE derivatives could transform into novel tetrasubstituted organic π-conjugated gem-diphenyldiethynylethylene (DPDEE), vinylphenyldiethynylethylene (VPDEE), and phenyltriethynylethylene (PTEE) derivatives by a stepwise process, which provides a flexible platform for the synthesis of complex π-bond enrichment frameworks that were difficult to synthesize by previous methods. The initial optical characterization revealed that the synthesized molecules exhibited aggregation-induced emission (AIE) properties, which further establishes the groundwork for future applications and enriches and advances the field of functional π-conjugated frameworks research.

Boosting Luminescence Efficiency of Near-Infrared-II Aggregation-Induced Emission Luminogens via a Mash-Up Strategy of π-Extension and Deuteration for Dual-Model Image-Guided Surgery

The simultaneous pursuit of accelerative radiative and restricted nonradiative decay is of tremendous significance to construct high-luminescence-efficiency fluorophores in the second near-infrared wavelength window (NIR-II), which is seriously hindered by the energy gap laws. Herein, a mash-up strategy of π-extension and deuteration is proposed to efficaciously ameliorate the knotty problem. By extending the π-conjugation of the aromatic fragment and introducing an isotope effect to the aggregation-induced emission luminogen (AIEgen), an improved oscillator strength (f), coupled with suppressed deformation and high-frequency oscillation in the excited state, are successively implemented. In this case, a faster rate of radiative decay (kr) and restricted nonradiative decay (knr) are simultaneously achieved. Moreover, the preeminent emissive property of AIEgen in the molecular state could be commendably inherited by the aggregates. The corresponding NIR-II emissive AIEgen-based nanoparticles display high brightness, large Stokes shift, and superior photostability simultaneously, which can be applied for image-guided cancer and sentinel lymph node (SLN) surgery. This work thus provides a rational roadmap to improve the luminescence efficiency of NIR-II fluorophores for biomedical applications.

Organic Optoelectronic Materials: A Rising Star of Bioimaging and Phototherapy

Recently, many organic optoelectronic materials (OOMs), especially those used in organic light-emitting diodes (OLEDs), organic solar cells (OSCs), and organic field-effect transistors (OFETs), are explored for biomedical applications including imaging and photoexcited therapies. In this review, recently developed OOMs for fluorescence imaging, photoacoustic imaging, photothermal therapy, and photodynamic therapy, are summarized. Relationships between their molecular structures, nanoaggregation structures, photophysical mechanisms, and properties for various biomedical applications are discussed. Mainly four kinds of OOMs are covered: thermally activated delayed fluorescence materials in OLEDs, conjugated small molecules and polymers in OSCs, and charge-transfer complexes in OFETs. Based on the OOMs unique optical properties, including excitation light wavelength and exciton dynamics, they are respectively exploited for suitable biomedical applications. This review is intended to serve as a bridge between researchers in the area of organic optoelectronic devices and those in the area of biomedical applications. Moreover, it provides guidance for selecting or modifying OOMs for high-performance biomedical uses. Current challenges and future perspectives of OOMs are also discussed with the hope of inspiring further development of OOMs for efficient biomedical applications.

The luminescent principle and sensing mechanism of metal-organic framework for bioanalysis and bioimaging

Metal-organic frameworks (MOFs) porous material have obtained more and more attention during the past decade. Among various MOFs materials, luminescent MOFs with specific chemical characteristics and excellent optical properties have been regarded as promising candidates in the research of cancer biomarkers detection and bioimaging. Therefore, the latest advances and the principal biosensing and imaging strategies based on the luminescent MOFs were discussed in this review. The effective synthesis methods of luminescent MOFs were emphasized firstly. Subsequently, the luminescent principle of MOFs has been summarized. Furthermore, the luminescent MOF-based sensing mechanisms have been highlighted to provide insights into the design of biosensors. The designability of LMOFs was suitable for different needs of biorecognition, detection, and imaging. Typical examples of luminescent MOF in the various cancer biomarkers detection and bioimaging were emphatically introduced. Finally, the future outlooks and challenges of luminescent MOF-based biosensing systems were proposed for clinical cancer diagnosis.

Aggregation induced emission and volatile acid vapour sensing in acridine appended poly (aryl ether) based low molecular weight organogelator

Considerable research attention has been devoted to the development of portable and rapid fluorescence sensors that can selectively detect volatile acids, due to the harmful effects of acid vapour on the environment and human health. Although various types of fluorophores have been reported for sensing volatile acid vapours, regulation of the sensory response using aggregation induced emissive (AIE) based gelators has rarely been reported. In this study, we present the design and synthesis of a novel organogelator that is capable of sensing volatile acids through AIE. An acridine-attached poly(aryl ether) dendron molecular system is synthesized through an aldimine coupling reaction, which self-assembles and forms a gel, exhibiting AIE behavior. The synthesized molecule and prepared gel were characterized using NMR, MASS, XRD, HRSEM and rheology techniques. The AIE property of APD was investigated using steady-state absorption and emission spectroscopic techniques. The sensory response of the APD gelator was tested with various analytes, and the results indicated that APD shows rapid response, particularly to acid vapours, where the detection limits (DL) of trifluoroacetic acid (TFA), hydrochloric acid (HCl) and nitric acid (HNO3) vapor were as low as 0.22, 0.9 and 0.30 ppm, respectively. An APD solid film in filter paper shows a visual color change from yellow to red in an aqueous acidic medium, and the effect is reversed in an alkaline medium. These findings suggest that an APD gelator could potentially be utilized to generate a portable acid vapor sensor kit due to its low detection limit and rapid response time, and it could be also be used as a substitute for existing acid indicators.

