Silver Trifluoroacetate Research Articles

Coordination Assemblies of Acetylenic Dithioether Ligands on Silver(I) Salts: Crystal Structure, Antibacterial and Cytotoxicity Activities.

Coordination polymers (CPs) and metal-organic frameworks (MOFs) constitute a new class of antibacterial materials. Interest in them stems from their wide range of topology, dimensionality, and secondary building units that can be tuned by an appropriate choice of metal ions and ligands. In particular, silver-based species feature good antibacterial properties. In this study, we explored the coordination of three acetylenic dithioether RSCH2C≡CCH2SR [R = phenyl (LPh), cyclohexyl (LCy), or tert-butyl (LtBu)] ligands on several silver salts (silver tosylate, silver triflate, and silver trifluoroacetate). The crystallographic characterization evidenced the formation of a molecular macrocycle and six CPs with different dimensionalities, ranging from one to two dimensions. In most cases, they are composed of four-coordinated silver atoms in a tetrahedral environment. Their antibacterial activity was investigated against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. All CPs present good antibacterial properties against the tested bacteria with minimal inhibitory concentrations ranging from 5 to 40 μg of Ag/mL. Interestingly, we found that these values could not be correlated to their architecture or morphology or to the amount of silver released. The cytotoxicity of these compounds was also evaluated on normal human dermal fibroblasts, and three of these CPs were found to be biocompatible.

Heterophase Synthesis of Silver Trifluoroacetate with Copper, Indium, and Zinc. Standard Enthalpy of Formation of Copper Trifluoroacetate

Heterophase Synthesis of Silver Trifluoroacetate with Copper, Indium, and Zinc. Standard Enthalpy of Formation of Copper Trifluoroacetate

Heterophase Synthesis of Silver Trifluoroacetate with Copper, Indium, and Zinc. Standard Enthalpy of Formation of Copper Trifluoroacetate

Solid-phase reactions of silver trifluoroacetate CF3COOAg with copper, indium, and zinc are studied by thermogravimetry, differential scanning calorimetry, and mass spectrometry. In a temperature range of 358–428 K, the reactions are found to afford trifluoroacetates of these metals without mass loss of the weighed samples. The obtained experimental data make it possible to calculate the enthalpy of formation of copper trifluoroacetate H298 (CF3СООСu, cr) = –1020.5 ± 18.0 kJ/mol.

Analysis of polyisoprene oligomers via in situ silver nanoparticle formation on thin-layer chromatography plate using matrix-assisted laser-induced desorption/ionization mass spectrometry.

The direct mass spectrometry (MS) detection of polyisoprene (PI) oligomers on a thin-layer chromatography (TLC) plate using matrix-assisted laser-induced desorption/ionization (MALDI) with silver trifluoroacetate as the cationization reagent was investigated. The spots of PI oligomers and silver trifluoroacetate on the TLC plate resulted in brown materials after UV laser irradiation. It was suggested that silver trifluoroacetate yielded Ag nanoparticles as brown materials after heating via laser irradiation. The nanoparticles behaved as an inorganic matrix and a source of Ag+ adduct in the analysis of PI oligomers. The use of organic matrices together with silver trifluoroacetate reduced the signal intensity of PI oligomers on MALDI-MS on a TLC plate. The separation of PI oligomers (polymerization degree, n = 5-11) by TLC resulted in a single elliptical spot without a clear separation after the chromatographic procedure. However, in MS imaging, differences in migration lengths based on degrees of polymerization were clearly observed and the degrees of polymerization were identified without comparison with standards.

Solvent-Dependent Self-Assembly of a Pillar[5]arene-Based Poly-Pseudo-Rotaxane Linked and Threaded by Silver(I) Trifluoroacetate: A Double Role

In the supramolecule area, the fabrication of a new concept called polyrotaxanes or poly-pseudo-rotaxanes remains challenging. We herein report the formation of a poly-pseudo-rotaxane in which the same salt-type guest serves both linking and threading in the resulting structure. The combination of A1/A2-thiopyridyl pillar[5]arene (L) and silver(I) trifluoroacetate in CHCl3/CH3OH afforded a one-dimensional (1D) poly-pseudo-rotaxane. In this structure, to our surprise, the AgCF3CO2 guest not only links the di-armed L ligands via an infinite -L-Ag-L-Ag- arrangement but also threads into a pillar[5]arene cavity in a dimer form, (AgCF3CO2)2. In contrast, the same reaction in CH2Cl2/CH3OH yielded a simple 1D coordination polymer because an included CH2Cl2 molecule in the pillar[5]arene cavity prevents the threading of the silver(I) trifluoroacetate guest. Comparative 1H- and 19F-NMR studies support the solvent-dependent poly-pseudo-rotaxane formation at a lower concentration of L.

