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Enamine–azide [2+3]-cycloaddition as a method to introduce functional groups into fluorescent dyes
摘要： Fluorescent dyes are a significant research tool with various applications in modern science. However, many experiments require the preparation of covalent dye conjugates, which is impossible without the presence of a functional group on the dye molecule. Unfortunately, the introduction of such groups is often a complicated task. Herein, we report a novel approach for the introduction of functional groups into fluorescent dyes, based on the [2+3]-cycloaddition reaction of 'terminal' enamines with azides. The synthesis of such 'terminal' enamines is carried out by the condensation of formamide acetals with a methyl group that is influenced by a strong electron withdrawing group. Thus, the proposed functionalization technique requires only the presence of a methyl group in the relevant position of the initial non-functionalized fluorescent dye.
关键词： Enamine,Azide,Cycloaddition,Fluorophore
更新于2025-09-23 15:22:29
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Anti-Markovnikov Hydroazidation of Alkenes by Visible Light Photoredox Catalysis
摘要： The anti-Markovnikov hydroazidation of alkenes has been accomplished using [Ir(dF(CF3)ppy)2(dtbbpy)]PF6 as photocatalyst and trimethylsilyl azide as azidating agent. The reactions were greatly facilitated by water, whose beneficial effect can be attributed to its participation in the reaction as the hydrogen donor, as indicated by deuterium isotope experiments. The reactions can be effected under solvent free conditions in the presence of water. 4-Dimethylaminopyridine also exhibited a beneficial effect on the reactions. The present method enabled hydroazidation of several types of unactivated alkenes with good yield and high regionselectivity.
关键词： hydroazidation,water,trimethylsilyl azide,radical reactions,photoredox catalysis
更新于2025-09-23 15:22:29
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Synthesis of low surface-energy polyepichlorohydrin triazoles thin film
摘要： In this investigation, a new polymer with low surface energy was synthesized by grafting a triazole group onto polyepichlorohydrin (PECH) rubber that contained no halogens. The chlorine on PECH was first replaced by an azide group, and this attached azide was then converted to a triazole group with alkyl chains using the azide-alkyne Huisgen cycloaddition reaction. Analyses confirmed the structure of final product, PECH-triazole polymer. The grafting reactions increased the surface roughness. The static contact angles of water or CH2I2 droplets on the PECH-azole film were 101.7° and 71.3°, respectively. The advancing and receding contact angles for water on PECH-azide were 119.8° and 13.7°, respectively. The PECH-triazole polymer has omniphobic properties with rose petal characteristics. The PECH-triazole has low dispersive surface energy (21 mN/m) and negligible non-dispersive surface energy, giving a wetting envelope that is similar to the one of PTFE polymer. X-ray photoelectron spectroscopy and transmission infrared spectroscopy suggested that the interactions of the N atoms on the triazole ring and the O atoms on the PECH backbone constrained the orientation of CH2 groups and reduced the surface energy of the thin film.
关键词： Azide-alkyne Huisgen cycloaddition,Polyepichlorohydrin,Low surface free energy,High water adhesion,Triazole
更新于2025-09-23 15:22:29
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Lithium Pentazolate Synthesized by Laser Heating Compressed Lithium Azide and Nitrogen
摘要： Searching for polynitrogen compounds has attracted great attention due to their potential applications as high energy density materials. Here, we report a facile approach to the synthesis of solid lithium pentazolate (LiN5) compound by compressing lithium azide and molecular nitrogen under high pressure with laser heating. The formation of LiN5 with crystal structure P21/m-LiN5 was identified according to the appearance of the vibrational modes of N5ˉ rings in Raman spectra and synchrotron X-ray diffraction measurements under high pressure. The LiN5 remains stable down to 18.5 GPa upon decompression. The bond lengths in N5ˉ are between single bond and double bond length. This study indicates that the precursor can effectively tune the high pressure phase of pentazolate providing us an alternative route to synthesize polynitrogen compound with novel structure.
关键词： Lithium azide,Laser heating,High pressure,Nitrogen and Lithium pentazolate
更新于2025-09-23 15:21:01
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Modular medical imaging agents based on azidea??alkyne Huisgen cycloadditions: Synthesis and prea??clinical evaluation of 18Fa??labeled PSMAa??tracers for prostate cancer imaging.
