A series of tetraphenylene-acetonitrile AIE compounds with D-A-D' structure for drugs delivery systems of paclitaxel: Synthesis, structure-activity relationship and anti-tumors effect

Aggregation-induced emission (AIE) materials are attracting great attention in biomedical fields such as sensors, bioimaging, and cancer treatment, et al. due to their strong fluorescence emission in the aggregated state. In this contribution, a series of tetraphenylene-acetonitrile AIE compounds with D-A-D' structures were synthesized by Suzuki coupling reaction and Knoevenagel condensation, and their relationship of chemical structure and fluorescence properties was investigated in detail, among which TPPA compound was selected as the monomer owing to the longest emission wavelength at about 530 nm with low energy band gap ΔE 3.09 eV of neutral TPPA and 1.43 eV of protonated TPPA. Novel amphiphilic AIE PEG-TA copolymers were prepared by RAFT polymerization of TPPA and PEGMA with about 1.44×104 Mw and narrow PDI, and the molar ratio of TPPA in the PEG-TA1 and PEG-TA2 copolymers was about 23.4 % and 29.6 %. The as-prepared PEG-TA copolymers would self-assembled in aqueous solution to form core-shell structures with a diameter of 150-200 nm, and their emission wavelength could reversibly convert from 545 nm to 650 nm with excellent pH sensitivity. The CLSM images showed that the PEG-TA FONs and PTX drugs-loaded PTX-TA FONs could be endocytosed by cells and mainly enriched in the cytoplasm, and CCK-8 results showed that the PEG-TA FONs had excellent biocompatibility but PTX-TA FONs had high inhibition ratio for A549 cells, moreover, the flow cytometry also showed that PTX-TA FONs could result in the apoptosis of A549 cells with some extent anti-tumor effect.

Recent progress of porous cage materials in sample preparation, chromatographic separation, and detection

Porous cage materials with certain dimensions, sizes, shapes, and functions have been regarded as promising materials for sample preparation, chromatographic separation, and detection process. In contrast to infinite frameworks such as metal-organic frameworks or covalent organic frameworks, porous cage materials are constructed from discrete molecules containing at least one internal cavity. The well-defined cavities in porous cage materials provide opportunities for non-covalent interactions. These interactions can be programmed into the ligand design or supramolecular cage constructing using the cages as building blocks, offering various host-guest recognition with great selectivity. In this review, we desire to elucidate the fundamental principles governing the design and fabrication of porous cage materials with well-defined cavities, good solvent processability, and modifiable groups, the applications of these porous cage materials in sample preparation, chromatographic separation, and detection were discussed. The recent advantages of porous cage materials for the analysis process were summarized. We state the potential of these materials and provide an outlook for further application strategies. We expect that this review can inspire interest in the porous cage materials research area for analysis.

Highly Efficient Multicolor-Emitting Tetraphenylethylene-Based Organic Salts with Commercialization Prospects

Since the discovery of aggregation-induced emission from tetraphenylethylene derivatives, various methods have been explored to prepare highly efficient multicolored luminescent materials. Herein, we report a simple and efficient strategy for constructing luminescent organic salts of the tetracationic luminogen, tetrapyridinium-tetraphenylethylene (T4Py-TPE4+), combined with seven di- and tetra-anionic aromatic sulfonate ligands. When aqueous solutions of the cationic luminogen and the anionic ligands were mixed, they rapidly aggregated into organic salts within seconds to minutes, giving yields of up to >90%. This was accompanied by an increase in the emission efficiency from ∼58% to almost 100%, and the ability to tune the emission color between 511 and 586 nm. These improvements were mainly attributed to the strong electrostatic attractions between the cation and anions, which resulted in the formation of a rigid hydrophobic network of the T4Py-TPE4+ luminogen with various π-conjugation lengths. Because these compounds are commercially available, this method opens the possibility of fabricating novel light-emitting materials for device fabrication and research.

Covalent Bond Torsion-Enabled Unique Crystal-Phase Transformation of an Organic Semiconductor for Multicolor Light-Emitting Transistors

High-mobility and color-tunable highly emissive organic semiconductors (OSCs) are highly promising for various optoelectronic device applications and novel structure-property relationship investigations. However, such OSCs have never been reported because of the great trade-off between mobility, emission color, and emission efficiency. Here, we report a novel strategy of molecular conformation-induced unique crystalline polymorphism to realize the high mobility and color-tunable high emission in a novel OSC, 2,7-di(anthracen-2-yl) naphthalene (2,7-DAN). Interestingly, 2,7-DAN has unique crystalline polymorphism, which has an almost identical packing motif but slightly different molecular conformation enabled by the small bond rotation angle variation between anthracene and naphthalene units. More remarkably, the subtle covalent bond rotation angle change leads to a big change in color emission (from blue to green) but does not significantly modify the mobility and emission efficiency. The carrier mobility of 2,7-DAN crystals can reach up to a reliable 17 cm2 V-1 s-1, which is rare for the reported high-mobility OSCs. Based on the unique phenomenon, high-performance light-emitting transistors with blue to green emission are simultaneously demonstrated in an OSC crystal. These results open a new way for designing emerging multifunctional organic semiconductors toward next-generation advanced molecular (atomic)-scale optoelectronics devices.

Unique Fluorescence of Aggregation-Induced Emission Luminogens on Solid Surfaces Modified by Silicone Nanofilaments

Aggregation-induced emission (AIE) has revolutionized solid-state fluorescence by overcoming the limitations of aggregation-caused quenching. While extensively studied in solutions, AIE's potential on solid surfaces remains largely unexplored, which can be fundamentally interesting and practically useful. In this work, we demonstrate the successful dispersion of tetraphenylethylene (TPE), one of the most classical AIE luminogens, on solid surfaces coated with silicone nanofilaments (SNF). The high surface area of SNF enables the uniform immobilization of TPE luminogens, replicating their dispersal behavior in solutions. Compared to unmodified surfaces, TPE dispersed on SNF-coated surfaces exhibits significantly enhanced fluorescence intensity. Moreover, a fascinating dynamic blue shift in TPE emission on SNF-coated surfaces is observed, with the velocity controllable by the surface group of SNF by up to 4 orders of magnitude, showing that TPE can be applied to the judgment of the nanoscale morphology and surface free energy of the solid surface. Owing to the superhydrophobicity and self-cleaning properties of SNF, the on-surface fluorescence can be sustained underwater and is resistant to dust contamination and rain erosion, with potential applications of information encryption presented. Our approach of uniformly dispersing AIE luminogens on nanomaterials with high surface areas provides a general methodology for creating on-surface fluorescence and saving the usage of expensive AIE luminogens in applications.

