A new thermally activated delayed fluorescence (TADF) acceptor (A) segment, acenaphtho[1,2-b]quinoxaline (AQ) group, is designed. And a novel red TADF material 10,10',10''-(acenaphtho[1,2-b]quinoxaline-3,9,10-triyl)tris(10H-phenoxazine) (AQ-TPXZ) is developed by the conjunction of AQ group with phenoxazine as donor (D) moieties. The density functional theory calculation shows that this D-A molecule has a well separation between the highest occupied molecular orbital and the lowest unoccupied molecular orbital. And the energy splitting between the lowest singlet state and the lowest triplet state is calculated to be 0.02 eV. The transient photoluminescence decays of AQ-TPXZ doped 4,4'-di(9H-carbazol-9-yl)-1,1'-biphenyl film exhibit double-component emission decay profiles. The organic light-emitting diode (OLED) using AQ-TPXZ as dopant realizes red emission with a peak at 624 nm. Moreover, the device obtains maximum external quantum efficiency (EQE) up to 7.4%, which is higher than the theoretical maximum EQE (5%) of traditional fluorescent OLEDs. This result not only indicates that AQ-TPXZ is a red TADF material but also provides a newly electron acceptor segment for designing novel red TADF emitters.

A series of pillar[5]arene monoamide derivatives with different lengths of alkylenediamine unites as the side chains on the pillar[5]arene's rim can form pseudo[1]rotaxanes. Thus, based on the construction of this intermediate of pseudo[1]rotaxane, eight pillar[5]arene-baed mechanically interlocked molecules (MIMs) of bis-[1]rotaxane were successful constructed through condensation reaction of pillar[5]arene monoamide derivative and salicylaldehyde. The newly synthesized bis-[1]rotaxane was investigated in detail by various methods, including ¹H NMR, ¹³C NMR, 2D NOESY NMR and MS analysis. It was found that this kind of MIMs has a strong recognition effect with Cu²⁺, which complexed by 1:2.

As an important endogenous gas transmitter, carbon monoxide (CO) has been found taking part in multiple physiological and pathological processes for life. Therefore, the selective recognition and sensitive detection of CO are of great biological and medical significance. Fluorescent probe method is highlighted by its good selectivity, high sensitivity, suitable for high-throughput screening, especially noninvasive detection, and real-time monitoring in situ. Therefore, the development of fluorescent probes for intracellular CO has been becoming one of the hot topics. Herein, the progress during the last decade of fluorescent molecular probes based on the small molecules for CO detection is reviewed. These fluorescent probes are classified and concluded according to the design concepts, detection mechanism, and biological applications. In addition, the relationship between molecular structures and properties is elucidated. Finally, the challenge and application prospects for the development of CO fluorescent probes are also discussed.

An "off-on" fluorescent probe CO-NBS based coumarin derivative was designed and synthesized, which can respond selectively with biothiols including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH). The optical properties were studied by UV-Vis absorption spectrum and fluorescence spectrum. The results showed that probe was capable to respond rapidly, sensitively and selectively to Cys, Hcy and GSH with the detection limits of 92, 30 and 62 nmol/L, respectively. In addition, with low cytotoxicity and good biocompatibility, the probe can be successfully applied to image biothiols in living cells and in living zebrafish.

Color-tunable and white light-emitting lanthanide-based complex/coordination polymer materials have attracted increasing interest recently due to the exceptional luminescent and chromogenic properties. Recent advances from 2014 to 2018 on white-light-emitting lanthanide-based materials are classifiedly highlighted in light of different aggregate states and lanthanide species in the coordination assemblies. The future advances in this field are also predicted.

In recent years, molecular fluorescent probes have attracted extensive attention due to their high sensitivity, high selectivity, specificity and simplicity of design. Perylene tetracarboxylic diimide derivatives (PDIs) are well known for their excellent photothermal stability, chemical stability, high fluorescence quantum yield, large stokes shift and easy modification. Therefore, they can be used as excellent fluorophores. PDI itself has strong electron-withdrawing group and easily to be reduced but it is hard to be oxidized. However, due to their inherent structure, the poor water solubility and aggregatable ablility limited their applications in biological fields. The water solubility of PDI was improved by introducing hydrophilic groups into the structure. Therefore, the PDIs with the unique advantages will have potential application values in the field of fluorescence probe and has been developed rapidly for the past few years. The development of PDI as a chromophore in fluorescent probe for the detection of ion, gas, biomolecules, etc. is systematically summarized. Meanwhile, the design of the probes, fluorescence response mechanism and application of the probe are also discussed. Finally, a novel type of PDI fluorescent probe is proposed. The challenge of construction of the PDIs and future development are also reviewed.