Ultrasensitive fluorometric determination of aluminum using the CoFe2O4 NPs/SDS/oxine system with the aid of ultrasound waves

In this study, we present a thoughtful integration of a dispersive solid-phase sorbent and oxine for the ultrasensitive and highly selective determination of Al3+ ions. Cobalt ferrite nanoparticles (CoFe2O4 NPs) modified with oxine were employed to facilitate the pre-concentration and estimation of Al3+, forming highly fluorescent chelate. The modification process included the assistance of sodium dodecyl sulfate (SDS) and sonication. The results indicated that the fluorescence intensity of Al3+-oxine/SDS@CoFe2O4 NPs surpassed that of Al3+-oxine alone. The confirmation of the successful functionalization of CoFe2O4 NPs with oxine was established through various techniques. Under optimal conditions, the fluorescence intensity exhibited a positive correlation with increasing concentrations of Al3+ within the range of 0.029-600 ng mL-1, achieving a detection limit of 0.0087 ng mL-1 based on signal to noise ratio 3 : 1. The developed method was effectively applied to the determination of Al3+ in drinking water samples, yielding recoveries in the range of 97.19% to 103.13%, with a relative standard deviation (RSD%) not exceeding 3.78%.

Rigidifying AIEgens in covalent organic framework nanosheets for electrochemiluminescence enhancement: TABE-PZ-CON as a novel emitter for microRNA-21 detection

Enhancing electrochemiluminescence (ECL) properties of luminophores is a hot direction in the current ECL field. Herein, we found that covalent rigidification of the aggregation-induced emission luminogens (AIEgens) TABE (TABE = tetra-(4-aldehyde-(1,1-biphenyl))ethylene) into covalent organic framework nanosheets (TABE-PZ-CON, PZ = piperazine) could result in stronger ECL emission than those of TABE aggregates and TABE monomers. We termed the interesting phenomenon "covalent rigidification-triggered electrochemiluminescence (CRT-ECL) enhancement". The superior ECL performance of TABE-PZ-CON not only because massive TABE luminogens were covalently assembled into the rigid TABE-PZ-CON network, which limited the intramolecular motions of TABE and hampered the radiationless transition, but also because the ultrathin porous TABE-PZ-CON significantly reduced the transportation distance of ions, electrons, and coreactants, which enabled the electrochemical excitation of more TABE luminogens and thus enhanced the ECL efficiency. Bearing in mind the exceptional ECL performance of TABE-PZ-CON, it was utilized as a high-efficient ECL indicator in combination with the DNA walker and duplex-specific nuclease-assisted target recycling amplification strategies to design an "off-on" ECL biosensor for the ultrasensitive assay of microRNA-21, exhibiting a favorable response range (100 aM-1 nM) with an ultralow detection limit of 17.9 aM. Overall, this work offers a valid way to inhibit the intramolecular motions of AIEgens for ECL enhancement, which gives a new vision for building high-performance AIEgen-based ECL materials, thus offering more chances for assembling hypersensitive ECL biosensors.

A Rational Design of Electrochemically and Photophysically Tunable Triarylamine Luminophores by Consecutive (Pseudo-)Four-Component Syntheses

The concatenation of Suzuki coupling and two-fold Buchwald-Hartwig amination in sequentially palladium-catalyzed consecutive multicomponent syntheses paves a concise, convergent route to diversely functionalized para-biaryl-substituted triarylamines (p-bTAAs) from simple, readily available starting materials. An extensive library of p-bTAAs permits comprehensive investigations of their electronic properties by absorption and emission spectroscopy, cyclic voltammetry, and quantum chemical calculations, which contribute to a deep understanding of their electronic structure. The synthesized p-bTAAs exhibit tunable fluorescence from blue to yellow upon photonic excitation with quantum yields up to 98 % in solution and 92 % in the solid state. Furthermore, a pronounced bathochromic shift of the emission maxima by increasing solvent polarity indicates positive emission solvatochromism. Aggregation-induced enhanced emission (AIEE) in dimethyl sulfoxide (DMSO)/water mixtures causes the formation of intensely blue fluorescent aggregates. Cyclic voltammetry shows reversible first and second oxidations of p-bTAAs at low potentials, which are tunable by variation of the introduced para substituents. 3D Hammett plots resulting from the correlation of oxidation potentials and emission maxima with electronic substituent parameters emphasize the rational design of tailored p-bTAAs with predictable electrochemical and photophysical properties.

Cationic Ir(III) Complexes with 4-Fluoro-4'-pyrazolyl-(1,1'-biphenyl)-2-carbonitrile as the Cyclometalating Ligand: Synthesis, Characterizations, and Application to Ultrahigh-Efficiency Light-Emitting Electrochemical Cells

Light-emitting electrochemical cells (LECs) promise low-cost, large-area luminescence applications with air-stabilized electrodes and a versatile fabrication that enables the use of solution processes. Nevertheless, the commercialization of LECs is still encountering many obstacles, such as low electroluminescence (EL) efficiencies of the ionic materials. In this paper, we propose five blue to yellow ionic Ir complexes possessing 4-fluoro-4'-pyrazolyl-(1,1'-biphenyl)-2-carbonitrile (ppfn) as a novel cyclometalating ligand and use them in LECs. In particular, the device within di[4-fluoro-4'-pyrazolyl-(1,1'-biphenyl)-2-carbonitrile]-4,4'-di-tert-butyl-2,2'-bipyridyl iridium(III) hexafluorophosphate (DTBP) shows a remarkable photoluminescence quantum yield (PLQY) of 70%, and by adjusting the emissive-layer thickness, the maximal external quantum efficiency (EQE) reaches 22.15% at 532 nm under the thickness of 0.51 μm, showing the state-of-the-art value for the reported blue-green LECs.