Handcuff-like metallo-pseudorotaxanes consisting of tiara[5]arene wheels and dimeric silver trifluoroacetate axles.

The complexation between tiara[5]arene (T[5]) and silver trifluoroacetate affords a binuclear metallo-pseudorotaxane on account of multiple endo-cavity AgI η2-arene interactions. Furthermore, two such enantiomeric [(CF3CO2Ag)2⊂T[5]] complexes are bridged by an extra (CF3CO2Ag)2 dimer through exo-wall AgI η2-arene coordination, resulting in a unique handcuff metallo-bis-pseudorotaxane structure in the solid state.

Silver trifluoroacetate as a bifunctional reagent for palladium-catalyzed oxidative carbonylative [4 + 1] annulation of aromatic acids

AgTFA is disclosed as a bifunctional reagent, i.e. unprecedented in-situ CO source and oxidant in oxidative carbonylative annulation. The simple operation enables silver to be recovered easily and make AgTFA superior to other transition-metal carbonyl agents.

Tetrapyridineplatinum(II) Carboxylates: Synthesis and Crystal Structure

A series of mono- and bimetallic cation-anionic complexes based on the [PtPy4]2+ cation with different single-charge anions of carboxylic acids (RCOO–) is synthesized and structurally characterized. A synthetic approach to the preparation of tetrapyridineplatinum complexes [PtPy4]2+ soluble in polar solvents from available reagents is developed. The reaction of tetrapyridineplatinum dichloride [PtPy4](Cl)2 with silver acetate or trifluoroacetate affords compounds [PtPy4](OOCMe)2·6H2O (I) and [PtPy4](OOCCF3)2· 2H2O (II) in the form of crystalline hydrates (CIF files CCDC nos. 2161100 and 2161101, respectively) in high yields. Other carboxylates can be prepared by the treatment of compound I with an excess of a stronger acid, for example, trifluoroacetic acid, with the formation of the corresponding complex trifluoroacetate [PtPy4](OOCCF3)2·4CF3COOH (IIa) (CIF file CCDC no. 2161102). Another method consists of the displacement of acetic acid with an excess of a lowly volatile acid, for example, pivalic acid, when [PtPy4](Piv)2· 5HPiv (III) is formed from the acid melt, and solvatomorph [PtPy4](Piv)2·4HPiv·3C6H12 (IIIa) (CIF files CCDC nos. 2161103 and 2161104, respectively) is formed in a cyclohexane medium. Heteroanionic heterometallic complex [PtPy4](OOCFc)(OOCMe) (IV) (CIF file CCDC no. 2161105) is shown to be formed by the reaction of complex I with ferrocenecarboxylic acid under mild conditions.

Silver(I) trifluoroacetate complexes with n-allylic derivatives of quinoline and isoquinoline: synthesis and crystal structure

Silver(I) trifluoroacetate complexes with n-allylic derivatives of quinoline and isoquinoline: synthesis and crystal structure

Imaging Analysis of Phosphatidylcholines and Diacylglycerols Using Surface-Assisted Laser Desorption/Ionization Mass Spectrometry with Metal Film Formed by Mist Chemical Vapor Deposition.

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) has been widely used for analyses of biomolecules and industrial materials. Surface-assisted laser desorption/ionization (SALDI) is studied to complement the ionization ability for the MALDI/MS. In this study, lab-made mist chemical vapor deposition (mist CVD) system was used to produce metal films as ionization assistance materials for SALDI/MS. The system could give Ag film from inexpensive silver trifluoroacetate solution rapidly and simply under atmospheric pressure. Phosphatidylcholines could be detected high sensitively and diacylglycerols (DAGs) could not be detected in MALDI/MS. In the SALDI/MS and the MS imaging with Ag film by mist CVD, both the phosphatidylcholines and the DAGs could be detected and the localized images. In the Ag film-SALDI/MS of lipids, not only Ag-adducted ions but also Na- and K-adducted ions were detected. The Ag film formed by the mist CVD to act as an ionization-assistance material and a cationization agent in SALDI would be useful in MS imaging of biological tissue sections.

"Rim-Differentiated" Pillar[6]arenes.

A "rim-differentiated" pillar[6]arene (RD-P[6]) was obtained successfully, with the assistance of a dimeric silver trifluoroacetate template, among eight different constitutional isomers in a direct and regioselective manner. The solid-state conformation of this macrocycle could switch from the 1,3,5-alternate to a truly rim-differentiated one upon guest inclusion. This highly symmetric RD-P[6] not only hosts metal-containing molecules inside its cavity, but also can form a pillar[6]arene-C60 adduct through co-crystallization on account of donor-acceptor interactions. The development of synthetic strategies to desymmetrize pillararenes offers new opportunities for engineering complex molecular architectures and organic electronic materials.