Quinoxaline-based azamacrocycles: synthesis, AIE behavior and acidochromism

The development of luminescent molecular materials has advanced rapidly in recent decades, primarily driven by the synthesis of novel emissive compounds and a deeper understanding of excited-state mechanisms. Herein, we report a streamlined synthetic approach to light-emitting diazapolyoxa- and polyazamacrocycles N2CnOxQ and NyCnQ (n = 3-10; x = 2, 3; y = 2-5), incorporating a 2,3-diphenylquinoxaline residue (DPQ). This synthetic strategy based on macrocyclization through Pd-catalyzed amination reaction yields the target macrocycles in good or high yields (46-92%), enabling precise control over their structural parameters. A key role of the PhPF-tBu ligand belonging to the JosiPhos series in this macrocyclization was elucidated through DFT computation. This macrocyclization reaction eliminates the need for complex protecting-deprotecting procedures of secondary amine groups, offering a convenient and scalable method for the preparation of target compounds. Moreover, it boasts a potentially broad substrate scope, making it promising for structure-properties studies within photophysics, sensor development, and material synthesis. Photophysical properties of representative macrocycles were investigated, employing spectroscopic techniques and DFT computation. It was demonstrated that DPQ-containing macrocycles display aggregation-induced emission in a DCM-hexane solvent mixture despite the presence of flexible tethers within their structures. Single-crystal X-ray diffraction analysis of a representative compound N2C8O3Q allowed us to gain deeper insight into its molecular structure and AIE behaviour. The emissive aggregates of the N2C10O3Q macrocycle were immobilized on filter paper yielding AIE-exhibiting test strips for measuring acidity in vapors and in aqueous media.

Adaptive Helical Chirality in Supramolecular Microcrystals for Circularly Polarized Lasing

Chiral organic molecules offer a promising platform for exploring circularly polarized lasing, which, however, faces a great challenge that the spatial separation of molecular chiral and luminescent centers limits chiroptical activity. Here we develop a helically chiral supramolecular system with completely overlapped chiral and luminescent units for realizing high-performance circularly polarized lasing. Adaptive helical chirality is obtained by incorporating chiral agents into organic microcrystals. Benefiting from the efficient coupling of stimulated emission with the adaptive helical chirality, the supramolecular microcrystals enable high-performance circularly polarized lasing emission with dissymmetry factors up to ~0.7. This work opens up the way to rational design of chiral organic materials for circularly polarized lasing.

Facile synthesis and characterization of aza-bridged all-benzenoid quinoidal figure-eight and cage molecules

Synthesis of conjugated compounds with unusual shape-persistent structures remains a challenge. Herein, utilizing thermodynamically reversible intermolecular Friedel-Crafts alkylation, a dynamic covalent chemistry (DCC) reaction, we facilely synthesized a figure-eight shaped macrocycle FEM and cage molecules CATPA/CACz. X-ray crystallographic analysis confirmed the chemical geometries of tetracation FEM4+(PF6 -)4 and hexacation CACz6+(SbF6 -)6. FEM and CATPA displayed higher photoluminescence quantum yield in solid states compared to that in solution, whereas CACz gave the reverse result. DFT calculations showed that fluorescence-related frontier molecular orbital profiles are mainly localized on their arms consisting of a p-quinodimethane (p-QDM) unit and two benzene rings of triphenylamine or carbazole. Owing to their space-confined structures, variable-temperature 1H NMR measurements showed that FEM, CATPA and FEM4+ have intramolecular restricted motion of phenyl rings on their chromophore arms. Accordingly, FEM and CATPA with flexible triphenylamine subunits displayed aggregation-induced emission behavior (AIE), whereas CACz with a rigid carbazole subunits structure showed no AIE behavior.

Solid-Emission-Tunable Squaraine with Thermal-Promoted Aggregate-State Transitions for Fast Thermal History Sensing

Determining thermal history is crucial in many industrial processes, but reliable and sensitive organic thermal history indicators are currently absent. Herein, we report on the development of a squaraine-based fluorescent molecule, DPEA-SQ, for the detection of thermal exposure histories up to 436 K. DPEA-SQ forms multiple single crystals (DPEA-SQ-I, DPEA-SQ-II, and DPEA-SQ-III) with different conformations and aggregate-state packing modes, contributing to their different fluorescence wavelengths, lifetimes, and efficiencies. Interestingly, DPEA-SQ-I and DPEA-SQ-III undergo aggregate-state structural transitions to form the thermodynamically more stable DPEA-SQ-II, which are accompanied by changes in their fluorescence. By taking advantage of similar aggregate-state structural transformations during heating, a high-temperature thermal exposure history of up to 436 K is recorded and reflected by their fluorescence. To demonstrate the potential practical applications of DPEA-SQ, a DPEA-SQ-Powder/PDMS film is prepared and coated on an electric circuit board, which enables real-time monitoring of localized overheating by the naked eye. Additionally, the fluorescence peaks of DPEA-SQ-Powder and DPEA-SQ-Powder/PDMS films remain unchanged after storage at 373 K for 52 days, demonstrating high aggregate-state stability. The fast and reliable responses of this system make it an excellent candidate for the detection of overtemperature traces in electronic components and circuit diagnosis.

Incorporation of an Anion-Coordinated Triple Helicate into a Thin Film for Choline Recognition in an Aqueous System

Functional thin films, being fabricated by incorporating discrete supramolecular architectures, have potential applications in research areas such as sensing, energy storage, catalysis, and optoelectronics. Here, we have determined that an anion-coordinated triple helicate can be solution-processed into a functional thin film by incorporation into a polymethyl methacrylate (PMMA) matrix. The thin films fabricated by the incorporation of the anion-coordinated triple helicate show multiple optical properties, such as fluorescence, CD, and CPL. In addition, the film has the ability to recognize choline and choline derivatives in a water system. The successful recognition of Ch+ by the film represents the first example of utilizing 'aniono'-supramolecular architectures for biomolecule detection in aqueous solution and opens up a new route for designing biocompatible functional materials.