Novel Near-Infrared-II In Vivo Visualization Revealed Rapid Calcium Intestine Turnover in Daphnia magna with Delayed Impact by Cadmium and Acidification

Calcium is a highly demanded metal, and its transport across the intestine of Daphnia magna remains a significant unresolved question. Due to technical constraints, the visualization of the kinetic process of Ca passage through D. magna has been challenging. Here, we developed the second near-infrared Ca sensor (NIR-II Ca) and conducted real-time in vivo imaging of Ca in daphnids with a high signal-to-noise ratio, deep tissue penetration, and minimal damage. Through the utilization of the NIR-II Ca sensor, we for the first time visualized and quantified the kinetic process of Ca passage in the intestine in real time. The results revealed that trophically available Ca passed through the intestines in 24 h, whereas waterborne Ca required only 35 min. This rapid "flushing through" mechanism established waterborne Ca as the primary source of Ca absorption. However, environmental stressors such as water acidification and cadmium significantly delayed the Ca passage and absorption. The development of NIR imaging and sensors allows for real-time dynamic visualization of contaminants/nutrients in organisms and holds great potential as a powerful tool for future studies into material kinetic processes in living animals.

Realization of white-light-emitting diodes from a high-brightness zirconium-based metal-organic gel driven by the AIE effect

Developing luminescent materials with suitable correlated color temperature (CCT) and sufficient color-rendering index (CRI) is a challenging problem in the field of commercialized warm white LED lighting. Herein, a novel metal-organic gel (MOG) material named YTU-G-1(SE) was synthesized, consisting of zirconium metal coordinated with 1,1,2,2-tetrakis(4-carboxyphenyl) ethylene. YTU-G-1(SE) exhibits strong fluorescent properties with an aggregation-induced emission (AIE) effect, emitting yellow-green fluorescence at 515 nm. The internal and external quantum efficiencies (IQE/EQE) of YTU-G-1(SE) are close to unity, with values of 95.74 ± 0.5% and 88.67 ± 0.5%, respectively. Finally, we combined YTU-G-1(SE) with a commercial blue chip and a commercial red phosphor (Sr,Ca)AlSiN3:Eu2+ to fabricate a warm white light LED with a color temperature of 3736 K, a color-rendering index Ra of 88.2, and a lumen efficiency of 79.42 lm W-1. This work provides a new approach to regulating the emission of AIE and offers a novel idea for developing high-performance warm-white pc-WLEDs.

Co-aggregation as A Simple Strategy for Preparing Fluorogenic Tetrazine Probes with On-Demand Fluorogen Selection

Life science has progressed with applications of fluorescent probes-fluorophores linked to functional units responding to biological events. To meet the varied demands across experiments, simple organic reactions to connect fluorophores and functional units have been developed, enabling the on-demand selection of fluorophore-functional unit combinations. However, organic synthesis requires professional equipment and skills, standing as a daunting task for life scientists. In this study, we present a simple, fast, and convenient strategy for probe preparation: co-aggregation of hydrophobic molecules. We focused on tetrazine-a difficult-to-prepare yet useful functional unit that provides effective bioorthogonal reactivity and strong fluorogenicity. Simply mixing the tetrazine molecules and aggregation-induced emission (AIE) luminogens in water, co-aggregation is induced, and the emission of AIE luminogens is quenched. Subsequent click reaction bioorthogonally turns on the emission, identifying these coaggregates as fluorogenic probes. Thanks to this bioorthogonal fluorogenicity, we established a new time-gated fluorescence bioimaging technique to distinguish overlapping emission signals, enabling multi-organelle imaging with two same-color fluorophores. Our study showcases the potential of this co-aggregation method for the on-demand preparation of fluorescent probes as well as protocols and molecular design principles in this approach, offering an effective solution to evolving needs in life science research.

Aggregation-Induced Emission Luminogens: A New Possibility for Efficient Visualization of RNA in Plants

RNAs play important roles in regulating biological growth and development. Advancements in RNA-imaging techniques are expanding our understanding of their function. Several common RNA-labeling methods in plants have pros and cons. Simultaneously, plants' spontaneously fluorescent substances interfere with the effectiveness of RNA bioimaging. New technologies need to be introduced into plant RNA luminescence. Aggregation-induced emission luminogens (AIEgens), due to their luminescent properties, tunable molecular size, high fluorescence intensity, good photostability, and low cell toxicity, have been widely applied in the animal and medical fields. The application of this technology in plants is still at an early stage. The development of AIEgens provides more options for RNA labeling. Click chemistry provides ideas for modifying AIEgens into RNA molecules. The CRISPR/Cas13a-mediated targeting system provides a guarantee of precise RNA modification. The liquid-liquid phase separation in plant cells creates conditions for the enrichment and luminescence of AIEgens. The only thing that needs to be looked for is a specific enzyme that uses AIEgens as a substrate and modifies AIEgens onto target RNA via a click chemical reaction. With the development and progress of artificial intelligence and synthetic biology, it may soon be possible to artificially synthesize or discover such an enzyme.

Jellyfish-inspired smart tetraphenylethene lipids with unique AIE fluorescence, thermal response, and cell membrane interaction

Smart lipids with fluorescence emission, thermal response, and polyethylene glycolation (PEGylation) functions can be highly valuable for formulation, image-traceable delivery, and targeted release of payloads. Herein, a series of jellyfish-shaped amphiphiles with a tetraphenylethene (TPE) core and four symmetrical amphiphilic side chains were conveniently synthesized and systematically investigated as smart lipids. Compared with regular amphiphilic TPE lipids and phospholipids, the unprecedented jellyfish-shaped molecular geometry was found to enable a series of valuable capabilities, including sensitive and responsive aggregation-induced emission of fluorescence (AIE FL) and real-time FL monitoring of drug uptake. Furthermore, the jellyfish-shaped geometry facilitated the concentration-dependent aggregation from unimolecular micelles at low concentrations to "side-by-side" spherical aggregates at high concentrations and a unique mode of AIE. In addition, the size and the arrangement of the amphiphilic side chains were found to dominate the aggregate stability, cell uptake, and thus the cytotoxicity of the amphiphiles. This study has unprecedentedly developed versatile smart TPE lipids with precise structures, and unique physicochemical and biological properties while the peculiar structure-property relationship may shed new light on the design and application of AIE fluorophores and functional lipids in biomedicine and materials science.