“Rim‐Differentiated” Pillar[6]arenes

AbstractA “rim‐differentiated” pillar[6]arene (RD‐P[6]) was obtained successfully, with the assistance of a dimeric silver trifluoroacetate template, among eight different constitutional isomers in a direct and regioselective manner. The solid‐state conformation of this macrocycle could switch from the 1,3,5‐alternate to a truly rim‐differentiated one upon guest inclusion. This highly symmetric RD‐P[6] not only hosts metal‐containing molecules inside its cavity, but also can form a pillar[6]arene‐C60 adduct through co‐crystallization on account of donor‐acceptor interactions. The development of synthetic strategies to desymmetrize pillararenes offers new opportunities for engineering complex molecular architectures and organic electronic materials.

Ortho-Deuteration of Aromatic Aldehydes via a Transient Directing Group-Enabled Pd-Catalyzed Hydrogen Isotope Exchange.

A practical and scalable ortho-selective deuteration of aromatic aldehydes was accomplished by Pd-catalyzed hydrogen isotope exchange with deuterium oxide as an inexpensive deuterium source. The use of tert-leucine as a transient directing group facilitates the exchange, affording a wide range of ortho-deuterated aromatic aldehydes with deuterium incorporation up to 97%. The control experiments suggest that the addition of silver trifluoroacetate resists the unexpected reduction of Pd(II), while the theoretical study indicates a rapid reversible concerted metalation-deprotonation process.

Optimized MALDI-TOF MS Strategy for Characterizing Polymers.

In recent years, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) plays an essential role in the analysis of polymers. To acquire a more reliable strategy for polymer profiling, we characterized four representative polymers including polyethylene glycol 6000, polyvinylpyrrolidone K12, polymer polyol KPOP-5040, and polyether polyol DL-4000. The preparation methods of these four polymer samples have been optimized from six aspects, including matrix, cationization reagent, solvent, mixing ratio of cationization reagent to polymer, mixing ratio of matrix to polymer, and laser intensity. After investigating the effects of seven commonly used matrices on the ionization efficiency of four polymers, trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene] malononitrile (DCTB) was found to be the only matrix suitable for the analysis of all the four polymers. Our experimental results suggested that different polymers showed a certain preference for different cationization reagents. For example, the polymer polyol KPOP-5040 was suitable for sodium iodide as the cationization reagent, while polyvinylpyrrolidone K12 was more suitable for silver trifluoroacetate (AgTFA). For the choice of solvent, tetrahydrofuran is a reagent with rapid evaporation and a wide range of dissolution which can achieve the best results for the analysis of four polymers. The optimized method was successfully applied to the identification of DSPE-PEG-NH2 with different polymerized degrees. This MALDI-TOF strategy potentially provided the supplementary function through the polymer’s application in biomedical and visible probing.

Evaluation of halogen chain-end functionality in 2-bromo-2-methylpropanoate esters of poly(oxyalkylene) polymers by MALDI-TOF spectroscopy

Esters of 2-bromo-2-methylpropanoate of poly(oxyalkylene) polymers such as poly(ethylene glycol) or α-methyl poly(ethylene glycol) were prepared in high yields and characterized by spectroscopic and chromatographic methods (NMR, FT-IR, mass spectroscopy and SEC). The halogen chain-end group in the poly(oxyalkylene) bromine-terminated esters were characterized by MALDI-TOF MS. The effect of the solvents (methanol or tetrahydrofuran) and the cationic agents such as silver trifluoroacetate (AgTFA), silver trifluoromethanesulfonate (AgTFS) and sodium trifluoroacetate (NaTFA) on the mass spectra was studied. Analysis of the mass spectra demonstrated that the analyte was transformed to unsaturated (elimination), alkoxy or hydroxyl end groups (substitution) molecules when silver cationic agents were used, these results were also supported by 1H NMR study. When sodium salt was used as a cationic agent, well-defined bromine-terminated macromolecules were successfully determined through MALDI-TOF MS. Well characterized esters of 2-bromo-2-methylpropanoate of poly(oxyalkylene) polymers could be used as ATRP macroinitiators for the synthesis of a variety of polymeric architectures of interest as drug delivery bioconjugates.

