Search results for "Solvolysis"
showing 9 items of 9 documents
Real-Time Observation of “Soft” Magic-Size Clusters during Hydrolysis of the Model Metallodrug Bismuth Disalicylate
2021
International audience; Colloidal bismuth therapeutics have been used for hundreds of years, yet remain mysterious. Here we report an X-ray pair distribution function (PDF) study of the solvolysis of bismuth disalicylate, a model for the metallodrug bismuth subsalicylate (Pepto-Bismol). This reveals catalysis by traces of water, followed by multistep cluster growth. The ratio of the two major species, {Bi9O7} and {Bi38O44}, depends on exposure to air, time, and the solvent. The solution-phase cluster structures are of significantly higher symmetry in comparison to solid-state analogues, with reduced off-center Bi3+ displacements. This explains why such “magic-size” clusters can be both stab…
Organometallic complexes with biological molecules
2002
Novel triorganotin(IV) complexes of two beta-lactamic antibiotics, 6-[D-(-)-beta-amino-p-hydroxyphenyl-acetamido]penicillin (=amoxicillin) and 6-[D-(-)-alpha-aminobenzyl]penicillin (=ampicillin), have been synthesized and investigated both in solid and solution states. The complexes corresponded to the general formula R(3)Sn(IV)antib*H(2)O (R=Me, n-Bu, Ph; antib=amox=amoxicillinate or amp=ampicillinate). Structural investigations about configuration in the solid state have been carried out by interpreting experimental IR and 119Sn Mossbauer data. In particular, IR results suggested polymeric structures both for R(3)Sn(IV)amox.H(2)O and R(3)Sn(IV)amp*H(2)O. Moreover, both antibiotics appear …
Ferromagnetism in Cu II 4 and Co II 4 Complexes Derived from Metal‐Assisted Solvolysis of Di‐2,6‐(2‐pyridylcarbonyl)pyridine: Syntheses, Structures, …
2008
Metal-assisted solvolysis of di-2,6-(2-pyridylcarbonyl)pyr-idine (pyCOpyCOpy, dpcp) by M(0 2 CMe) 2 ·xH 2 O (M II = Cu II , CO II ) led to complex [Cu 4 {pyC(O) 3 pyC(O)(OEt )py}(O 2 CMe )5-(EtOH) 2 ] (1), when the reaction was carried out in EtOH, and to complex [Co4{pyC(O)(OMe )pyC(O)(OMe )py} 2 (02CMe)2-(N 3 ) 2 ] (2), when the reaction was carried out in MeOH in the presence of azide anions. Complex 1 consists of four Cu II ions bridged by the hemiacetal-gem-diol form of the ligand, which is found in a μ 4 -η 2 :η 2 :η 2 :η 1 :η 1 :η 1 coordination mode. It exhibits ferromagnetic couplings among all nearest neighbors and antiferromagnetic next-nearest-neighbor interactions (J 12 = J 1 =…
The Hydrogen‐Storage Challenge: Nanoparticles for Metal‐Catalyzed Ammonia Borane Dehydrogenation
2021
International audience; Dihydrogen is one of the sustainable energy vectors envisioned for the future. However, the rapidly reversible and secure storage of large quantities of hydrogen is still a technological and scientific challenge. In this context, this review proposes a recent state-of-the-art on H 2 production capacities from the dehydrogenation reaction of ammonia borane (and selected related amine-boranes) as a safer solid-source of H 2 by hydrolysis (or solvolysis), according to the different developed nanoparticle-based catalysts. The review groups the results according to the transition metals constituting the catalyst according a special view to current cost/availability consid…
Defective dicubane-like tetranuclear nickel(II) cyanate and azide nanoscale magnets.
2010
Four tetrameric nickel(II) pseudohalide complexes have been synthesized and structurally, spectroscopically, and magnetically characterized. Compounds 1-3 are isostructural and exhibit the general formula [Ni(2)(dpk·OH)(dpk·CH(3)O)(L)(H(2)O)](2)A(2)·2H(2)O, where dpk = di-2-pyridylketone; L = N(3)(-), and A = ClO(4)(-) for 1, L = NCO(-) and A = ClO(4)(-) for 2, and L = NCO(-) and A = NO(3)(-) for 3. The formula for 4 is [Ni(4)(dpk·OH)(3) (dpk·CH(3)O)(2)(NCO)](BF(4))(2)·3H(2)O. The ligands dpk·OH(-) and dpk·CH(3)O(-) result from solvolysis and ulterior deprotonation of dpk in water and methanol, respectively. The four tetramers exhibit a dicubane-like core with two missing vertexes where the…
Identification of hexanuclear Actinide(IV) carboxylates with Thorium, Uranium and Neptunium by EXAFS spectroscopy
2012
International audience; Hydrated actinide(IV) ions undergo hydrolysis and further polymerization and precipitation with increasing pH. The resulting amorphous and partly crystalline oxydydroxides AnO(n)(OH)(4-2n)center dot xH(2)O can usually be observed as colloids above the An(IV) solubility limit. The aging process of such colloids results in crystalline AnO(2). The presence of carboxylates in the solution prevents the occurrence of such colloids by formation of polynuclear complexes through a competing reaction between hydrolysis and ligation. The majority of recently described carboxylates reveals a hexanuclear core of [An(6)(mu(3)-O)(4)(mu(3)-OH)(4)](12+) terminated by 12 carboxylate l…
Dipeptide analogues of fluorinated aminophosphonic acid sodium salts as moderate competitive inhibitors of cathepsin C
2023
In this paper, we present the solvolysis reaction of dipeptide analogues of fluorinated aminophosphonates with simultaneous quantitative deprotection of the amino group. To the best of our knowledge, this work is the first reported example of the application of fluorinated aminophosphonates in cathepsin C inhibition studies. The new molecules show moderate inhibition of the cathepsin C enzyme, which opens the door to consider them as potential therapeutic agents. Overall, our findings provide a new avenue for the development of fluorinated aminophosphonate-based inhibitors. This article is part of the thematic issue "Organophosphorus chemistry: from model to application".
Kinetische untersuchungen zur reaktionsfähighkeit von chlormethylgruppen in methylendiphenolen
1984
The chloromethyl derivatives of 16 differently substituted methylenediphenols were synthesized for the first time. To compare their reactivity, the solvolysis in methanol and the animolysis with an excess of p-nitroaniline in dimethyl sulfoxide were studied kinetically at 25°C. The rate constants for the methanolysis do not differ very much, beside of the fact that para-chloromethyl derivatives react about 100 times faster than ortho-chloromethyl derivatives. However, for the aminolysis a large acceleration up to 103 was found for compounds having both hydroxyl groups in ortho-position to the methylene bridge. Obviously, the cleavage of the OH bond, which occurs in the rate determining step…
Fluorinated heterocyclic compounds: an assay on the photochemistry of some fluorinated 1-oxa-2-azoles: an expedient route to fluorinated heterocycles
2004
Abstract Photoinduced heterocyclic rearrangements of ON bond-containing azoles have been claimed in the synthesis of target fluorinated heterocyclic compounds. In this context, the photochemical behavior of some fluorinated 1,2,4-oxadiazoles has been investigated. Irradiations of 3-amino-5-perfluoroalkyl-1,2,4-oxadiazoles at λ =313 nm in methanol gave open-chain products arising from a reaction of the nucleophilic solvent with either the first formed ring-photolytic species or with a nitrilimine moiety generated from it. Differently, irradiations in methanol with the presence of triethylamine (TEA) followed competing phototransposition pathways leading to the ring-isomers 2-amino-5-perfluo…