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In the past two decades, transition-metal-catalyzed keto carbonyl-directed C—H bond activation has evloved as a powerful and convenient tool for the construction of C—C and C—X (X=N, F, O) bonds at the unconventional reaction sites of ketones. Among them, keto carbonyl-directed C—H bond activation reactions catalyzed by noble metals, involving ruthenium, rhodium, palladium and iridium, have been widely explored, whilst inexpensive 3d metals, such as manganese, iron and cobalt, have gradually emerged as hotspot catalysts in keto carbonyl-directed C—H activation reactions recently. In this review, advances on transition-metal-catalyzed keto carbonyl-directed C—H bond functionalization reactions from 2014 to 2021 are summarized, which are devided by reaction categories such as alkylation, alkenylation, amidation, arylation, cyclization, and so on.
Sulfonyl compounds are important organic sulfur compounds, which are widely used in the fields of medicine, pesticides, functional materials and so on. Therefore, efficient strategies for the synthesis of sulfonyl compounds have become the focus of extensive research. Organic electrochemical synthesis is a green, mild and efficient synthesis strategy, which shows great potential in the synthesis of sulfonyl compounds. The reactions of electrochemical synthesis of C-sulfonyl compounds in recent years are introduced. The reactions of electrochemical synthesis of C(sp)-sulfonyl compounds, C(sp2)-sulfonyl compounds and C(sp3)-sulfonyl compounds are classified, summarized and discussed, and the corresponding reaction mechanism is described, so as to provide reference for the application of such reactions in organic synthesis in the future.
The trifluoromethylselenylation reaction is another important research topic after trifluoromethylsulfanylation reaction in recent years. Because the trifluoromethylselenyl group contains two important chemical elements, fluorine and selenium, and the compounds containing trifluoromethyl selenide have important potential biological activities, more and more researchers begin to turn their attention to this new group in recent years. In this paper, according to the three reaction types of nucleophilic trifluoromethylselenylation reaction, electrophilic trifluoromethylselenylation reaction and radical trifluoromethylselenylation reaction, the research results of domestic and foreign scholars on direct trifluoromethylselenylation reaction in recent 6 years are comprehensively summarized, and some reaction mechanisms are discussed in detail. Finally, the direct trifluoromethylselenylation reaction is summarized and prospected.
2H-Pyrrol-2-ones as an important class of γ-lactam compounds, widely exist in the structure of natural products, drugs and biologically active molecules, and they are also the important synthetic intermediates in drug development and organic synthesis. In recent years, the synthesis methods and strategies based on 2H-pyrrol-2-ones skeleton including 1,5-dihydro-2H-pyrrol-2-ones have made great progress. In this paper, the different synthetic methods and strategies for the construction of 2H-pyrrol-2-one skeletons are summarized.
N-Ts cyanamide, which has been widely used in the construction of nitrogen-containing framework, is one of the efficient and practical multifunctional synthetic precursors in organic synthesis. The progress in application of N-Ts cyanamide according to the reaction types is summarized, including the application in cyanation, cyclization reaction via cyanamide anion, cyanamidation, sulfonylation and cyclization reaction via cyano-group. The future development direction of this field is also prospected.
1,3-Dichloro-7-hydroxy-9,9-dimethyl-2(9H)-acridone (DDAO) is an excellent near-infrared fluorescent dye with near-infrared emission, low pKa (≈5.0), high water solubility and high quantum yield (Φ=0.39), which has attracted much attention in recent years in the field of fluorescent probes. The researches prove that the fluorescent probes designed and synthesized based on this dye can work in mild aqueous solutions, and have excellent sensing performance, such as rapid reaction, high selectivity and sensitivity, low detection limit and obvious colorimetric signal change. In addition, the low cytotoxicity of this class of probes is of significant application for the detection of living cells and organisms. The research progress of fluorescent probes based on DDAO and its derivatives, mainly including the molecular design, action mechanism and application of probes in the recognition and detection of biological enzymes, reactive oxygen species, reactive nitrogen species, proteins and Pd0, is reviewed, and the development prospect of this type of fluorescent probes is prospected.
With the national plastic reduction order issued, the development of biodegradable materials such as poly(lactic acid) (PLA) has gradually become a hot topic. The different methods for synthesizing polylactic acid are discussed. Since the ring-opening polymerization of lactide has become the major method for preparing PLA, we focused on the catalyst design for the process, and clarified the related mechanisms. This short review may point out the direction for the design and development of low-toxicity and high-selectivity catalyst systems for application.