Supramolecular Assembly Based on Calix(4)arene and Aggregation-Induced Emission Photosensitizer for Phototherapy of Drug-Resistant Bacteria and Skin Flap Transplantation

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

"Gear-driven"-type chirality transfer of tetraphenylethene-based supramolecular organic frameworks for peptides in water

Chirality transfer for natural chiral biomolecules can reveal the indispensable role of chiral structures in life and can be used to develop the chirality-sensing biomolecular recognition. Here, we report the synthesis and characterization of a series of achiral supramolecular organic frameworks (SOF-1, SOF-2, and SOF-3), constructed from cucurbit[8]uril (CB[8]) and tetraphenylethene (TPE) derivatives (1, 2, and 3), respectively, as chirality-sensing platforms to explore their chirality transfer mechanism for peptides in water. Given the right-handed (P) and left-handed (M) rotational conformation of TPE units and the selective binding of CB[8] to aromatic amino acids, these achiral SOFs can be selectively triggered in water by peptides containing N-terminal tryptophan (W) and phenylalanine (F) residues into their P- or M-rotational conformation, exhibiting significantly different circular dichroism (CD) spectra. Although various peptides have the same l-type chiral configuration, they can induce positive CD signals of SOF-1 and negative CD signals of SOF-2 and SOF-3, respectively. Based on the structural analysis of the linkage units between CB[8] and TPE units in these SOFs, a "gear-driven"-type chirality transfer mechanism has been proposed to visually illustrate the multiple-step chirality transfer process from the recognition site in the CB[8]'s cavity to TPE units. Furthermore, by utilizing the characteristic CD signals generated through the "gear-driven"-type chirality transfer, these SOFs can serve as chiroptical sensor arrays to effectively recognize and distinguish various peptides based on their distinctive CD spectra.

Recent advances in combatting bacterial infections via well-designed metallacycles/metallacages

Bacterial infections can lead to the development of large-scale outbreaks of diseases that pose a serious threat to human life and health. Also, conventional antibiotics are prone to producing resistance and allergic reactions, and their therapeutic effect is dramatically diminished when bacterial communities form biofilms. Fortunately, well-designed supramolecular coordination complexes (SCCs) have been used as antibacterials or anti-biofilms in recent years. SCCs can kill bacteria by directly engaging with the bacterial surface through electrostatic interactions or by penetrating the bacterial membrane through the auxiliary effect of cell-penetrating peptides. Furthermore, scientists have engineered fluorescent SCCs that can produce reactive oxygen species (ROS) to eliminate bacteria when exposed to laser irradiation, and they also demonstrate outstanding performance in in vivo imaging, enabling integrated diagnosis and treatment. In this review, we summarize the design strategy and applications of SCCs in antibacterials or anti-biofilms and provide an outlook on future research.

N-Vinylthio Phthalimides (N-VTPs): Modular Reagents for Vinylthio AIEgen Transfer

Novel sulfur reagents N-vinylthio phthalimides (N-VTPs) have been employed as modular reagents for vinylthiolation, enabling the construction of aggregation-induced emission (AIE)-active tetraaryldivinyl sulfides (TADVSs) and diarylvinyl sulfides (DAVSs). Notably, TADVSs with sulfur insertion to ethene stators are reported as AIE luminogens (AIEgens) for the first time, and the corresponding photophysical properties and aggregated confirmation have been detailed for the demonstration of the AIE effect. A water-soluble TADVS with a quinolinium salt was prepared for cell imaging.

A Reusable Fluorescent Molecular Self-Assembly Cage for Simultaneous Detection and Recycling of Silver(I) Ion

Although molecular self-assembled porous materials capable of ratiometric fluorescence probing and recycling of metal ions are both economically and environmentally attractive, very few current efforts have been devoted. Herein, we demonstrated a three-dimensional pure organic cage, namely 4-cage, which can serve as a fluorescent probe for simultaneous ratiometric detection and recycling of Ag+ ion. Taking advantage of the promising emission behavior of its rigidified tetraphenylethylene scaffolds and the chelating ability of its dynamically reversible imine moieties, on one hand, upon the addition of Ag+ , 4-cage undergoes coordination to form a stable but poorly soluble fluorescent complex, Ag+ @4-cage, accompanied by a fluorescence color change from bluish-green to yellowish-green. This allows us to differentiate Ag+ from other cations with high selectivity. On the other hand, upon the addition of Cl- anion, Ag+ @4-cage can be effectively converted into free 4-cage due to the competitive coordination of Cl- with Ag+ . Through this process, secondary usage of 4-cage and the recycling of Ag+ ion can be achieved.

A ratiometric fluorescent probe for rapid and specific detection of hypochlorite

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

Spontaneous and Selective Macrocyclization in Nitroaldol Reaction Systems

Through a dynamic polymerization and self-sorting process, a range of lowellane macrocycles have been efficiently generated in nitroaldol systems composed of aromatic dialdehydes and aliphatic or aromatic dinitroalkanes. All identified macrocycles show a composition of two repeating units, resulting in tetra-β-nitroalcohols of different structures. The effects of the building block structure on the macrocyclization process have been demonstrated, and the influence from the solvent has been explored. In general, the formation of the lowellanes was amplified in response to phase-change effects, although solution-phase structures were, in some cases, favored.

Superstructure-Induced Hierarchical Assemblies for Nanoconfined Photocatalysis

Most attempts to synthesize supramolecular nanosystems are limited to a single mechanism, often resulting in the formation of nanomaterials that lack diversity in properties. Herein, hierarchical assemblies with appropriate variety are fabricated in bulk via a superstructure-induced organic-inorganic hybrid strategy. The dynamic balance between substructures and superstructures is managed using covalent organic frameworks (COFs) and metal-organic frameworks (MOFs) as dual building blocks to regulate the performances of hierarchical assemblies. Significantly, the superstructures resulting from the controlled cascade between COFs and MOFs create highly active photocatalytic systems through multiple topologies. Our designed tandem photocatalysis can precisely and efficiently regulate the conversion rates of bioactive molecules (benzo[d]imidazoles) through competing redox pathways. Furthermore, benzo[d]imidazoles catalyzed by such supramolecular nanosystems can be isolated in yields ranging from 70 % to 93 % within tens of minutes. The multilayered structural states within the supramolecular systems demonstrate the importance of hierarchical assemblies in facilitating photocatalytic propagation and expanding the structural repertoire of supramolecular hybrids.

