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Carolyn R Bertozzi - One of the best experts on this subject based on the ideXlab platform.
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A Homologation Approach to the Synthesis of Difluorinated Cycloalkynes
Organic letters, 2014Co-Authors: Ellen M. Sletten, Gabriela De Almeida, Carolyn R BertozziAbstract:Difluorinated Cyclooctynes are important reagents for labeling azido-biomolecules through copper-free click chemistry. Here, a safe, scalable synthesis of a difluorinated Cyclooctyne is reported, which involves a key homologation/ring-expansion reaction. Sequential ring expansions were also employed to synthesize and study a novel difluorinated cyclononyne.
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reactivity of biarylazacyclooctynones in copper free click chemistry
Journal of the American Chemical Society, 2012Co-Authors: Chelsea G Gordon, Ellen M. Sletten, John C. Jewett, Joel L Mackey, K N Houk, Carolyn R BertozziAbstract:The 1,3-dipolar cycloaddition of Cyclooctynes with azides, also called “copper-free click chemistry”, is a bioorthogonal reaction with widespread applications in biological discovery. The kinetics of this reaction are of paramount importance for studies of dynamic processes, particularly in living subjects. Here we performed a systematic analysis of the effects of strain and electronics on the reactivity of Cyclooctynes with azides through both experimental measurements and computational studies using a density functional theory (DFT) distortion/interaction transition state model. In particular, we focused on biarylazacyclooctynone (BARAC) because it reacts with azides faster than any other reported Cyclooctyne and its modular synthesis facilitated rapid access to analogues. We found that substituents on BARAC’s aryl rings can alter the calculated transition state interaction energy of the cycloaddition through electronic effects or the calculated distortion energy through steric effects. Experimental dat...
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Synthesis of a fluorogenic Cyclooctyne activated by Cu-free click chemistry.
Organic letters, 2011Co-Authors: John C. Jewett, Carolyn R BertozziAbstract:Cyclooctyne-based probes that become fluorescent upon reaction with azides are important targets for real-time imaging of azide-labeled biomolecules. The concise synthesis of a coumarin-conjugated Cyclooctyne, coumBARAC, that undergoes a 10-fold enhancement in fluorescence quantum yield upon triazole formation with organic azides is reported. The design principles embodied in coumBARAC establish a platform for generating fluorogenic Cyclooctynes suited for biological imaging.
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DifluorobenzoCyclooctyne: Synthesis, Reactivity, and Stabilization by β-Cyclodextrin
Journal of the American Chemical Society, 2010Co-Authors: Ellen M. Sletten, John C. Jewett, Hitomi Nakamura, Carolyn R BertozziAbstract:Highly reactive Cyclooctynes have been sought as substrates for Cu-free cycloaddition reactions with azides in biological systems. To elevate the reactivities of Cyclooctynes, two strategies, LUMO lowering through propargylic fluorination and strain enhancement through fused aryl rings, have been explored. Here we report the facile synthesis of a difluorobenzoCyclooctyne (DIFBO) that combines these modifications. DIFBO was so reactive that it spontaneously trimerized to form two asymmetric products that we characterized by X-ray crystallography. However, we were able to trap DIFBO by forming a stable inclusion complex with β-cyclodextrin in aqueous media. This complex could be stored as a lyophilized powder and then dissociated in organic solvents to produce free DIFBO for in situ kinetic and spectroscopic analysis. Using this procedure, we found that the rate constant for the cycloaddition reaction of DIFBO with an azide exceeds those for difluorinated Cyclooctyne (DIFO) and dibenzoCyclooctyne (DIBO). Cyclodextrin complexation is therefore a promising approach for stabilizing compounds that possess the high intrinsic reactivities desired for Cu-free click chemistry.