Porous organic molecular cage (POC) is a kind of discrete molecule with specific sized cavities. Due to stable pore structure, high specific surface area, and good solubility, POC is emerging as a promising multi-functional material by accepting specific-sized molecules or ions within the cavity. In addition, derived from the stable and open pores, POCs can be utilized to a variety of applications, such as gas separation and storage, sensors, drug delivery, and so on, which is becoming a research hotspot at home and abroad. At present, given to the strong binding sites with metal nanoparticles (MNPs) and spatial confinement effect within the cage, POCs provide a new and stable way to protect metal nanoparticles from aggregation. Therefore, POCs are often used to prepare the metal nanoparticles of specific size, forming the metal-porous organic cage nanocomposites. The advantage of POCs in the metal-POCs nanocomposite is not only to regulate the size of metal nanoparticles but also to stabilize the micro/nanostructures without affecting the surface accessibility of active atoms within cages. Compared with traditional method to stabilize catalytic nanoparticles, MNPs-POCs composite has better stability and more active catalytic centers. The recent research achievements in MNPs-POCs nanocomposites and their important applications are summarized in this review, which is expected to inspire the further application in catalysis, sensors, medicine, etc.
Nine-membered N-heterocycle scaffolds are widely found in natural products and biologically active molecules. The rigid structure of the medium-sized ring plays important roles in the regulation of their biological and pharmacological activities. Therefore, nine-membered N-heterocycle is one of the most attractive medium-sized ring compounds. Because of the increasing entropy and ring extension of nine-membered ring skeleton, the synthesis of nine-membered N-heterocycles is still difficult; especially the effective control of substituent stereoselectivity for the nine-membered ring is one of the greatest challenging topics This review summarizes the novel synthetic strategies of nine-membered N-heterocycles and their applications in the synthesis of natural products and pharmaceutically active molecules containing nine-membered ring scaffold in recent years.
The intrinsic directing group is a functional group in the substrates and also serves as an essential component in products. Thus, the preinstallation and removal of directing groups are avoided. 7-Azaindole has been used as intrinsic directing group for the N-aryl-C—H functionalization of N-aryls under the catalysis of transition metals. Utilizing the C—H functionalization strategy, numerous functional groups were installed into the ortho-position of N-aryls of the corresponding N-aryl-7-azaindoles. In this review, the recent achievements on the transition-metal catalyzed N-aryl ortho-C—H functionalization directed by 7-azaindole are summarized.
Among the tiniest Daphniphyllum alkaloid subfamilies, daphnezomine A-type alkaloids consist of only three known members, namely daphnezomine A (1), daphnezomine B (2) and dapholdhamine B. These alkaloids contain a unique aza-adamantane core along with nine contiguous stereogenic centers, thus presenting remarkable synthetic challenges. The synthesis of tetracyclic core structure of 1 and 2 was reported. The key steps in our approach include a Huang’s amide-activa tion-annulation and a Hutchins-Kabalka reductive rearrangement.
Biothiols, such as cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) play crucial roles in physiological and pathological processes. GSH, especially, is overexpressed in numerous types of tumor cells and could be considered as a biomarker. However, owing to the difficulty and challenge in sensing normal and cancer cells simultaneously, it is important to solve this problem in biological processes. Herein, a naked-eye visible, “off-on” long-wavelength fluorescent probe (4) based on N,N-(dimethylamino)naphthalenyl flavone (3) was designed and synthesized. This probe showed high selectivity for biothiols and low detection limits. The mechanism study revealed that biothiols catalyzed the cleavage of the ester bond, and strongly fluorescent flavone 3 was released. Probe 4 could be used for the imaging of biothiols in living cells and mice. In addition, the probe was optimized to achieve the selective imaging of normal hepatocyte HL-7702 and heptocarcinoma cell HepG2.
A direct electrochemical sulfonylation of C(sp3)—H bonds of xanthenes with sodium sulfinates was studied. A wide variety of 9-(arylsulfonyl)-9H-xanthenes and 9-(alkylsulfonyl)-9H-xanthenes were constructed in a single step at room temperature. This reaction proceeded through a radical pathway and a new C—S bond was formed under this electrochemical sulfonylation transformation. The significant advantages of this strategy include transition metal- and additional oxidant-free, mild reaction conditions, operational simplicity, broad substrate scope and excellent functional group tolerance.