Recent applications of organic cages in sensing and separation processes in solution

Organic cages are three-dimensional polycyclic compounds of great interest in the scientific community due to their unique features, which generally include simple synthesis based on the dynamic covalent chemistry strategies, structural tunability and high selectivity. In this feature article, we present the advances over the last ten years in the application of organic cages as chemosensors or components in chemosensing devices for the determination of analytes (pollutants, analytes of biological interest) in complex aqueous media including wine, fruit juice, urine. Details on the recent applications of organic cages as selective (back-)extractants or masking agents for potential applications in relevant separation processes, such as the plutonium and uranium recovery by extraction, are also provided. Over the last ten years, organic cages with permanent porosity in the liquid and solid states have been highly appreciated as porous materials able to discriminate molecules of different sizes. These features, combined with good solvent processability and film-forming tendency, have proved useful in the fabrication of membranes for gas separation, solvent nanofiltration and water remediation processes. An overview of the recent applications of organic cages in membrane separation technologies is given.

Realizing long range π-conjugation in phenanthrene and phenanthrene-based molecular crystals for anomalous piezoluminescence

Unlike the known aggregation-caused quenching (ACQ) that the enhancement of π-π interactions in rigid organic molecules usually decreases the luminescent emission, here we show that an intermolecular "head-to-head" π-π interaction in the phenanthrene crystal, forming the so-called "transannular effect", could result in a higher degree of electron delocalization and thus photoluminescent emission enhancement. Such a transannular effect is molecular configuration and stacking dependent, which is absent in the isomers of phenanthrene but can be realized again in the designed phenanthrene-based cocrystals. The transannular effect becomes more significant upon compression and causes anomalous piezoluminescent enhancement in the crystals. Our findings thus provide new insights into the effects of π-π interactions on luminescence emission and also offer new pathways for designing efficient aggregation-induced emission (AIE) materials to advance their applications.

Dual reactivity based dynamic covalent chemistry: mechanisms and applications

Dynamic covalent chemistry (DCC) focuses on the reversible formation, breakage, and exchange of covalent bonds and assemblies, setting a bridge between irreversible organic synthesis and supramolecular chemistry and finding wide utility. In order to enhance structural and functional diversity and complexity, different types of dynamic covalent reactions (DCRs) are placed in one vessel, encompassing orthogonal DCC without crosstalk and communicating DCC with a shared reactive functional group. As a means of adding tautomers, widespread in chemistry, to interconnected DCRs and combining the features of orthogonal and communicating DCRs, a concept of dual reactivity based DCC and underlying structural and mechanistic insights are summarized. The manipulation of the distinct reactivity of structurally diverse ring-chain tautomers allows selective activation and switching of reaction pathways and corresponding DCRs (C-N, C-O, and C-S) and assemblies. The coupling with photoswitches further enables light-mediated formation and scission of multiple types of reversible covalent bonds. To showcase the capability of dual reactivity based DCC, the versatile applications in dynamic polymers and luminescent materials are presented, paving the way for future functionalization studies.

Tying a knot between crown ethers and porphyrins

Porphyrins and crown ether hybrids have emerged as a promising class of molecules composed of elements of a tetrapyrrole macrocycle and an oligo(ethylene glycol) segment. These hybrid systems constitute a broad group of compounds, including crowned porphyrins, crownphyrins, and calixpyrrole-crown ether systems forming Pacman complexes with transition metals. Their unique nature accustoms them as excellent ligands and hosts capable of binding guest molecules/ions, but also to undergo unusual transformations, such as metal-induced expansion/contraction. Depending on the design of the particular hybrid, they present unique features involving intriguing redox chemistry, interesting optical properties, and reactivity towards transition metals. In this perspective article, the overview of both the early designs of porphyrin-crown ether hybrids, as well as the most recent advances in the synthesis and characterisation of this remarkable group of macrocyclic systems, are addressed. The discussion covers the strategies employed in synthesising these systems, including cyclisation reactions, self-assembly, and their remarkable reactivity. The potential applications of porphyrin-crown ether hybrids are also highlighted. Moreover, the discussion identifies the challenges associated with synthesising and characterising hybrids, outlining the possible future directions.

New Fluorophore and Its Applications in Visualizing Polystyrene Nanoplastics in Bean Sprouts and HeLa Cells

In the domain of environmental science, pollutants of nanoscale plastic dimensions are acknowledged as subjects of intricate significance. Such entities, though minuscule, present formidable challenges to ecological systems and human health. The diminutive dimensions of these contaminants render their detection arduous, thus demanding the inception of avant-garde methodologies. The present manuscript postulates the employment of the tetraphenylethylene functional group with a fused xanthene (TPEF), a distinguished fluorophore, as an exemplary system for the discernment of nanoplastic particulates. The synthesis and characterization of TPEF have been exhaustively elucidated, revealing its paramount fluorescence attributes and inherent affinity for interaction with nanoplastics. When subjected to comparison with TPEF, nanoplastics are observed to manifest a more pronounced fluorescent luminescence than when associated with the conventional Nile Red (NR). Particularly, the TPEF has shown exceptional affinity for polystyrene (PS) nanoplastics. Further, the resilience of nanoplastics within the hypocotyl epidermis of soybeans, as well as their persistence in mung bean sprouts subsequent to rigorous rinsing protocols, has been meticulously examined. Additionally, this investigation furnishes empirical data signifying the existence of nano-dimensional plastic contaminants within HeLa cellular structures. The urgency of addressing the environmental ramifications engendered by these diminutive yet potent plastic constituents is emphatically highlighted in this manuscript. TPEF paves the way for prospective explorations, with the aspiration of devising efficacious mitigation strategies. Such strategies might encompass delineating the trajectories undertaken by nanoplastics within trophic networks or their ingress into human cellular architectures.

Tetraphenylethylene-Based Photoluminescent Self-Assembled Nanoparticles: Preparation and Biological Evaluation

The conjugation of tetraphenylethylene (TPE) with podophyllotoxin, N-desacetylthiocolchicine, and cabazitaxel through a sebacic acid linker led to the formation of fluorescent nanoparticles. Dynamic light scattering (DLS) and photoluminescence spectroscopy were used for the identification and characterization of the fluorescent nanoparticles. The biological evaluation was determined in three human ovarian (KURAMOCHI, OVCAR3, OVSAHO) and three human breast (MCF7, SKBR 3, and MDA-MB231) cancer cell lines. In the case of cabazitaxel, the nanoparticles maintained the activity of the parent drug, at the low nanomolar range, while exhibiting high blue fluorescence. The internalization of the fluorescent NPs into cells was detected using immunofluorescence assay.