Solvent modulation of the morphology of homochiral gadolinium coordination polymers and its impact on circularly polarized luminescence

Studying the effect of morphology on the circularly polarized luminescence (CPL) of chiral molecular materials is important for the development of CPL-active materials for applications. Herein, we report that the morphology of Gd(NO3)3/R-,S-AnempH2 [AnempH2 = (1-anthrylethylamino)methylphosphonic acid] assemblies can be controlled by solvent modulation to form spiral bundles Gd(R-,S-AnempH)3·2H2O (R-,S-1), crystals Gd(R-,S-AnempH)3·2H2O (R-,S-2) and spindle-shaped particles Gd(R-,S-AnempH)3·3H2O·0.5DMF (R-,S-3) with similar chain structures. Interestingly, R-,S-1 are CPL active and show the highest value of dissymmetric factor among the three pairs of enantiomers (|glum| = 2.1 × 10-3), which is 2.8 times larger than that of R-,S-2, while R-,S-3 are CPL inactive with |glum| ≈ 0. This work provides a new route to control the morphology of chiral coordination polymers and improve their CPL performance.

Aggregation-Induced Emission-Based Chemiluminescence Systems in Biochemical Analysis and Disease Theranostics

Chemiluminescence (CL) is of great significance in biochemical analysis and imaging due to its high sensitivity and lack of need for external excitation. In this review, we summarized the recent progress of AIE-based CL systems, including their working mechanisms and applications in biochemical analysis, bioimaging, and disease diagnosis and treatment. In ion and molecular detection, CL shows high selectivity and high sensitivity, especially in the detection of dynamic reactive oxygen species (ROS). Further, the integrated NIR-CL single-molecule system and nanostructural CL platform harnessing CL resonance energy transfer (CRET) have remarkable advantages in long-term imaging with superior capability in penetrating deep tissue depth and high signal-to-noise ratio, and are promising in the applications of in vivo imaging and image-guided disease therapy. Finally, we summarized the shortcomings of the existing AIE-CL system and provided our perspective on the possible ways to develop more powerful CL systems in the future. It can be highly expected that these promoted CL systems will play bigger roles in biochemical analysis and disease theranostics.

Thiophene Stability in Photodynamic Therapy: A Mathematical Model Approach

Thiophene-containing photosensitizers are gaining recognition for their role in photodynamic therapy (PDT). However, the inherent reactivity of the thiophene moiety toward singlet oxygen threatens the stability and efficiency of these photosensitizers. This study presents a novel mathematical model capable of predicting the reactivity of thiophene toward singlet oxygen in PDT, using Conceptual Density Functional Theory (CDFT) and genetic programming. The research combines advanced computational methods, including various DFT techniques and symbolic regression, and is validated with experimental data. The findings underscore the capacity of the model to classify photosensitizers based on their photodynamic efficiency and safety, particularly noting that photosensitizers with a constant rate 1000 times lower than that of unmodified thiophene retain their photodynamic performance without substantial singlet oxygen quenching. Additionally, the research offers insights into the impact of electronic effects on thiophene reactivity. Finally, this study significantly advances thiophene-based photosensitizer design, paving the way for therapeutic agents that achieve a desirable balance between efficiency and safety in PDT.

Photophysical Analysis of Aggregation-Induced Emission (AIE) Luminogens Based on Triphenylamine and Thiophene: Insights into Emission Behavior in Solution and PMMA Films

Aggregation-Induced Emission (AIE) luminogens have garnered significant interest due to their distinctive applications in different applications. Among the diverse molecular architectures, those based on triphenylamine and thiophene hold prominence. However, a comprehensive understanding of the deactivation mechanism both in solution and films remains lacking. In this study, we synthesized and characterized spectroscopically two AIE luminogens: 5-(4-(bis(4-methoxyphenyl)amino)phenyl)thiophene-2-carbaldehyde (TTY) and 5'-(4-(bis(4-methoxyphenyl)amino)phenyl)-[2,2'-bithiophene]-5-carbaldehyde (TTO). Photophysical and theoretical analyses were conducted in both solution and PMMA films to understand the deactivation mechanism of TTY and TTO. In diluted solutions, the emission behavior of TTY and TTO is influenced by the solvent, and the deactivation of the excited state can occur via locally excited (LE) or twisted intramolecular charge transfer (TICT) state. In PMMA films, rotational and translational movements are constrained, necessitating emission solely from the LE state. Nevertheless, in the PMMA film, excimers-like structures form, resulting in the emergence of a longer wavelength band and a reduction in emission intensity. The zenith of emission intensity occurs when molecules are dispersed at higher concentrations within PMMA, effectively diminishing the likelihood of excimer-like formations. Luminescent Solar Concentrators (LSC) were fabricated to validate these findings, and the optical efficiency was studied at varying concentrations of luminogen and PMMA.

