- Thermodynamic origin of the increased rate of hydrolysis of phosphate and phosphorothioate esters in DMSO/water mixtures
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The hydrolysis rates of the dianions of phosphate and phosphorothioate esters are substantially accelerated by the addition of polar aprotic solvents such as DMSO and acetonitrile. The activation barrier ΔG? is smaller due to a lower enthalpy of activatio
- Sorensen-Stowell, Kerensa,Hengge, Alvan C.
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- Synthesis of hydroxylated group IV metal oxides inside hollow graphitised carbon nanofibers: Nano-sponges and nanoreactors for enhanced decontamination of organophosphates
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The confinement and enhanced catalytic properties of hydroxylated group IV metal oxide nanostructures inside hollow graphitised carbon nanofibers (GNF) has been demonstrated. GNF-a structural analogue of carbon nanotubes-were effectively filled with suitable precursor molecules of metal chlorides from the gas and liquid phases. Subsequent base-catalysed hydrolysis afforded amorphous, nanostructured hydroxylated metal oxide (MOx(OH)y where M = Zr, Ti, and Hf) thin films, which coat the internal surfaces of GNF. This versatile and general strategy allows the chemical composition and morphology of the encapsulated material to be modified by varying the conditions used for hydrolysis and post-synthesis thermal treatment. The increased Lewis acidic properties and high surface area of the zirconium composite promote the catalysed hydrolysis of dimethyl nitrophenyl phosphate (DMNP)-a toxic organophosphorus chemical. A four-fold enhancement in the rate of DMNP hydrolysis relative to its separate constituent components was observed, highlighting the surprising synergistic abilities of this composite material to perform both as a 'nano-sponge', absorbing the harmful compounds inside the GNF, and a nanoreactor, enhancing the local concentration of organophosphate around the hydroxylated metal oxide species, leading to improved catalytic performance.
- Astle, Maxwell A.,Rance, Graham A.,Fay, Michael W.,Notman, Stuart,Sambrook, Mark R.,Khlobystov, Andrei N.
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- Cetylpyridinium bromide-based oil-in-water microemulsions as a medium for hydrolysis of esters of phosphorus acids in the presence of primary amines
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High-resolution 1H NMR technique with Fourier-transform and pulsed-gradient spin-echo was used to study the structure of oil-in-water microemulsions based on cetylpyridinium bromide. The sizes of microdrops and the distribution of components between the disperse and continuous phases were found. It was shown for the hydrolytic decomposition of O,O-bis-(p-nitrophenyl) methyl phosphonate in the presence of amines that the microemulsion medium can affect both the rate and mechanism of hydrolysis. The reaction rate constants depend on the structure of microdrops.
- Mirgorodskaya,Kudryavtseva,Zuev,Idiyatullin,Fedotov
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- Supramolecular systems based on aminomethylated calix[4]resorcinarene and a cationic surfactant: Catalysts of the hydrolysis of esters of phosphorus acids
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Kinetics of alkaline hydrolysis of 4-nitrophenyl esters of tetracoordinated phosphorus acids in micellar solutions of aminomethylated calix[4]resorcinarene containing sulfonatoethylene groups on the lower rim of the macrocycle, 4-aza-1-hexadecyl-azoniabicyclo[2.2.2]octane bromide and their mixtures was investigated spectrophotometrically. It is established that the catalytic effect of aggregates depends on the concentration of calixarene and surfactants, pH, presence of lanthanum salt and reaches more than two orders of magnitude. The parameters of the catalyzed reactions and their dependence on the composition are determined.
- Kashapov,Pashirova,Zhiltsova,Lukashenko,Ziganshina,Zakharova
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- Synthesis and phosphatase activity of a Cobalt(II) phenanthroline complex
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Abstract: A mononuclear cobalt(II) complex, [Co (phen) 2Cl 2], (phen = 1,10-phenanthroline) has been synthesized and structurally characterized by different spectroscopic methods including single crystal X-ray structural study. X-ray
- Garai, Mamoni,Dey, Dhananjay,Yadav, Hare Ram,Maji, Milan,Choudhury, Angshuman Roy,Biswas, Bhaskar
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- Metallomicellar hydrolytic catalysts containing ligand surfactants derived from alkyl pyridin-2-yl ketoxime
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N-Hexyl-(2a), N-octyl-(2b), N-decyl-(2c) and N-dodecyl-N-[2-(hydroxyimino)-2-(pyridin-2-yl)-ethyl]dimethylammonium (2d) nitrates were synthesized as water-soluble cationic ligand surfactants. Three types of micellar catalytic systems employing salts 2 were prepared: homomicellar water solutions of salts 2, comicellar solutions of salts 2 wilh an inert cationic tenside hexadecyltrimethylammonium bromide (CTAB) and comicellar systems consisting of complexes of ligand surfactants 2 with transition metal ions (Co(II), Ni(II), Cu(II) and Zn(II)) and CTAB. Hydrolytic efficiency of all micellar and metallomicellar systems was tested by measuring the kinetics of the model substrate cleavage under pseudo-firsl-order reaction conditions. Of the above-mentioned catalysts, comicellar systems of salts 2 comicellized with CTAB were most efficient. In all cases, with the exception of Zn(II), coordination of a metal ion decreased the hydrolytic efficiency of salts 2.
- Cibulka, Radek,Dvorak, David,Hampl, Frantisek,Liska, Frantisek
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- A study on a primitive artificial esterase model: Reactivity of a calix[4]resorcinarene bearing carboxyl groups
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The host molecule octacarboxymethyl calix[4]resorcinarene 1 catalyses the hydrolysis of substituted phenyl N-methylpyridinium-4-carboxylate esters 3a-f by complexation followed by intracomplex reaction via an anhydride intermediate. The reactivity in the
- Cevasco, Giorgio,Galatini, Andrea,Pirinccioglu, Necmettin,Thea, Sergio,Williams, Andrew
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- One Step Backward Is Two Steps Forward: Enhancing the Hydrolysis Rate of UiO-66 by Decreasing [OH-]
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The rapid destruction of chemical threats, such as phosphate-based nerve agents, is of considerable current interest. The hydrolysis of the nerve-agent simulant methylparaoxon, as catalyzed by UiO-66 and UiO-67, was examined as a function of pH. Surprisingly, even though typical phosphate-ester hydrolysis mechanisms entail nucleophilic attack of the simulant by aqueous hydroxide, the rate of hydrolysis accelerates as the solution pH is lowered. The unexpected behavior is attributed to a pH-dependent composition change followed by ligand substitution at the Zr6-based node.
- Katz, Michael J.,Klet, Rachel C.,Moon, Su-Young,Mondloch, Joseph E.,Hupp, Joseph T.,Farha, Omar K.
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- Structural, electrochemical, phosphate-hydrolysis, DNA binding and cleavage studies of new macrocyclic binuclear nickel(ii) complexes
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New macrocyclic binuclear nickel(ii) complexes have been synthesized by using the bicompartmental mononuclear complex [NiL] [3,30-((1E,7E)-3,6-dioxa-2, 7-diazaocta-1,7-diene-1,8-diyl)bis(3-formyl-5-methyl-2-diolato)nickel(ii)] with various diamines like 1
- Anbu, Sellamuthu,Kandaswamy, Muthusamy,Varghese, Babu
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- Supramolecular catalytic systems based on 1, 4-diazabicyclo[2.2.2]octane, its alkylated quaternary derivatives, and lanthanum nitrate
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Spectrophotometry was used to study the catalytic effects of the systems composed of N-monoand N, N-dialkylated 1, 4-diazabicyclo[2.2.2]octanes and lanthanum nitrate on the hydrolysis rate of O-alkyl O-4-nitrophenyl chloromethylphosphonates (Alk = Et, Bun, and n-hexyl). The mechanism of action and efficiency of the catalytic system depend on the structure of the heterocycle, its propensity to aggregation and complexation with the lanthanum cation, and the relative content of the components in solution. The maximum catalytic effect (a ~115-fold increase in the hydrolysis rate constant) was achieved in micellar solutions of the cationic monoalkylated derivative of 1, 4-diazabicyclo[2.2.2]octane and lanthanum nitrate.
- Zhiltsova,Lukashenko,Pashirova,Zakharova, L. Ya.,Konovalov
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- POLYMER-BOUND IODOSOBENZOATE REAGENTS FOR THE CLEAVAGE OF REACTIVE PHOSPHATES
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Two polymer-bound iodosobenzoate derivatives have been prepared and found to be phosphorolytically active against both p-nitrophenyldiphenyl phosphate and the nerve agent, Soman.
- Moss, Robert A.,Bolikal, Durgadas,Durst, H. Dupont,Hovanec, Joseph W.
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- Exploring the catalytic activity of new water soluble dinuclear copper(ii) complexes towards the glycoside hydrolysis
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Two water soluble dinuclear copper(ii) complexes of a new dinucleating ligand, H3phpda [H3phpda = N,N′-bis(2-pyridylmethyl)-2-hydroxy-1,3-propanediamine-N,N′-dipropionic acid] have been synthesized and characterized for the investiga
- Haldar, Shobhraj,Patra, Ayan,Bera, Manindranath
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- Development of a lipase-based optical assay for detection of DNA
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A lipase-based assay for detection of specific DNA sequences has been developed. Lipase from Candida antarctica was conjugated to DNA and captured on magnetic beads in a sandwich assay, in which the binding was dependent on the presence of a specific target DNA. For amplification and to generate a detectable readout the captured lipase was applied to an optical assay that takes advantage of the enzymatic activity of lipase. The assay applies p-nitrophenol octanoate (NPO) as the substrate and in the presence of lipase the ester is hydrolyzed to p-nitrophenolate which has a strong absorbance at 405 nm. The method provides detection a detection limit of 200 fmol target DNA and it was able to distinguish single base mismatches from the fully complementary target.