Emissive Click Cages

This study reports the synthesis of cofacial organic cage molecules containing aggregation-induced emissive (AIE) luminogens (AIEgens) through four-fold Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) "click" reactions. The shorter AIEgen, tetraphenylethylene (TPE), afforded two orientational isomers (TPE-CC-1A and TPE-CC-1B). The longer AIEgen, tetrabiphenylethylene (TBPE), afforded a single isomer (TBPE-CC-2). The click reaction employed is irreversible, yet it yielded remarkable four-fold click products above 40 %. The phenyl rings around the ethylene core generate propeller-shaped chirality owing to their orientation, which influences the chirality of the resulting cages. The shorter cages are a mixture of PP/MM isomers, while the longer ones are a mixture of PM/MP isomers, as evidenced by their x-ray structures. The newly synthesized cage molecules are emissive even in dilute solutions (THF) and exhibit enhanced AIE upon the addition of water. The aggregated cage molecules in aqueous solution exhibit turn-off emission sensing of nitroaromatic explosives, with selectivity to picric acid in the 25-38 nanomolar detection range.

Boosting Solid-State Luminescence of Thiazolothiazole Viologen by Incorporating Metal Halide Clusters to Hinder π-Stacking

A new strategy is developed herein to improve the solid fluorescence of thiazolothiazole viologen by using the ZnCl42- cluster as a scaffold to hinder π-stacking. Importantly, the Cl···H bonds are formed in the solid state to sustain the framework and can be automatically dissociated when dissolved in H2O, thus having no impact on the strong emission in aqueous solution. As such, the first case of organic-inorganic viologen-zinc halide named 4PV·ZnCl4 was designed and synthesized, and a significant increase in photoluminescence quantum yield (ΦF) is realized from 4PV·2Br (ΦF = 0%) to 4PV·ZnCl4 (ΦF = 27.0%) in solid and from 97% to 98% in H2O. 4PV·ZnCl4 also displays pH stimuli-responsive naked-eye chromic behavior and photoluminescence with different coloring states and intensities. The multifunctional performance of 4PV·ZnCl4 provides a prerequisite for carrying different information, expanding their promising application in multilevel information encryption.

Aggregation behaviour of pyrene-based luminescent materials, from molecular design and optical properties to application

Molecular aggregates are self-assembled from multiple molecules via weak intermolecular interactions, and new chemical and physical properties can emerge compared to their individual molecule. With the development of aggregate science, much research has focused on the study of the luminescence behaviour of aggregates rather than single molecules. Pyrene as a classical fluorophore has attracted great attention due to its diverse luminescence behavior depending on the solution state, molecular packing pattern as well as morphology, resulting in wide potential applications. For example, pyrene prefers to emit monomer emission in dilute solution but tends to form a dimer via π-π stacking in the aggregation state, resulting in red-shifted emission with quenched fluorescence and quantum yield. Over the past two decades, much effort has been devoted to developing novel pyrene-based fluorescent molecules and determining the luminescence mechanism for potential applications. Since the concept of "aggregation-induced emission (AIE)" was proposed by Tang et al. in 2001, aggregate science has been established, and the aggregated luminescence behaviour of pyrene-based materials has been extensively investigated. New pyrene-based emitters have been designed and synthesized not only to investigate the relationships between the molecular structure and properties and advanced applications but also to examine the effect of the aggregate morphology on their optical and electronic properties. Indeed, new aggregated pyrene-based molecules have emerged with unique properties, such as circularly polarized luminescence, excellent fluorescence and phosphorescence and electroluminescence, ultra-high mobility, etc. These properties are independent of their molecular constituents and allow for a number of cutting-edge technological applications, such as chemosensors, organic light-emitting diodes, organic field effect transistors, organic solar cells, Li-batteries, etc. Reviews published to-date have mainly concentrated on summarizing the molecular design and multi-functional applications of pyrene-based fluorophores, whereas the aggregation behaviour of pyrene-based luminescent materials has received very little attention. The majority of the multi-functional applications of pyrene molecules are not only closely related to their molecular structures, but also to the packing model they adopt in the aggregated state. In this review, we will summarize the intriguing optoelectronic properties of pyrene-based luminescent materials boosted by aggregation behaviour, and systematically establish the relationship between the molecular structure, aggregation states, and optoelectronic properties. This review will provide a new perspective for understanding the luminescence and electronic transition mechanism of pyrene-based materials and will facilitate further development of pyrene chemistry.

High AIECL performance of tetraphenylethene derivatives originated from the linear increasing of benzene ring and solvent regulation for sensitive measurement of melatonin

The efficiency of aggregation-induced electrochemiluminescence (AIECL) in tetraphenylethene (TPE) derivatives were significantly enhanced by combining the regulation of molecular structure and solvent. Firstly, the linear increase of the benzene ring resulted in enhanced molecular aggregation and promoted the electrochemical reaction of the anode, due to increased molecular conjugation and higher lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO). The ECL efficiency of 4,4,4,4-(Ethene-1,1,2,2-tetrayl) tetrakis (([1,1,4,1-terphenyl]-4-carbaldehyde)) (T3) nanoparticles (NPs) with more benzene rings were 5558 times that of 4,4,4,4-(ethene-1,1,2,2-tetrayl) tetrabenzaldehyde (T1) NPs, and its relative ECL efficiency of T3 NPs reached 55.58% compared to the [Ru (bpy)3]2+/tripropylamine (TPrA) system. Furthermore, solvents with different polarities played a crucial role in modulating the degree of molecular aggregation, which also effectively facilitated the AIE process and reduced the aggregation-caused quenching (ACQ) effect caused by excessively dense aggregation. This aspect had often been overlooked in previous AIECL studies. T3 NPs demonstrated optimal ECL performance at fw = 70% (fw was the H2O content in tetrahydrofuran (THF)/H2O), and its ECL efficiency was 232 times greater than fw = 100% and 1853 times greater than fw = 0%. Additionally, it was found that melatonin (MT), one of the hormones widely used to treat insomnia, exhibited antioxidant and free radical scavenging properties, which exerted a significant quenching effect on the ECL of the T3 NPs/TPrA system. Consequently, a sensitive sensing platform was developed for MT with a low detection limit of 8.78 × 10-10 mol L-1, which promoted the application of AIECL in efficient ultra-sensitive biosensing.

Construction of Covalent Organic Cages with Aggregation-Induced Emission Characteristics from Metallacages for Mimicking Light-Harvesting Antenna

A series of covalent organic cages built from fluorophores capable of aggregation-induced emission (AIE) were elegantly prepared through the reduction of preorganized M2 (LA )3 (LB )2 -type metallacages, simultaneously taking advantage of the synthetic accessibility and well-defined shapes and sizes of metallacages, the good chemical stability of the covalent cages as well as the bright emission of AIE fluorophores. Moreover, the covalent cages could be further post-synthetically modified into an amide-functionalized cage with a higher quantum yield. Furthermore, these presented covalent cages proved to be good energy donors and were used to construct light-harvesting systems employing Nile Red as an energy acceptor. These light-harvesting systems displayed efficient energy transfer and relatively high antenna effect, which enabled their use as efficient photocatalysts for a dehalogenation reaction. This research provides a new avenue for the development of luminescent covalent cages for light-harvesting and photocatalysis.