An I2-catalyzed cyclization reaction of 1H-pyrazol-5-amine and β-ketonitrile for the synthesis of pyrazolo[1,5- a]pyrimidines was developed. This method provides an efficient way to obtain structurally diverse pyrazolo[1,5-a]pyrimidine derivatives in good to excellent yields. The method has the advantages of simple operation, mild reaction conditions and a wide range of substrates. It can also be scaled up.
In recent years, the widespread use of neonicotinoid insecticides caused the resistance of pests to gradually become stronger, especially more and more attention on the toxic effect on bees. Therefore, it is urgent to design and synthesize novel eco-friendly alternatives to neonicotinoid insecticides. In our previous study, a novel furan α-butenolactone skeleton was found to have aphicidal activity based on the structrue similariy searching strategy to the butenolide pharmacophore from the low-bee toxicity commercial insecticide flupyradifurone. In this work, a series of novel furan α-butenolactone compounds were designed and synthesized combined the characteristics of nicotinic acetylcholine receptor protein and empirical design method. The bioassay results at the concentration of 500 μg/mL showed that all target compounds exhibited some aphicidal activity against soybean aphid and peach aphid. Especially, (E)-3-((5-(3-chlorophenyl)furan-2-yl)methylene)-5-methylfuran-2(3H)- one (7bh) and (E)-3-((5-ethylfuran-2-yl)methylene)-5-(p-tolyl)furan-2(3H)-one (7ch) were found to be more than 70% with a mortality rate against not only soybean aphid but also peach aphid. Furthermore, the insecticidal activities of 7bh were the same order of magnitude with pymetrozine against soybean aphid (LC50=70.83 μg/mL) and green peach aphid (LC50=71.96 μg/mL). To our surprised, these target compounds also showed certain antifungal activity in vitro against Rhizoctonia solani at the concentration of 50 μg/mL. Molecular docking studies indicated that the furan α-butenolactone compounds displayed moderate aphicidal activity due to their similar interaction with flupyradifurone toward nicotinic acetylcholine receptor. The study on new furan α-butenolactone compounds will lay a foundation for the development of new aphicidal candidates with high efficiency and low bee-toxicity in the future.
A series of 3-hydrazone quinazolinone derivatives were synthesized via introducing hydrazone structure into quinazolinone 3-position by active splicing principle. Their structures were confirmed by nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR) and high resolution mass spectrometry (HRMS). The results of antitumor activity test showed that these compounds have effective inhibitory activity on A549, PC-3, HepG2 and K562 tumor cell lines. The IC50 value of (E)-N-((2-chloro-1-methyl-1H-indol-3-yl)methylene)-2-(7-fluoro-4-oxoquinazolin-3(4H)-yl)acetohydrazide (H1) on HepG2 was (9.90±1.13) μmol/L and (E)-2-(7-fluoro-4-oxoquinazolin-3(4H)-yl)-N-((2-morpholino-1-propyl-1H-indol-3-yl)methyl- ene)acetohydrazide (H2) on PC-3 was (10.70±0.78) μmol/L. The inhibitory activities were better than those of positive control drug gefitinib [IC50=(23.33±4.14) μmol/L, IC50=(12.02±5.39) μmol/L]. In order to explore the anti-tumor mechanism of these compounds, a series of cell biological experiments were set out on PC-3 cells with compound H2. The apoptosis and 4',6-diamidino-2-phenylindole (DAPI) staining experiments showed that the compound H2 could induce apoptosis in PC-3 cells, and the cell cycle experiment further demonstrated that the compound H2 arrested PC-3 cells in G0/G1 phase.
Indeno fluorene-6,12-dione derivatives 5 modified by different alkyl substitutions were designed and synthesized from 2,5-dibromo-p-xylene and phenylboronic acid derivatives through oxidation, esterification, Suzuki coupling, saponi- fication and cyclization reactions. Alkyl chains of different lengths were introduced into molecules to improve the solubility of the compounds and investigate the effects of systematic substitution variation on their properties. It was found that the solubility, thermal and optical stability of the new compounds were better than those of pentacene. Compounds 5 have increased electronegativities because of the low lowest unoccupied molecular orbital (LUMO) energies (≤–3.4 eV). 2,8- Diisopropylindeno[1,2-b]fluorene-6,12-dione (5b) and 2,8-dibutylindeno[1,2-b]fluorene-6,12-dione (5c) have rigid molecular frameworks and pack into slipped face-to-face π-stacks, the layer spacings are 0.3457 and 0.3423 nm, respectively. The molecular packing could facilitate carrier transport. The properties of these new materials indicate that they are good candidates for applications in organic optoelectronics.