- Pinijsuwan, Suttiporn,Shipovskov, Stepan,Surareungchai, Werasak,Ferapontova, Elena E.,Gothelf, Kurt V.
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- Structure-based discovery of new small molecule inhibitors of low molecular weight protein tyrosine phosphatase
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The application of a fully integrated and automated virtual screening method for identifying potential and novel inhibitors of bovine lmwPTP is described. The protocol makes extensive use of our recently introduced LINGO tools, which allow the extraction
- Vidal, David,Blobel, Jascha,Perez, Yolanda,Thormann, Michael,Pons, Miquel
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- Polypeptides with supersecondary structures as templates in rational catalyst design. Catalysis of self functionalization by designed helix-loop-helix motifs
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Three designed polypeptides with 42 amino acids each, SA-42, RA-42 and PA-42, were engineered to catalyse acyl-transfer reactions of mono-p-nitrophenylfumarate I. The second-order rate constants of the peptides for the formation of p-nitrophenol were larger than that of the background reaction with factors of 331, 1750 and 1937, respectively. The background reaction is the reaction between I and trifiuoroethoxide ion to form the trifluoroethyl ester. The second-order rate constant for the 4-methylimidazole catalysed reaction between I and trifluoroethoxide ion was 211 times larger than that of the background reaction and the similarity in rate constants suggests that the histidine residues in the polypeptides act as nucleophilic catalysts. The observed rate increases in RA-42 and PA-42 over that of SA-42 identifies the location of the reaction centre. The identity of the reaction products in the RA-42 catalysed reaction was established by NMR spectroscopy and mass spectrometry. The side chain of ornithine-15 was acylated by the fumaryl residue. Thus, in a fast and selective second reaction step the fumaryl group was transferred from histidine-11 to the side chain of ornithine-15. The ability of a designed helix-loop-helix motif, RA-42, to catalyse its own functionalization is thereby demonstrated for the first time.
- Baltzer, Lars,Lundh, Ann-Christin,Broo, Klas,Olofsson, Susanne,Ahlberg, Per
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- The micellar effect of the sodium bis(2-ethylhexyl)sulfosuccinate - decane - water reverse system on the hydrolysis of phosphoric acid esters
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The reactivity of alkyl aryl chloromethylphosphonates in alkaline hydrolysis in the sodium bis(2-ethylhexyl)sulfosuccinate - decane - water reverse micellar system is mainly determined by the electronic properties of substituents and depends only slightly on their hydrophobicity.
- Zakharova,Valeeva,Shagidullina,Kudryavtseva
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- Phosphodiester cleavage by trivalent lanthanides in the presence of native cyclodextrins
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Testing phosphodiesterase activity of Eu(III) in the presence of native cyclodextrins revealed capacity of β-cyclodextrin (β-CD) to stabilize catalytically active metal hydroxocomplexes in mildly basic solutions. Kinetics of the hydrolysis of bis(4-nitrop
- Ruiz Kubli, Mariel,Yatsimirsky, Anatoly K.
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- Kinetic study on quinuclidinolysis of O-4-nitrophenyl X-substituted thionobenzoates and O-3,4-dinitrophenyl thionobenzoate: Effect of amine nature on reactivity and reaction mechanism
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Second-order rate constants (kquin) have been measured spectrophotometrically for the reactions of O-3,4-dinitrophenyl thionobenzoate (1a) with a series of quinuclidine derivatives and of O-4-nitrophenyl X-substituted thionobenzoates (2a-2f) with quinuclidine in 80 mol% H2O/20 mol% DMSO at 25.0 ± 0.1 °C. Quinuclidine is less reactive toward the thione esters than less basic benzylamine. Steric hindrance exerted by the tertiary amine is responsible for the decreased reactivity. The Hammett plot for the reactions of 2a-2f with quinuclidine consists of two intersecting straight lines, while the Yukawa-Tsuno plot for the same reactions exhibits an excellent linear correlation with ρX = 1.10 and r = 0.71. This indicates that the nonlinear Hammett plot is not due to a change in the rate-determining step but is caused by ground-state stabilization of substrates possessing an electron-donating group in the thionobenzoyl moiety through resonance interactions. Bronstedtype plot for the reactions of 1a with quinuclidines is linear with βnuc = 0.89, which is typical for reactions reported to proceed through a stepwise mechanism. However, the reactions have been concluded to proceed through a forced concerted mechanism. Instability of a plausible intermediate T± forces the reactions to proceed through such a mechanism.
- Yang, Eun-Ji,Kim, Min-Young,Um, Ik-Hwan
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- Coordination sphere of the third metal site is essential to the activity and metal selectivity of alkaline phosphatases
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Alkaline phosphatases (APs) are commercially applied enzymes that catalyze the hydrolysis of phosphate monoesters by a reaction involving three active site metal ions. We have previously identified H135 as the key residue for controlling activity of the p
- Koutsioulis, Dimitris,Lyskowski, Andrzej,Maeki, Seija,Guthrie, Ellen,Feller, Georges,Bouriotis, Vassilis,Heikinheimo, Pirkko
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- Single-electron oxidation and nucleophilicity of aminomethylated calix[4]resorcinarenes
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The electrochemical oxidation of a number of aminomethylated calix[4]resorcinarenes (AMC) with different substituents at the nitrogen atom and the kinetics of nucleophilic substitution reactions of these compounds with p-nitrophenyl bis(chloromethyl)phosphinate were studied. The reactivity of the ionic associates of AMC in the nucleophilic substitution and the behavior of AMC in electrooxidation are determined by the same factors, namely, the amino-group basicity and the nature of the substituents at the nitrogen atom. These factors influence the ratio of the zwitter-ionic and anionic forms of AMC.
- Yanilkin,Ryzhkina,Nastapova,Pashirova,Babkina,Burilov,Morozov,Konovalov
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- Endonuclease-like activity of the N-terminal domain of: Euplotes octocarinatus centrin
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Euplotes octocarinatus centrin (EoCen) is a member of the EF-hand superfamily of calcium-binding proteins, which refer to nucleotide excision repair (NER). However, the role of centrin in NER is not clear. To explore the possible role of centrin, we initi
- Zhang, Wenlong,Shi, Enxian,Feng, Yanan,Zhao, Yaqin,Yang, Binsheng
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- Phosphatase models: Synthesis, structure and catalytic activity of zinc complexes derived from a phenolic Mannich-base ligand
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A series of dinuclear [Zn2(L1)2X2] (1-3) and mononuclear [Zn(HL2)X2] complexes (4-6), (X = Cl, Br, I) were synthesised from two Mannich-base compartmental ligands, namely [bis(2-methoxyethyl)aminomethyl]-4-chlor
- Sanyal, Ria,Chakraborty, Prateeti,Zangrando, Ennio,Das, Debasis
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- Halogen bonding in UiO-66 frameworks promotes superior chemical warfare agent simulant degradation
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Herein, a series of halogenated UiO-66 derivatives was synthesized and analyzed for the breakdown of the chemical warfare agent simulant dimethyl-4-nitrophenyl phosphate (DMNP) to analyze ligand effects. UiO-66-I degrades DMNP at a rate four times faster than the most active previously reported MOFs. MOF defects were quantified and ruled out as a cause for increased activity. Theoretical calculations suggest the enhanced activity of UiO-66-I originates from halogen bonding of the iodine atom to the phosphoester linkage allowing for more rapid hydrolysis of the P-O bond.
- Kalaj, Mark,Momeni, Mohammad R.,Bentz, Kyle C.,Barcus, Kyle S.,Palomba, Joseph M.,Paesani, Francesco,Cohen, Seth M.
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- Physical and kinetic analysis of the cooperative role of metal ions in catalysis of phosphodiester cleavage by a dinuclear Zn(II) complex
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A dinuclear metal ion complex Zn2(L20) and its mononuclear analogue Zn(L10H) were synthesized and studied as catalysts of the cleavage of the phosphate diester 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP). X-ray crystal structure data, potentiometric titrations, and 1H NMR spectra obtained over a wide range of pH values provide strong evidence that the alcohol linker in the complex Zn2(L20) is ionized below pH 6.0, while the alcohol group in the complex Zn(L10H) remains protonated even at high pH. The ionizations observed at high pH correspond to the formation of the monohydroxo complexes, Zn2(L20)(OH) and Zn(L10H)(OH), with pKa's of 8.0 and 9.2, respectively. The pH-rate profiles of second-order rate constants for metal-ion complex-catalyzed cleavage of HPNP are reported. These show downward curvature centered at the pKa's for the respective zinc-bound waters, and limiting second-order rate constants at high pH of kc = 0.71 M-1 s-1 for Zn2(L20) and 0.061 M-1 s-1 for Zn(L10H). The larger catalytic activity of Zn2(L20) compared with Zn(L10H) is due to the cooperative role of the metal ions in facilitating the formation of the ionized zinc-bound water at close to neutral pH and in providing additional stabilization of the rate-limiting transition state for phosphodiester cleavage. Zn2(L20) complex (1 M) at pH 7.6 stabilizes the transition state for the uncatalyzed reaction by 9.3 kcal/mol. Assuming that the dissociation constant determined for a diethyl phosphate inhibitor is similar to that for substrate, then ca. 2.4 kcal/mol of these stabilizing interactions are expressed in the ground-state Michaelis complex, while the bulk of these interactions are only expressed as the reaction approaches the transition state for phosphodiester cleavage.
- Iranzo, Olga,Kovalevsky, Andrey Y.,Morrow, Janet R.,Richard, John P.
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- Kinetics of reactions of ethyl p-nitrophenyl ethylphosphonate with anionic nucleophiles in a detergentless microemulsion
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The kinetics of reactions of ethyl p-nitrophenyl ethylphosphonate with anionic nucleophiles in a delergentless water - oil microemulsion, formed in the n-hexane - water - isopropyl alcohol system, was studied. The rate constants of the reactions in the microemulsion are higher than those in aqueous solutions and increase with increasing isopropyl alcohol : water ratio.