Adenosine triphosphate (ATP) is a high-energy phosphate compound commonly existing in various living cells, which plays important roles in the biological activities such as energy storage, cell respiration and enzyme catalytic reactions. Therefore, it is very crucial to ATP research in bio-organism. Fluorescence detection techniques has the advantages of convenient operation, good selectivity and high sensitivity, etc. In recent years, the design and synthesis of efficient ATP fluorescence sensors have become a research focus in the fields of biochemistry and analytical chemistry. According to the structure characteristics, ATP fluorescence chemosensors are categorized as Zn(Ⅱ) metal ions as recognition of bonding site type, other metal ions as recognition of bonding site type and electrostatic or hydrogen bond as interaction type. Based on organic small molecule fluorescence sensors, the recent progress in research of ATP fluorescence sensors in molecular design and application is reviewed, and the prospects for their development are discussed.

A dual-reactable H₂S fluorescent probe was designed and synthesized by employing ortho-fluoro-substituted coumarin azide and 7-nitrobenzofurazan-piperazine as the H₂S reactive groups and the fluorescence quenching groups. The recognition behaviors of the probe to H₂S were investigated and the results showed that the probe exhibited high selectivity and sensitivity. The fluorescence off-on enhancement was ca. 3600-fold, and the detection limit was 4.0×10^-8 mol/L. The results of enzyme activity test indicated that the probe could be used for cystathionine β-synthase (CBS) activity detection and inhibitor screening. Furthermore, the probe was successfully applied for the imaging of H₂S in living cells.

Alkaline phosphatase (ALP) is an important enzyme for various mammalian tissues. As a biomarker and diagnostic indicator, ALP provides important information for the applied research of molecular biology and the treatment of human diseases. Due to its reliability of information in human health, the research on fluorescence detection as important detection method has become intense in recent years. The fluorescent chemosensors are categorized by different luminous feature involving excitedstate intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT) chemosensors, aggregation-induced luminescent molecules (AIE), diminishes the electron donating ability (D d-E) and disruption of the π conjugated systems (D π-C), inner filter e?ect (IFE) chemosensors, and other sensing systems. In the end, the development tendency of the sensing ensembles for ALP is prospected.

Selective detection of Fe³⁺ has considerable importance due to its active involvement in various biological processes. Based on the mechanism of excited-state intramolecular proton transfer (ESIPT) plus aggregation induced emission (AIE), a fluorescence probe of phenanthro[9, 10-d]imidazole modified by the phenolic hydroxyl (PIP-o-OH) had been designed, synthesized and applied in the detection of Fe³⁺. The structure of PIP-o-OH was characterized by ¹H NMR, ¹³C NMR, IR, HRMS and X-ray single diffraction. Furthermore, a clear intramolecular hydrogen bond was observed between hydroxyl O-H and imidazole N atom in X-ray single structure, which improved the impossibility of ESIPT activity. ESIPT and AIE activities of PIP-o-OH were adequately determined by absorption, emission spectra and scanning electron microscope (SEM). The aggregated PIP-o-OH in MeOH/H₂O (V:V=1:9, Hepes 10 μmol/L, pH=7.4) exhibited a good sensitivity towards Fe³⁺ with "turn-off" fluorescence response just after 20 s. The limit of detection (LOD) was calculated as low as 0.49 μmol/L. So it could be utilized to detect Fe³⁺ in biology and environmental samples. In addition, the calculation of the density functional theory (DFT) confirmed the formation of PIP-o-OH-Fe³⁺ complex. Also, PIP-o-OH was successfully applied to monitor Fe³⁺ in HeLa cells by the fluorescence change and quantificationally detect Fe³⁺ in water samples.