Enhancing Fluorescence in Both Solution and Solid States Induced by Imine Cage Formation

Developing luminescent materials that exhibit strong emissions in both solution and solid phases is highly desirable and challenging. Herein, we report imine-bond directed formation of a rigid organic cage (TPE-cage) that was synthesized by [2+4] imine condensation of a TPE-cored tetra-aldehyde (TPE-TA) with a clip-like diamine (XA) to illustrate confinement-induced fluorescence enhancement. Compared to the non-emissive TPE-TA (ϕF =0.26 %) in the dichloromethane (DCM) solution, the TPE-cage achieved a remarkable (~520-fold) emission enhancement (ϕF =70.38 %). In contrast, a monomeric tetra-imine model compound (TPE-model) showed only a minor enhancement (ϕF =0.56 %) in emission compared to the parent tetra-aldehyde TPE-TA. The emission of TPE-cage was further enhanced by ~1.5-fold (ϕF =80.96 %) in the aggregated state owing to aggregation-induced emission enhancement (AIEE). This approach establishes the potential for synthesizing luminescent materials with high emission in both solution and solid-state by employing a single-step imine condensation reaction.

A facile and novel AIE vesicle as nanoprobe for simple and rapid detection of TNT in water

Trinitrotoluene (TNT) in water will damage biological tissues and organs of the human body due to its high toxicity and risk. However, the simple and rapid detection of TNT in water is always a challenging task. Herein, we reported a novel aggregation-induced emission-a vesicle (AIE-a-V) as fluorescent nanoprobe for the detection of TNT in water by π-π self-assembly of π-π stacking induced aggregation-emission. The AIE-a-V was spherical in shape with a hydrodynamic diameter of ∼106 nm and possessed robust stability. In addition, the AIE-a-V showed strong fluorescence and its fluorescence would quickly disappear after contact with TNT. Based on this, without any cumbersome operation, the AIE-a-V could detect the presence of TNT in water within 60 s, and its minimum detectable concentration was as low as 50 nM. Moreover, the AIE-a-V could selectively detect TNT in water and would not be affected by other components, including other aromatic compounds, toxic metals, and acid-base. Therefore, the new AIE-a-V with simplicity, rapidity, sensitivity and selectivity have great application potential in the detection of TNT in water.

In situ peptide assemblies for bacterial infection imaging and treatment

Bacterial infections, especially antibiotic-resistant ones, remain a major threat to human health. Advances in nanotechnology have led to the development of numerous antimicrobial nanomaterials. Among them, in situ peptide assemblies, formed by biomarker-triggered self-assembly of peptide-based building blocks, have received increasing attention due to their unique merits of good spatiotemporal controllability and excellent disease accumulation and retention. In recent years, a variety of "turn on" imaging probes and activatable antibacterial agents based on in situ peptide assemblies have been developed, providing promising alternatives for the treatment and diagnosis of bacterial infections. In this review, we introduce representative design strategies for in situ peptide assemblies and highlight the bacterial infection imaging and treatment applications of these supramolecular materials. Besides, current challenges in this field are proposed.

Solvatochromism of new tetraphenylethene luminogens: integration of aggregation-induced emission and conjugation-induced rigidity for emitting strongly in both solid and solution state

In this study, we synthesized and characterized four tetraphenylethene (TPE) analogs, investigated their photophysical properties, and conducted quantum chemical calculations. Some molecules exhibited aggregation-induced emission enhancement behavior and showed efficient emission in both solid and solution states. Solvatochromism was observed in particular derivatives, with solvent polarity influencing either a bathochromic or hypsochromic shift, indicating the occurrence of photoinduced intramolecular charge transfer (ICT) processes. Quantum chemical calculations confirmed that variations in molecular packing and rigidity among the TPE analogs contributed to their diverse behavior. The study showcases aggregation in luminophores without significant impact on the excited state and highlights how minor alterations in terminal substituents can lead to unconventional behavior. These findings have implications for the development of luminescent materials. Furthermore, the synthesized compounds exhibited biocompatibility, suggesting their potential for cell imaging applications.

Enzyme-Activatable Near-Infrared Photosensitizer with High Enrichment in Tumor Cells Based on a Multi-Effect Design

Enzyme-activatable near-infrared (NIR) fluorescent probes and photosensitizers (PSs) have emerged as promising tools for molecular imaging and photodynamic therapy (PDT). However, in living organisms selective retention or even enrichment of these reagents after enzymatic activation at or near sites of interest remains a challenging task. Herein, we integrate non-covalent and covalent retention approaches to introduce a novel "1-to-3" multi-effect strategy-one enzymatic stimulus leads to three types of effects-for the design of an enzyme-activatable NIR probe or PS. Using this strategy, we have constructed an alkaline phosphatase (ALP)-activatable NIR fluorogenic probe and a NIR PS, which proved to be selectively activated by ALP to switch on NIR fluorescence or photosensitizing ability, respectively. Additionally, these reagents showed significant enrichment (over 2000-fold) in ALP-overexpressed tumor cells compared to the culture medium, accompanied by massive depletion of intracellular thiols, the major antioxidants in cells. The investigation of this ALP-activatable NIR PS in an in vivo PDT model resulted in complete suppression of HeLa tumors and full recovery of all tested mice. Encouragingly, even a single administration of this NIR PS was sufficient to completely suppress tumors in mice, demonstrating the high potential of this strategy in biomedical applications.

Effect of Polymer Host on Aggregation-Induced Enhanced Emission of Fluorescent Optical Brighteners

Fluorophores displaying concentration-dependent luminescence are becoming increasingly valuable in stress-sensing, tagging, and dyeing applications, including the quantification of recycled content in plastic packaging. In this work, we investigate the effects of the polymer matrix, dye structure, and crystallinity on aggregation-induced enhanced emission (AIEE). We demonstrate that the aggregation threshold required for successful quantification can be adjusted through modulation of guest-host (dye-polymer) interactions and monitored using an array of fluorescence characterization. Modification of guest-host interactions is realized through choice of host, change of guest, and tuning of the crystallinity of the host system. Increasing the number of guest-host interactions and solubility between guest and host, loosely predicted through the calculation of the solubility parameter, increases the aggregation threshold relative to other low-polarity and low-interacting systems. We demonstrate that issues, such as loading level and cost, associated with high aggregation thresholds, can be circumvented by increasing system crystallinity, improving spectral intensities, and subsequent quantification. These insights explore the fundamental understanding of supramolecular interactions that govern dye-polymer systems.