Phototriggered structures: Latest advances in biomedical applications

Non-invasive control of the drug molecules accessibility is a key issue in improving diagnostic and therapeutic procedures. Some studies have explored the spatiotemporal control by light as a peripheral stimulus. Phototriggered drug delivery systems (PTDDSs) have received interest in the past decade among biological researchers due to their capability the control drug release. To this end, a wide range of phototrigger molecular structures participated in the DDSs to serve additional efficiency and a high-conversion release of active fragments under light irradiation. Up to now, several categories of PTDDSs have been extended to upgrade the performance of controlled delivery of therapeutic agents based on well-known phototrigger molecular structures like o-nitrobenzyl, coumarinyl, anthracenyl, quinolinyl, o-hydroxycinnamate and hydroxyphenacyl, where either of one endows an exclusive feature and distinct mechanistic approach. This review conveys the design, photochemical properties and essential mechanism of the most important phototriggered structures for the release of single and dual (similar or different) active molecules that have the ability to quickly reason of the large variety of dynamic biological phenomena for biomedical applications like photo-regulated drug release, synergistic outcomes, real-time monitoring, and biocompatibility potential.

Interplay between Dual-State and Aggregation-Induced Emission with ESIPT Scaffolds Containing Triphenylamine Substituents: Experimental and Theoretical Studies

We detail the synthesis of a series of fluorophores containing triphenylamine derivatives along with their photophysical, electrochemical, and electronic structure properties. These compounds include molecular structures derived from imino-phenol (anil) and hydroxybenzoxazole scaffolds originating from similar salicylaldehyde derivatives and display excited-state intramolecular proton transfer. We show that depending on the nature of the π-conjugated scaffold, different photophysical processes are observed: aggregation-induced emission or dual-state emission, with a modulation of the fluorescence color and redox properties. The photophysical properties are further rationalized with the help of ab initio calculations.

Tailor-Made Pdn L2n Metal-Organic Cages through Covalent Post-Synthetic Modification

Post-synthetic modification (PSM) is an effective approach for the tailored functionalization of metal-organic architectures, but its generalizability remains challenging. Herein we report a general covalent PSM strategy to functionalize Pd_n L_2n metal-organic cages (MOCs, n=2, 12) through an efficient Diels-Alder cycloaddition between peripheral anthracene substituents and various functional motifs bearing a maleimide group. As expected, the solubility of functionalized Pd₁₂ L₂₄ in common solvents can be greatly improved. Interestingly, concentration-dependent circular dichroism and aggregation-induced emission are achieved with chiral binaphthol (BINOL)- and tetraphenylethylene-modified Pd₁₂ L₂₄ , respectively. Furthermore, Pd₁₂ L₂₄ can be introduced with two different functional groups (e.g., chiral BINOL and achiral pyrene) through a step-by-step PSM route to obtain chirality-induced circularly polarized luminescence. Moreover, similar results are readily observed with a smaller Pd₂ L₄ system.

Heteroaryl-Substituted Bis-Anils: Aggregation-Induced Emission (AIE) Derivatives with Tunable ESIPT Emission Color and pH Sensitivity

The two-step synthesis, structural, and photophysical properties of a series of heteroaryl-substituted bis-anil derivatives presenting aggregation-induced emission (AIE) coupled with an excited-state intramolecular proton transfer (ESIPT) process is described. The fluorescence color of the aggregates can be fine tuned by changing the electronic nature of the peripheral substitution, leading to a wide range of emission wavelengths (from green to the near infra-red). Moreover, upon introduction of strong electron-withdrawing groups such as cyano (CN), a competition between ESIPT and deprotonation is observed leading to the emission of the anionic species at low water percentage. This observation led to the synthesis of an additional mixed AIE fluorophore, functionalized by methoxy groups on one side and cyano groups on the other side. Upon addition of water, this dye displays first anionic emission, followed by typical AIE/ESIPT red fluorescence upon formation of the aggregates. TD-DFT calculations on selected AIE dyes were performed to rationalize the nature of the emissive transitions in these derivatives.

In Vivo Fluorescence Imaging-Guided Development of Near-Infrared AIEgens

In vivo fluorescence imaging has received extensive attention due to its distinguished advantages of excellent biosafety, high sensitivity, dual temporal-spatial resolution, real-time monitoring ability, and non-invasiveness. Aggregation-induced emission luminogens (AIEgens) with near-infrared (NIR) absorption and emission wavelengths are ideal candidate for in vivo fluorescence imaging for their large Stokes shift, high brightness and superior photostability. NIR emissive AIEgens provide deep tissue penetration depth as well as low interference from tissue autofluorescence. Here in this review, we summarize the molecular engineering strategies for constructing NIR AIEgens with high performances, including extending π-conjugation system and strengthen donor (D)-acceptor (A) interactions. Then the encapsulation strategies for increasing water solubility and biocompatibility of these NIR AIEgens are highlighted. Finally, the challenges and prospect of fabricating NIR AIEgens for in vivo fluorescence imaging are also discussed. We hope this review would provide some guidelines for further exploration of new NIR AIEgens.

Dimeric Pillar[5]arene as a Novel Fluorescent Host for Controllable Fabrication of Supramolecular Assemblies and Their Photocatalytic Applications

A dimeric fluorescent macrocycle m-TPE Di-EtP5 (meso-tetraphenylethylene dimeric ethoxypillar[5]arene) is synthesized based on the meso-functionalized ethoxy pillar[5]arene. Through the connectivity of two pillar[5]arenes by CC double bond, the central tetraphenylethylene (TPE) moiety is simultaneously formed. The resultant bicyclic molecule not only retains the host-guest properties of pillararenes but also introduces the interesting aggregation-induced emission properties inherent in the embedded TPE structure. Three dinitrile derivatives with various linkers are designed as guests (G1, G2, and G3) to form host-guest assemblies with m-TPE Di-EtP5. The morphological control and fluorescence properties of the assemblies are successfully realized. G1 with a shorter alkyl chain as the linker completely threads into the cavities of the host. G2, due to its longer chain length, forms a linear supramolecular polymer upon binding to m-TPE Di-EtP5. G3 differs from G2 by possessing a bulky phenyl group in the middle of the chain, which can be further assembled with m-TPE Di-EtP5 to form supramolecular layered polymer and precipitated out in solution, and can be efficiently applied to photocatalytic reactions.