摘要： The seminal contribution of Rolf Huisgen to develop the [3+2]-cycloaddition of 1,3-dipolar compounds, its azide-alkyne variant has established itself as the key step in numerous organic syntheses and bioorthogonal processes in materials science and chemical biology. In the present study, the copper(I)-catalyzed azide-alkyne cycloaddition was applied for the development of a modular molecular platform for medical imaging of the prostate specific membrane antigen (PSMA), using positron emission tomography. This process is shown from molecular design, through synthesis automation and in vitro studies, all the way to preclinical in vivo evaluation of fluorine-18– labeled PSMA-targeting ‘F-PSMA-MIC’ radiotracers (t? = 109.7 min). Preclinical data indicate that the modular PSMA-scaffold has similar binding affinity and imaging properties to the clinically used [68Ga]PSMA-11. Furthermore, we demonstrated that targeting the arene-binding in PSMA, facilitated through the [3+2]-cycloaddition, can improve binding affinity, which was rationalized by molecular modeling. The here presented PSMA-binding scaffold potentially facilitates easy coupling to other medical imaging moieties, enabling future developments of new modular imaging agents.
关键词： prostate specific membrane antigen,positron emission tomography,fluorine-18,azide-alkyne Huisgen cycloaddition,modular imaging agents
更新于2025-09-23 15:19:57
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Preparation of pyrido[1,2-c][1,2,4]triazole-based π-conjugated triazene as a Fe3+ ion fluorescent sensor
摘要： A highly efficient coupling reaction of N-heterocyclic carbene precursors with sulfonyl azides has been developed, affording a variety of pyrido[1,2-c][1,2,4]triazole-based π-conjugated triazenes. The present reaction proceeds under very mild conditions with good functional group tolerance. The resulting triazenes exhibit selective and sensitive fluorescent response toward Fe3+ ion.
关键词： Fluorescence,Triazene,Sulfonyl azide,Iron ion,Sensor
更新于2025-09-19 17:15:36
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Surface plasmon-polariton: a novel initiation way for azide alkyne cycloaddition
摘要： Plasmon-catalysis has recently generated tremendous interest in the field of modern chemistry. Application of plasmon introduces the principally new stimuli for the activation of organic reactions, keeping the optical energy concentrated in the vicinity of plasmonic structure, creating optical near-field enhancement as well as hot electrons injection. In this work, for the first time, we presented a new way for the initiation of the azide-alkyne cycloaddition (AAC) using the surface plasmon-polariton wave, supported by the gold grating. With this concept in hand, the plasmon-active gold grating was functionalized with the 4-ethynylbenzenediazonium compound. Then, surface grafted 4-ethynylphenyl groups were plasmon activated and clicked with 4-azidobenzoic acid. Additional experiments excluded the potential effect of photon, heating, and metal impurities confirmed the key role of surface plasmon-polariton AAC activation. For investigation of plasmon-induced AAC mechanism, 4-azidophenyl groups (instead of 4-ethynylphenyl groups) were also grafted to the grating surface. Further careful evaluation of reaction kinetics demonstrates that AAC reaction rate is significantly higher in the case of acetylene activation than in the case of azide activation.
关键词： gold grating,azide alkyne cycloaddition,surface modification,plasmon catalysis,surface plasmon-polariton
更新于2025-09-19 17:15:36
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Fluorometric visualization of mucin 1 glycans on cell surfaces based on rolling-mediated cascade amplification and CdTe quantum dots
摘要： A rolling-mediated cascade (RMC) amplification strategy is described for improved visualization of profiling glycans of mucin 1 (MUC 1) on cell surfaces. CdTe quantum dots (QDs) are used as fluorescent labels. The RMC based amplification allows even distinct glycoforms of MUC1 to be visualized on the surface of MCF-7 cell via an amplified F?rster resonance energy transfer (FRET) imaging strategy that works at excitation/emission wavelengths of 345/610 nm. This is achieved by utilizing antibody against MUC1 modified with the fluorescent label 7-amino-4-methylcoumarin-3-acetic acid (AMCA) as the energy donor in FRET. The QDs (used to label surface glycans) act as acceptors. N-Azidoacetylgalactosamine-Acetylated (Ac4GalNAz) as a non-natural azido sugar, can be incorporated into the glycans of the cell surface, which can promote further labeling. The method has the advantage of only requiring a small amount of non-natural sugar to be introduced in metabolic glycan labeling since too much of an artificial sugar will interfere with the physiological functions of cells.