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Copper-free click chemistry in living animals
Proceedings of the National Academy of Sciences, 2010Co-Authors: P. V. Chang, A Lo, I A Miller, Ellen M. Sletten, Jeremy M Baskin, Nicholas J Agard, Jennifer A. Prescher, Carolyn R BertozziAbstract:Chemical reactions that enable selective biomolecule labeling in living organisms offer a means to probe biological processes in vivo. Very few reactions possess the requisite bioorthogonality, and, among these, only the Staudinger ligation between azides and triarylphosphines has been employed for direct covalent modification of biomolecules with probes in the mouse, an important model organism for studies of human disease. Here we explore an alternative bioorthogonal reaction, the 1,3-dipolar cycloaddition of azides and Cyclooctynes, also known as "Cu-free click chemistry," for labeling biomolecules in live mice. Mice were administered peracetylated N-azidoacetylmannosamine (Ac(4)ManNAz) to metabolically label cell-surface sialic acids with azides. After subsequent injection with Cyclooctyne reagents, glycoconjugate labeling was observed on isolated splenocytes and in a variety of tissues including the intestines, heart, and liver, with no apparent toxicity. The Cyclooctynes tested displayed various labeling efficiencies that likely reflect the combined influence of intrinsic reactivity and bioavailability. These studies establish Cu-free click chemistry as a bioorthogonal reaction that can be executed in the physiologically relevant context of a mouse.
Ellen M. Sletten - One of the best experts on this subject based on the ideXlab platform.
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A Homologation Approach to the Synthesis of Difluorinated Cycloalkynes
Organic letters, 2014Co-Authors: Ellen M. Sletten, Gabriela De Almeida, Carolyn R BertozziAbstract:Difluorinated Cyclooctynes are important reagents for labeling azido-biomolecules through copper-free click chemistry. Here, a safe, scalable synthesis of a difluorinated Cyclooctyne is reported, which involves a key homologation/ring-expansion reaction. Sequential ring expansions were also employed to synthesize and study a novel difluorinated cyclononyne.
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reactivity of biarylazacyclooctynones in copper free click chemistry
Journal of the American Chemical Society, 2012Co-Authors: Chelsea G Gordon, Ellen M. Sletten, John C. Jewett, Joel L Mackey, K N Houk, Carolyn R BertozziAbstract:The 1,3-dipolar cycloaddition of Cyclooctynes with azides, also called “copper-free click chemistry”, is a bioorthogonal reaction with widespread applications in biological discovery. The kinetics of this reaction are of paramount importance for studies of dynamic processes, particularly in living subjects. Here we performed a systematic analysis of the effects of strain and electronics on the reactivity of Cyclooctynes with azides through both experimental measurements and computational studies using a density functional theory (DFT) distortion/interaction transition state model. In particular, we focused on biarylazacyclooctynone (BARAC) because it reacts with azides faster than any other reported Cyclooctyne and its modular synthesis facilitated rapid access to analogues. We found that substituents on BARAC’s aryl rings can alter the calculated transition state interaction energy of the cycloaddition through electronic effects or the calculated distortion energy through steric effects. Experimental dat...