A novel fluorescent sensor based on 5-(3-nitrophenyl)-furan-2-carbaldehyde functionalized barbituric acid derivative (QS) was successfully synthesized. QS was characterized by ¹H NMR, ¹³C NMR and MS. The maximum fluorescence emission wavelength of QS in dimethyl sulfoxide (DMSO) solution was determined to be 498 nm and green fluorescence was emitted under 365 nm ultraviolet lamp. QS showed different fluorescence identification ability for aqueous solution of Hg ²⁺ and Fe ³⁺. Hg ²⁺ can enhance the fluorescence of probe QS to orange, and Fe ³⁺ quenches its fluorescence, thus realizing real- time detection. The limits of detection of QS for Hg ²⁺ and Fe ³⁺ are 3.25×10 ^–8 and 4.0×10 ^–8 mol? L ^–1, respectively. The fluorescence measurements and MS studies suggest that the binding stoichiometry ratios of QS with Hg ²⁺ and Fe ³⁺ are recognized as 1∶1, respectively. The possible modes of QS with Hg ²⁺ and Fe ³⁺ are proposed. The addition of $H_{2}PO_{4}^{-}$ caused the fluorescence of QS-Fe recover, indicating that QS can be used for cyclic detection of Fe ³⁺. More importantly, the separation percentages of the solid QS for Hg ²⁺and Fe ³⁺ are 92.0% and 91.8% in aqueous solution, respectively, indicating that it has excellent ingestion capacity.

Novel reactive probes (C1 and C2) towards homocysteine/cysteine (Hcy/Cys) were designed and synthesized, based on the unique nucleophilic nature of bio-thiols. In the presence of Hcy/Cys, probe C1 displayed remarkable fluorescence enhancement. Meanwhile, ratiometric fluorescent probe C2 was designed through subtle structure adjustment. Differently, compound C2 displayed dramatic blue-shift in both fluorescence (100 nm) and absorption (95 nm) spectra upon the addition of Hcy/Cys. By virtue of the specific nucleophilic reaction, probe C2 had outstanding selectivity towards Hcy over Cys, GSH and other amino acids. The detection limit of probe C2 was calculated to be as low as 2.8×10 ^–7 mol/L. Moreover, C2 was successfully applied to microscopic imaging for the detection of Hcy in HeLa cells with ratiometric fluorescent methods.

A tetrapyridyl substituted corannulene derivative COPY2 was designed and synthesized. Only in the presence of template molecule C₆₀ or C₇₀, COPY2 and palladium could form 1∶1 molecular cage complex C_60/70?COPY2-Pd by self-assembly at room temperature and 55 ℃ respectively. C₆₀ and C₇₀ were used not only as a template for constructing target molecular cages, but also as a stabilizer for molecular cage. When 1.0 equiv. C₇₀ mixed with C₆₀?COPY2-Pd or 1.0 equiv. C₆₀ mixed with C₇₀?COPY2-Pd, the ratio of complex C₆₀?COPY2-Pd to C₇₀?COPY2-Pd is 4∶1 after the mixtures were heated at 90 ℃ for 48 h, which is consistent with the ratio of COPY2 and Pd(CH₃CN)₂Cl₂ mixed with C₆₀ and C₇₀ (1∶1). Only the complex C₆₀?COPY2-Pd was observed when the ratio of C₆₀ to C₇₀ is 2∶1. However, even the ratio of C₆₀ to C₇₀ is 1∶2, complex C₆₀?COPY2-Pd is still the dominant species in the mixture. These results demonstrate that complexing ability of COPY2 with C₆₀ is stronger than that of COPY2 with C₇₀. 4-Dimethylaminopyridine (DMAP) was chosen to dissociate the cage so as to release fullerene and ligand. Therefore, the ligand COPY2 could be used to the enrichment of C₆₀ at room temperature.

Benzo five-/six-membered nitrogen-containing heterocyclic compound with a rigid plane and a large conjugate structure can emit characteristic fluorescence in a variety of organic solvents and mixed solutions, and N, O, S heteroatoms in the structure can serve as binding sites for fluorescent probes. Therefore, in recent years, benzo nitrogen-containing heterocyclic compounds are increasingly becoming one of the research focuses in the field of fluorescent probes. From the perspective of starting materials, synthesis methods, molecular structure, interaction mechanism, benzo five- / six-membered nitrogen-containing heterocyclic fluorescent probes containing the structure of benzoxazole, benzothiazole, benzimidazole, indole, carbazole, quinoline, benzopyrazine and phenazine are introduced with emphasis. And their detection application for a variety of analytes, such small molecules, metal cations, anions and pH are reviewed. In the future, it is worthy of further attention to the research on the integration of multiple heterocyclic functional structures into a multifunctional fluorescent probe by simple and green synthesis.

A novel alternating amphiphilic copolymer poly(tetra glycol-a-N,N-bis[2-(1H-1,2,3-triazol-1-yl)ethyl]-4-phenyl- diazenyl-aniline) [P(EG₄-a-NAzo)] with azobenzene pendants was synthesized through the azide-alkyne click reaction, in which the hydrophilic unit was tetra glycol (EG₄) and N,N-bis[2-(1H-1,2,3-triazol-1-yl)ethyl]-4-phenyldiazenyl-aniline (NAzo) performed the hydrophobic unit. P(EG₄-a-NAzo) could self-assemble into worm-like aggregate in aqueous solution with initially low concentration. Because of its unique alternating topologies, the azobenzene moiety of P(EG₄-a-NAzo) micelle could not pile up orderly. This novel azobenzene copolymer has arisen new thoughts and approaches for the molecular design of photo-functional polymers.