Abstract In order to develop novel pyrimidine fungicides, thirteen 2-(1-methyl-1H-pyrazol-4-yl) pyrimidine-4-carboxami- des were synthesized from 2-chloropyrimidine-4-carboxylic acid, 1-methyl-4-pyrazole borate pinacol ester, substituted anilines or substituted benzylamines as starting materials. The structures of target compounds were characterized by 1H NMR, 13C NMR, IR, HRMS, and the crystal structure of N-benzyl-2-(1-methyl-1H-pyrazol-4-yl)pyrimidine-4-carboxamide (4h) was also determined by X-ray diffraction method. The preliminary fungicidal activities against three plant fungi were evaluated, and the results showed that at a dosage of 100 mg/L, N-(4-methyl)phenyl-2-(1-methyl-1H-pyrazol-4-yl)pyrimidine-4-carboxamide (4f) and N-(4-chlorobenzyl)-2-(1-methyl-1H-pyrazol-4-yl)pyrimidine-4-carboxamide (4j) possessed relatively high activities against Rhizoctonia solani with inhibitory rates of 85.3% and 79.1%, respectively. Molecular docking study showed that 4f can form two hydrogen bonds and one cation-π interaction with succinate dehydrogenase.
Using the oxidation between 2-iodoylbenzoic acid (IBX) and tetrabutylammonium bromide (TBAB), thiophenols and thiols reacted rapidly to form corresponding thiosulfonates at room temperature, and 11 thiosulfonates were obtained with yields ranging from 54% to 83%. It was also found that the catalytic system in the presence of aqueous HCl (w=36%) and HBr (w=46%) oxidatively halogenated thiophenols and thiols, respectively, 11 kinds of sulfonyl chlorides and 11 kinds of sulfonyl bromides were obtained with yields ranging from 62% to 84%. The method has the advantages of simple and efficient, simple post-treatment, green oxidant and solvent, mild conditions, etc. All products were confirmed by 1H NMR, 13C NMR structure.
A series of temperature-responsive polymers (poly N-isopropylacrylamide-co-N,N-dimethylacrylamide, PNxDy) were prepared by using N-isopropylacrylamide (NIPAAm) and N,N-dimethylacrylamide (DMAM) as reaction monomers, azobisisobutyronitrile as chain initiator, and mercaptoethylamine hydrochlorides as chain transfer agents. Then, a novel thermoresponsive surfactant-type chiral salen MnIII catalyst PNxDyMn was developed by axially grafting “smart” polymer (PNxDy) onto the metal center of a neat chiral salen MnIII complex. The temperature-sensitivity, structure and morphology of the polymers were studied through a series of characterizations, and it was found that these temperature-responsive chiral polymers can efficiently catalyze the asymmetric epoxidation of olefins in pure water. Only 0.5 mol% PN75D5Mn was sufficient to exhibit extremely high activity (conversion>99%) with up to 76% enantioselectivity and turnover frequency (TOF) (396/h) for a substrate of indene in water. The conversion rate of the substrate styrene was as high as 99% in 5 min, and the TOF value reached 2376/h. Characterization and experiments proved that PNxDyMn can self-assemble into nanoreactors for the asymmetric epoxidation of olefin in water, leading to an acceleration of reaction and causing selective effects. After reaction, the PNxDyMn exhibited hydrophobic properties upon heating above its lower critical solution temperature (LCST), and precipitated from the aqueous system for recovery. It can be recycled and reused for seven times without significant loss of activity, and no organic solvents were required for the reaction and separation process.
Visible light-mediated 1,5-hydrogen atom transfer and radical coupling reactions have been accomplished using N-fluoro-substituted benzamides. This method exhibits a broad substrate scope and high functional group tolerance, giving the corresponding bibenzyl products with generally good yields. Furthermore, this strategy could also be used to N-fluoro-substi- tuted aliphatic amides.