- Bel'skii,Valeeva
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- Kinetic study on aminolysis of aryl X-substituted-cinnamates in acetonitrile: Differential medium effect determines reactivity and reaction mechanism
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A kinetic study on nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted-cinnamates (1a-1f) and Y-substituted-phenyl cinnamates (2a-2g) with a series of alicyclic secondary amines in MeCN at 25.0 ± 0.1 °C is reported. The Br?nsted-type pl
- Um, Ik-Hwan,Bae, Ae-Ri,Dust, Julian M.
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- Selective adsorption of nitro-substituted aromatics and accelerated hydrolysis of 4-nitrophenyl acetate on carbon surfaces
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Nitrobenzene, 4-nitrotoluene and 4-nitrophenyl acetate are selectively adsorbed from aqueous 1% sodium dodecyl sulfate solutions onto aligned, randomly oriented and oxidised carbon nanotubes, as well as graphite and C60 fullerene. The rate of h
- Meyer,Dai,Chen,Easton,Xia
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- Cyclen based lanthanide ion ribonuclease mimics: The effect of pyridine cofactors upon phosphodiester HPNP hydrolysis
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The cyclen based pyridine complexes 1Ln-3Ln (Ln = La(III) and Eu(III)) were synthesised as metallo-ribonuclease mimics and their ability to hydrolytically cleave the phosphodiester of HPNP at 37°C was investigated using UV-vis spectroscopy, whereas the bi
- Gunnlaugsson, Thorfinnur,Davies, R. Jeremy H.,Kruger, Paul E.,Jensen, Paul,McCabe, Thomas,Mulready, Sinead,O'Brien, John E.,Stevenson, Clarke S.,Fanning, Ann-Marie
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- Tuning the Lewis acidity of metal-organic frameworks for enhanced catalysis
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The kinetics of hydrolysis of dimethyl nitrophenyl phosphate (DMNP), a simulant of the nerve agent Soman, was studied and revealed transition metal salts as catalysts. The relative rates of DMNP hydrolysis by zirconium and hafnium chlorides are in accordance with their Lewis acidity.In situconversion of zirconium chloride to zirconium oxy-hydroxide was identified as the key step. We propose a precursor-MOF activity relationship.
- Devulapalli, Venkata Swaroopa Datta,Richard, Mélissandre,Luo, Tian-Yi,De Souza, Mattheus L.,Rosi, Nathaniel L.,Borguet, Eric
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- Dissection of activation parameters in the bell-shaped α-effect following solvent modulation (DMSO-H2O Media)
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This paper comprises results of our investigation of the α-effect phenomenon for the reaction of O-p-nitrophenyl thionobenzoate (PNPTB) with butane-2,3-dione monoximate (Ox-, α-nucleophile) and p-chlorophenoxide (p-ClPhO-, normal-nucleophile) in DMSO-H 2O mixtures of varying compositions at 15.0 C, 25.0 C, and 35.0 C. The reactivity of Ox- and p-ClPhO- increases significantly as the DMSO content in the medium increases, although the effects of medium on reactivity are not the same for the reactions with Ox- and p-ClPhO-. Ox- exhibits the α-effect in all solvent compositions and temperatures. The α-effect increases up to 50 mol % DMSO and then decreases thereafter, resulting in a bell-shaped α-effect profile. Dissection of the activation parameters (i.e., ΔH a and TΔSa) has revealed that the bell-shaped α-effect behavior is due to entropy of activation differences rather than enthalpy terms, although the enthalpy term controls almost entirely the solvent dependence of the reaction rate. Differences in the transition-state (TS) structures for the reactions with Ox- (a six-membered cyclic TS) and p-ClPhO- (an acyclic TS) are consistent with the entropy-dependent α-effect behavior.
- Um, Ik-Hwan,Kang, Ji-Sun,Kim, Min-Young,Buncel, Erwin
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- Effect of electrolytes on the catalytic properties and sructural characteristics of dodecylpyridinium bromide micelles
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Electrolyte-induced structural rearrangements of dodecylpyridinium bromide micelles affect their catalytic properties in alkaline hydrolysis of phosphonic esters.
- Zakharova,Kudryavtsev,Kudryavtseva,Zuev,Zakharchenko,Vylegzhanina,Idiyatullin,Fedotov
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- Structure and properties of water-oil microemulsions
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The parameters determining the structure and properties (surface potential and size of microdrops) of oil-water microemulsions containing various surfactants, and also the distribution of components between the dispersed phase and dispersing medium were d
- Mirgorodskaya,Kudryavtseva,Zuev,Idiyatullin,Fedotov
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- The conformation and function of a multimodular glycogen-degrading pneumococcal virulence factor
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SpuA is a large multimodular cell wall-attached enzyme involved in the degradation of glycogen by the pathogenic bacterium Streptococcus pneumoniae. The deletion of the gene encoding SpuA from the bacterium resulted in a strain with reduced competitiveness in a mouse model of virulence relative to the parent strain, linking the degradation of host-glycogen to the virulence of the bacterium. Through the combined use of X-ray crystallography, small-angle X-ray scattering, and inhibitor binding, the molecular features involved in substrate recognition by this complex protein are revealed. This uniquely illustrates the complexity of the active site, the conformational changes incurred during carbohydrate binding by this protein, and the interaction and cooperation of its composite modules during this process. New insight into the function of this particular pneumococcal virulence factor is provided along with substantial contributions to the nascent framework for understanding the structural and functional interplay between modules in multimodular carbohydrate-active enzymes.
- Lammerts Van Bueren, Alicia,Ficko-Blean, Elizabeth,Pluvinage, Benjamin,Hehemann, Jan-Hendrik,Higgins, Melanie A.,Deng, Lehua,Ogunniyi, A. David,Stroeher, Uwe H.,El Warry, Nahida,Burke, Robert D.,Czjzek, Mirjam,Paton, James C.,Vocadlo, David J.,Boraston, Alisdair B.
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- Phosphate diesters and DNA hydrolysis by dinuclear Zn(II) complexes featuring a disulfide bridge and H-bond donors
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The dinuclear ligand 1 based on the bis-(2-amino-pyridinyl-6-methyl)amine (BAPA) metal binding unit and featuring a two-atom disulfide bridge was synthesized and studied as hydrolytic catalysts for phosphate diesters. The Zn(II) complexes of BAPA are know
- Lombardo, Valentina,Bonomi, Renato,Sissi, Claudia,Mancin, Fabrizio
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- Toward a new avenue in ruthenium-sulphur chemistry of binuclear μ-sulphido bridged (μ-S)2complexes having Ru2S2core: Targeted synthesis, crystal structure, biomolecules interaction and their in vitro anticancer activities
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A series of hybrid thiosemicarbazone derivatives (H2L1–3) were synthesized by the reactions of diacetyl-2-(4-methyl-3-thiosemicarbazone) with hydrazine derivatives such as 2-hydrazinoquinoline, 2-hydrazinobenzothiazole and 6-hydrazinonicotinic acid arm. The resulting hybrid diacetyl-2-(4-methyl-3-thiosemicarbazonato-hydrazine derivatives were successfully employed as tetradentate ligands to react with [RuHClCO(PPh3)3]. The reactions have led to the binuclear organo-ruthenium(II) complexes of the core type [Ru2(Ln)2(CO)2(μ-S)2], (n?=?1–3) in which the ruthenium(II) ion bridged by sulphur atoms (μ-S)2. In the new complexes, the ligand charge and stoichiometry proportions could be controlled by the addition of base. All the compounds have been characterized by IR, UV–vis, ESI-MS, (1H,13C) NMR spectra and elemental analyses. The crystal structure of complexes 1, 2 has been determined by X-ray crystallography, which confirmed the coordination mode of the ligands and revealed a distorted octahedral geometry around the ruthenium ion. Natural bond orbital calculations of complexes 1 and 2 showed that the majority of the electron density of donors tends to the ruthenium ion, since the calculated Mulliken charge for the ruthenium ion is much lesser than the formal value. The binding mode of these complexes with biomolecules such as calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) protein have been investigated by diverse spectrophotometric methods and the results revealed an intercalative mode of interaction. Furthermore, the bio-catalytic efficiencies such as catecholase and phosphatase like activities of ruthenium complexes exhibited high rate (kcat) constant. Furthermore, the complexes (1–3) displayed more cytotoxicity against anticancer cell lines such as MCF-7 (breast), A549 (lung), and HepG2 (liver) than normal Vero cell line. The less cytotoxic activity towards normal cell lines showed that they affect only cancer cell lines. The antiproliferative efficacy of complexes (1–3) has also been analyzed using morphological staining properties (AO/EB, DAPI) by fluorescence microscopy visualization.
- Vijayan, Paranthaman,Viswanathamurthi, Periasamy,Sugumar, Paramasivam,Ponnuswamy, Mondikalipudur Nanjappagounder,Velmurugan, Krishnaswamy,Nandhakumar, Raju,Balakumaran, Manickam Dakshinamoorthi,Kalaichelvan, Pudupalayam Thangavelu
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- The salt effect in the alkaline hydrolysis of O-ethyl O-(p-nitrophenyl) chloromethylphosphonate catalyzed by cetylpyridinium bromide
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The alkaline hydrolysis of O-ethyl O-(p-nitrophenyl) chloromethylphosphonate catalyzed by the micelles of cetylpyridinium bromide is inhibited on addition of KCl, KBr, or sodium salicylate (NaSal). This is caused by both a decrease in the nucleophile concentration in micelles owing to a reduction in the surface potential and a change in the micellar structure and properties.
