共查询到20条相似文献,搜索用时 15 毫秒
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Philipp Michael Prof. Dr. Wolfgang H. Binder 《Angewandte Chemie (International ed. in English)》2015,54(47):13918-13922
“Click” chemistry represents one of the most powerful approaches for linking molecules in chemistry and materials science. Triggering this reaction by mechanical force would enable site‐ and stress‐specific “click” reactions—a hitherto unreported observation. We introduce the design and realization of a homogeneous Cu catalyst able to activate through mechanical force when attached to suitable polymer chains, acting as a lever to transmit the force to the central catalytic system. Activation of the subsequent copper‐catalyzed “click” reaction (CuAAC) is achieved either by ultrasonication or mechanical pressing of a polymeric material, using a fluorogenic dye to detect the activation of the catalyst. Based on an N‐heterocyclic copper(I) carbene with attached polymeric chains of different flexibility, the force is transmitted to the central catalyst, thereby activating a CuAAC in solution and in the solid state. 相似文献
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Haozhe Yang Prof. Dr. Frank Seela 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(4):1435-1444
A highly effective and convenient “bis‐click” strategy was developed for the template‐independent circularization of single‐stranded oligonucleotides by employing copper(I)‐assisted azide–alkyne cycloaddition. Terminal triple bonds were incorporated at both ends of linear oligonucleotides. Alkynylated 7‐deaza‐2′‐deoxyadenosine and 2′‐deoxyuridine residues with different side chains were used in solid‐phase synthesis with phosphoramidite chemistry. The bis‐click ligation of linear 9‐ to 36‐mer oligonucleotides with 1,4‐bis(azidomethyl)benzene afforded circular DNA in a simple and selective way; azido modification of the oligonucleotide was not necessary. Short ethynyl side chains were compatible with the circularization of longer oligonucleotides, whereas octadiynyl residues were used for short 9‐mers. Compared with linear duplexes, circular bis‐click constructs exhibit a significantly increased duplex stability over their linear counterparts. The intramolecular bis‐click ligation protocol is not limited to DNA, but may also be suitable for the construction of other macrocycles, such as circular RNAs, peptides, or polysaccharides. 相似文献
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Copper(I)‐Catalyzed Cycloaddition of Azides to Multiple Alkynes: A Selectivity Study Using a Calixarene Framework 下载免费PDF全文
Alexander Gorbunov Dmitry Cheshkov Prof. Vladimir Kovalev Dr. Ivan Vatsouro 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(26):9528-9534
Copper(I)‐catalyzed addition of limited amounts of azides to multiple alkynes, which led to statistical mixtures of triazole/acetylene derivatives or, in other cases, resulted in preferred formation of multiple triazoles, was studied at pre‐organizable calixarene platforms bearing up to four propargyl groups. Depending on calixarene structures and reaction conditions, the unprecedented specific or selective formation of exhaustively triazolated calixarenes or a complete loss of the selectivity were observed. Both autocatalytic copper activation and a local copper(I) concentration increase due to copper–triazole complexation were thoroughly studied as the most expected reasons for the selectivity and both were disproved. Mixed triazolated/propargylated calixarenes and their copper(I) complexes proved not to be involved in the cascade‐like process that was modeled to be driven by an intramolecular transfer of two copper(I) ions from a just‐formed binuclear copper intermediate to the adjacent acetylene unit. 相似文献
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Dr. Antonio Toppino Maria Elena Bova Dr. Simonetta Geninatti Crich Dr. Diego Alberti Prof. Eliano Diana Dr. Alessandro Barge Prof. Silvio Aime Prof. Paolo Venturello Dr. Annamaria Deagostino 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(2):721-728
In this study, the Huisgen reaction has been used to functionalise a carborane cage with a lipophilic moiety and a 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA) ligand to obtain a new Gd boron neutron‐capture therapy (BNCT)/magnetic resonance imaging (MRI) agent. The introduction of the triazole units has been accomplished under both heterogeneous conditions, by the use of a Cu‐supported ionic‐liquid catalyst, and homogeneous conditions. The ability of the Gd complex of the synthesised ligand to form stable adducts with low‐density lipoproteins (LDLs) has been evaluated and then MRI has been performed on tumour melanoma cells incubated in the presence of a Gd‐complex/LDL imaging probe. It has been concluded that the high amount of intracellular boron necessary to perform BNCT can be reached even in the presence of a relatively low‐boron‐containing LDL concentration. 相似文献
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Mikołaj Chromiński Prof. Dorota Gryko 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(16):5141-5148
A “clickable” vitamin B12 derivative possessing the azide functionality at the 5′‐position was synthesized by means of a two‐step procedure on the gram scale. The reaction of cobalamin with mesyl chloride (MsCl) afforded the 5′‐OMs derivative, which was subsequently transformed to the desired 5′‐azide, the structure of which was confirmed using X‐ray analysis. It proved to be reactive in the azide–alkyne 1,3‐dipolar cycloaddition reaction to give substituted triazoles in high yields. A study of the reaction conditions and the scope of the process are reported. 相似文献
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Jérémy Camponovo Jaime Ruiz Prof. Dr. Eric Cloutet Dr. Didier Astruc Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(12):2990-3002
Dendrimers for ion sensing : The synthesis and use of new tris‐alkynyl dendrons are reported. So‐called “click” reactions of the dendrimers described with azidomethylferrocene give 27‐ferrocenyl, 81‐ferrocenyl, and 243‐ferrocenyl dendrimers. Electrochemical recognition of oxo‐anions and Pd2+ cations has been compared using the three polyferrocenyl dendrimers.