Amphiphilic block copolypeptides of polyethylene glycol-b-poly(L-glutamic acid) (PEG-b-PGlu) were synthesized to self-assemble with 4-methyl-4-aza[4]helicene onium ion (Me[4]H) in water through charge-conjugation. The morphology of the assemblies was studied by varying PGlu block length, the molar ratio of Glu unit/Me[4]H and pH value. It was found that when rigid-flexible block copolymers were assembled together with small molecules which had rigid, large size and inductive effect, they would follow a completely different law from the charge-conjugated assembly of flexible macromolecules. The self-assemblies were controlled by the π-π stacking of helicene, together with the volume fraction of the hydrophobic parts and the rigidity of PGlu segments. These effects restricted each other in the assembly process. When π-π stacking was dominant, assembly morphologies with pointer-like and strip-like planar structures were obtained.

Mercury ion pollution has serious harmful impact on the ecological environment and human health. It is of great significance to develop a probe with high selectivity and sensitivity that could be applied to the detection of mercury ion in water environment. In this paper, a novel excited-state intramolecular proton transfer (ESIPT) fluorescent probe containing barbitone unit was designed and synthesized from salicylaldehyde. Mechanism studies showed that mercury ions and probes formed a structure similar to “(thymine)T-Hg-T” which has high selectivity in determining mercury ions. The calibration curve indicated that there was a good linear correlation between the relative fluorescent intensities over the concentration range of 4~20 μmol·L ^–1 of Hg ²⁺ ion.

Human serum albumin (HSA) is the most abundant protein in human blood plasma, which plays important roles in physiological and biological processes, such as keeping the osmotic pressure and transporting small molecular ligands. The level of HSA in in biological samples especially in blood serum can reveal several health conditions, and thus, quantitative determination of HSA has vital importance for disease diagnosis. In recent years, as the rapid development of fluorescent probe technique, a great number of fluorescent probes have been reported for sensitive and selective detection of HSA. This article summarizes recent reported organic-based fluorescent probes, subsequently carefully describes the chemical structures, sensing mechanisms, spectral features, limit of detection, and binding sites, and moreover, the future developments and prospects for HSA detection by using fluorescent probes have been discussed

Camptothecin derivatives exist mainly as inactive open ring carboxylates in physiological media. Tumor microenvironment is generally weakly acidic, whereas supramolecular organic frameworks can adsorb and deliver anionic antitumor drugs into tumor cells. In principle, supramolecular organic frameworks (SOFs) can adsorb and deliver camptothecin open ring carboxylates to tumor microenvironment and the delivered carboxylates can undergo lactonization to afford active molecules due to the weak acid character of the tumor microenvironment, which may lead to efficient utilization of the carboxylates as predrugs. To explore this potential, dialysis experiments for the open ring carboxylates of camptothecin, SN-38 and 10-hydroxycamptothecin in the presence of two SOFs were conducted, which revealed important adsorption and retaining capacity of the SOFs for the carboxylates. Absorption spectroscopy was also utilized to evaluate the lactonization kinetics of the three carboxylates in weakly acidic saline solution. The result reveals that at pH=6.5, the half lives of the conversion are 120, 22 and 31 h, respectively, which are considerably shorter than the time gap for repeated administrations of clinically used irinotican (14 d) or topotecan (21 d), which provides the experimental basis for further study.

A novel fluorescent sensor L based on 8-hydroxyquinoline (8-HQ) has been designed and synthesized. The sensor L displayed excellent sensitivity specific toward Cd²⁺ and pyrophosphate anion (PPi), respectively. The fluorescence emission peak at 537 nm was quenched when Cd²⁺ was added to the DMSO/H₂O (V/V=1/1, 0.01 mol/L, Hepes-HCl buffer, pH=7.20) solution of sensor L and the detection limit was as low as 5.87×10^-8 mol/L. The 1:1 stoichiometry was verified by Job's plot and mass spectrum, and the association constant was obtained to be 4.37×10⁴ L/mol. The further study found that the L-Cd²⁺ system has high selectivity for detection of PPi by ligand replacement method and L could be used as a logic gate fluorescence sensor. In addition, the sensor L was employed for imaging the Cd²⁺ and PPi in living cells.