关键词： Cancer marker,Azide polysaccharide,FRET,Glycosylation,Glycoprotein,DNA probe,Quantum dots,Click reaction,Metabolic labeling,Rolling-mediated cascade amplification
更新于2025-09-19 17:13:59
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Nitrato, Pseudohalo-Linked Zn(II)/Cd(II) Schiff-Base Complexes with 1,3-Diimine Spacer Group: Syntheses, Crystal Structures, DFT, TD-DFT and Fluorescence Studies
摘要： Self assemblies of (N2O4) salen-type bi-compartmental ligand (H2L°Me) [N,N’-Bis(3-methoxysalicylidenimino)-1,3-diaminopropane] afforded two series of complexes, a trinuclear nitrate [Cd3(L°Me)2(NO3)2] (1) and a dinuclear [Zn2(L°Me)(η1-N3)2(CH3OH)2] (2). Elemental analysis, UV-visible and Fourier transform Infrared spectroscopic methods were employed successfully to characterize the complexes. Single-crystal X-ray studies reveal that complex 1 consists of planar trinuclear Cd(II)3 core coordinated by two fully deprotonated dianionic ligands [L1]2(cid:0) and nitrato (NO3(cid:0)) bridging but complex 2 is a centrosymmetric hexacoordinated Zn(II) double end-on azide (η1-N3) with methanol as co-ligands. Both complexes satisfied a common 4-membered M(II)2(μ2-O)2 basic core. Fluorescence properties in DMSO solvent reveal that complexes enhance appreciably the fluorescence behavior over free salen-type ligand (H2L°Me). Complexes are optimized using Density functional theory calculated at B3LYP/TZVP level of theory to obtain insights into optimized structure, Frontier molecular orbital, Electrostatic potential maps, charge analyses gives an insight into the electronic structure and charge/potential distribution in the molecule etc. which substantiate the experimentally observed supramolecular interactions. Existing different non-covalent supramolecular interactions have been explained by means of Hirshfeld surface and 2D fingerprint plot analysis. Further the observed experimental electronic spectra of both complexes were explained by using Time-dependent density functional theory level of calculations.
关键词： Cd(II)/Zn(II) Complex,Fluorescence,TD-DFT,DFT,Azide
更新于2025-09-09 09:28:46
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Inorganic Salts and Antimicrobial Photodynamic Therapy: Mechanistic Conundrums?
摘要： We have recently discovered that the photodynamic action of many different photosensitizers (PSs) can be dramatically potentiated by addition of a solution containing a range of different inorganic salts. Most of these studies have centered around antimicrobial photodynamic inactivation that kills Gram-negative and Gram-positive bacteria in suspension. Addition of non-toxic water-soluble salts during illumination can kill up to six additional logs of bacterial cells (one million-fold improvement). The PSs investigated range from those that undergo mainly Type I photochemical mechanisms (electron transfer to produce superoxide, hydrogen peroxide, and hydroxyl radicals), such as phenothiazinium dyes, fullerenes, and titanium dioxide, to those that are mainly Type II (energy transfer to produce singlet oxygen), such as porphyrins, and Rose Bengal. At one extreme of the salts is sodium azide, that quenches singlet oxygen but can produce azide radicals (presumed to be highly reactive) via electron transfer from photoexcited phenothiazinium dyes. Potassium iodide is oxidized to molecular iodine by both Type I and Type II PSs, but may also form reactive iodine species. Potassium bromide is oxidized to hypobromite, but only by titanium dioxide photocatalysis (Type I). Potassium thiocyanate appears to require a mixture of Type I and Type II photochemistry to ?rst produce sul?te, that can then form the sulfur trioxide radical anion. Potassium selenocyanate can react with either Type I or Type II (or indeed with other oxidizing agents) to produce the semi-stable selenocyanogen (SCN)2. Finally, sodium nitrite may react with either Type I or Type II PSs to produce peroxynitrate (again, semi-stable) that can kill bacteria and nitrate tyrosine. Many of these salts (except azide) are non-toxic, and may be clinically applicable.
关键词： potassium thiocyanate,potentiation by inorganic salts,potassium bromide,potassium iodide,sodium azide,antimicrobial photodynamic inactivation,potassium selenocyanate,sodium nitrite
更新于2025-09-09 09:28:46