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Bioorthogonal Chemistries for Labeling Living Systems
2011Co-Authors: Ellen M. SlettenAbstract:Author(s): Sletten, Ellen | Advisor(s): Bertozzi, Carolyn R | Abstract: Bioorthogonal is defined as not interfering or interacting with biology. Chemical reactions that are bioorthogonal have recently become valuable tools to visualize biomolecules in their native environments, particularly those that are not amenable to traditional genetic modification. The field of bioorthogonal chemistry is rather young, with the first published account of the term bioorthogonal in 2003, yet it is expanding at a rapid rate. The roots of this unique subset of chemistry are in classic protein modification and subsequent bioconjugation efforts to obtain uniformly and site-specifically functionalized proteins. These studies are highlighted in Chapter 1. Chapter 2 opens with a summary of the bioorthogonal chemical reporter strategy, a two-step approach where a bioorthogonal functional group is installed into a biomolecule of interest, most often using endogenous metabolic machinery, and detected through a secondary covalent reaction with an appropriately functionalized chemical partner. It is this chemical reporter strategy that empowers bioorthogonal chemistry and allows for a wide variety of biological species to be assayed. Chapter 2 proceeds to outline the discovery of the Staudinger ligation, the first chemical reaction developed for use in the bioorthogonal chemical reporter strategy. The Staudinger ligation employed the azide as the chemical reporter group and, since its debut in 2000, many laboratories have capitalized on the exquisite qualities of the azide (small, abiotic, kinetically stable) that make it a versatile chemical reporter group. The success of the azide prompted the development of other bioorthogonal chemistries for this functional group. One of these chemistries, Cu-free click chemistry, is the 1,3-dipolar cycloaddition between Cyclooctynes and azides. The cycloaddition is promoted at physiological conditions by the ~18 kcal/mol of ring strain contained within Cyclooctyne, and further modifications to the Cyclooctyne reagents have lead to increased reactivity through augmentation of the ring strain or optimization of orbital overlap. When I began my graduate work, a difluorinated Cyclooctyne (DIFO), which was 60-fold more reactive than other existing bioorthogonal chemistries, had just been synthesized and employed for labeling azides on live cells and within living mice. DIFO performed very well on cultured cells, but it was outperformed by the slower Staudinger ligation in the more complex environment of the mouse. We hypothesized that DIFO was too hydrophobic to be effective in mice and designed a more hydrophilic Cyclooctyne reagent, a dimethoxyazaCyclooctyne (DIMAC). DIMAC was synthesized in nine steps in a 10% overall yield (Chapter 3). As predicted, DIMAC displayed reaction kinetics similar to early generation Cyclooctynes, but exhibited improved water-solubility. Consequently, DIMAC labeled cell-surface azides with comparable efficiencies to the early generation Cyclooctynes but greater signal-to-noise ratios were achieved due to minimal background staining. Encouraged by these results, we assayed the ability for DIMAC to label azides in living mice and found that DIMAC was able to modify azides in vivo with moderate signal over background. However, the Staudinger ligation was still the superior bioorthogonal reaction for labeling azides in vivo. Our results collectively indicated that both hydrophilicity and reactivity are important qualities when optimizing the Cyclooctynes for in vivo reaction with azides (Chapter 4).We were also interested in modifying DIMAC so that it would become fluorescent upon reaction with an azide. Previous work in the lab had established that fluorogenic reagents could be easily created if a functional group was cleaved from the molecule upon reaction with an azide. We envisioned a leaving group could be engineered into the azaCyclooctyne scaffold by strategically positioning a labile functional group across the ring from a nitrogen atom. The Cyclooctyne structure should be stable, as it is rigid and intramolecular reactions are not favorable. However, upon reaction with an azide, a significant amount of strain is liberated and the intramolecular reaction should readily occur. Efforts toward the synthesis of this modified DIMAC reagent are chronicled in Chapter 5.Chapter 6 is a very short account of our early work to use DIFO-based reagents for proteomics. The results contained in this chapter are preliminary and further endeavors towards this goal are underway by others within the group.Chapters 7, 8 and 9 are devoted to strategies to increase the second-order rate constant of Cu-free click chemistry. In Chapter 7, various routes toward a tetrafluorinated Cyclooctyne are outlined, although none of them successfully yielded this putatively highly reactive Cyclooctyne. Chapter 8 describes the synthesis of a difluorobenzoCyclooctyne (DIFBO), which is more reactive than DIFO, but unstable due to its propensity to form trimer products. However, DIFBO can be kinetically stabilized by encapsulation in beta-cyclodextrin. Only beta-cyclodextrin and not the smaller (alpha) or larger (gamma) cyclodextrins were able to protect DIFBO. We did observe an