Cooperative dissolution of peptidomimetic vesicles and amyloid β fibrils

The aggregation of amyloid proteins in the brain is a significant neurotoxic event that contributes to neurodegenerative disorders. The aggregation of amyloid beta (Aβ), particularly Aβ42 monomers, into various forms such as oligomers, protofibrils, fibrils, and amyloid plaques is a key pathological feature in Alzheimer's disease. As a result, Aβ42 is a primary target and the development of molecular strategies for the dissolution of Aβ42 aggregates is considered a promising approach to mitigating Alzheimer's disease pathology. A set of pyrene-conjugated peptidomimetics derived from Aβ14-23 (AkdcPy, AkdmPy, and AkdnPy) by incorporating an unnatural amino acid [kd: cyclo(Lys-Asp)] were studied for their ability to modulate Aβ42 aggregation. AkdcPy and AkdmPy formed vesicular structures in aqueous media. The vesicles of AkdmPy loaded with the neuroprotective compound berberine (Ber), dissipated mutually in the presence of preformed Aβ42 fibrils. During this process, the active drug Ber was released. This work is expected to inspire the development of drug-loaded peptidomimetic-based therapeutic formulations to modulate disorders associated with amyloid toxicity.

Synthesis of V-shaped Thiophene Based Rotor-Stilbene: Substituent Dependent Aggregation and Photophysical Properties

Thiophene core V-shaped rotor-stilbene derivatives have been synthesized utilizing two-fold Heck coupling reaction. These compounds are blue emitters with moderate quantum yield in dilute solution. Rotor nature of the synthesized stilbenes supports aggregation induced emission (AIE) behaviour and they show substituent dependent emission behavior in aggregate state. In presence of donating groups (e.g., tert-butyl, methoxy, diphenylamine group) in stilbenes, they exhibit AIE property. But with the introduction of electron withdrawing group (nitro group), they shows aggregation caused quenching (ACQ) behavior. Different types of nano-aggregates formation is observed in aggregated state, which was confirmed by dynamic light scattering (DLS) and scanning electron microscopy (SEM) studies. The details photophysical (absorption, fluorescence, and lifetime), electrochemical property (cyclic voltammetry) and thermal stability have been investigated. Optimized structure, energy and electronic distribution of molecular orbitals have been studied by theoretical calculation.

Visible to NIR-II Photoluminescence of Atomically Precise Gold Nanoclusters

Atomically precise gold nanoclusters (NCs) have emerged as a new class of precision materials and attracted wide interest in recent years. One of the unique properties of such nanoclusters pertains to their photoluminescence (PL), for it can widely span visible to near-infrared-I and -II wavelengths (NIR-I/II), and even beyond 1700 nm by manipulating the size, structure, and composition. The current research efforts focus on the structure-PL correlation and the development of strategies for raising the PL quantum yields, which is nontrivial when moving from the visible to the near-infrared wavelengths, especially in the NIR-II regions. This review summarizes the recent progress in the field, including i) the types of PL observed in gold NCs such as fluorescence, phosphorescence, and thermally activated delayed fluorescence, as well as dual emission; ii) some effective strategies that are devised to improve the PL quantum yield (QY) of gold NCs, such as heterometal doping, surface rigidification, and core phonon engineering, with double-digit QYs for the NIR PL on the horizons; and iii) the applications of luminescent gold NCs in bioimaging, photosensitization, and optoelectronics. Finally, the remaining challenges and opportunities for future research are highlighted.

Recent strategies for evoking immunogenic Pyroptosis in antitumor immunotherapy

Pyroptosis is a specific type of programmed cell death (PCD) characterized by distinct morphological changes, including cell swelling, membrane blebbing, DNA fragmentation, and eventual cell lysis. Pyroptosis is closely associated with human-related diseases, such as inflammation and malignancies. Since the initial observation of pyroptosis in Shigella flexneri-infected macrophages more than 20 years ago, various pyroptosis-inducing agents, including ions, small molecules, and biological nanomaterials, have been developed for tumor treatment. Given that pyroptosis can activate the body's robust immune response against tumor and promote the formation of the body's long-term immune memory in tumor treatment, its status as a type of immunogenic cell death is self-evident. Therefore, pyroptosis should be used as a powerful anti-tumor strategy. However, there still is a lack of a comprehensive summary of the most recent advances in pyroptosis-based cancer therapy. Therefore, it is vital to fill this gap and inspire future drug design to better induce tumor cells to undergo pyroptosis to achieve advanced anti-tumor effects. In this review, we summarize in detail the most recent advances in triggering tumor cell immunogenic pyroptosis for adequate tumor clearance based on various treatment modalities, and highlight material design and therapeutic advantages. Besides, we also provide an outlook on the prospects of this emerging field in the next development.

