Reversible fluorescence sensing of Zn2+ based on pyridine-constrained bis(triazole-linked hydroxyquinoline) sensor

Zinc ion (Zn²⁺) is an important and a most useful biological trace nutrient responsible for the activity of several enzymes. Zn²⁺ concentrations in the environment as well as in the human body increase beyond permissible limits as a consequence of its mining and widespread industrial applications. Such excess Zn²⁺ concentrations are toxic to humans and many aquatic organisms. The magnetic inertness and spin paired electronic configuration of Zn²⁺ makes it hard to detect by common analytical techniques. Therefore, fluorometric detection using chemosensor is the most effective tool for the environmental and biological detection of Zn²⁺. We have developed a novel pyridine-constrained bis(triazole-linked hydroxyquinoline) ligand as a reversible fluorescent chemosensor for Zn²⁺. The symmetrical ligand is highly selective for Zn²⁺ and fluoresces brightly upon complexation compared with other metal ions based on chelation-enhanced fluorescence mechanism. Interestingly, free ligand can be regenerated by treating the ligand–Zn²⁺ complex with aqueous ammonia.     

Dodecyl thioglycopyranoside sulfates: novel sugar-based surfactants for enantiomeric separations by micellar electrokinetic capillary chromatography

Four novel chiral anionic surfactants having carbohydrate hydrophilic heads, sodium n-dodecyl 1-thio-beta-D-glucopyranoside 6-hydrogen sulfate (6-betaGlcD), sodium n-dodecyl 1-thio-beta-L-glucopyranoside 6-hydrogen sulfate (6-betaGlcL), sodium n-dodecyl 1-thio-beta-L-fucopyranoside 3-hydrogen sulfate (3-betaFucL), and sodium n-dodecyl 1-thio-alpha-L-rhamnopyranoside 3-hydrogen sulfate (3-alphaRhaL), were synthesized by selective sulfation of the corresponding thioglycosides. Their CMC determined by fluorescence using pyrene as a probe in water was 1.3-2.7 mM. These surfactants found to be useful as chiral selectors for enantiomeric separation by MEKC. The enantiomeric separation was optimized with respect to pH, buffer concentration, and surfactant concentration. Under the optimized conditions (50 mM phosphate buffer at pH 6.5, 30 mM surfactant, 20 kV), the enantiomeric separations of five dansylated amino acids (Dns-AAs) were achieved within approximately 20 min with the migration order of Val相似文献   

四种三唑化合物的合成及它们在盐酸介质中对碳钢缓蚀性能的研究

本文通过“点击化学”的方法合成了四种1,2,3-三唑化合物(3a, 3b, 4a和4b)，通过IR, ¹H NMR, ¹³C NMR 和 single crystal X-ray 晶体结构衍射分析对化合物进行了表征。通过交流阻抗和动电位扫描极化曲线研究四种化合物在1 mol/L HCl 中对碳钢的缓蚀性能。研究结果表明，四种化合物均可作为高效阳离子缓蚀剂，其中化合物4b的缓蚀效果最好，最高抑制效率可达97％。     

Unclicking the Click: Metal-Assisted Mechanochemical Cycloreversion of Triazoles Is Possible

The mechanochemical cycloreversion of 1,2,3-triazole compounds, which serve as unusually stable building blocks in materials and biomolecular chemistry as a result of mild “click chemistry”, remains puzzling. We show that the hitherto discussed straight-forward retro-click mechanism of the 1,4-disubstituted isomer, even if Cu^I catalyzed, can be ruled out in view of more favorable activation free energies of destructive pathways. In stark contrast, the 1,5-regioiomer can undergo cycloreversion under rather mild mechanochemical conditions owing to its favorable response to the external force in conjunction with standard Ru^II catalysis.     