Ligand effects on the photoluminescence of atomically precise silver nanoclusters

Photoluminescence (PL) is one of the most exciting properties of atomically precise metal nanoclusters (NCs), making them a prime choice for various applications, from sensing to bio-imaging. While there are several advantages of metal NCs for PL-based applications, their PLQY is significantly low compared to other PL-active nanomaterials or organic dyes. It is essential to understand the PL mechanism in detail to tune the PLQY of NCs. There are numerous reports on gold NCs with a known structure where the origin of PL has been explored, and it was found that ligands play a vital role in their PL properties along with the kernel (core). Reports on understanding the ligand effects on PL properties are also evolving for the case of atomically precise silver NCs. This mini-review will summarize the ligands' role in PL of 29 atom Ag NCs, the most reported NCs with diversity in the silver family. The ligands were classified as primary and secondary, and their effects on tuning the PL properties were explained. The review will also address some of the answers to open questions for AgNCs, such as the origin of PL, dynamics, and the tunability of PLQY using ligand modifications.

Photoredox-Catalyzed Cascade sp2 C-H Bond Functionalization to Construct Substituted Acridine with Diarylamine and Hypervalent Iodine(III) Reagents

A photocatalyzed cascade double C-C formation via sp² C-H bond activation of diarylamines with hypervalent iodine diazo reagents was developed. A variety of diarylamines and hypervalent iodine(III) reagents were tolerated well, and a range of substituted acridines with yields ranging from moderate to excellent was provided efficiently. The protocol introduces diazo groups onto diarylamines and enables subsequent late-stage assembly point functionalization with the diazonium structure, forming two new C-C bonds in a sequential fashion.

Chiral adaptive recognition with sequence specificity of aromatic dipeptides in aqueous solution by an achiral cage

Sequence-specific recognition of peptides and proteins by synthetic compounds or systems remains a huge challenge in biocompatible media. Here, we report the chiral adaptive recognition (CAR) with sequence specificity of aromatic dipeptides in a purely aqueous solution using an achiral tetraphenylethene-based octacationic cage (1) as both a molecular receptor and chiroptical sensor. 1 can selectively bind and dimerize aromatic dipeptides to form 1 : 2 host-guest complexes with high binding affinity (>10¹⁰ M^-2), especially up to ∼10¹⁴ M^-2 for TrpTrp. Given the dynamic rotational conformation of TPE units, achiral 1 can exhibit chiral adaptive responses with mirror-symmetrical circular dichroism (CD) and circularly polarized luminescence (CPL) spectra to enantiomeric dipeptides via supramolecular chirality transfer in the host-guest complexes. Furthermore, this CAR with sequence specificity of 1 can be applied for molecular recognition of TrpTrp- or PhePhe-containing tetrapeptides, polypeptides (e.g., amyloid β-peptide_1-20 and somatostatin), and proteins (e.g., human insulin) with characteristic CD responses.

Conjugating Coumarin with Tetraphenylethylene to Achieve Dual-State Emission for Reversible Mechanofluorochromism and Live Cell Imaging

Dual-state emission luminogens (DSEgens) are receiving research interest in the construction of multifunctional materials due to their inherent advantage of high emission efficiency in both the molecularly dispersed solution state and the solid state. However, it remains challenging in synthesizing DSEgens via a delicate manipulation of the molecular structures. This work presents an example of bright DSEgen synthesis by tuning the molecular electronic structures and conformations. Three coumarin-tetraphenylethylene (TPE) molecules with a donor-acceptor electronic structure and highly twisting conformations have been synthesized. While compound resulting from direct conjugation of coumarin with a TPE unit shows aggregation-induced emission, compound with an N,N-diaminoethyl modification on the 7-position of coumarin and compound with a further phenyl linker between coumarin and TPE units feature strong dual-state emission. Benefiting from their strong solid emission and twisting conformations, these fluorophores display reversible mechanofluorochromism. Finally, applications for rewritable information storage in the solid state and live-cell imaging in the solution state were demonstrated.

Design Concepts for Solution and Solid-State Emitters - A Modern Viewpoint on Classical and Non-Classical Approaches

For a long time, luminescence phenomena were strictly distinguished between the emission of isolated molecules in dilute solutions or close-packed structures such as in powders or aggregates. This changed with the breakthrough observation of dual-state efficient materials, which led to a rapid boost of publications examining the influence of structural features to achieve balanced emission with disregarded molecular surroundings. Some first general structural design concepts have already been proposed based on reoccurring patterns and pivotal motifs. However, we have found another way to classify these solution and solid-state emitters (SSSEs). Hence, this minireview aims to present an overview of published structural features of SSSEs while shining light on design concepts from a more generalized perspective. Since SSSEs are believed to bridge the gap of hitherto known aggregation-sensitive compound classes, we hope to give future scientists a versatile tool in hand to efficiently design novel luminescent materials.

Recognition-Induced Enhanced Emission of Core-Fluorescent ESIPT-type Macrocycles

Core-fluorescent cavitands based on 2-(2'-resorcinol)benzimidazole fluorophores (RBIs) merged with the resorcin[4]arene skeleton were designed and synthesized. The cavitands, due to the presence of intramolecular hydrogen bonds and increased acidity, show excited state intramolecular proton transfer (ESIPT) and readily undergo deprotonation to form dianionic cavitands, capable of strong binding to organic cations. The changes in fluorescence are induced by deprotonation and binding events and involve huge Stokes shifts (due to emission from anionic double keto tautomers) and cation-selective enhancement of emission originating from the restriction of intramolecular motion (RIR) upon recognition in the cavity. Ab initio calculations indicate that the macrocyclic scaffold stabilizes the ground state tautomeric forms of the fluorophores that are not observed for non-macrocyclic analogs. In the excited state, the emitting forms for both macrocyclic scaffolds and non-macrocyclic analogs are anionic double keto tautomers, which are the result of excited state intramolecular proton transfer (ESIPT) or excited state double proton transfer (ESDPT).