Porous Complex-Mediated Dual Emission of Porphyrins for the Electrochemiluminescence Bioassay

Although porphyrins make up a promising class of electrochemiluminescence (ECL) luminophors, their aggregation-caused quenching (ACQ) characteristics lead to inferior ECL efficiency (ΦECL). Furthermore, current application of porphyrins is limited to cathodic emission. This work creatively exploited a cage-like porous complex (referred to as SWU-1) as the microreactor to recede the ACQ effect while modulating dual ECL emission of meso-tetra(4-carboxyphenyl)porphine (TCPP), which self-assembled with SWU-1 to form TCPP@SWU-1 nanocapsules (TCPP@SWU-1 NCs). As the microreactor, SWU-1 not only effectively constrained TCPP aggregation to improve electron-hole recombination efficiency but also improved stability of anion and cation radicals, thus significantly enhancing the dual emission of TCPP. Compared with TCPP aggregates, the resulting TCPP@SWU-1 NCs exhibited significantly enhanced anodic and cathodic emission, and their ΦECL was increased by 8.7-fold and 3.9-fold, respectively. Furthermore, black hole quencher-2 (BHQ2) can simultaneously quench anodic and cathodic signals. TCPP@SWU-1 NCs coupling BHQ2 conveniently achieved an ECL ratio detection of miRNA-126, and the limit of detection (S/N = 3) was 4.1 aM. This work pioneered the development of the cage-like porous complex SWU-1 as the microreactor to alleviate defects of the ACQ effect and mediate dual emission of TCPP. The coupling of dual-emitting TCPP@SWU-1 NCs and dual-function moderator BHQ2 created a novel single-luminophor-based ratio system for bioanalysis and provided a promising ECL analysis approach for miRNA-126.

Fluorescence and colorimetric dual-mode multienzyme cascade nanoplatform based on CuNCs/FeMn-ZIF-8/PCN for detection of sarcosine

It is critical to develop a highly efficient and sensitive method for detecting the biomarker sarcosine (SA) of prostate cancer due to its importance for men's health. In our work, a fluorescence (FL) and colorimetric dual-mode multienzyme cascade nanoplatform for SA detection was designed and constructed. CuNCs/FeMn-ZIF-8/PCN nanocomposites with high FL properties and peroxidase-like activity were successfully prepared by encapsulating copper nanoclusters (CuNCs) into FeMn-ZIF-8 and then loaded onto P-doped graphitic carbon nitride (PCN). Furthermore, the nanocomposites served as carriers for the immobilization of sarcosine oxidase (SOX) to construct a high-efficiency dual-mode multienzyme cascade nanoplatform CuNCs/SOX@FeMn-ZIF-8/PCN for the detection of SA. The intermediate H2O2 generated in the cascade caused the FL quenching of nanocomposites and the discoloration of 3,3',5,5'-tetramethylbenzidin. The linear ranges for SA detection in the dual-mode system were 1-100 μM (FL) and 1-200 μM (colorimetric), with detection limits of 0.34 and 0.59 μM, respectively. This nanoplatform exhibited notable repeatability, specificity, and stability, making it suitable for detecting sarcosine in real human urine samples. Therefore, this dual-mode multienzyme cascade nanoplatform would have a potential applicative prospect for detecting SA and other biomarkers in real clinical samples.

Detecting Disruption of HER2 Membrane Protein Organization in Cell Membranes with Nanoscale Precision

The spatiotemporal organization of proteins within the cell membrane can affect numerous biological functions, including cell signaling, communication, and transportation. Deviations from normal spatial arrangements have been observed in various diseases, and a better understanding of this process is a key stepping stone to advancing development of clinical interventions. However, given the nanometer length scales involved, detecting these subtle changes has primarily relied on complex super-resolution and single-molecule imaging methods. In this work, we demonstrate an alternative fluorescent imaging strategy for detecting protein organization based on a material that exhibits a unique photophysical behavior known as aggregation-induced emission (AIE). Organic AIE molecules have an increase in emission signal when they are in close proximity, and the molecular motion is restricted. This property simultaneously addresses the high background noise and low detection signal that limit conventional widefield fluorescent imaging. To demonstrate the potential of this approach, the fluorescent molecule sensor is conjugated to a human epidermal growth factor receptor 2 (HER2)-specific antibody and used to investigate the spatiotemporal behavior of HER2 clustering in the membrane of HER2-overexpressing breast cancer cells. Notably, the disruption of HER2 clusters in response to an FDA-approved monoclonal antibody therapeutic (Trastuzumab) is successfully detected using a simple widefield fluorescent microscope. While the sensor demonstrated here is optimized for sensing HER2 clustering, it is an easily adaptable platform. Moreover, given the compatibility with widefield imaging, the system has the potential to be used with high-throughput imaging techniques, accelerating investigations into membrane protein spatiotemporal organization.

Polymerization-Mediated Through-Space Charge Transfer: An Emerging Strategy for Light-Emitting Materials

Through-space charge transfer (TSCT) has attracted increasing attention owing to its great potential in designing efficient light-emitting molecules and polymers. Complementary to through-bond charge transfer and Förster resonance energy transfer, TSCT offers an alternative approach for the manipulation of molecular fluorescence. Recently, the synergy between TSCT and polymer systems through polymerization-mediated charge transfer has fostered the advancements of innovative light-emitting functional materials featuring thermally activated delayed fluorescence and/or aggregation-induced emission. This perspective highlights the significant progress in tailoring emission properties through structural engineering of donor and acceptor groups within polymeric systems, leveraging the TSCT mechanism. This strategy has transcended the limitations of traditional charge transfer systems with its tolerance to extended donor-acceptor distance, paving the way for novel applications beyond organic light-emitting diodes. The discussion concludes with a forward-looking analysis of potential future research trajectories in the field of polymerization-mediated charge transfer for developing next-generation light-emitting materials.