三氮唑连接的多聚Salen-Mn催化剂的制备及其对苯乙烯环氧化的催化性能研究

采用链接化学的策略,通过带有水杨醛单体的双三氮唑化合物与二胺反应,制备了以三氮唑为连接单元的多聚Salen配体及其Mn(Ⅲ)配合物(7),并以PhIO为氧化剂,考察了7在苯乙烯环氧化反应中的催化性能。     

利用分子内Click反应合成哌嗪并三唑和哌嗪并四唑化合物

利用分子内的"点击化学"反应合成了三唑和四唑类化合物。在直接加热或金属铜粉催化下加热的条件下,不饱和炔键和氰基与叠氮基发生分子内的成环反应,以较高的收率分别生成哌嗪并三唑化合物和哌嗪并四唑化合物,其结构经NMR,IR和MS表征。     

A selective fluorescent probe of Hg2+ based on triazole-linked 8-oxyquinoline calix[4]arene by click chemistry

Calixarene compound 1 with two 8-oxyquinoline subunits was synthesised using ‘click’ chemistry. Compound 1 shows strong fluorescence quenching by Hg²⁺ and lower pH. Using the fluorescence behaviour of 1 towards Hg²⁺ and lower pH, a NOR (not an OR) logic gate was established.     

Expeditious preparation of triazole-linked glycolipids via microwave accelerated click chemistry and their electrochemical and biological assessments

A series of triazole-linked ester-type glycolipids were efficiently prepared via a two-step sequence involving microwave accelerated ‘click’ chemistry and debenzylation. All carbon chain length varied O-alkynyl fatty esters used to couple with 1-azido-tetra-O-benzyl-β-d-glucoside showed excellent tolerance to the microwave-assisted 1,3-dipolar cycloaddition (click reaction), forming the unique cycloadducts in almost quantitative yields of 92.9-99.0% within a quarter. The desired glycolipids were then readily afforded via the successive hydrogenolysis promoted by PdCl₂/H₂. Their adsorption competence on gold electrode were evaluated through EIS (electrochemical impedance spectroscopy) measurement and the resulting structure-activity relationship (SAR) was discussed. In addition, the cytotoxicity of this triazolyl glycolipid class on HeLa (cervix cancer) cell line was identified by MTT assay.     

Click Chemistry Derived Pyridazines: Electron‐Deficient Building Blocks with Defined Conformation and Packing Structure

A series of 3,6‐bis(4‐triazolyl)pyridazines equipped with terminal phenyl substituents with varying degree of fluorination were synthesized by using the facile copper‐catalyzed azide–alkyne cycloaddition and their structures were thoroughly investigated in the gas phase, in solution, and in the solid state by employing DFT calculations, NMR spectroscopy, and single‐crystal X‐ray diffraction, respectively. On the molecular level, their structure is governed by the strong preference of the triazole‐pyridazine linkages for the anti ‐conformation. The supramolecular organization of the molecules in the crystalline solid is controlled by π‐stacking, C−H⋅⋅⋅π as well as C−F⋅⋅⋅H interactions. The latter can conveniently be tuned by the number and position of fluorine substituents in the terminal phenyl units, giving rise to either herringbone‐like, 1D or 2D lamellar packing. Electrochemistry and optical spectroscopy of all compounds suggest that they might find use as electron‐transporting/hole‐blocking materials in organic electronics.     

Synthesis,Crystal Structure and Antimicrobial Activity of Ethyl 2-（1-cyclohexyl-4-phenyl-1H-1,2,3-triazol-5-yl）-2-oxoacetate

A novel 1,4,5-trisubstituted 1,2,3-triazole(C18H21N3O3) was synthesized by a one-pot three component reaction of 1-azidocyclohexane, 1-copper(I) phenylethyne and ethoxalyl chloride at room temperature. The molecular structure was determined by single-crystal X-ray analysis. The compound crystallizes in the monoclinic system, space group P21/n with a = 12.8167(9), b = 8.0966(6), c = 16.7079(9) , β = 98.716(2)o, Z = 4 and V = 1713.8(2). In the crystal, the molecules are related by inversion and paired into dimers via C–H···O and C–O···C interactions involving(oxo) acetate groups. Furthermore, X-ray analysis results are compared with the optimized structure computed by using B3 LYP method with 6-311 G basis set. The calculated results showed that optimized geometry can well reproduce the crystal structure parameters. The bioassay results indicate that the compound has good antibacterial and antifungal activities.     

Duplex‐forming Oligonucleotide of Triazole‐linked RNA

An oligonucleotide of triazole‐linked RNA (^TLRNA) was synthesized by performing consecutive copper‐catalyzed azide‐alkyne cycloaddition reactions for elongation. The reaction conditions that had been optimized for the synthesis of 3‐mer ^TLRNA were found to be inappropriate for longer oligonucleotides, and the conditions were reoptimized for the solid‐phase synthesis of an 11‐mer ^TLRNA oligonucleotide. Duplex formation of the 11‐mer ^TLRNA oligonucleotide was examined with the complementary oligonucleotide of natural RNA to reveal the effects of the 2′‐OH groups on the duplex stability.     