Synthesis of urea compounds is highly significant for pharmaceutical chemistry, agricultural chemistry, matterials science and organic synthesis. By ultilizing ligands to switch the chemoselectivity, two transformations of vinyl cyclic carbamates and isocyanates were developed to afford linear and cyclic ureas in a controlled manner. When phosphoramidite was used as the monodentate P-ligand, a wide range of (E)-1,3-diene-substituted linear ureas were produced in high yields and selectivity (21 examples, 51%~95% yields). While, using bidentate biphosphine ligand to replace the phosphoramidite ligand, a variety of highly functionalized vinyl-substitued cyclic ureas, tetrahydro-2-pyrimidinones, were delivered instead starting from the same chemical feedstocks (8 examples, 72%~94% yields). To illusrate the switched chemoselectivity, two possible reaction mechanisms were proposed based on the experiment results and proceeding literatures. The keys of these two reactions, dienylation and annulation, are the β-hydride elimination and the N-allylic alkylation of ally-Pd species, respectively. It is supposed that the basicity of the ligand will affect the reactivity of π-ally-Pd intermediates toward electrophilic ring closing. It is believed that this research not only enriches the application of vinyl carbamate reagents in organic synthesis, but also provides a new protocol to access significant nitrogen-containing molecules.
To discover new antibacterial agents, twenty-three 1,3,4-oxadiazolsulfone compounds containing a sulfonamide structure were designed and synthesized by active substructure splicing, and their antibacterial activities were tested. Most of the compounds exhibited excellent in vitro antibacterial activity against Xanthomonas oryzae pv. oryzicola (Xoc) and Xanthomonas oryzae pv. oryzae (Xoo) at a concentration of 100 µg/mL. Except for N-((5-(propylsulfonyl)-1,3,4-oxadiazo- 2-yl)methyl)-4-(trifluoromethyl)benzenesulfonamide (18), the median effective concentration (EC50) values of other compounds against Xoc were 1.3~22.5 µg/mL, and the EC50 of all compounds against Xoo were 1.1~32.7 µg/mL, which were better than the control agents bismerthiazol (84.1 and 71.4 µg/mL) and thiodiazole copper (122.1 and 84.0 µg/mL). In addition, 4-fluoro-N-((5-(methylsulfonyl)-1,3,4-oxadiazole-2-yl)methyl)benzenesulfonamide (4) can inhibit the growth of Xoc and Xoo by inhibiting the production of exopolysaccharide (EPS) and the formation of biofilm, changing the permeability of cell membrane and cell surface morphology.
Homolytic cleavage of covalent bonds is very common during the pyrolysis of energetic molecules. However, instead of locating the transition state and calculating the free energy barrier ΔG, the bond dissociation energy (ΔH, BDE) is usually considered as the “energy barrier” of the homo-cleavage processes. This simplification brings large errors. In the present work, several pyrolysis pathways of 3-nitro-1,2,4-triazol-5-one (NTO) were studied using broken-symmetry density functional theory method (BS-UB3LYP/6-311+G**). Each transition state of homolytic cleavage was located. The results show that the best pyrolysis pathway under the experimental conditions proceeds via the homolytic cleavage of the C—NO2 bond and the subsequent radical recombination, the energy barrier of the rate-determining step is 216.9 kJ•mol–1 (523 K). Then, NO can promote the subsequent ring-opening, and finally yielding HNCO, N2O and CO. Further reactions between these small molecules lead to NO2, N2 and CO2. These products are consistent well with the experimental observations.
The fungus Eutypella sp. is well known for producing bioactive compounds with diverse structures. Chemical investigation of the fungi Eutypella sp. F0219 isolated from marine sediment, yielded a new prenylated dihydroisocoumarin and a new chromene amide derivative, named eutypellarins A and B (1 and 2), together with two known prenylated benzaldehyde derivatives (3 and 4). The structures of these compounds were elucidated based on HR-ESIMS, extensive nucler magneti resonance (NMR) experiments, and quantum-chemical electronic circular dichroism (ECD) calculations. Prenylated dihydroisocoumarin and chromene amide derivatives are reported from the genus Eutypella for the first time. The total antioxidant capacities of all compounds were measured through 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) and ferric-reducing antioxidant power (FRAP) assay. The results showed that compounds 1 and 4 exhibited moderate antioxidant properities with Trolox equivalent antioxidant capacity (TEAC) values (0.51±0.016) and (0.76±0.007), respectively.