intriguing result when complexation with the larger gamma-cyclodextrin was attempted. It appears as though two DIFBO molecules can fit inside the gamma-cyclodextrin and dimeric products, which were not apparent in the absence of gamma-cyclodextrin, were observed. We hypothesized that all oligomer products of DIFBO were derived from a common cyclobutadiene intermediate. While DIFBO was chemically interesting, it was not a useful reagent for labeling azides in biological settings. Thus, Chapter 9 is devoted to the modification of DIFBO, with the aim of identifying a reactive yet stable Cyclooctyne. The data from Chapter 9 suggest we are rapidly approaching the reactivity/stability limit for Cyclooctyne reagents. The results contained within Chapters 7-9 indicated that it was time to explore other bioorthogonal chemistries. When embarking on the development of a new bioorthogonal chemical reaction, we aimed to explore unrepresented reactivity space, such that the new reaction would be orthogonal to existing bioorthogonal chemistries. We became attracted to the highly strained hydrocarbon quadricyclane and performed a screen to find a suitable reactive partner for this potential chemical reporter group (Chapter 10). Through this analysis, we discovered that quadricyclane cleanly reacts with Ni bis(dithiolene) reagents and this transformation appeared to be a good prototype for a new bioorthogonal chemical reaction. After a thorough mechanistic investigation and many rounds of modification to the Ni bis(dithiolene) species, a nickel complex with suitable reaction kinetics, water-solubility, and stability was obtained (Chapter 11). Gratifyingly, this Ni bis(dithiolene) reagent selectively modified quadricyclane-labeled bovine serum albumin, even in the presence of cell lysate (Chapter 12). Other results in Chapter 12 highlight that this new bioorthogonal ligation reaction is indeed orthogonal to Cu-free click chemistry as well as oxime ligation chemistry. Additionally, quadricyclane-dependent labeling is observed on live cells, although further optimization is necessary.The final chapter of this dissertation outlines the current state of the field. There are now many methods to modify biomolecules including several new, although relatively untested, bioorthogonal chemistries. The rapid pace of this field makes it an exciting time to be pursuing bioorthogonal chemistry.
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DifluorobenzoCyclooctyne: Synthesis, Reactivity, and Stabilization by β-Cyclodextrin
Journal of the American Chemical Society, 2010Co-Authors: Ellen M. Sletten, John C. Jewett, Hitomi Nakamura, Carolyn R BertozziAbstract:Highly reactive Cyclooctynes have been sought as substrates for Cu-free cycloaddition reactions with azides in biological systems. To elevate the reactivities of Cyclooctynes, two strategies, LUMO lowering through propargylic fluorination and strain enhancement through fused aryl rings, have been explored. Here we report the facile synthesis of a difluorobenzoCyclooctyne (DIFBO) that combines these modifications. DIFBO was so reactive that it spontaneously trimerized to form two asymmetric products that we characterized by X-ray crystallography. However, we were able to trap DIFBO by forming a stable inclusion complex with β-cyclodextrin in aqueous media. This complex could be stored as a lyophilized powder and then dissociated in organic solvents to produce free DIFBO for in situ kinetic and spectroscopic analysis. Using this procedure, we found that the rate constant for the cycloaddition reaction of DIFBO with an azide exceeds those for difluorinated Cyclooctyne (DIFO) and dibenzoCyclooctyne (DIBO). Cyclodextrin complexation is therefore a promising approach for stabilizing compounds that possess the high intrinsic reactivities desired for Cu-free click chemistry.
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Copper-free click chemistry in living animals
Proceedings of the National Academy of Sciences, 2010Co-Authors: P. V. Chang, A Lo, I A Miller, Ellen M. Sletten, Jeremy M Baskin, Nicholas J Agard, Jennifer A. Prescher, Carolyn R BertozziAbstract:Chemical reactions that enable selective biomolecule labeling in living organisms offer a means to probe biological processes in vivo. Very few reactions possess the requisite bioorthogonality, and, among these, only the Staudinger ligation between azides and triarylphosphines has been employed for direct covalent modification of biomolecules with probes in the mouse, an important model organism for studies of human disease. Here we explore an alternative bioorthogonal reaction, the 1,3-dipolar cycloaddition of azides and Cyclooctynes, also known as "Cu-free click chemistry," for labeling biomolecules in live mice. Mice were administered peracetylated N-azidoacetylmannosamine (Ac(4)ManNAz) to metabolically label cell-surface sialic acids with azides. After subsequent injection with Cyclooctyne reagents, glycoconjugate labeling was observed on isolated splenocytes and in a variety of tissues including the intestines, heart, and liver, with no apparent toxicity. The Cyclooctynes tested displayed various labeling efficiencies that likely reflect the combined influence of intrinsic reactivity and bioavailability. These studies establish Cu-free click chemistry as a bioorthogonal reaction that can be executed in the physiologically relevant context of a mouse.