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Reaction of Alkynes and Azides: Not Triazoles Through Copper–Acetylides but Oxazoles Through Copper–Nitrene Intermediates 下载免费PDF全文
Dr. Estela Haldón Dr. Maria Besora Dr. Israel Cano Dr. Xacobe C. Cambeiro Prof. Miquel A. Pericàs Prof. Feliu Maseras Prof. M. Carmen Nicasio Prof. Pedro J. Pérez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(12):3463-3474
Well‐defined copper(I) complexes of composition [Tpm*,BrCu(NCMe)]BF4 (Tpm*,Br=tris(3,5‐dimethyl‐4‐bromo‐pyrazolyl)methane) or [Tpa*Cu]PF6 (Tpa*=tris(3,5‐dimethyl‐pyrazolylmethyl)amine) catalyze the formation of 2,5‐disubstituted oxazoles from carbonyl azides and terminal alkynes in a direct manner. This process represents a novel procedure for the synthesis of this valuable heterocycle from readily available starting materials, leading exclusively to the 2,5‐isomer, attesting to a completely regioselective transformation. Experimental evidence and computational studies have allowed the proposal of a reaction mechanism based on the initial formation of a copper–acyl nitrene species, in contrast to the well‐known mechanism for the copper‐catalyzed alkyne and azide cycloaddition reactions (CuAAC) that is triggered by the formation of a copper–acetylide complex. 相似文献
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A Family of “Click” Nucleosides for Metal‐Mediated Base Pairing: Unravelling the Principles of Highly Stabilizing Metal‐Mediated Base Pairs 下载免费PDF全文
Tim Richters Dr. Olga Krug Jutta Kösters Dr. Alexander Hepp Prof. Dr. Jens Müller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7811-7818
A family of artificial nucleosides has been developed by applying the CuI‐catalyzed Huisgen 1,3‐dipolar cycloaddition. Starting from 2‐deoxy‐β‐D ‐glycosyl azide as a common precursor, three bidentate nucleosides have been synthesized. The 1,2,3‐triazole involved in all three nucleobases is complemented by 1,2,4‐triazole ( TriTri ), pyrazole ( TriPyr ), or pyridine ( TriPy ). Molecular structures of two metal complexes indicate that metal‐mediated base pairs of TriPyr may not be fully planar. An investigation of DNA oligonucleotide duplexes comprising the new “click” nucleosides showed that they can bind AgI to form metal‐mediated base pairs. In particular the mispair formed from TriPy and the previously established imidazole nucleoside is significantly stabilized in the presence of AgI. A comparison of different oligonucleotide sequences allowed the determination of general factors involved in the stabilization of nucleic acids duplexes with metal‐mediated base pairs. 相似文献
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Kazuya Yamaguchi Dr. Takamichi Oishi Tatsuyori Katayama Noritaka Mizuno Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(40):10464-10472
An easily prepared supported copper hydroxide on titanium oxide (Cu(OH)x/TiO2) showed high catalytic performance for the 1,3‐dipolar cycloaddition of organic azides to terminal alkynes in non‐polar solvents under anaerobic conditions. The reactions of various combinations of organic azides (four examples, including aromatic and aliphatic ones) and terminal alkynes (eleven examples, including aromatic, aliphatic, and double bond‐containing ones) exclusively proceeded to give the corresponding 1,4‐disubstituted‐1,2,3‐triazole derivatives in a completely regioselective manner. For the transformation of benzyl azide and ethynylbenzene with 0.12 mol % of Cu(OH)x/TiO2, the turnover frequency was 505 h?1 and the turnover number reached up to 800. These values were the highest among those with previously reported heterogeneous catalysts including Cu(OH)x/Al2O3. The observed catalysis was truly heterogeneous and the retrieved catalyst after the reaction could be reused at least three times with retention of its high catalytic performance. It was confirmed by the UV/Vis spectrum of Cu(OH)x/TiO2 and the amount of diyne formed that the CuII species in Cu(OH)x/TiO2 were reduced to CuI species by the alkyne–alkyne homocoupling at the initial stage of the reaction (during the pretreatment of Cu(OH)x/TiO2 with an alkyne). The catalytic reaction rate for the 1,3‐dipolar cycloaddition linearly increased with an increase in the amount of in situ generated CuI species. Therefore, the in situ generated CuI species would be the catalytically active species for the present 1,3‐dipolar cycloaddition. 相似文献
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Dr. Sandra Ast Tobias Fischer Holger Müller Dr. Wulfhard Mickler Mathias Schwichtenberg Dr. Knut Rurack Prof. Dr. Hans‐Jürgen Holdt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(9):2990-3005