- Zakharova,Kudryavtseva,Konovalov
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- Nucleophilic oxidizing systems based on hydrogen peroxide for decomposition of ecotoxicants
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The kinetics of oxidation of methylsulfanylbenzene and nucleophilic decomposition of diethyl 4-nitrophenyl phosphate with hydrogen peroxide in the presence of ammonium hydrogen carbonate or boric acid in aqueous, aqueous-alcoholic, micellar, and microemulsion media were studied. Quantitative parameters of the examined processes were determined, and the possibility of using hydrogen peroxide for the design of oxidative nucleophilic decontaminating systems was demonstrated.
- Vakhitova,Matvienko,Taran,Lakhtarenko,Popov
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- Effect of Pressure on the Pre-Steady-State Kinetics of the Hydrolysis of p-Nitrophenyl Pivalate Catalyzed by α-Chymotrypsin
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The pre-steady-state of the hydrolysis of p-nitrophenyl pivalate (pNPT) catalyzed by α-chymotropsyn (α-CHT) in Tris buffer solutions was measured up to 2.4 k bar at 25 deg C.The reaction was initiated by substrate binding, and followed by acylation and de
- Makimoto, Syoichi,Suzuki, Keizo,Taniguchi, Yoshihiro
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- Kinetic method for the quantitative resolution of structural isomers based on the catalytic properties of β-cyclodextrin
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This paper describes a new approach for the quantitative resolution of mixtues of structural isomers. The method is based on the observation that rate constants for the cyclodextrin-catalyzed hydrolysis of selected structural isomers are significantly dif
- Chen, Ellen Tuanying,Pardue, Harry L.
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- Synthesis and phosphodiester transesterification activity of the La3+- complex of a novel functionalized octadentate ligand
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Various lanthanide complexes have been shown to promote phosphodiester hydrolysis. Distribution of the available coordination sites of the lanthanides between the ligand and the labile water molecules has proved to be critical in determining the activity and stability of the complex in water at neutral pH. Since the final goal is to conjugate such hydrolytically active molecules to DNA oligomers, the design must include a functionality that can be made reactive in standard conjugation protocols. To that end, we have synthesized a nitrophenyl-derivatized TCMC-La3+ complex, and it is as active as the unmodified TCMC-La3+ in the transesterification of an RNA model substrate.
- Baykal, Ulku,Akkaya, Engin U.
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- Superactivity of α-chymotrypsin with biological buffers, TRIS, TES, TAPS, and TAPSO in aqueous solutions
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Biological buffers are always considered as non-toxic, biocompatible and green compounds. Therefore, we analyzed the catalytic activity of a commercial enzyme α-chymotrypsin (α-CT) in aqueous solutions of some common biological buffers (TRIS, TES, TAPS, a
- Gupta, Bhupender S.,Taha, Mohamed,Lee, Ming-Jer
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- Kinetics of alkaline hydrolysis of ethyl p-nitrophenyl ethylphosphonate in the reverse micellar system: Sodium dodecyl sulfate-hexanol-water
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The kinetics of alkaline hydrolysis of ethyl p-nitrophenyl ethylphosphonate in the reverse micellar system sodium dodecyl sulfate-hexanol-water was studied. At high pH and low water content, the process occurs at the surface layer and can satisfactorily b
- Zakharova,Valeeva,Kudryavtseva,Bel'skii,Zhil'tsova,Zakharchenko,Zuev
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- Role of solvent in the phosphatase activity of a dinuclear nickel(II) complex of a Schiff base ligand: Mechanistic interpretation by DFT studies
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A novel dinuclear μ-diphenoxo-μ-acetato metallohydrolase [Ni2L2(NCS)(Ac)(H2O)0.5(MeOH)0.5]·1.25H2O (HL = 2-((E)-(2-(pyridin-2-yl)ethylimino)methyl)-4-chlorophenol) with an intermetallic sep
- Sanyal, Ria,Zhang, Xuepeng,Chakraborty, Prateeti,Giri, Sanjib,Chattopadhyay, Shyamal Kumar,Zhao, Cunyuan,Das, Debasis
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- Stability of 1:1 and 2:1 α-cyclodextrin-p-nitrophenyl acetate complexes and the effect of α-cyclodextrin on acyl transfer to peroxide anion nucleophiles
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The presence of a rate maximum rather than simple saturation-type kinetics in a study of the effect of α-cyclodextrin on the hydrolysis of p-nitrophenyl acetate (PNPA) indicates that α-cyclodextrin forms not only 1:1 but also 2:1 complexes with PNPA. This is confirmed using a spectrophotometric method to determine binding constants directly for PNPA, giving values of 46 ± 9 and 66 ± 19 dm3 mol-1 for the first and second binding steps respectively. These results contradict the majority of literature studies of this reaction in which it is assumed that only a 1:1 complex is formed. Formation of a 1 :1 complex with cyclodextrin increases the reactivity of PNPA towards hydrolysis, as has been widely reported, whereas the addition of a second cyclodextrin molecule to the complex results in the PNPA taking up a less reactive configuration. The effect of α-cyclodextrin on the reaction between PNPA and the anions of hydrogen peroxide, peroxomonosulfate, peracetic acid, perbenzoic acid, 4-methylperbenzoic acid, 4-nitroperbenzoic acid, 4-sulfonatoperbenzoic acid, 3-chloroperbenzoic acid and 4-tert-butylperbenzoic acid is described. Linear free energy studies for transition state stabilisation of the reaction by one molecule of cyclodextrin reveal that the main pathway involves the bound PNPA reacting with free peroxide anions, although for m-chloroperbenzoic acid an alternative pathway may be significant. This is in contrast to the behaviour observed for the α-cyclodextrin-mediated reaction of the molecular acid form of these peroxides with a series of aryl alkyl sulfides in which the main pathway involves nucleophilic attack of the free sulfide on the cyclodextrin-peracid complex. With the exception of the m-chloroperbenzoic acid anion there is no evidence of transition state stabilisation of the title reaction by two molecules of cyclodextrin.
- Davies, D. Martin,Deary, Michael E.
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- Solvent effect on ground-state versus transition-state stabilization by metal ions. Contrasting metal ion behaviour in tetraglyme and ethanol for nucleophilic displacement at a phosphorus centre
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The rate of reaction of p-nitrophenyl diphenylphosphinate with alkali metal phenoxide follows the order LiOPh> KOPh in ethanol as solvent but in tetraglyme the reactivity order is KOPh? LiOPh and the reaction rate is much faster, which is accounted for on the basis of differing stabilization of the ground-state through hydrogen-bonding and of the transition-state by interaction with M+ in the two solvents.
- Buncel,Dunn,Van Truong,Bannard,Purdon
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- Carbonic Anhydrase Models. 4. phosphine oxide>cobalt(2+); A Small-Molecule Mimic of the Spectroscopic Properties of Co(II) Carbonic Anhydrase
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The title compound when bound to Zn(II) or Co(II) displays many properties in common with carbonic anhydrase.These include a weak ability of the Zn(II) complex to catalyze the interconversion of CO2 and HCO3(-) and anion-dependent visible absorption spect
- Brown, R. S.,Salmon, D.,Curtis, N. J.,Kusuma, S.
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- Conformational Effect (Induced-Fit) on Catalytic Activity of α-Chymotrypsin
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The kinetics for the hydrolyses of p-nitrophenyl esters of acetic acid and certain amino acid derivatives mediated by α-chymotrypsin have been studied. The kinetics are a function of the medium viscosity, which indicate that the enzyme must change its con
- Kawai, Yasushi,Matsuo, Takashi,Ohno, Atsuyoshi
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- Comparison of the structure and activity of glycosylated and aglycosylated human carboxylesterase 1
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Human Carboxylesterase 1 (hCES1) is the key liver microsomal enzyme responsible for detoxification and metabolism of a variety of clinical drugs. To analyse the role of the single N-linked glycan on the structure and activity of the enzyme, authentically
- De Souza, Victoria Arena,Scott, David J.,Nettleship, Joanne E.,Rahman, Nahid,Charlton, Michael H.,Walsh, Martin A.,Owens, Raymond J.
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- Modulation of aggregation behavior, antimicrobial properties and catalytic activity of piperidinium surfactants by modifying their head group with a polar fragment
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To establish the effect of surfactants structure on their functional activity a number of alkyl-N-hydroxyethylpiperidinium bromides with different length of the hydrophobic tail were synthesized and characterized. Aggregation parameters of these surfactan
- Gumerova, Sumbela K.,Kushnazarova, Rushana A.,Kuznetsov, Denis M.,Lenina, Oxana A.,Mirgorodskaya, Alla B.,Nikitin, Eugeny N.,Tyryshkina, Anna A.,Voloshina, Alexandra D.,Zakharova, Lucia Ya.
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- Soft nanosystems based on hydroxypiperidinium surfactants as adjuvants and micellar catalysts
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Quantitative parameters characterizing aggregation behaviour and wetting effect of 1-(2-hydroxyethyl)-piperidinium surfactants have been obtained. Their ability to act as adjuvants in herbicidal compositions based on clopyralid has been revealed. The kine
- Kushnazarova, Rushana A.,Lukashenko, Svetlana S.,Mirgorodskaya, Alla B.,Sinyashin, Oleg G.,Tyryshkina, Anna A.,Valeeva, Farida G.,Zakharova, Lucia Ya.
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p. 323 - 325
(2021/06/07)
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- Homodinuclear copper(II) and zinc(II) complexes of a carboxylate-rich ligand as synthetic mimics of phosphoester hydrolase in aqueous solutions
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The synthesis, characterization and catalytic activities of two homodinuclear Cu(II) and Zn(II) complexes of a carboxylate-rich ligand, N,N′-Bis[2-carboxybenzomethyl]-N,N′ -Bis[carboxymethyl]-1,3-diaminopropan-2-ol (H5ccdp) ligand towards the h
- Foley, William,Arman, Hadi,Musie, Ghezai T.