The multifunctional fluorescent probes can detect a plurality of anions and cations or other small molecules. These probes can greatly improve the detection efficiency and reduce the analysis cost with respect to the mono-analyte fluorescent probes. Thus, they have attracted much attention in recent years. According to their molecular structural characteristics, the reported multifunctional fluorescent probes are divided into three types as organic small molecules, polymers and metal-organic complexes. The new progress on their molecular design, synthesis and detecting application is reviewed on the viewpoint of sensing objects and performances. The developing potential of multifunctional fluorescent probes is envisioned also, and the probes capable of simultaneously identifying multiple analytes in the same system should be highlighted in the future

A new diarylethene 1-(3,5-dimethylisoxazole-4-yl)-2-(2-methyl-5-[(3-aminonaphthol-2-yl)phenol-yl]-thiophene-3-yl)perfluorocyclopentene (1O) dual-response chemosensor has been synthesized, and its photochromic and fluorescent switch behaviors were systematically investigated by stimulation of lights and ions. The results indicated that 1O could serve as a CN^-/F^- "naked-eyes" colorimetric sensor with the color change from colorless to yellow, and act as a "Turn-on" fluorescence probe for specific detecting Zn²⁺. Moreover, the limits of detection of CN^- and Zn²⁺ were determined to be 1.03×10^-6 and 2.98×10^-8 mol•L^-1, respectively.

Small molecules (biological small molecules) in vivo are not only in a large number, involving inorganic small molecules, such as SO₂, H₂S, NO and CO, and more organic small molecules, such as monosaccharides, oligosaccharides, hormones, coenzymes, glycerol, stimulating factors, regulatory factors, Vitamins, etc., moreover, play an important role in pathology, physiology, and so on. Therefore, it is necessary to observe and monitor small molecules in vivo in real time, and the two-photon fluorescence probe is a necessary tool to achieve this goal. The advantages of two-photon fluorescence probe, such as fixed target (very small dot) excitation, high horizontal and vertical resolution, no photobleaching, no phototoxicity and deep imaging in tissues, and so on, demonstrate its unparalleled superiority. It can be used for dynamic 3D observation and monitoring of biological small molecules in cells or tissues. In this paper, CO, monosaccharide (glucose, β-galactosidase), SO₂, H₂S, NO, peroxy (sulfur) compounds, mercaptan/thiophenol, ¹O₂, formaldehyde, HNO, HclO, O₂^·- and ONOO^- two-photon fluorescence probes which have been developed in recent 5 years were reviewed. The sensing mechanisms of these two-photon fluorescence probes were systematically analyzed, and the development and prospect of two-photon fluorescence probes for small biomolecules are prospected.

Three azobenzenes 4~6 conjugated with 4,4'-dimethoxy-triphenylamine redox center have been synthesized by palladium-catalyzed Sonogashira coupling reactions in moderate yield after column chromatographic purification. They are all stable when exposed in air and moisture in both the solid and solution state. The ¹H NMR spectra of 4~6 showned that the azobenzene groups are in the trans configuration. The UV/Vis spectra of the target molecule were studied. The UV/Vis absorption bands of 4~6 are less clearly separated, which is similar to those for aminoazobenzen or pseudostilbene. The absorption bands at the π→π^* band of 4 and 6 are redshifted, due to the strong electronic interaction between the azobenzene unit and the para-triphenylamine unit, which results in the formation of a longer conjugation system than the corresponding meta isomers. Electrochemical and spectroelectrochemical studies indicate excellent redox reversibility of these compounds. Significant spectra change upon the process of redox makes these compounds have potential applications of electrochemical switching. Among the derivatives, compound 4 exhibits the highest cis form (45%) in the photostationary state (PSS) upon light irradiation at 435 nm. The photoisomerization studies indicate that the photochemistry properties is strongly influenced by the substituted position of the triphenylamine moiety. Photoisomerization studies showed that these compounds have fast photoisomerization rate due to the higher photoisomerization quantum yield, which is an order of magnitude larger than that of ferrocenyl (ethynyl) azobenzenes. Both compounds 4 and 6 exhibit excellent fatigue resistance and reversibility under several repeated reversible isomerization cycles. The cis-to-trans photoisomerization of 4 can be not only achieved by irradiation at UV lignt, but also realized by a more efficient way of change the state of redox center. Our study will provide a good basis for research in design new type of multiple-response molecular switches.