F.l. Van Delft - One of the best experts on this subject based on the ideXlab platform.
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Strain-Promoted Oxidation-Controlled Cyclooctyne–1,2-Quinone Cycloaddition (SPOCQ) for Fast and Activatable Protein Conjugation
Bioconjugate chemistry, 2015Co-Authors: Annika Borrmann, Jan Dommerholt, O. Fatunsin, Anika M. Jonker, Dennis W. P. M. Löwik, J.c.m. Van Hest, F.l. Van DelftAbstract:A main challenge in the area of bioconjugation is to devise reactions that are both activatable and fast. Here, we introduce a temporally controlled reaction between Cyclooctynes and 1,2-quinones, induced by facile oxidation of 1,2-catechols. This so-called strain-promoted oxidation-controlled Cyclooctyne–1,2-quinone cycloaddition (SPOCQ) shows a remarkably high reaction rate when performed with bicyclononyne (BCN), outcompeting the well-known cycloaddition of azides and BCN by 3 orders of magnitude, thereby allowing a new level of orthogonality in protein conjugation.
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strain promoted oxidation controlled Cyclooctyne 1 2 quinone cycloaddition spocq for fast and activatable protein conjugation
Bioconjugate Chemistry, 2015Co-Authors: Annika Borrmann, Jan Dommerholt, O. Fatunsin, Anika M. Jonker, Dennis W. P. M. Löwik, J.c.m. Van Hest, F.l. Van DelftAbstract:A main challenge in the area of bioconjugation is to devise reactions that are both activatable and fast. Here, we introduce a temporally controlled reaction between Cyclooctynes and 1,2-quinones, induced by facile oxidation of 1,2-catechols. This so-called strain-promoted oxidation-controlled Cyclooctyne–1,2-quinone cycloaddition (SPOCQ) shows a remarkably high reaction rate when performed with bicyclononyne (BCN), outcompeting the well-known cycloaddition of azides and BCN by 3 orders of magnitude, thereby allowing a new level of orthogonality in protein conjugation.
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Biomolecular patterning of glass surfaces via strain-promoted cycloaddition of azides and Cyclooctynes
RSC Advances, 2014Co-Authors: Marloes A. Wijdeven, Annika Borrmann, Carlo Nicosia, Jurriaan Huskens, F.l. Van DelftAbstract:Metal-free, strain-promoted alkyne–azide cycloaddition (SPAAC) is employed as a versatile technology for the modification of glass with biomolecules. Patterning is executed by stamping of a fluorogenic azidocoumarin or a Cyclooctyne to the glass surface, to obtain a unique anchor point for subsequent functionalization by SPAAC. The azidocoumarin at the same time enables straightforward fluorescent read-out of surface reactions. A strong increase in fluorescence is indeed observed upon metal-free reaction with two readily available Cyclooctynes, BCN or DIBAC. In addition, functionalized BCN derivatives are employed for glass surface patterning with biotin or even a 27 kDa protein (green fluorescent protein), upon simple incubation.