Silver(I)-Mediated Cascade Reaction of 2-(1-Alkynyl)-2-alken-1-ones with 2-Naphthols

An efficient cascade reaction of 2-(1-alkynyl)-2-alken-1-ones with 2-naphthols promoted by silver trifluoroacetate is disclosed, providing an expeditious access to 1,2-dihydronaphtho[2,1-b]furans with moderate to good yields. This domino process involves highly regio- and diastereoselective sequential cyclization/nucleophilic addition/oxidative ring opening/oxa-Michael addition reactions to construct three new chemical bonds and one new five-membered ring. A gram-scale experiment and the preliminary results to develop an asymmetric variant are also presented to show the practicality and potential of the current reaction.

Silver-Catalyzed Trifluoromethylalkynylation of Unactivated Alkenes with Hypervalent Iodine Reagents.

A catalytic method for the trifluoromethylalkynylation of unactivated alkenes is presented. The reaction is catalyzed by silver(I) trifluoroacetate for the simultaneous construction of two C-C bonds (alkyl-alkyne and alkyl-CF3). By employing versatile hypervalent iodine reagents, ethynylbenziodoxolones, useful trifluoromethylalkynylated compounds can be prepared from simple alkenes displaying excellent functional group tolerability. A radical mechanism is proposed with supporting evidence, providing a new entry to silver(I)-catalyzed trifluoromethylation reactions.

Formation of a Pillar[5]arene‐Based Two‐Dimensional Poly‐Pseudo‐Rotaxane: Threading and Crosslinking by the Same Guest Molecules

AbstractA one‐pot reaction of the A1/A2‐thiopyridyl pillar[5]arene L with silver(I) trifluoroacetate in the presence of the linear dinitrile guest C8, [CN(CH2)nCN, n=8], afforded the first example of a two‐dimensional (2D) poly‐pseudo‐rotaxane {[(μ4‐Ag)2(C8@L)2(μ‐C8)](CF3CO2)2}n. Surprisingly, in this structure the C8 guest not only threads into the pillar[5]arene unit but also crosslinks the 1D coordinative polymeric arrays. The formation of the 2D poly‐pseudo‐rotaxane is driven by an adaptive rearrangement of the components that minimizes the steric clashes not only between the threaded guests but also between the threaded and crosslinked guests where crosslinking occurs. A pathway for the formation of the 2D poly‐pseudo‐rotaxane is proposed.

Formation of a Pillar[5]arene-Based Two-Dimensional Poly-Pseudo-Rotaxane: Threading and Crosslinking by the Same Guest Molecules.

A one-pot reaction of the A1/A2-thiopyridyl pillar[5]arene L with silver(I) trifluoroacetate in the presence of the linear dinitrile guest C8, [CN(CH2 )n CN, n=8], afforded the first example of a two-dimensional (2D) poly-pseudo-rotaxane {[(μ4 -Ag)2 (C8@L)2 (μ-C8)](CF3 CO2 )2 }n . Surprisingly, in this structure the C8 guest not only threads into the pillar[5]arene unit but also crosslinks the 1D coordinative polymeric arrays. The formation of the 2D poly-pseudo-rotaxane is driven by an adaptive rearrangement of the components that minimizes the steric clashes not only between the threaded guests but also between the threaded and crosslinked guests where crosslinking occurs. A pathway for the formation of the 2D poly-pseudo-rotaxane is proposed.

An Approach to the 9-Oxo-10-oxabicyclo[5.3.0]dec-2-ene Core of the Guaianolide and Pseudoguaianolide Sesquiterpenes via a Domino Electrocyclic Ring-Opening/Carboxylic Acid Trapping of a gem-Dibromocyclopropane.

A domino silver(I)-promoted electrocyclic 2π-disrotatory electrocyclic ring-opening/intramolecular nucleophilic trapping of [ n.1.0]-dibromocyclopropanes by tethered carboxylic acids results in cyclization to butyrolactones fused to six- and seven-membered carbocycles. In the case of bicyclic [4.3.0] lactones the cis-fused stereoisomer was formed, whereas for the bicyclic [5.3.0] lactones the trans-fused stereoisomer was formed. Optimal conditions for the reaction used silver(I) trifluoroacetate (2.0 equiv) in trifluoroethanol or with added pyridine (2.0 equiv) and NaPF6 (5.0 equiv). The dibromocyclopropane precursors were made through cyclopropanation with in situ-generated dibromocarbene. The trans-fused lactones are potentially useful building blocks for pseudoguaianolide, guaianolide, and xanthanolide total synthesis. A computational study on the conformational preferences of these systems indicates that the trans-fused bicyclic [5.3.0] butyrolactones are lower in energy than the corresponding cis-fused lactones at the B3LYP/cc-pVTZ level of theory.