In a systematic approach we synthesized a new series of fluorescent probes incorporating donor–acceptor (D‐A) substituted 1,2,3‐triazoles as conjugative π‐linkers between the alkali metal ion receptor N‐phenylaza‐[18]crown‐6 and different fluorophoric groups with different electron‐acceptor properties (4‐naphthalimide, meso‐phenyl‐BODIPY and 9‐anthracene) and investigated their performance in organic and aqueous environments (physiological conditions). In the charge‐transfer (CT) type probes 1 , 2 and 7 , the fluorescence is almost completely quenched by intramolecular CT (ICT) processes involving charge‐separated states. In the presence of Na+ and K+ ICT is interrupted, which resulted in a lighting‐up of the fluorescence in acetonitrile. Among the investigated fluoroionophores, compound 7 , which contains a 9‐anthracenyl moiety as the electron‐accepting fluorophore, is the only probe which retains light‐up features in water and works as a highly K+/Na+‐selective probe under simulated physiological conditions. Virtually decoupled BODIPY‐based 6 and photoinduced electron transfer (PET) type probes 3 – 5 , where the 10‐substituted anthracen‐9‐yl fluorophores are connected to the 1,2,3‐triazole through a methylene spacer, show strong ion‐induced fluorescence enhancement in acetonitrile, but not under physiological conditions. Electrochemical studies and theoretical calculations were used to assess and support the underlying mechanisms for the new ICT and PET 1,2,3‐triazole fluoroionophores. 相似文献
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Emiliano Tamanini Dr. Stephen E. J. Rigby Dr. Majid Motevalli Matthew H. Todd Dr. Michael Watkinson Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(15):3720-3728
Click to detect! Azamacrocyclic complexes with a triazole scorpion ligand may be easily assembled, as shown for a biotin‐functionalised cyclam derivative. Coordination of the triazole to the metal is perturbed by the binding of avidin to the pendant ligand (see scheme). This event can be sensitively detected with EPR and ENDOR spectroscopy, which confirm the loss of the axial triazole nitrogen donor upon avidin binding. This general strategy may have wide applications in imaging and therapeutics.
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David D. Díaz Sreenivas Punna Philipp Holzer Andrew K. McPherson K. Barry Sharpless Valery V. Fokin M. G. Finn 《Journal of polymer science. Part A, Polymer chemistry》2004,42(17):4392-4403
The copper(I)‐catalyzed cycloaddition reaction between azides and alkynes has been employed to make metal‐adhesive materials. Copper and brass surfaces supply the necessary catalytic Cu ions, and thus the polymerization process occurs selectively on these metals in the absence of added catalysts. Alternatively, copper compounds can be added to monomer mixtures and then introduced to reducing metal surfaces such as zinc to initiate polymerization. The resulting materials were found to possess comparable or superior adhesive strength to standard commercial glues, and structure‐activity correlations have identified several important properties of the monomers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4392–4403, 2004 相似文献
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Sravendra Rana Diana Döhler Ali Shaygan Nia Mahmood Nasir Mario Beiner Wolfgang H. Binder 《Macromolecular rapid communications》2016,37(21):1715-1722
Strategies to compensate material fatigue are among the most challenging issues, being most prominently addressed by the use of nano‐ and microscaled fillers, or via new chemical concepts such as self‐healing materials. A capsule‐based self‐healing material is reported, where the adverse effect of reduced tensile strength due to the embedded capsules is counterbalanced by a graphene‐based filler, the latter additionally acting as a catalyst for the self‐healing reaction. The concept is based on “click”‐based chemistry, a universal methodology to efficiently link components at ambient reaction conditions, thus generating a “reactive glue” at the cracked site. A capsule‐based healing system via a graphene‐based Cu2O (TRGO‐Cu2O‐filler) is used, acting as both the catalytic species for crosslinking and the required reinforcement agent within the material, in turn compensating the reduction in tensile strength exerted by the embedded capsules. Room‐temperature self‐healing within 48 h is achieved, with the investigated specimen containing TRGO‐Cu2O demonstrating significantly faster self‐healing compared to homogeneous (Cu(PPh3)3F, Cu(PPh3)3Br), and heterogeneous (Cu/C) copper(I) catalysts.