Synthesis of Isoxazole Conjugates of 1,4-Benzodioxane Moiety via Intermolecular 1,3-Dipolar Cycloaddition

1,3-Dipolar cycloaddition was utilized as a tool to conjugate the 1,4-benzodioxane moiety with several biologically active compounds such as steroid, sugar, and other aromatic scaffolds via isoxazole or triazole bridge. The propynyl ether of 2-hydroxymethyl-1,4-benzodioxane underwent 1,3-dipolar cycloadditions smoothly with different in situ generated nitrile oxides in good yields. The triazole conjugate of 1,4-benzodioxane was synthesized via click chemistry.     

New Triazolyl N^N Bidentate Rh(III), Ir(III), Ru(II) and Os(II) Complexes: Synthesis and Characterization,Probing Possible Relations between Cytotoxicity with Transfer Hydrogenation Efficacy and Interaction with Model Biomolecules

Cisplatin and other metallodrugs have realised great success in clinical chemotherapeutic applications as anticancer drugs. However, severe toxicity to healthy cells and non-selectivity to cancer cells remains a challenge, warranting the further search for alternative agents. Herein, we report the anticancer potential of a series of complexes of the general formula [MCl(p-cym)(k²-N^N-L)]⁺ X⁻ and [MCl(Cp*)(k²-N^N-L)]⁺ X⁻, where M is the metal centre (Ru(II), Os(II), Rh(III) or Ir(III)), L = 1-benzyl-4-pyridinyl-1-H-1,2,3-triazole for L1 and 1-picolyl-4-pyridinyl-1-H-1,2,3-triazole for L2 and X⁻ = Cl⁻, BF₄⁻, BPh₄⁻. When evaluated for activity against some cancerous and non-cancerous cell lines (namely, HeLa, HEK293, A549 and MT4 cancer cells and the normal healthy kidney cells (BHK21)), most of the compounds displayed poor cytotoxicities against cancer cells except for complexes C2 ([RuCl(p-cym)(k²-N^N-L1)]⁺ BPh₄⁻, EC₅₀ = 9–16 µM and SI = 14), C7 ([RuCl(p-cym)(k²-N^N-L2)]⁺ BPh₄⁻, EC₅₀ = 17–53 µM and SI = 4) and C11 ([IrCl(Cp*)(k²-N^N-L2)]⁺ BF₄⁻, EC₅₀ < 5 µM and SI > 10). Selected complexes C1 ([RuCl(p-cym)(k²-N^N-L1)]⁺ BF₄⁻), C5 ([IrCl(Cp*)(k²-N^N-L1)]⁺ BF₄⁻) and C11 showed significant interactions with model biomolecules such as guanosine-5′-monophosphate (5′-GMP), bovine serum albumin (BSA) and amino acids under physiological conditions, possibly through carbenylation and N-coordination with 5′-GMP, N-coordination with L-Histidine and L-proline. While the compounds showed good activities in reducing pyruvate to lactate, there was no direct correlation between catalytic transfer hydrogenation of pyruvate and the observed cytotoxic activities. As observed in this work, the marked influence of single atom replacement in ligand may provide a pivotal approach to improving the cytotoxicity and fine-tuning the selectivity to cancer cells.     

Synthesis of 7‐Triazole‐substituted Camptothecin via Click Chemistry and Evaluation of in vitro Antitumor Activity

Camptothecin (CPT) is a natural topoisomerase I inhibitor with powerful antineoplastic activity against colorectal, breast, lung and ovarian cancers. To discover more potent antitumor agents, a series of new CPT derivatives were synthesized utilizing click chemistry. All compounds were assessed for cytotoxicity against A549, HCT‐116, HT‐29, LoVo, MDA‐MB‐231 cell lines, and some compounds exhibited good in vitro potency. Furthermore, all compounds kept or enhanced Topo I inhibition.     