A near-infrared fluorescence probe CS-Cys was synthesized using rhodamine analoguse as near-infrared fluorescent group. The probe can specifically response to Cys, not to other sulfhydryl amino acids. The response mechanism is that Cys reacts with the acrylic ester of CS-Cys and the conjugated addition-cyclization reaction occurs, then the hydroxyl groups are exposed and fluorescence is released. Through studying the fluorescence changes of CS-Cys and Cys in different pH environments, it was found that the donor ability of the electron-donor group and the process of the ICT could be monitored by changing the pH of probe solution, and the fluorescence excitation wavelength and the emission wavelength could be adjusted to the near infrared region.

Tumor is one of the diseases with the highest mortality rate in the world. In view of the high risk and high mortality of tumor, researchers around the world are committed to develop more accurate and rapid diagnostic strategies and more effective treatments to fight tumor. Gradually, integrated optical diagnosis and treatment technologies for tumors have emerged. Fluoroboron fluorescein (BODIPY) has been widely used in tumor phototherapy because of its excellent optical properties. In this paper, BODIPY and its derivatives are introduced in detail as photosensitizers, photothermal transformants, and contrast agents in the diagnosis and treatment of tumors (photodynamic therapy, photothermal therapy, photoacoustic imaging) and integration of diagnosis and treatment. The effects of different BODIPY structures and their derivatives in tumor diagnosis and treatment were evaluated systematically. This is of great significance for the rational design of near-infrared BODIPY materials with high singlet oxygen quantum yield, high photothermal conversion, and good light stability and solubility.

Cyanide ion has strong toxicity for mammals, because it can affect many normal function of body, such as blood vessels, visual, as well as central nervous system, heart, endocrine and metabolic system. In addition, the cyanide salts are widely used in the production of human life, especially in electroplating and plastic manufacturing, mining, gold and silver leather industry, metallurgy, etc., which resulting in the pollution of environment. Therefore, the artificial cyanide selective receptor or fluorescent sensor has attracted widely attention in the field of anionic recognition. Due to the advantages of simple synthesis method, low cost, fast response, colorimetry and/or fluorescence change before and after reaction with cyanide, chemical sensors have been deeply studied by many researchers in the past decades. Based on the reaction of cyanide ions in different media, the research progress of cyanide sensors is summarized since 2010 from four aspects:(1) identification of cyanide in pure organic phase, (2) identification of cyanide ions in aqueous media, (3) identification of cyanide ions in pure water phase, and (4) identification of cyanide ions in solid phase. These sensors for cyanide in solution and solid material test and detect cyanide by naked eyes, which realizes the convenient, fast and real-time detection of cyanide in environmental and food samples.

Cyclodextrin is a kind of cyclic oligosaccharide which is composed of the D-pyran glucose units connected with the α-1,4-glycosidic bond. Cyclodextrin has the rigidly tapered cavity of hydrophobic inner and hydrophilic outer. Cyclodextrin has been attracted more and more attention from scientists since it was discovered, owning to its special space cavity of hydrophilic inner and hydrophilic outer. As an important industrial catalyst, transition metal catalyst can combine with the cyclodextrin system to simultaneously exert the catalytic properties of the metal and the molecular recognition and phase transfer of cyclodextrin, which greatly improves its catalytic performance. In this paper, the transition metal catalyzed organic reactions involving cyclodextrin are reviewed, and these reactions are described in terms of the metal valence from 0 to 4. Finally, the development and foreground of these co-catalyst systems involving metal and cyclodextrin are prospected. It is expected that the catalytic system will have a wider application in the future, and a more efficient and selective catalytic system will be continuously developed.

Hydrazine (N₂H₄) is a highly toxic biochemical reagent with the capability of mutagenic, teratogenic and carcinogenic. For accurately monitoring the concentration of N₂H₄ in the environment and life, two FRET (fluorescence resonance energy transfer)-based dual-emissive ratiometric fluorescent probes (FRET-1/2) were designed and synthesized. The structures of both probes were charactered by ¹H NMR, ¹³C NMR and HRMS. The results prove that both probes exhibit good selectivity and sensitivity to N₂H₄ and can be used for detecting N₂H₄ in water samples.

Sulfhydryl compounds, such as cysteine (Cys), homocysteine (Hcy), glutathione (GSH) and so on, play an important role in the normal human physiological processes. Molecular fluorescent probes have attracted much attention of scholar in the detection of sulfhydryl compounds, since it has the advantage of good selectivity, high sensitivity, good biocompatibility and real-time in situ monitoring. At present, the design of thiol-based fluorescent probes is mainly based on the strong nucleophilicity of sulfhydryl groups. In this paper, the synthesis of fluorescent probes for detecting sulfhydryl compounds, which was reported from 2013 to 2018, is reviewed based on the different mechanism of the reaction between fluorescence probe and sulfhydryl, including Michael addition, cyclization of aldehyde groups, sulfonamides or sulfonates of the lysis, natural chemical linkage and so on. The detection limit of the probe, response time, equivalence ratio were elaborated.