H. V. Rasika Dias - One of the best experts on this subject based on the ideXlab platform.
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Coordination and Ligand Substitution Chemistry of Bis(Cyclooctyne)copper(I)
Organometallics, 2014Co-Authors: Animesh Das, Chandra Kanta Dash, Muhammed Yousufuddin, H. V. Rasika DiasAbstract:Cationic bis(alkyne)copper(I) carbonyl and bis(alkyne)copper(I) isocyanide complexes have been synthesized from the precursor (Cyclooctyne)2CuBr. [Cu(Cyclooctyne)2(CO)][SbF6] and [Cu(Cyclooctyne)2(CNtBu)][SbF6] have trigonal-planar and three-coordinate copper centers. The copper carbonyl complex [Cu(Cyclooctyne)2(CO)][SbF6] displays its C–O stretching frequency in the “nonclassical” metal carbonyl region (2171 cm–1), and the analogous copper(I) isocyanide complex [Cu(Cyclooctyne)2(CNtBu)][SbF6] also has an unusually high CN stretching band at 2230 cm–1. The reaction of 3,5-Me2C6H3NH2 and 4-tBuC6H4NH2 with [Cu(Cyclooctyne)2(CO)][SbF6] led to CO displacement rather than addition to CO. CNtBu reacts with [Cu(Cyclooctyne)2(CO)][SbF6] to afford [Cu(Cyclooctyne)2(CNtBu)][SbF6]. The syntheses of [Cu(Cyclooctyne)(CNtBu)2][SbF6] and [Cu(CNtBu)4][SbF6] from the (Cyclooctyne)2CuBr precursor are also reported.
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Tris(alkyne) and Bis(alkyne) Complexes of Coinage Metals: Synthesis and Characterization of (Cyclooctyne)3M+ (M = Cu, Ag) and (Cyclooctyne)2Au+ and Coinage Metal (M = Cu, Ag, Au) Family Group Trends
Organometallics, 2013Co-Authors: Animesh Das, Chandra Kanta Dash, Muhammed Yousufuddin, Mehmet Ali Celik, Gernot Frenking, H. V. Rasika DiasAbstract:The tris(alkyne) copper complex [(Cyclooctyne)3Cu][SbF6] has been synthesized using Cyclooctyne and in situ generated CuSbF6. Tris(alkyne) silver complexes [(Cyclooctyne)3Ag]+ involving weakly coordinating counterions such as [SbF6]− and [PF6]− have also been isolated in good yield using Cyclooctyne and commercially available AgSbF6 and AgPF6. These coinage metal tris(alkyne) adducts have trigonal-planar metal sites. The alkyne carbon atoms and the metal site form distorted spoke-wheel (rather than upright trigonal-prismatic) structures in the solid state. In [(Cyclooctyne)3Cu][SbF6], these distortions result in a propeller-like arrangement of alkynes. A cationic gold(I) complex having two alkynes has been prepared by a reaction of equimolar amounts of Au(Cyclooctyne)2Cl and AgSbF6 in dichloromethane. The gold atom of [(Cyclooctyne)2Au]+ coordinates to the Cyclooctynes in a linear fashion, while the carbon atoms of the alkyne groups form a tetrahedron around gold(I). Optimized geometries of cationic [(cyc...
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End-on and side-on π-acid ligand adducts of gold(I): carbonyl, cyanide, isocyanide, and Cyclooctyne gold(I) complexes supported by N-heterocyclic carbenes and phosphines.
Inorganic chemistry, 2012Co-Authors: Mehmet Ali Celik, Chandra Kanta Dash, Muhammed Yousufuddin, Gernot Frenking, Animesh Das, Venkata A. K. Adiraju, H. V. Rasika DiasAbstract:N-Heterocyclic carbene ligand SIDipp (SIDipp = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) and trimesitylphosphine ligand have been used in the synthesis of gold(I) cyanide, t-butylisocyanide, and Cyclooctyne complexes (SIDipp)Au(CN) (3), (Mes3P)Au(CN) (4), [(Mes3P)2Au][Au(CN)2] (5), [(SIDipp)Au(CNtBu)][SbF6] ([6][SbF6]), [(SIDipp)Au(Cyclooctyne)][SbF6] ([8][SbF6]), and [(Mes3P)Au(Cyclooctyne)][SbF6] ([9][SbF6]). A detailed computational study has been carried out on these and the related gold(I) carbonyl adducts [(SIDipp)Au(CO)][SbF6] ([1][SbF6]), [(Mes3P)Au(CO)][SbF6] ([2][SbF6]), and [(Mes3P)Au(CNtBu)]+ ([7]+). X-ray crystal structures of 3, 5, [6][SbF6], [8][SbF6], and [9][SbF6] revealed that they feature linear gold sites. Experimental and computational data show that the changes in π-acid ligand on (SIDipp)Au+ from CO, CN–, CNtBu, Cyclooctyne as in [1]+, 3, [6]+, and [8]+ did not lead to large changes in the Au–Ccarbene bond distances. A similar phenomenon was also observed in Au–P distance ...