Based on the strategy of introducing the “dihydroquinazolinone” bioactive group into 8-position of caffeine, thirteen novel caffeine derivatives containing dihydroquinazolinone moiety have been synthesized using theophylline and isatoic anhydride/5-bromoisatoic anhydride as materials, via multi-step reactions such as N-methylation, palladium-catalyzed coupling, nucleophilic addition-elimination and condensation, etc. The bioassay results showed that most of the compounds possess favourable insecticidal activity against Plutella xylostella L., among which 1,3,7-trimethyl-8-(4-(4-oxo-3-propyl-1,2,3,4- tetrahydroquinazolin-2-yl)phenyl)-3,7-dihydro-1H-purine-2,6-dione (Ia) and 8-(4-(6-bromo-3-(4-fluorobenzyl)-4-oxo-1,2,3,4- tetrahydroquinazolin-2-yl)phenyl)-1,3,7-trimethyl-3,7-dihydro-1H-purine-2,6-dione (Im) held lethality rate of 50% and 43% respectively at a test concentration of 50 mg•L–1, especially Ia still had 20% lethality rate at 10 mg•L–1. Partial compounds also showed good herbicidal activities. In particular, Ia held an growth inhibition rate of 96.6% against root of Brassica campestris L. at a test concentration of 100 mg•L–1, which was better than that of the control chlorsulfuron. In addition, partial compounds possessed >50% fungicidal activities at 50 mg•L–1 against Sclerotinia sclerotiorum, Phytophthora capsicum, Physalospora piricola, etc. The inhibitory activity of Ia against Phytophthora capsicum reached 80.6%, which greatly exceeded that of the contrast caffeine. Compounds Ia exhibited good biological activities in almost all the insecticidal, herbicidal and fungicidal bioassays, and could be considered as a novel pesticide lead compound to carry out further structural optimizations. The results of this study provide useful reference for the design of new pesticidal agents based on the structure of natural products.
In this paper, a novel triphenylamine derivative (Tdip) was synthesized. Tdip can recognize hydrogen sulfide (H2S) with turn-on fluorescence response through tandem reaction triggered by HS– to release precursor compound, which produces a strong fluorescent signal. Tdip displayed good selectivity and anti-interference ability toward H2S, a large Stokes shift (146 nm), a pH range of 8~13, and a low detection limit (2.24 μmol/L). In addition, Tdip can detect H2S in actual red wine samples and image H2S in living cells.
(–)-Colchicine and its natural analogue (–)-N-acetylcolchinol methyl ether have been synthesized in a com- paratively conciser asymmetric synthetic approach. Firstly, the carbon framework was constructed by Aldol condensation of simple aldehydes and ketones, and then the chiral amine intermediates were synthesized economically and efficiently through asymmetric reductive amination with chiral tert-butanesulfinamide. The 3-rings skeleton of colchicine and related alkaloids was then constructed by oxidation with hypervalent iodine reagent. Our strategy provides an efficient method for the convenient and economical synthesis of these alkaloids.
As an environmental pollutant, mercury ion (Hg2+) cannot be biodegraded, and will accumulate through the food chain and cause damage to human body. Therefore, it is of great significance to develop a simple and effective method for detecting Hg2+. In this paper, a novel triphenylamine derivative Tbia was synthesized by a simple two-step reaction. Tbia can react with Hg2+ specifically in hydroxyethylpiperazine ethane sulfonic acid (HEPES) solution and release the precursor compound with aggregation-induced emission (AIE) properties, which realized recognition of Hg2+ with “off-on” response. Tbia has good selectivity and sensitivity for Hg2+, a wide range of pH, and the detection limit of 63 nmol/L. In addition, Tbia can be prepared into invisible ink and is expected to be used in packaging of anti-counterfeiting. The test paper loaded with Tbia can be used for qualitative or roughly quantitative detection of Hg2+, and Tbia can detect Hg2+ in real water samples as well as image of Hg2+ in living cells.