Endoplasmic reticulum (ER) is an important organelle in eukaryotic cells and participates in the synthesis and secretion of various proteins, glycogen, lipids, and cholesterol substances. It is surrounded by a single membrane in the cytoplasm, which is a three-dimensional mesh structure formed by flat cysts, membrane tubes, and bubbles. Research on the physiological morphology of ER can facilitate the resolution of certain metabolic diseases. Due to the good optical properties and outstanding specific localization, fluorescent probe technology has been widely used in structural investigation and activity tracking of organelles. The ER fluorescent probes can be divided into two types, one is a single functional ER localization probe, the other is a multi-functional ER probe, which has multiple functions of locating and detecting active species in ER, the morphology and environment of ER. In this article, the structure, function and biological application of ER fluorescent probes in recent years are summarized and reviewed. Various localization mechanisms of ER fluorescent probes are described. The development trend of ER fluorescent probes in life science research is prospected.

This review summarizes studies on halogen bonding of fluorine-containing alkyl and aryl iodides in China. From 1987 to 1993, Chen et al. found that there existed donor-acceptor interaction between fluorinated organic (di)iodides, as Lewis acids, and organic Lewis bases such as amines and ethers, which represented early important advances for the research on the non-covalent force currently called as halogen bonding. From 2001 to now, several groups have used halogen bonding as driving force to conduct researches on crystal engineering. In this catogery, Zhu et al. investigated the one-dimensional self-assembly between perfluoro-α,?-diioodalkanes and amines, ethers, and hexamethylphosphamide. Jin et al. studied the complexation between fluorinated aryl iodides and various N-heterocycles, whereas Zhang and Li et al. constructed supramolecular double and quadruple helices from one or two molecular components. Jin et al. conducted extensive studies on C—I…p halogen bonding and its applications in crystal engineering. Wang and Wan et al. utilized halogen bonding to induce trianglular aromatic molecules to co-assemble into two-dimensional honeycomb arrays on surface, whereas Wang et al. utilized halogen bond to induce mono-layer and layer-by-layer self-assembly of two polymers or organic molecules. Zhao and Li et al. developed the applications of halogen bonding in solution-phase multi-site molecular recognition of foldamer receptors for ICF₂-incorporated tri-armed guests. Hu, Gong, Liao et al. utilized halogen bonding to improve the material properties of a variety of organic aromatic molecules. Several groups have also used halogen bonding to increase the selectivity of a number of organic reactions. Representative examples are described, which highlight the utility of halogen bonding.

A novel benzimidazole-hydrazone derivative,N'-(2-hydroxy-1-naphthyl)methylene-2-[2-(4-methylphenylsulfonyl-methyl)-1H-benzoimidazol-1-yl]acetohydrazide (L), was synthesized and characterized by IR, ¹H NMR, ¹³C NMR, HRMS and elemental analysis. The recognition properties of L for anions were studied by naked eye, ultraviolet-vis and fluorescence spectroscopy. The results showed that the color of the solution changes from colorless to bright yellow upon addition of F^-, AcO^- and H₂PO₄^- to the CH₃CN solution of compound L. The solution of L emitted yellow fluorescence after the addition of F^- and AcO^- under the UV lamp (λ=365 nm). It indicated that compound L can be used as a probe for the naked eye to recognize F^-, AcO^- and H₂PO₄^-. The experimental results of UV and fluorescence spectroscopy showed that the probe L can recognize F^- and AcO^- with high selectivity and sensitivity. The binding constants (K_a) of probe L to F^- and AcO^- were 4.25×10³ and 2.96×10⁴ L·mol^-1, respectively. The detection limits (DL) were 3.63×10^-7 and 8.51×10^-8 mol·L^-1, respectively. The stoichiometry of complexation between L and F^-/AcO^- was 1:1, which was supported by the Job's plot and density functional theory (DFT) calculations. The mechanism of binding of L with F^-/AcO^- was established by ¹H NMR titration. The results showed that compound L can be used as a colorimetric and fluorescent probe for detecting F^- and AcO^-.