Calix[6]arene-Based [3]Rotaxanes as Prototypes for the Template Synthesis of Molecular Capsules

In this work, the ability of several bis-viologen axles to thread a series of heteroditopic tris(N-phenylureido)calix[6]arene wheels to give interwoven supramolecular complexes to the [3]pseudorotaxane type was studied. The unidirectionality of the threading process inside these nonsymmetric wheels allows the formation of highly preorganised [3]pseudorotaxane and [3]rotaxane species in which the macrocycles phenylureido moieties, functionalised with either ester, carboxylic, or hydroxymethyl groups, are facing each other. As verified by NMR and semiempirical computational studies, these latter compounds possess the correct spatial arrangement of their subcomponents, which could lead, in principle, upon proper bridging reaction, to the realisation of upper-to-upper molecular capsules that are based on calix[6]arene derivatives.

Chiral emissive porous organic cages

A pair of chiral, emissive and porous tubular multi-functional organic molecular cages were synthesized easily by imine chemistry of 4,4',4'',4'''-(ethene-1,1,2,2-tetrayl)-tetrabenzaldehyde (ETTBA) with (R,R)- or (S,S)-diaminocyclohexane (CHDA). It was found that the chirality of CHDA was transferred and amplified to tetraphenylethylene (TPE) in the process of formation of cages, which further endowed the cages with circularly polarized luminescence (CPL) characteristics. As a result of the synergy of the chirality and porous structure in the solid state, both cages exhibited a good chiral adsorption enantioselectivity to a series of aromatic racemates.

A Platinum(II)-Based Molecular Cage with Aggregation-Induced Emission for Enzymatic Photocyclization of Alkynylaniline

Enzymes facilitate chemical conversions through the collective activity of aggregated components, but the marriage of aggregation-induced emission (AIE) with molecular containers to emulate enzymatic conversion remains challenging. Herein, we report a new approach to construct a Pt^II -based octahedral cage with AIE characteristics for the photocyclization of alkynylaniline by restricting the rotation of the pendant phenyl rings peripheral to the Pt^II corner. With the presence of water, the C-H⋅⋅⋅π interactions involving the triphenylphosphine fragments resulted in aggregation of the molecular cages into spherical particles and significantly enhanced the Pt^II -based luminescence. The kinetically inert Pt-NP chelator, with highly differentiated redox potentials in the ground and excited states, and the efficient coordination activation of the platinum corner facilitated excellent catalysis of the photocyclization of alkynylaniline. The enzymatic kinetics and the advantages of binding and activating substrates in an aqueous medium provide a new avenue to develop mimics for efficient photosynthesis.

Aggregation-Induced Emission Metallocuboctahedra for White Light Devices

Materials for organic light-emitting devices which exhibit superior emission properties in both the solution and solid states with a high fluorescence quantum yield have been extensively sought after. Herein, two metallocages, S1 and S2, were constructed, and both showed typical aggregation-induced emission (AIE) features with intense yellow fluorescence. By adding blue-emissive 9,10-dimethylanthracene, pure white light emission can be produced in the solution of S1 and S2. Furthermore, due to the remarkable AIE feature and good fluorescence quantum yield in the solid state, metallocages are highly emissive in the solid state and can be utilized to coat blue LED bulbs or integrate with blue-emitting chips to obtain white light. This study advances the usage of metallocages as practical solid-state fluorescent materials and provides a fresh perspective on highly emissive AIE materials.

Tunable Construction of Sandwich-Type Double-[1 + 1] and Half-Folded [2 + 2] Schiff-Base Complexes Controlled by the Combination of Primary and Secondary Template Effects

The first-row transition-metal ions Mn²⁺-Cu²⁺ could serve as effective templates to construct three types of double-[1 + 1], [2 + 2], and [1 + 1] Schiff-base dinuclear macrocyclic complexes in the presence of dialdehydes with different pendant arms and a common 1,8-diamine. The extremely flexible nature of macrocyclic ligands allows for the multiple template-directed syntheses, but the final products could be finely tuned by the subtle variations of Mn²⁺-Cu²⁺ ions in a 3d-electronic configuration, radius, and coordination number/geometry as well as the auxiliary (pendant-armed and anionic) template effect at the same time. Two borderlines are observed at the Co²⁺ ion for forming double-[1 + 1] and [2 + 2] metallacycles involving the H₂pdd precursor and the [1 + 1] Cu²⁺ complex for double-[1 + 1] and [2 + 2] macrocycles containing the H₂hpdd unit, respectively. The structural diversity is originated from the non-perfect match between [1 + 1]/[2 + 2] Schiff-base macrocycles and dinuclear metal centers; hence, a compromise between the metal coordination modes and alterations of the ligand conformation takes place.

On-surface synthesis and spontaneous segregation of conjugated tetraphenylethylene macrocycles

Creating conjugated macrocycles has attracted extensive research interest because their unique chemical and physical properties, such as conformational flexibility, intrinsic inner cavities and aromaticity/antiaromaticity, make these systems appealing building blocks for functional supramolecular materials. Here, we report the synthesis of four-, six- and eight-membered tetraphenylethylene (TPE)-based macrocycles on Ag(111) via on-surface Ullmann coupling reactions. The as-synthesized macrocycles are spontaneously segregated on the surface and self-assemble as large-area two-dimensional mono-component supramolecular crystals, as characterized by scanning tunneling microscopy (STM). We propose that the synthesis benefits from the conformational flexibility of the TPE backbone in distinctive multi-step reaction pathways. This study opens up opportunities for exploring the photophysical properties of TPE-based macrocycles.

A Review on Electrospinning as Versatile Supports for Diverse Nanofibers and Their Applications in Environmental Sensing

Rapid industrialization is accompanied by the deterioration of the natural environment. The deepening crisis associated with the ecological environment has garnered widespread attention toward strengthening environmental monitoring and protection. Environmental sensors are one of the key technologies for environmental monitoring, ultimately enabling environmental protection. In recent decades, micro/nanomaterials have been widely studied and applied in environmental sensing owing to their unique dimensional properties. Electrospinning has been developed and adopted as a facile, quick, and effective technology to produce continuous micro- and nanofiber materials. The technology has advanced rapidly and become one of the hotspots in the field of nanomaterials research. Environmental sensors made from electrospun nanofibers possess many advantages, such as having a porous structure and high specific surface area, which effectively improve their performance in environmental sensing. Furthermore, by introducing functional nanomaterials (carbon nanotubes, metal oxides, conjugated polymers, etc.) into electrospun fibers, synergistic effects between different materials can be utilized to improve the catalytic activity and sensitivity of the sensors. In this review, we aimed to outline the progress of research over the past decade on electrospinning nanofibers with different morphologies and functional characteristics in environmental sensors.