A General Method to Access Sterically Encumbered Geminal Bis(boronates) via Formal Umpolung Transformation of Terminal Diboron Compounds

General methods for the preparation of geminal bis(boronates) are of great interest due to their widespread applications in organic synthesis. While the terminal gem-diboron compounds are readily accessible, the construction of the sterically encumbered, internal analogues has remained a prominent challenge. Herein, we report a formal umpolung strategy to access these valuable building blocks. The readily available 1,1-diborylalkanes were first converted into the corresponding α-halogenated derivatives, which then serve as electrophilic components, undergoing a formal substitution with a diverse array of nucleophiles to form a series of C-C, C-O, C-S, and C-N bonds. This protocol features good tolerance to steric hindrance and a wide variety of functional groups and heterocycles. Notably, this strategy can also be extended to the synthesis of diaryl and terminal gem-diboron compounds, therefore providing a general approach to various types of geminal bis(boronates).

AIE-based ratiometric fluorescent probe for mercury ion, medium-dependent fluorescence color change and optimized sensitivity in solid state

A new AIE-based luminogen TPES, as a ratiometric fluorescence probe for mercury(II) was readily synthesized. The probe combined the advantages of the outstanding specificity of Hg2+-triggered deprotection reaction of thioketal and the brilliant emission of AIEgens in aggregated state. Once encountered aqueous Hg2+, fluorescent color of TPES in THF-H2O (fw = 98%) altered from blue to green rapidly, while other metal cations gave no interference to the probe. And the mechanism of this chemosensor was carefully verified by 1H NMR analysis, FTIR and MS spectra. As expected, TPES exhibits excellent selectivity and sensitivity towards Hg2+ in the solid state. When using filter paper as the solid medium, the fabricated test strips could signify Hg2+ ions with the LOD as 1 × 10-5 M (Hg2+ in aqueous solution), accompanied with a distinct emitting altered from blue to green. Furthermore, by changing the medium from filter paper to silica gel plate, a more significant fluorescence alteration from blue to yellow was achieved, and the LOD was further optimized to 1 × 10-6 M as discerned by naked-eye.

Sensing of picric acid using an AIEE active "Turn Off" fluorescent probe derived from hydroxy naphthaldehyde and benzyloxy benzaldehyde

A novel Schiff base with AIEE characteristics has been developed and used as a chemosensor for picric acid in aqueous media. The Schiff base 1-((E)-((E)-(4-(benzyloxy) benzylidene) hydrazono) methyl) naphthalen-2-ol [BBHN] with strong fluorescence emission was obtained by the simple condensation of 1-(hydrazonomethyl)naphthan-2-ol and 4-benzoxy benzaldehyde. The characterization of BBHN was done using Fourier Transfer Infra-Red, UV-visible, Magnetic Resonance (1H and 13C) spectroscopy, and HRMS. The sensing behaviour of BBHN aggregates towards nitro explosive was then investigated. The aggregates of BBHN showed a quick, highly selective, and sensitive fluorescence 'Turn Off' response towards picric acid (PA) in an aqueous medium among various other nitroaromatics. The limit of detection was 4.04 µM with 2.03 × 106 M-1 as the quenching constant. The fluorescence "Turn Off" response in the presence of PA is mainly due to π-π interactions, and non-covalent hydrogen bonding interactions. Moreover, steady-state fluorescence lifetime measurement and Stern - Volmer plots reveal that the fluorescence quenching followed mixed quenching strategies.

An Expanded EDA Complex Profile: Construction of Aza-arenes and Their Synthetic Application as Fluorescence Probes

We developed a visible-light-driven expanded EDA complex profile for the synthesis of aza-arenes via aza-6π electrocyclization of 2-styrylanilines with aromatic aldehydes. This protocol relies on the EDA complexes of AlCl3 with imine to induce the absorption red-shift to visible light from ultraviolet light. An array of 2,3-disubstituted quinolines were constructed smoothly after excitation with blue-light-emitting diodes at room temperature. In addition, the resultant product, used as a cell permeable lipid droplet-specific probe, shows a low working concentration, a short staining time, and functionality in living and fixed cells.

Pressure-induced luminescence evolution of 3,3'-diamino-4,4'-azofurazan: Role of restricting chemical bond vibration and conformational modification

The luminescence and electronic structure of 3,3'-Diamino-4,4'-azofurazan (DAAzF) were studied under high pressure conditions through experimental and calculation approaches. The transition of π* → π was primarily responsible for DAAzF's broad light emission. Upon applying pressure to DAAzF, high-pressure-stiffened hydrogen-bond interactions enable the restriction of the stretching vibration of NH2 group. The reduced energy loss through nonradiative rotational relaxation and molecular motions lead to a ∼20 times luminescent enhancement of DAAzF from 1 atm to 8.9 GPa. With the further strengthening of interlayer hydrogen bond interactions at higher pressure, the deviation of hydrogen atoms in amino groups from the molecular plane lessens the radiation transition efficiency. In addition, the bending of the C-C-N=N bond further leads to molecular conformation changes at approximately 20.7 GPa, which induces an abrupt redshift and moderate quenching of the luminescence. Furthermore, the band gap of DAAzF is significantly influenced by pressure. As the color undergoes a transition from yellow to red, and becomes darker as the pressure increases, the absorption edge shifted towards red. At 3.4, 9, and 21 GPa, three conformational variations were identified in conjunction with electronic structural alterations.

Extensional Flow-Induced Concentration Gradient in Entangled Polymer Solutions with Chemically Identical Species

Entangled polymer solutions show different rheological behavior from melts in fast extensional flow. This discrepancy is not expected according to the classic tube model and is an urgent issue to be solved in polymer physics. While in the tube model the polymer concentration is considered to be homogeneous, we show that extensional flow-induced concentration gradient may happen in polymer solutions even with chemically identical solutes and solvents. Through labeling an aggregation-induced emission (AIE) probe on oligomeric solvents, the flow-induced concentration gradient is visualized by combining extensional rheology and ex situ fluorescence microscopy. Microdomains of oligomeric solvents with a length scale of tens of micrometers are observed, and their influence on rheological behavior cannot be ignored.