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Isolable tris(alkyne) and bis(alkyne) complexes of gold(I).
Angewandte Chemie, 2012Co-Authors: Chandra Kanta Dash, Muhammed Yousufuddin, Mehmet Ali Celik, Gernot Frenking, H. V. Rasika DiasAbstract:: Golden trefoils: Tris(alkyne)gold complex [(coct)(3)Au][SbF(6)] (see picture; 1-SbF(6)) can be synthesized from Cyclooctyne (coct) and AuSbF(6) generated in situ. Treatment of AuCl with Cyclooctyne led to the bis(alkyne)gold complex [Au(coct)(2)Cl] (2). DFT analysis indicates that the Cyclooctyne ligands are net electron donors in 1 but overall electron acceptors in 2. AuSbF(6) is shown to mediate [2+2+2] cycloaddition reactions of alkynes.
Animesh Das - One of the best experts on this subject based on the ideXlab platform.
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Coordination and Ligand Substitution Chemistry of Bis(Cyclooctyne)copper(I)
Organometallics, 2014Co-Authors: Animesh Das, Chandra Kanta Dash, Muhammed Yousufuddin, H. V. Rasika DiasAbstract:Cationic bis(alkyne)copper(I) carbonyl and bis(alkyne)copper(I) isocyanide complexes have been synthesized from the precursor (Cyclooctyne)2CuBr. [Cu(Cyclooctyne)2(CO)][SbF6] and [Cu(Cyclooctyne)2(CNtBu)][SbF6] have trigonal-planar and three-coordinate copper centers. The copper carbonyl complex [Cu(Cyclooctyne)2(CO)][SbF6] displays its C–O stretching frequency in the “nonclassical” metal carbonyl region (2171 cm–1), and the analogous copper(I) isocyanide complex [Cu(Cyclooctyne)2(CNtBu)][SbF6] also has an unusually high CN stretching band at 2230 cm–1. The reaction of 3,5-Me2C6H3NH2 and 4-tBuC6H4NH2 with [Cu(Cyclooctyne)2(CO)][SbF6] led to CO displacement rather than addition to CO. CNtBu reacts with [Cu(Cyclooctyne)2(CO)][SbF6] to afford [Cu(Cyclooctyne)2(CNtBu)][SbF6]. The syntheses of [Cu(Cyclooctyne)(CNtBu)2][SbF6] and [Cu(CNtBu)4][SbF6] from the (Cyclooctyne)2CuBr precursor are also reported.
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tris alkyne and bis alkyne complexes of coinage metals synthesis and characterization of Cyclooctyne 3m m cu ag and Cyclooctyne 2au and coinage metal m cu ag au family group trends
Organometallics, 2013Co-Authors: Animesh Das, Chandra Kanta Dash, Muhammed Yousufuddin, Mehmet Ali Celik, Gernot Frenking, H Rasika V DiasAbstract:The tris(alkyne) copper complex [(Cyclooctyne)3Cu][SbF6] has been synthesized using Cyclooctyne and in situ generated CuSbF6. Tris(alkyne) silver complexes [(Cyclooctyne)3Ag]+ involving weakly coordinating counterions such as [SbF6]− and [PF6]− have also been isolated in good yield using Cyclooctyne and commercially available AgSbF6 and AgPF6. These coinage metal tris(alkyne) adducts have trigonal-planar metal sites. The alkyne carbon atoms and the metal site form distorted spoke-wheel (rather than upright trigonal-prismatic) structures in the solid state. In [(Cyclooctyne)3Cu][SbF6], these distortions result in a propeller-like arrangement of alkynes. A cationic gold(I) complex having two alkynes has been prepared by a reaction of equimolar amounts of Au(Cyclooctyne)2Cl and AgSbF6 in dichloromethane. The gold atom of [(Cyclooctyne)2Au]+ coordinates to the Cyclooctynes in a linear fashion, while the carbon atoms of the alkyne groups form a tetrahedron around gold(I). Optimized geometries of cationic [(cyc...
