36207-44-0Relevant academic research and scientific papers
Production of hydroxamic acids by immobilized Pseudomonas aeruginosa cells: Kinetic analysis in reverse micelles
Bernardo, Marisa,Pacheco, Rita,Serralheiro, Maria Luisa M.,Karmali, Amin
, p. 28 - 33 (2013/07/19)
Intact cells from Pseudomonas aeruginosa strain L10 containing amidase were used as biocatalysts both free and immobilized in a reverse micellar system. The apparent kinetic constants for the transamidation reaction in hydroxamic acids synthesis, were determined using substrates such as aliphatic, amino acid and aromatic amides and esters, in both media. In reverse micelles, K m values decreased 2-7 fold relatively to the free biocatalyst using as substrates acetamide, acrylamide, propionamide and glycinamide ethyl ester. We have concluded that overall the affinity of the biocatalyst to each substrate increases when reactions are performed in the reversed micellar system as opposed to the buffer system. The immobilized biocatalyst in general, exhibits higher stability and faster rates of reactions at lower substrates concentration relatively to the free form, which is advantageous. Additionally, the immobilization revealed to be suitable for obtaining the highest yields of hydroxamic acids derivatives, in some cases higher than 80%.
Influencing the size and anion selectivity of dimeric Ln 3+[15-Metallacrown-5] compartments through systematic variation of the host side chains and central metal
Jankolovits, Joseph,Lim, Choong-Sun,Mezei, Gellert,Kampf, Jeff W.,Pecoraro, Vincent L.
experimental part, p. 4527 - 4538 (2012/05/20)
Dimeric Ln3+[15-metallacrown-5] compartments selectively recognize carboxylates through guest binding to host metal ions and intermolecular interactions with the phenyl side chains. A systematic study is presented on how the size, selectivity, and number of encapsulated guests in the dimeric containers is influenced by the Ln3+[15-metallacrown Cu(II)-5] ligand side chain and central metal. Compartments of varying heights were assembled from metallacrowns with S-phenylglycine hydroxamic acid (pgHA), S-phenylalanine hydroxamic acid (pheHA), and S-homophenylalanine hydroxamic acid (hpheHA) ligands. Guests that were examined include the fully deprotonated forms of terephthalic acid, isonicotinic acid, and bithiophene dicarboxylic acid (btDC). X-ray crystallography reveals that the side-chain length constrains the maximum and minimum length guest that can be encapsulated in the compartment. Compartments with heights ranging from 9.7 to 15.2 A are formed with different phenyl side chains that complex 4.3-9.2 A long guests. Up to five guests are accommodated in Ln 3+[15-metallacrownCu(II)-5] compartments depending on steric effects from the host side chains. The nine-coordinate La3+ central metal promotes the encapsulation of multiple guests, while the eight-coordinate Gd3+ typically binds only one dicarboxylate. Electrospray ionization mass spectrometry reveals that the dimerization phenomenon occurs beyond the solid state, suggesting that these containers can be utilized in solid-state and solution applications.
Amino acid derived amides and hydroxamic acids as ligands for asymmetric transfer hydrogenation in aqueous media
Ahlford, Katrin,Adolfsson, Hans
scheme or table, p. 1118 - 1121 (2012/01/15)
Amides and hydroxamic acids derived from α-amino acids were evaluated as ligands in combination with rhodium and iridium half-sandwich complexes in asymmetric transfer hydrogenation (ATH) of ketones. The reactions were performed in aqueous media using lithium formate as hydride source. The catalyst systems turned out to be highly efficient and ee's up to 90% were obtained.
Effects of the central lanthanide ion crystal radius on the 15-MCCu II(N)pheHA-5 structure
Zaleski, Curtis M.,Lim, Choong-Sun,Cutland-Van Noord, Annabel D.,Kampf, Jeff W.,Pecoraro, Vincent L.
experimental part, p. 7707 - 7717 (2011/10/18)
Twenty crystal structures of the LnIII[15-MC CuII(N)pheHA-5]3+ complex, where pheHA = phenylalanine hydroxamic acid and where LnIII = YIII and La III-TmIII, except PmIII, with the nitrate and/or hydroxide anion are used to assess the effect of the central metal ion on the metallacrown structure. Each LnIII[15-MCCuII(N)pheHA- 5]3+ complex is amphiphilic with a hydrophobic side consisting of the phenyl groups of the pheHA ligand and a side without the aromatic residues. Three general structures are observed for the LnIII[15-MC CuII(N)pheHA-5]3+ complexes. In the Type 1 structures, the central metal ion does not bind a nitrate anion on the metallacrown's hydrophobic face, and two adjacent metallacrowns dimerize through their phenyl groups producing a hydrophobic compartment. In the Type 2 structures, the central metal ion binds a nitrate in a bidentate fashion on the hydrophobic face. There are two distinct types of Type 2 metallacrowns, designated A and B. Type 2A metallacrowns have a water molecule bound to the central metal ion on the hydrophilic face, while Type 2B metallacrowns have a monodentate nitrate ion bound on the hydrophilic face to the central metal ion. The Type 2 metallacrowns also dimerize via the phenyl groups to form a hydrophobic compartment. In Type 3 structures, the central metal ion binds a nitrate in a bidentate fashion on the hydrophobic side, but instead of forming dimers, the metallacrowns pack in a helical arrangement to give either P or M one-dimensional helices. Regardless of the type of metallacrown, the overall trend observed is that as the LnIII ion crystal radius increases, the metallacrown cavity radius also increases while the metallacrown becomes more planar. This conclusion is demonstrated by a decrease in the oxime oxygen distances to the oxime oxygen mean plane and a decrease in the ring Cu II distances to the CuII mean plane as the metallacrown cavity radius increases and the lanthanide crystal radius increases. In addition, a decrease in the Ooxime-CuII-N oxime-Ooxime torsion (dihedral) angles is also observed as the metallacrown cavity radius and the lanthanide crystal radius both increase. These observations help explain the thermodynamic preferences for Ln III ions within this class of metallacrowns and may be used to design compartments capable of binding guests in different orientations within chiral, soft solids.