In this paper, a novel aggregation-induced emission (AIE) effect Zn2+ fluorescent probe L was constructed with aggregation-induced emission (AIE), tetraphenylethylene as the fluorescent group and 5-tert-butyl-2-hydroxybenzene as the recognition group. The structure of probe L was characterized by NMR and ESI-MS, and its fluorescence properties was studied by UV-vis and fluorescence spectroscopy. In ethanol/phosphate (PBS) (V∶V=7∶3, pH=7.4) solution, the probe L exhibited fluorescence-enhanced high selectivity and sensitivity detection of Zn2+, the detection limit was 34.1 nmol•L–1. In the range of 0~3.0×10–5 mol•L–1, the probe showed a good linear relationship to Zn2+. The obvious color change can be observed with the naked eye under UV light and natural light, which can realize the visual detection of Zn2+. The response mechanism of the probe to Zn2+ was studied by Job’s plot, ESI-MS and density functional theory (DFT) theoretical calculation. The novel probe reported in this paper can serve as a convenient tool for the analytical determination of Zn2+.
Three new compounds, together with eight known compounds, were isolated from the mangrove-derived fungus Daldinia eschscholtzii HJ004. The structure of 8-ethyl-7-hydroxy-5-carboxyl-2,3-dimethylchromone (1) was extensively elucidated and characterized by HRESIMS, 1D and 2D NMR, and single-crystal X-ray crystallography. The absolute configurations of felinone C (2) and helicascolide G (3) were determined by using electronic circular dichroism (ECD) method or comparing circular dichroism (CD) data with the literature. The radical scavenging capabilities of the 11 compounds obtained were tested by total antioxidant capacity assay kit with a rapid ABTS method. Among them 4 compounds exhibited stronger antioxidant activity with IC50 values range from 5.57 μmol/L to 195.03 μmol/L, than the positive control trolox (IC50=292.12 μmol/L). These results indicate that chromones have the potential values of developing antioxidants.
The difunctionalization of alkenes and alkynes is a simple and powerful strategy for the synthesis of various organic compounds and has been used to synthesize various important natural products, drug molecules and fine chemical products. The different effects of halo anions, substrates, solvents, temperature and reaction time to the stereospecific and reactivities of 1,1-carboborations of alkynes and B(C6F5)s were studied, meanwhile the corresponding catalytic mechanisum has been expoled. A convenient large-scale preparation method for the stereoselective (E)-1,1-carboboration products has been developed. The catalytic reactivities of ring-opening polymerization of cyclohexene oxide (CHO) have also been explored with different stereo-carboboranes isolated from 1,1-carboboration reaction, and it is noted that the stereospecificity E- or Z- has shown ambiguously different activities. To develop a stereo-specific approach in the synthesis of vinylboranes will not only be very important for the difunctionalization of alkenes and alkynes, but also for the novel stereospecificity organoborons.
A fluorescent probe (Z)-O-(2-(benzo[d]thiazol-2-yl)-4-(2-cyano-2-(4-cyanophenyl)vinyl)-6-methylphenyl) dimeth- yl cabarmothioate (HBTY-N) based on benzothiazole derivatives was synthesized. The probe can recognize ClO– with high selectivity through fluorescence Off-On change in Tris solution (pH=7). After adding ClO– to the probe, the probe solution changed from no fluorescence to orange-red fluorescence, the Stokes shift is 235 nm, and the recognition response is fast. The detection limit of the probe HBTY-N for ClO– is 2.127×10–7 mol/L, the applicable pH range is 1~10, and it has strong anti- interference ability. Mechanistic studies show that under the action of ClO–, the probe releases the fluorophore (Z)-4-(2- (3-(benzo[d]thiazol-2-yl)-4-hydroxy-5-methylphenyl)-1-cyanovinyl)benzonitrile (HBTY) with “aggregation-induced emission (AIE)+excited-state intramolecular proton yransfer (ESIPT)” properties through the “oxidative deprotection” mechanism, and the quantum yield changes from 0 to 42.88%. In addition, the probe HBTY-N can perform fluorescence imaging of ClO– in living cells with low cytotoxicity, and can also be used for the detection of ClO– in actual water samples, which has potential application value.
The complexation between the pyromellitic diimide-extended pillar[6]aren host and carboxylate guests in solution was investigated in detail. It was found that the host could form 1∶2 complexes with carboxylate salts in solution. Interestingly, the complexation and decomplexation of the complexes between the host and the guest could be achieved by changing the pH of the solution, and the process could also be observed by naked eye.