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- Hydrolysis of Organophosphorus Agents Catalyzed by Cobalt Nanoparticles Supported on Three-Dimensional Nitrogen-Doped Graphene
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Catalytic chemical degradations and many other methodologies have been explored for the removal and/or degradation of organophosphorus agents (OPs) that are often used as pesticides, nerve agents, and plasticizers. To explore more efficient and recyclable
- Li, Yanfang,Yan, Jiawei,Yu, Daobo,Lei, Puyi,Shen, Wenzhuo,Zhong, Min,Zhang, Jiali,Guo, Shouwu
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supporting information
p. 17635 - 17640
(2021/11/23)
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- Mono- and dinuclear zinc complexes bearing identical bis(thiosemicarbazone) ligand that exhibit alkaline phosphatase-like catalytic reactivity
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Mono- and dinuclear zinc(II) complexes bearing bis(thiosemicarbazone) (bTSC) ligand were employed in the cleavage of phosphoester bonds. Comparative kinetic studies combined with theory suggested that the P–O bond cleavage is much accelerated by dinuclear
- Cho, Kyung-Bin,Hong, Seungwoo,Jeon, Hyeri,Jeong, Haewon,Vazquez-Lima, Hugo
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- Defect Level and Particle Size Effects on the Hydrolysis of a Chemical Warfare Agent Simulant by UiO-66
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Defect engineering in metal-organic frameworks (MOFs) has recently become an area of significant research due to the possibility of enhancing material properties such as internal surface area and catalytic activity while maintaining stable 3D structures. Through a modulator screening study, the model Zr4+ MOF, UiO-66, has been synthesized with control of particle sizes (100-1900 nm) and defect levels (2-24%). By relating these properties, two series were identified where one property remained constant, allowing for independent analysis of the defect level or particle size, which frequently change coincident with the modulator choice. The series were used to compare UiO-66 reactivity for the hydrolysis of a chemical warfare agent simulant, dimethyl 4-nitrophenylphosphate (DMNP). The rate of DMNP hydrolysis displayed high dependence on the external surface area, supporting a reaction dominated by surface interactions. Moderate to high concentrations of defects (14-24%) allow for the accessibility of some interior MOF nodes but do not substantially promote diffusion into the framework. Individual control of defect levels and particle sizes through modulator selection may provide useful materials for small molecular catalysis and provide a roadmap for similar engineering of other zirconium frameworks.
- Bartlett, Eamon C.,Cai, Meng,Gibbons, Bradley,Johnson, Eric M.,Morris, Amanda J.,Yang, Xiaozhou
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supporting information
p. 16378 - 16387
(2021/11/13)
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- A combined experimental and theoretical rationalization of an unusual zinc(ii)-mediated conversion of 18-membered Schiff-base macrocycles to 18-membered imine-amine macrocycles with imidazolidine side rings: an investigation of their bio-relevant catalyti
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The 2?:?2 condensation reaction of 2,6-diformyl-4-isopropyl phenol andN′-(2-aminoethyl)ethane-1,2-diamine leads to a macrocycle Schiff base ligand (H2L) with the N6O2chromophore, which in the presence of ZnX2tra
- Chakraborty, Tonmoy,Mukherjee, Somali,Parveen, Rumana,Chandra, Arpita,Samanta, Debabrata,Das, Debasis
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p. 2550 - 2562
(2021/02/16)
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- Oxidative cyclization and synthesis of benzoxazole derivatives and hydrolytic phosphatase activity studies on dinuclear diphenoxo-bridged zinc(II)complexes
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Diphenoxo bridged dinuclear zinc complexes, [Zn2(Phimp)2(Cl)2] (1) (PhimpH = (E)-2-((2-phenyl-2-(pyridin-2-yl)hydrazono)methyl)phenol), [Zn2(Me-Phimp)2(Cl)2] (2) (Me-PhimpH = (E)-4-methyl-2-((2-phenyl-2-(pyridin-2-yl)hydrazono)methyl)phenol), [Zn2(OMe-Phimp)2(Cl)2] (3) (OMe-PhimpH = (E)-4-methoxy-2-((2-phenyl-2-(pyridin-2-yl)hydrazono)methyl)phenol), were synthesized and spectroscopically characterized. The molecular structure of 2 was determined using X-ray crystallography. DFT and TD-DFT calculations were performed to optimize the molecular geometry, interpret the spectroscopic results and investigate the contribution of the ligands to the redox properties of the complexes. Phenoxyl radical complexes were generated in solution via chemical oxidation using ceric ammonium nitrate (CAN) and the redox properties were examined through cyclic voltammetric measurements. The hydrolysis of para-nitrophenylphosphate (PNPP) by all the dinuclear zinc complexes was investigated to mimic phosphatase activity. Catalytic oxidative cyclization by these complexes and synthesis of benzoxazole derivatives was investigated.
- Kumar, Kapil,Chaudhary, Virendra Kumar,Singh,Ghosh, Kaushik
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- Wearable membranes from zirconium-oxo clusters cross-linked polymer networks for ultrafast chemical warfare agents decontamination
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The urgent need for immediate personal protection against chemical warfare agents (CWAs) spurs the requirement on robust and highly efficient catalytic systems that can be conveniently integrated to wearable devices. Herein, as a new concept for CWA decontamination catalyst design, sub-nanoscale, catalytically active zirconium-oxo molecular clusters are covalently integrated in flexible polymer network as crosslinkers for the full exposure of catalytic sites as well as robust framework structures. The obtained membrane catalysts exhibit high swelling ratio with aqueous content as 84 wt% and therefore, demonstrate quasi-homogeneous catalytic activity toward the rapid hydrolysis of both CWA, soman (GD) (t1/2 = 5.0 min) and CWA simulant, methyl paraoxon (DMNP) (t1/2 = 8.9 min). Meanwhile, due to the covalent nature of cross-linkages and the high flexibility of polymer strands, the membranes possess promising mechanical strength and toughness that can stand the impact of high gas pressures and show high permeation for both CO2 and O2, enabling their extended applications in the field of collective/personal protective materials with body comfort.
- Chen, Likun,Fan, Zhiwei,Li, Heguo,Lu, Lin,Ma, Litao,Xie, Jiamin,Xin, Yi,Yan, Xiaoshan,Yin, Panchao
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supporting information
(2021/12/09)
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- Folding Assessment of Incorporation of Noncanonical Amino Acids Facilitates Expansion of Functional-Group Diversity for Enzyme Engineering
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Protein design is limited by the diversity of functional groups provided by the canonical protein ?building blocks“. Incorporating noncanonical amino acids (ncAAs) into enzymes enables a dramatic expansion of their catalytic features. For this, quick identification of fully translated and correctly folded variants is decisive. Herein, we report the engineering of the enantioselectivity of an esterase utilizing several ncAAs. Key for the identification of active and soluble protein variants was the use of the split-GFP method, which is crucial as it allows simple determination of the expression levels of enzyme variants with ncAA incorporations by fluorescence. Several identified variants led to improved enantioselectivity or even inverted enantiopreference in the kinetic resolution of ethyl 3-phenylbutyrate.
- Drienovská, Ivana,Gajdo?, Matú?,Kindler, Alexia,Takhtehchian, Mahsa,Darnhofer, Barbara,Birner-Gruenberger, Ruth,D?rr, Mark,Bornscheuer, Uwe T.,Kourist, Robert
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p. 12338 - 12342
(2020/09/07)
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- Structures and esterolytic reactivity of novel binuclear copper(ii) complexes with reduced l-serine Schiff bases as mimic carboxylesterases
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Three novel binuclear copper(ii) complexes with reduced l-serine Schiff bases were synthesized and their structures were analyzed with single-crystal X-ray diffraction and DFT calculations. The crystal data revealed that all of these binuclear complexes a
- Chen, Zhongzhu,Jiang, Weidong,Liu, Xiaoqiang,Shu, Jun,Xu, Bin,Xu, Zhigang,Yue, Jian,Zhang, Qin,Zhang, Yajun
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supporting information
p. 10261 - 10269
(2020/08/17)
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- Organocatalytic Control over a Fuel-Driven Transient-Esterification Network**
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Signal transduction in living systems is the conversion of information into a chemical change, and is the principal process by which cells communicate. In nature, these functions are encoded in non-equilibrium (bio)chemical reaction networks (CRNs) controlled by enzymes. However, man-made catalytically controlled networks are rare. We incorporated catalysis into an artificial fuel-driven out-of-equilibrium CRN, where the forward (ester formation) and backward (ester hydrolysis) reactions are controlled by varying the ratio of two organocatalysts: pyridine and imidazole. This catalytic regulation enables full control over ester yield and lifetime. This fuel-driven strategy was expanded to a responsive polymer system, where transient polymer conformation and aggregation are controlled through fuel and catalyst levels. Altogether, we show that organocatalysis can be used to control a man-made fuel-driven system and induce a change in a macromolecular superstructure, as in natural non-equilibrium systems.
- Eelkema, Rienk,Fan, Bowen,Macchione, Mariano,Mendes, Eduardo,Wang, Chang-Lin,van der Helm, Michelle P.