Synthesis and Insecticidal Evaluation of Novel Phthalic Diamides Containing 1,2,3‐Triazoles via Click Reaction

A series of novel phthalic diamide derivatives containing 1,2,3‐triazole moiety were synthesized using one‐pot click chemistry approach and characterized by ¹H NMR and HRMS. The insecticidal activity against armyworm (Mythimna separata), Tetranychu scinnabarinus and cowpea aphid (Aphis craccivora) was evaluated. Compounds 4II‐a and 4II‐i showed 50% insecticidal activity against armyworm (Mythimna separata) at the concentration of 4 mg/L and one‐third of the compounds had moderate activity against Tetranychus cinnabarinus at 500 mg/L.     

Determination of the elastic constants of nematic liquid crystals by means of the affine transformation model

In this paper the affine connection approach will be used to calculate the elastic constants of nematic liquid crystals. Following this approach, which was originally conceived to compute the nematic viscosity coefficients, an expression for the elastic constants, without adjustable free parameters, will be formulated in terms of a temperature dependent metric, whose non‐isotropic part is proportional to the tensorial order parameter of the nematic phase. The dependence of the elastic constants on the scalar order parameter, in the geometry of the nematic molecules, and in the anisotropic part of the molecular interaction, will be determined.     

Impregnated copper ferrite on mesoporous graphitic carbon nitride: An efficient and reusable catalyst for promoting ligand‐free click synthesis of diverse 1,2,3‐triazoles and tetrazoles

Magnetic CuFe₂O₄/g‐C₃N₄ hybrids were synthesized through a facile method and their catalytic performances were evaluated in click chemistry for the first time. The structural and morphological characterization of prepared materials was carried out by different techniques such as X‐ray diffraction, high‐resolution transmission electron microscopy, field emission scanning electron microscopy, Fourier infrared spectroscopy, vibrating sample magnetometry, thermogravimetric analysis, and N₂ adsorption–desorption analysis (Brunauer–Emmett–Teller surface area). The utilization of magnetic CuFe₂O₄/g‐C₃N₄ enabled superior performance in the one‐pot azide–alkyne cycloaddition reaction in water using alkyl halides and epoxides as azide precursors without the need of any additional agents. The present system is broad in scope and especially practical for the synthesis of macrocyclic triazoles and also tetrazoles. In addition, the catalytic system highly fulfills the demands of “green click chemistry” with its convenient conditions, especially easy access to a variety of significant products in low catalyst loading and simple work‐up and isolation procedure.     

Synthesis of Triazole‐Linked Amino Acid‐Aryl C‐Glycoside Hybrids via Click Chemistry as Novel PTP1B Inhibitors

Triazolyl phenylalanine and tyrosine‐aryl C‐glycoside hybrids were readily synthesized via microwave‐assisted Cu(I)‐catalyzed azide‐alkyne 1,3‐dipolar cycloaddition in high yields. Successive enzymatic assay identified the synthesized glycoconjugates as novel PTP1B inhibitors with low micromole‐ranged inhibitory activity and at least several‐fold selectivity over other homologous PTPs tested. In addition, the benzyl groups on glucosyl moiety were found crucial toward PTP1B inhibition.     

Synthesis of Carbohydrate Based Macrolactones and Their Applications as Receptors for Ion Recognition and Catalysis

Glycomacrolactones exhibit many interesting biological properties, and they are also important in molecular recognitions and for supramolecular chemistry. Therefore, it is important to be able to access glycomacrocycles with different sizes and functionality. A new series of carbohydrate-based macrocycles containing triazole and lactone moieties have been designed and synthesized. The synthesis features an intramolecular nucleophilic substitution reaction for the macrocyclization step. In this article, the effect of some common sulfonate leaving groups is evaluated for macrolactonization. Using tosylate gave good selectivity for monolactonization products with good yields. Fourteen different macrocycles have been synthesized and characterized, of which eleven macrocycles are from cyclization of the C1 to C6 positions of N-acetyl D-glucosamine derivatives and three others from C2 to C6 cyclization of functionalized D-glucosamine derivatives. These novel macrolactones have unique structures and demonstrate interesting anion binding properties, especially for chloride. The macrocycles containing two triazoles form complexes with copper sulfate, and they are effective ligands for copper sulfate mediated azide-alkyne cycloaddition reactions (CuAAC). In addition, several macrocycles show some selectivity for different alkynes.