Fluorescence detection based on excited state intramolecular proton transfer (ESIPT) using reaction-based probes has attracted considerable attention in the scientific community as they offers promising advantages, including high selectivity, high sensitivity and large Stoke shift. The representative examples of design strategies, mechanism of actions, existing challenges and future developments for reaction-based ESIPT fluorophores reported in the last ten years are reviewed.

Trivalent chromium (Cr³⁺) plays an important role in the metabolismof fats, nucleic acids, carbohydrates and proteins. Moreover, Cr³⁺ is considered to be a carcinogen and is extremely harmful to humans. Therefore, Cr³⁺ fluorescent probe L was synthesized by reaction of 8-hydroxyquinolinaldehyde with thiocarbazone. The probe L showed high selectivity towards Cr³⁺ ion through the color of solution changed from colorless to yellow for naked-eye detection and significant fluorescence intensity enhanced in CH₃CN/H₂O (V:V=1:2, Tris buffer 50 mmol/L, pH=7.3) solution. The 1:1 binding stoichiometry between probe and Cr³⁺ was determined from Job's plot, fluorescence titration, ESI-MS and density functional theory (DFT) calculations. The association constant (K_a) and the detection limit for Cr³⁺ were found to be to be 1.00×10⁵ and 2.85×10^-7 mol/L, respectively. Moreover, bioimaging experiments showed that L could sense Cr³⁺ ion in living cells with a fluorescence enhancement signal.

Owing to the unique macrocyclic-cavity structure of crown ether and the capability of complexing with guest molecules, our group successfully designed and synthesized a novel Sailboat-Shaped self-complex by using intramolecular hydrogen bonds, which are able to switch its configuration during the different pH value. Furthermore, a novel catenane which based on the sailboat-shaped self-complex was obtained by using intermolecular charge transfer interaction and through the template-directed method, and its structure was identified by ¹H NMR, ¹³C NMR, HRMS and ¹H-¹H NOESY. It is hoped that it can be successfully controlled by the pH value conversion.

A pharmaceutical intermediate, 3-pyridyl benzoxazole derivatives (DIHY), was designed and synthesized as the guest molecule. The self-assembly binding models of tetramethyl cucurbit[6] uril (TMeQ[6]), cucurbit[7] uril (Q[7]) and cucurbit[8] uril (Q[8]) with DIHY were investigated by ¹H NMR, MS, isothermal titration calorimetry and UV-Vis spectrum. The results showed that there are different modes of interaction between these three different cucurbit[n] uril and DIHY. For the TMeQ[6]-DIHY system, the guest molecule is located at the port of the TMeQ[6], while for the Q[7]-DIHY system, the 4,5-dihydro-2H-benzoxazole moiety of the guest molecule reside within the cavity of Q[7] host, whereas the pyridyl group of DIHY guest remains outside of the portal to form the 1:1 inclusion complexes of pseudorotaxane structure. Nevertheless, the 4,5-dihydro-2H-benzoxazole moiety of two guest molecule is included in the cavity of Q[8] host in a "face to face" stacking way, while the pyridine group of DIHY is located at the port of Q[8] to form a 1:2 supramolecular structure.

Aminoclay (AC), as a kind of layered silicates with positive charges, shows high dispersity in water and has been widely applied in the fabrication of intelligent hybrid hydrogel. Herein, heptakis-[6-deoxy-6-(2-sulfanylethanesulfonic acid)]-β-cyclodextrin (SCD), a kind of negatively charged cyclodextrin, was employed to construct the supramolecular hydrogel with aminoclay through the static electronic interactions, and the resultant SCD-AC hydrogel was fully characterized by means of X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), fourier transform infrared spectroscopy (FT-IR), zeta potential, rheological test, etc. Significantly, the SCD-AC hydrogel can efficiently absorb not only I₃^- ion in aqueous solution but also I₂ molecule in organic solvent, giving a high adsorption capacity up to 90% with 10 min.

Aerogel is a kind of gel materials, of which the fluid phase is gas. Aerogel has the characteristics of low density and high porosity, and has a wide application prospects. In this work, a rapid solvents exchange method was developed, and using in-situ secondary extraction, rapid solvents exchange in aerogel preparation was achieved through the miscibility and immiscibility of ethanol-dichloromethane-water. Combined with hydrophobic treatment and vacuum drying, hydrophobic silica aerogel was obtained. The aerogel had a low density and a contact angle with water of 155.8°. The aerogel can load various organic fluorescent probe dyes, which can effectively avoid the fluorescence quenching caused by the aggregation of the probe molecules, which it will expand the practical application range of the organic fluorescent probes in wider fields.