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supporting information
p. 20604 - 20611
(2020/09/07)
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- Single-Crystal-to-Single-Crystal Installation of Ln4(OH)4 Cubanes in an Anionic Metallosupramolecular Framework
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Postsynthetic installation of lanthanide cubanes into a metallosupramolecular framework via a single-crystal-to-single-crystal (SCSC) transformation is presented. Soaking single crystals of K6[Rh4Zn4O(l-cys)12]
- Konno, Takumi,Meundaeng, Natthaya,Nakazawa, Yasuhiro,Tabe, Hiroyasu,Yamada, Yusuke,Yamashita, Satoshi,Yoshinari, Nobuto
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supporting information
p. 18048 - 18053
(2020/08/19)
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- A Simple but Efficient Catalytic Approach for the Degradation of Pollutants in Aqueous Media through Cicer arietinum Supported Ni Nanoparticles
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Plant based materials are considered to have broad applications in the remediation of toxic materials. In this report, we present an environmental friendly and economic Cicer arietinum, named as (CP) supported for the synthesis of Ni nanoparticles (NPs) designated as Ni@CP. The in situ Ni@CP NPs were obtained using aqueous medium in the presence of sodium borohydride (NaBH4) as a reducing agent. The prepared catalysts were applied for the hydrogenation/degradation of p-nitrophenol (PNP), o-nitrophenol (ONP), and 2,4-dinitrophenol (DNP), as well as congo red (CR), methyl orange (MO), methylene blue (MB) and rhodamine B (RB) dyes. The amount of total metal ions adsorbed onto the CP was evaluated by flame atomic absorption spectroscopy. The Ni@CP catalyst was characterized through PXRD, FTIR, FESEM and EDX analyses.
- Khan, Shahid Ali,Rasool, Shagufta,Rahman, Khaliq Ur,Hussain, Shah,Khan, Inamullah,Ismail, Muhammad,Farooq, Aliya,Khan, Sarzamin,Raza, Mian Ahmad,Asiri, Abdullah Muhammad,Khan, Sher Bahadar
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p. 1789 - 1802
(2019/09/20)
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- Magnetic Fe3O4/graphene oxide/copper-based nanocomposite as a reusable catalyst for the reduction of 4-nitrophenol
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In the present investigation, Fe3O4/Graphene oxide/Pr–NH2–CuII was reported as a novel magnetically recoverable nanocomposite and characterized using various analytical techniques such as FT-IR spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), vibrating sample magnetometry (VSM), X-ray diffraction (XRD), and inductively coupled plasma (ICP). The catalytic performance of the synthesized catalyst was evaluated in the reduction of 4-nitrophenol to 4-aminophenol by an excess amount of sodium borohydride as the source of hydrogen in aqueous solution. The reaction was monitored by UV-vis spectroscopy at ambient temperature. Magnetic nature of the catalyst led to its simple recovery by a permanent magnet and excellent recyclability without appreciable loss of the catalytic activity.
- Zabihzadeh, Mehdi,Shirini, Farhad,Tajik, Hassan,Shokri, Zahra,Karami, Shiva
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p. 121 - 127
(2020/01/21)
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- Catalytic reduction of 4-nitrophenol by means of nanostructured polymeric Schiff base complexes
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Polymeric Schiff base ligands were synthesized using 2-hydroxybenzaldehyde (L2), 4-hydroxy-3-methoxybenzaldehyde (L4), and 5-aminoisophthalic acid. The nanostructured complexes were then synthesized using Ni2+, Cu2+, and Mn3+. The ligands and complexes thus synthesized were characterized using Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis (TGA), and field-emission scanning electron microscopy. The thermal stability of the complexes was confirmed using TGA. The synthesized complexes were used as catalysts in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol in an aqueous phase in the presence of sodium borohydride. In this work, the catalytic reactivity of nanostructured complexes was compared using the rate constant (k) of the reaction. The reaction time for the reduction of 4-NP was 5–14 min for different complexes. The catalytic system based on Ni2+/2-hydroxybenzaldehyde was the most active and displayed reusability in the reduction of 4-NP.
- Aghaei, Marjan,Dinari, Mohammad,Kianfar, Ali Hossein
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- Direct Hydrogenation of Nitroaromatics at Room Temperature Catalyzed by Magnetically Recoverable Cu@Fe2O3 Nanoparticles
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Metal embedded in metal oxide nanoparticles are active as catalyst in plethora of industrially important reactions. Herein, embedded Cu@Fe2O3 nanoparticles was synthesized via a one step hydrothermal strategy which selectively catalyzes the hydrogenation of diverse nitroaromatics in H2O at room temperature. The remarkable catalytic performance is due to the successful hybridization of metallic Cu and Fe2O3 which in turn allows easy electroflipping between various oxidation states of Cu and Fe. Azo- and azoxy-compounds are not formed during the catalyzed process. This evidently establish that the hydrogenation of nitroaromatics proceeds via direct route with >99percent selectivity to the corresponding anilines.
- Borah, Biraj Jyoti,Bharali, Pankaj
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- Self-Assembled Quaternary Ammonium-Containing Comb-Like Polyelectrolytes for the Hydrolysis of Organophosphorous Esters: Effect of Head Groups and Counter-Ions
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The aim of this work was to increase the efficiency of catalytic systems for the hydrolytic cleavage of 4-nitrophenyl esters of phosphonic acids. Quaternary ammonium-containing comb-like polyelectrolytes (?polymerized micelles?) with ester cleavable fragments and a low aggregation threshold were used as catalysts. The synthesis of poly(11-acryloyloxyundecylammonium) surfactants with different counterions (Br?, NO3?, CH3C6H4SO3?) and head groups was realized by micellar free-radical polymerization. Molecular weight, critical association concentration, particle sizes and solubilization properties toward Orange OT were determined. Self-assemblies organized by poly(11-acryloyloxyundecyltrimethyl ammonium) bromide successfully catalyze the hydrolysis of 4-nitrophenyl butylchloromethylphosphonate up to two orders of magnitude compared to aqueous alkaline hydrolysis. The development of these catalysts is promising for industrial applications and organophosphorus compound detoxification.
- Bilibin, Alexander Yu.,Burilova, Evgenia A.,Fetin, Petr A.,Kadnikov, Matvey V.,Lezov, Alexey A.,Pashirova, Tatiana N.,Valeeva, Farida G.,Zorin, Ivan M.
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p. 1939 - 1948
(2020/09/02)
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- Synthesis and structural characterization of a linkage isomer to a mononuclear Nickel(II) complex: Experimental and computational depiction of phosphoesterase efficiency
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Synthesis and structural characterization of a linkage isomer, bis(2,2′-dipyridylamine)dithiocyanato(k-S)nickel(II), [Ni(dpa)2(k-SCN)2] (1) of a previously reported Ni(II) complex, [Ni(dpa)2(k-NCS)2] (dpa = 2,2′
- Mudi, Prafullya Kumar,Mahato, Rajani Kanta,Joshi, Mayank,Paul, Suvendu,Choudhury, Angshuman Roy,Biswas, Bhaskar
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- Catalytic promiscuity of two novel cobalt(III) complexes derived from redox non-innocent Schiff base ligands: Unraveling the role of methyl groups in the ligand backbone on catalytic efficiency
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Two Schiff base ligands namely (E)-4-bromo-2-(((1-hydroxy-2-methylpropan-2-yl)imino)methyl)-6-methoxyphenol(H2L1) and (E)-4-bromo-2-(((2-hydroxyethyl)imino)methyl)-6-methoxyphenol (H2L2) were designed and synthesized by varying methy
- Dasgupta, Sanchari,Paul, Sanchita,Samanta, Debabrata,Hansda, Sili,Zangrando, Ennio,Das, Debasis
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- Transesterification activity by a zinc(II)-Schiff base complex with theoretical interpretation
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The article demonstrates the synthesis, structural characterization and transesterification activity of a mononuclear zinc(II) complex, [Zn(HL)(H2O)]·(H2O) (1) containing a previously reported Schiff base ligand, H3L = N,N
- Kumar Pal, Chanchal,Mahato, Shreya,Joshi, Mayank,Paul, Suvendu,Roy Choudhury, Angshuman,Biswas, Bhaskar
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- Catalytic promiscuity of a copper(II)-Mannich base complex having unprecedented radical pathway in catecholase activity
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A flexible single-side Mannich base ligand namely 4-(tert-butyl)-2-((ethyl(2-hydroxyethyl)amino)methyl)phenol (H2L) having O, N, O donor sites has been designed and synthesized using 4-(tert-butyl)phenol, formaldehyde and 2-(ethylamino)ethanol
- Dasgupta, Sanchari,Mandal, Arnab,Samanta, Debabrata,Zangrando, Ennio,Maity, Suvendu,Das, Debasis
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supporting information
(2020/02/29)
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- Mapping of Solvent-Mediated Molecular Self-Assembly of Iron(III) Discrete Compounds: Exploring Their Magnetic Behavior and Phosphatase-Like Activity
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Two newly synthesized Fe(III) based complexes, [Fe4L2(μ3-O)2(Cl)2(MeOH)4(H2O)4](ClO4)2·4H2O·MeOH (1) and [Fe2L3]·4DMF (2) were isolated in solid crystalline form using the reaction of iron(III) perchlorate with the ligand H2L (H2L = 6,6′-((1E,1′E)-hydrazine-1,2-diylidenebis(methanylylidene))bis(2-methoxyphenol). (DMF= N,N-dimethylformamide, MeOH = methanol). Compound 1 was self-assembled in MeOH, but when the solvent was changed to DMF, compound 2 was harvested. Furthermore, compound 1 was converted to compound 2 just by dissolving compound 1 in DMF. Sequential self-assembly and conversion of compound 1 to 2 were monitored by UV-vis spectroscopy and ESI-Mass spectroscopy in solution phase. Single crystal X-ray analysis showed that compound 1 has μ3-oxo bridged tetranuclear structure whereas compound 2 has puckered dinuclear structure. Magnetic studies indeed revealed frustrated magnetic spin for compound 1 whereas antiferromagnetic interaction was observed for compound 2. The spectrophotometrical investigation on their phosphatase like activity revealed remarkable hydrolytic efficiency for both the complexes. Michaelis-Menten-derived kinetic parameters suggest the competitiveness of the rate of P-O bond fission employing the phosphomonoester (4-nitrophenyl)phosphate (PNPP) in 97.5% DMF is 1 > 2, and the kcat value lies in the range 28.95-38.43 s-1 at 298 K. Computational calculations have verified the higher catalytic activity of compounds 1 over 2 attributed to the large number of labile groups attached to the metal centers.