COMPOSITIONS AND METHODS FOR CYCLOFRUCTANS AS SEPARATION AGENTS
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Page/Page column 45-49; 60, (2010/12/31)
The present invention relates to derivatized cyclofructan compounds, compositions comprising derivatized cyclofructan compounds, and methods of using compositions comprising derivatized cyclofructan compounds for chromatographic separations of chemical species, including enantiomers. Said compositions may comprise a solid support and/or polymers comprising derivatized cyclofructan compounds.
Thermodynamics of core metal replacement and self-assembly of Ca 2+ 15-Metallacrown-5
Tegoni, Matteo,Furlotti, Michele,Tropiano, Manuel,Lim, Choong Sun,Pecoraro, Vincent L.
experimental part, p. 5190 - 5201 (2010/07/09)
The equilibria for core Ca2+ replacement by Ln3+ in copper(II) 15-MC-5 complexes have been investigated using a series of visible spectrophotometric titrations of calcium(II) metallacrowns ({Ca II[15-MCCuII(N)(L)-5]2+) with Ln3+ ions (H2L = pheha, (S)-α-phenylalaninehydroxamic acid, or trpha, (S)-α-tryptophanhydroxamic acid). These studies allowed the determination of the equilibrium constants for the reaction {Ca II[15-MCCuII(N)(L)-5]2+ + Ln3+ → {LnIII[15-MCCuII(N)(L)-5]3+ + Ca 2+ in methanol/water 9:1 (Ln3+ = La3+, Gd 3+, Dy3+, Er3+) or 99:1 (Ln3+ = La3+, Nd3+, Gd3+, Dy3+, Er 3+, Yb3+), respectively. The log K for these reactions decreases with increasing atomic number of the lanthanide(III), ranging from 6.1 to 3.91 in methanol/water 9:1. The same behavior is observed in methanol/water 99:1, although the constants are uniformly lower (log K = 4.09-2.52). A significant thermodynamic selectivity was observed for the later lanthanides (Gd3+-Yb3+) while a smaller selectivity is present throughout the beginning of the series (La3+-Gd3+). This observation has been interpreted on the basis of the size correspondence between the metal ions and the metallacrown cavity. The overall stability of the {CaII[15-MCCuII(N)(L)-5]2+ in methanol/water 9:1 has been determined by pH-spectrophotometric titrations with HCl. The resulting log K values are 63.46(12) and 65.05(13) for pheha and trpha, respectively (Ca2+ + 5Cu2+ + 5HL- = {Ca II[15-MCCuII(N)(L)-5]2+ +5H+). The stability of both the La3+ and Ca2+ 15-metallacrown-5 complexes in the presence of high Na+ concentrations has also been demonstrated by spectophotometric studies. Based upon these observations, the preference of the 15-MC-5 for Ca2+ complexation compared to crown ethers has been quantitatively demonstrated for the first time.
Design and evaluation of hydroxamate derivatives as metal-mediated inhibitors of a protein tyrosine kinase
Gu, Xianfeng,Wang, Yuehao,Kumar, Anil,Ye, Guofeng,Parang, Keykavous,Sun, Gongqin
, p. 7532 - 7539 (2008/02/01)
Protein tyrosine kinases use two Mg2+ ions as cofactors in catalysis, one as the ATP-Mg complex (M1) and the other as an essential activator (M2), The M2-binding site has high affinity for transition metal cations such as cobalt and zinc. Takin
Effects of Organic Solvents on Streptomyces griseus Protease I with Transfer Action
Muro, Tetsuo,Ueno, Michiyo,Tominaga, Yoshio
, p. 924 - 927 (2007/10/02)
The protease I from Streptomyces griseus var. alcalophilus strongly catalyzed the transfer reaction forming hydroxamic acids of various amino acids, especially aromatic and hydrophobic amino acids.Dimethyl sulfoxide (DMSO), 1,4-butane diol, and glycerol p