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Tris(alkyne) and Bis(alkyne) Complexes of Coinage Metals: Synthesis and Characterization of (Cyclooctyne)3M+ (M = Cu, Ag) and (Cyclooctyne)2Au+ and Coinage Metal (M = Cu, Ag, Au) Family Group Trends
Organometallics, 2013Co-Authors: Animesh Das, Chandra Kanta Dash, Muhammed Yousufuddin, Mehmet Ali Celik, Gernot Frenking, H. V. Rasika DiasAbstract:The tris(alkyne) copper complex [(Cyclooctyne)3Cu][SbF6] has been synthesized using Cyclooctyne and in situ generated CuSbF6. Tris(alkyne) silver complexes [(Cyclooctyne)3Ag]+ involving weakly coordinating counterions such as [SbF6]− and [PF6]− have also been isolated in good yield using Cyclooctyne and commercially available AgSbF6 and AgPF6. These coinage metal tris(alkyne) adducts have trigonal-planar metal sites. The alkyne carbon atoms and the metal site form distorted spoke-wheel (rather than upright trigonal-prismatic) structures in the solid state. In [(Cyclooctyne)3Cu][SbF6], these distortions result in a propeller-like arrangement of alkynes. A cationic gold(I) complex having two alkynes has been prepared by a reaction of equimolar amounts of Au(Cyclooctyne)2Cl and AgSbF6 in dichloromethane. The gold atom of [(Cyclooctyne)2Au]+ coordinates to the Cyclooctynes in a linear fashion, while the carbon atoms of the alkyne groups form a tetrahedron around gold(I). Optimized geometries of cationic [(cyc...
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End-on and side-on π-acid ligand adducts of gold(I): carbonyl, cyanide, isocyanide, and Cyclooctyne gold(I) complexes supported by N-heterocyclic carbenes and phosphines.
Inorganic chemistry, 2012Co-Authors: Mehmet Ali Celik, Chandra Kanta Dash, Muhammed Yousufuddin, Gernot Frenking, Animesh Das, Venkata A. K. Adiraju, H. V. Rasika DiasAbstract:N-Heterocyclic carbene ligand SIDipp (SIDipp = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) and trimesitylphosphine ligand have been used in the synthesis of gold(I) cyanide, t-butylisocyanide, and Cyclooctyne complexes (SIDipp)Au(CN) (3), (Mes3P)Au(CN) (4), [(Mes3P)2Au][Au(CN)2] (5), [(SIDipp)Au(CNtBu)][SbF6] ([6][SbF6]), [(SIDipp)Au(Cyclooctyne)][SbF6] ([8][SbF6]), and [(Mes3P)Au(Cyclooctyne)][SbF6] ([9][SbF6]). A detailed computational study has been carried out on these and the related gold(I) carbonyl adducts [(SIDipp)Au(CO)][SbF6] ([1][SbF6]), [(Mes3P)Au(CO)][SbF6] ([2][SbF6]), and [(Mes3P)Au(CNtBu)]+ ([7]+). X-ray crystal structures of 3, 5, [6][SbF6], [8][SbF6], and [9][SbF6] revealed that they feature linear gold sites. Experimental and computational data show that the changes in π-acid ligand on (SIDipp)Au+ from CO, CN–, CNtBu, Cyclooctyne as in [1]+, 3, [6]+, and [8]+ did not lead to large changes in the Au–Ccarbene bond distances. A similar phenomenon was also observed in Au–P distance ...