- Chowdhury, Tania,Adhikary, Amit,Roy, Manasi,Zangrando, Ennio,Samanta, Debabrata,Das, Debasis
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p. 1254 - 1265
(2020/02/25)
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- Reactivity of Inorganic α-Nucleophiles in Acyl Group Transfer Processes in Water and Surfactant Micelles: II.1 Alkaline Hydrolysis of Ethyl 4-Nitrophenyl Ethylphosphonate in Systems Based on Dimeric Cationic Surfactants
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Alkaline hydrolysis of ethyl 4-nitrophenyl ethylphosphonate in organized nanosized systems based on dimeric surfactants and co-micelles [with cetyl(trimethyl)ammonium bromide as co-surfactant]. Transfer of the reaction from water to the micellar pseudophase accelerates the alkaline hydrolysis by a factor of 10 to 170. The maximum acceleration has been observed for tetraalkylammonium surfactant 16–3–16. The main factors responsible for micellar effects of surfactants are both substrate concentration and change of the reactivity of hydroxide ion in going from bulk water to surfactant micelles.
- Belousova, I. A.,Gaidash, T. S.,Mikhailov, V. A.,Panchenko, B. V.,Prokop’eva, T. M.,Razumova, N. G.,Zubareva, T. M.
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- Modelling a ‘histidine brace’ motif in mononuclear copper monooxygenases
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A mononuclear copper complex bearing a ‘histidine brace’ is synthesised and characterised as an active-site model of mononuclear copper monooxygenases such as lytic polysaccharide monooxygenases (LPMOs) and particulate methane monooxygenase (pMMO). The co
- Fukatsu, Arisa,Morimoto, Yuma,Sugimoto, Hideki,Itoh, Shinobu
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supporting information
p. 5123 - 5126
(2020/05/26)
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- Bicarbonate Inhibition of Carbonic Anhydrase Mimics Hinders Catalytic Efficiency: Elucidating the Mechanism and Gaining Insight toward Improving Speed and Efficiency
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Carbonic anhydrase (CA) mimics are often studied with a focus on the hydration of CO2 for atmospheric carbon capture. Consequently, the reverse reaction (dehydration of HCO3-) has received minimal attention, so much so tha
- Rains, Jonathan G. D.,O'Donnelly, Kerry,Oliver, Thomas,Woscholski, Rudiger,Long, Nicholas J.,Barter, Laura M. C.
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p. 1353 - 1365
(2019/02/10)
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- The ability of a trinuclear zinc(II) Schiff base complex to act as a photocatalyst for the degradation of methylene blue and to mimic phosphatase
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A new trinuclear zinc(II) complex, [Zn(μ1,1-N3)2{Zn(L)(N3)}2]·0.5CH3OH {HL = [2-((3-(dimethylamino)propylimino)methyl)-6-methoxyphenol]} has been synthesized and characterized. X-ray crysta
- Basak, Tanmoy,Bhattacharyya, Anik,Harms, Klaus,Chattopadhyay, Shouvik
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p. 449 - 457
(2018/11/06)
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- A triple alkoxo bridged dinuclear cobalt(III) complex mimicking phosphatase and showing ability to degrade organic dye contaminants by photocatalysis
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A dinuclear cobalt(III) complex, [(N3)L1CoIIIL2CoIIIL1] (1), has been synthesized and characterized {H2L1 = 2-((1-hydroxybutan-2-ylimino)methyl)-4-bromophenol and HLs
- Ghosh, Kousik,Harms, Klaus,Franconetti, Antonio,Frontera, Antonio,Chattopadhyay, Shouvik
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- Mapping the working route of phosphate monoester hydrolysis catalyzed by copper based models with special emphasis on the role of oxoanions by experimental and theoretical studies
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Three copper(ii) complexes derived from a reduced Schiff base ligand namely 4-bromo-2-[(2-hydroxy-1,1-dimethyl-ethylamino)-methyl]-phenol (H2L) were prepared by varying oxoanions (ClO4?, NO3?, OAcsup
- Dasgupta, Sanchari,Aullón, Gabriel,Zangrando, Ennio,Das, Debasis
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p. 2501 - 2512
(2019/02/12)
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- Ruthenium(II) carbonyl complexes containing thiourea ligand: Enhancing the biological assets through biomolecules interaction and enzyme mimetic activities
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Abstract: The ligand H2L (N-(N,N-diethylaminothiocarbonyl)benzimidoylchloride-2-aminoacetophenone-N-methylthiosemicarbazone) reacts with ruthenium(II) building blocks [RuHCl(CO)(EPh3)3] (E = P or As) to form new complexes
- Vijayan, Paranthaman,Vijayapritha, Subbarayan,Ruba, Chidambaram,Viswanathamurthi, Periasamy,Linert, Wolfgang
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p. 1059 - 1071
(2019/05/29)
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- A new macrocyclic heterobinuclear Cu(II)-Zn(II) complex: synthesis, crystal structure, phosphate hydrolysis, and DNA binding studies
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A new macrocyclic heterobinuclear Cu(II)-Zn(II) complex was synthesized and characterized by elemental analysis, FT-IR, ES-MS, and single-crystal X-ray diffraction. Five-coordinate geometry for the new complex is proposed. The copper…zinc distance bridged by two phenolic oxygens and a acetate ligand is 2.9508 ?. The phosphate ester hydrolysis activity and the DNA binding ability of the complex were studied. The results showed that the present complex has an efficient catalytic activity of phosphoester bond cleavage. The catalytic rate constant kcat for the hydrolysis of 4-nitrophenyl phosphate disodium salt hexahydrate (pNPP) by the synthesized complex is 2.69 × 10?4 s?1 and 105 times faster than the spontaneous hydrolysis of the phosphate monoester. The complex shows a good binding ability to calf thymus (CT-DNA) and the corresponding binding constant is 1.9 × 105 M?1. The linear Stern-Volmer quenching constant obtained by the fluorescent spectroscopic is 6.3 × 104 M?1.
- Kou, Huizhi,Wang, Yang,Ding, Peipei,Li, Jianfen,Shi, Baoxian
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p. 1683 - 1696
(2019/05/22)
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- Synthetic stratagem and structures of two heteroleptic cobalt(III) complexes acting as biomimetic catalysts: Role of co-ligands in catalytic activities
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Two heteroleptic cobalt(III) complexes, [CoL1(acac)(N3)] (1) and [CoL1(acac)(NCS)] (2) {where HL1 = 1-((2-(dimethylamino)ethylimino)methyl)naphthalen-2-ol and Hacac = acetylacetone} have been synthesized and str
- Ghosh, Kousik,Chattopadhyay, Shouvik
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supporting information
p. 495 - 507
(2019/07/04)
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- Bio-mimetic of catecholase and phosphatase activity by a tetra-iron(III) cluster
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An oxido- and acetato-bridged tetranuclear iron(III) cluster, [Fe4III(μ-O)2(μ-OAc)6(phen)2(H2O)2](NO3)2·(H2O)3 (1), [OAc = acetate; ph
- Pal, Chanchal Kumar,Mahato, Shreya,Yadav, Hare Ram,Shit, Madhusudan,Choudhury, Angshuman Roy,Biswas, Bhaskar
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- Synthesis of Structurally Diverse Ferrimagnetically and Antiferromagnetically Coupled MII-MnII (M = Cu, Ni) Heterometallic Schiff Base Compounds with a Dicyanamide Spacer and Study of Biomimetic Catalytic Activity
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The two heterometallic Schiff base compounds {[(CuL)Mn(N(CN)2)2]·CH3CN}∞ (1) and [(NiL)4Mn2(N(CN)2)2](ClO4)2 (2) have been synthesized using the N2/su
- Chakraborty, Tonmoy,Sarkar, Abani,Adhikary, Amit,Chakiroy, Neha,Das, Debasis
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p. 7336 - 7348
(2019/11/19)
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- Beyond esterase-like activity of serum albumin. Histidine-(nitro)phenol radical formation in conversion cascade of p-nitrophenyl acetate and the role of infrared light
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Serum albumin, recognized mainly for its capacity to act as a carrier protein for many compounds, can also actively transform some organic molecules. As a starting point in this study, we consider esterase-like activity of bovine serum albumin (BSA) toward p-nitrophenyl acetate (p-NPA). Our results reveal that the reaction goes beyond ester hydrolysis step. In fact, the transformation product, p-nitrophenol (p-NP), becomes a substrate for further reaction with BSA in which its nitro group in subtracted and released in the form of HNO2. Spectral data indicate that this cascade of events proceeds through formation of phenoxyl radical via proton-coupled electron transport (PCET) between OH group of p-NP and imidazole ring of histidine from the protein. Furthermore, the effect of application of electromagnetic radiation in the infrared range suggests that this remote physical trigger can support interactions based on PCET mechanism by acting on polarization and mutual alignment of water dipoles serving as effective water wires.
- Kowacz, Magdalena,Warszyński, Piotr
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- Cavity Catalysis by Cooperative Vibrational Strong Coupling of Reactant and Solvent Molecules
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Here, we report the catalytic effect of vibrational strong coupling (VSC) on the solvolysis of para-nitrophenyl acetate (PNPA), which increases the reaction rate by an order of magnitude. This is observed when the microfluidic Fabry–Perot cavity in which the VSC is generated is tuned to the C=O vibrational stretching mode of both the reactant and solvent molecules. Thermodynamic experiments confirm the catalytic nature of VSC in the system. The change in the reaction rate follows an exponential relation with respect to the coupling strength of the solvent, indicating a cooperative effect between the solvent molecules and the reactant. Furthermore, the study of the solvent kinetic isotope effect clearly shows that the vibrational overlap of the C=O vibrational bands of the reactant and the strongly coupled solvent molecules is critical for the catalysis in this reaction. The combination of cooperative effects and cavity catalysis confirms the potential of VSC as a new frontier in chemistry.
- Lather, Jyoti,Bhatt, Pooja,Thomas, Anoop,Ebbesen, Thomas W.,George, Jino
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supporting information
p. 10635 - 10638
(2019/07/12)
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- Exploration of Intrinsic Lipase-Like Activity of Zirconium-Based Metal-Organic Frameworks
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To overcome the disadvantages of natural enzymes, artificial enzyme mimics attracted increasing attention of researchers. Metal-organic frameworks (MOFs) are expected as one of the most appropriate candidates for artificial enzyme mimics. In this work, we demonstrate that the zirconium-based MOF material UiO-66 and its analogues possess intrinsic lipase-like activity and can efficiently catalyze ester hydrolysis, transesterification and esterification reactions. Furthermore, the UiO-66(NH2) exhibits much higher catalytic activity than that of UiO-66, which can be attributed to the synergy effect between the zirconium cluster centres and the amino moieties during the catalytic cycle.
- Liu, Xiao,Qi, Wei,Wang, Yuefei,Su, Rongxin,He, Zhimin
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supporting information
p. 4579 - 4585
(2018/10/26)
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- Molecularly imprinted artificial esterases with highly specific active sites and precisely installed catalytic groups
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A difficult challenge in synthetic enzymes is the creation of substrate-selective active sites with accurately positioned catalytic groups. Covalent molecular imprinting in cross-linked micelles afforded such active sites in protein-sized, water-soluble nanoparticle catalysts. Our method allowed a systematic tuning of the distance of the catalytic group to the bound substrate. The catalysts displayed enzyme-like kinetics and easily distinguished substrates with subtle structural differences.
- Hu, Lan,Zhao, Yan
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supporting information
p. 5580 - 5584
(2018/08/17)
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- Mechanoresponsive and recyclable biocatalytic sponges from enzyme-polymer surfactant conjugates and nanoparticles
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The development of multifunctional hybrid biomaterials is an important area of focus in tissue engineering, drug delivery, biocatalysis, and biosensing applications. Combining bioconjugation methodology with ice templating technique, we show here the deve
- Jain, Mehak,Vaze, Rutuja G.,Ugrani, Suraj C.,Sharma, Kamendra P.
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p. 39029 - 39038
(2018/12/02)
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- High catalytic efficiency of nanostructured β-CoMoO4 in the reduction of the ortho-, meta- and para-nitrophenol isomers
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Nanostructured -CoMoO4 catalysts have been prepared via the thermal decomposition of an oxalate precursor. The catalyst was characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller method (BET), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The efficiency of these nanoparticles in the reduction of ortho- and meta-nitrophenol isomers (2-NP, 3-NP, and 4-NP) to their corresponding aminophenols was tested using UV-visible spectroscopy measurements. It was found that, with a -CoMoO4 catalyst, NaBH4 reduces 3-NP instantaneously, whilst the reduction of 2-NP and 4-NP is slower at 8 min. This difference is thought to arise from the lower acidity of 3-NP, where the negative charge of the phenolate could not be delocalized onto the oxygen atoms of the meta-nitro group.
- Al-Wadaani, Fahd,Omer, Ahmed,Abboudi, Mostafa,Hassani, Hicham Oudghiri,Rakass, Souad,Messali, Mouslim,Benaissa, Mohammed
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- Facile one-pot green synthesis of Au-Ag alloy nanoparticles using sucrose and their composition-dependent photocatalytic activity for the reduction of 4-nitrophenol
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Au-Ag alloy nanoparticles (NPs) less than 10 nm in size were synthesized using sucrose as a reductant and surfactant. Au-Ag alloy NPs with a homogeneous composition were continuously obtained by changing the synthesis time from 2 to 40 min in one pot. Bas
- Sun, Li,Yin, Yuechao,Wang, Fa,Su, Wenxian,Zhang, Lixin
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p. 4315 - 4324
(2018/03/26)
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- Eco-Friendly In Situ Fabrication of Reduced Graphene Oxide Gold Nanocomposites for Catalysis and Dye Degradation
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Abstract: The invention represents a development of robust eco-friendly method use for water waste management and polluted water. The inadvertent role of peanut peels extract helps to simultaneously convert and form reduced graphene oxide gold nanocomposite (rGO@AuNCs) in single step. Fabricated nanocomposite was evaluated for its catalytic performance using reduction of 4-nitrophenol to 4-aminophenol as well as elimination of methylene blue (MB) and malachite green (MG) dyes from water. Graphene oxide (GO) and rGO@AuNCs, were synthesized using simplified approaches and preliminary characterization was done using UV–Vis spectrophotometer and Fourier transform infrared spectroscopy. Least concentration of rGO@AuNCs is required to eliminate MB and MG around 77 and 93%, respectively. Furthermore, surface morphology and elemental analysis of rGO@AuNCs confirm successful fabrication methods as well as X?ray diffraction pattern confirms the crystalline behavior of nanocomposite. The study illustrates an environment-friendly and cost effective in situ fabrication rGO@AuNCs from industrial agro waste for an environmental remediation.
- Patil, Pravin O.,Mahale, Sanchita S.,More, Mahesh P.,Bhandari, Pravin V.,Deshmukh, Prashant K.,Bari, Sanjay B.
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p. 2750 - 2756
(2019/02/26)
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- Enhanced activity of trinuclear Zn(II) complexes towards phosphate ester bond cleavage by introducing three-metal cooperativity
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Three Zn(ii) complexes, namely, [Zn3(L1)2]·4CH3CN (1), [Zn3(L1)2(H2O)4]·H2O·2DMF (2) and [Zn2(L2)2·(H2O)2·2H+]·2ClO4- (3) were synthesized by reacting nitrophenol-based tripodal and dipodal Schiff-base ligands with Zn(ii) salts. The complexes were characterized using different techniques such as elemental analyses, ESI-MS, IR and NMR. The solid-state structures of all the complexes were determined. Complex 1 has a rigid trinuclear structure with an octahedral environment around each metal ion. The coordination environment of the rigid trinuclear complex 1 was purposely disturbed by changing the reaction conditions to obtain the flexible trinuclear complex 2. The dinuclear complex 3, containing coordinated water molecules, was also synthesized. DNA binding abilities and phosphatase-like activities of all the complexes were investigated. The catalytic activity of the rigid trinuclear complex 1 was compared with the cup shaped trinuclear complex 2 and closed structure dinuclear complex 3. The different structural factors (such as flexibility of the complex, number of metal centers, labile sites at the metal centre and coordination environment around the metal center) collectively modulate the phosphatase-like activity toward the transesterification of 2-hydroxypropyl-p-nitropenylphosphate (HPNP). Complex 2 exhibits the highest catalytic activity among all the complexes due to its flexible cup-shaped structure, three metal centers and coordinated water molecules.
- Joshi, Pooja,Hussain, Navid,Ali, Shah Raj,Rishu,Bhardwaj, Vimal K.
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p. 2204 - 2215
(2018/02/07)
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- Reconstitution of full-length P450BM3 with an artificial metal complex by utilising the transpeptidase Sortase A
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Haem substitution is an effective approach to tweak the function of haemoproteins. Herein, we report a facile haem substitution method for self-sufficient cytochrome P450BM3 (CYP102A1) from Bacillus megaterium utilising the transpeptidase Sortase A from Staphylococcus aureus. We successfully constructed Mn-substituted BM3 and investigated its catalytic activity.
- Omura, Keita,Aiba, Yuichiro,Onoda, Hiroki,Stanfield, Joshua Kyle,Ariyasu, Shinya,Sugimoto, Hiroshi,Shiro, Yoshitsugu,Shoji, Osami,Watanabe, Yoshihito
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supporting information
p. 7892 - 7895
(2018/07/25)
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- Portraying the role of halo ligands and the auxiliary part of ligands of mononuclear manganese(iii)-Schiff base complexes in catalyzing phospho-ester bond hydrolysis
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Four mononucleating Schiff base ligands, namely HL1, HL2, HL3 and HL4, were prepared via condensation between 2-hydroxybenzaldehyde and 2-morpholinoethanamine, 2-(piperazin-1-yl)ethanamine, 2-(piperidin-1-yl)ethanamine and 2-(pyrrolidin-1-yl)ethanamine, r
- Chakraborty, Tonmoy,Dasgupta, Sanchari,Zangrando, Ennio,Das, Debasis
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supporting information
p. 14933 - 14942
(2018/09/29)
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- Non-photochemical catalytic hydrolysis of methyl parathion using core-shell Ag@TiO2 nanoparticles
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Highly water-dispersible core-shell Ag@TiO2 nanoparticles were prepared and shown to be catalytically active for the rapid degradation of the organothiophosphate pesticide methyl parathion (MeP). Formation of the hydrolysis product, p-nitrophenolate was monitored at pH 7.5 and 8.0, using UV-Vis spectroscopy. 31P NMR spectroscopy confirmed that hydrolysis is the predominant pathway for substrate breakdown under non-photocatalytic conditions. We have demonstrated that the unique combination of TiO2 with silver nanoparticles is required for catalytic hydrolysis with good recyclability. This work represents the first example of MeP degradation using TiO2 doped with AgNPs under mild and ambient conditions. Analysis of catalytic data and a proposed dark mechanism for MeP hydrolysis using core-shell Ag@TiO2 nanoparticles are described.
- Talebzadeh, Somayeh,Forato, Florian,Bujoli, Bruno,Trammell, Scott A.,Grolleau, Stéphane,Pal, Hemant,Queffélec, Clémence,Knight, D. Andrew
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p. 42346 - 42352
(2019/01/03)
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