Search results for "inorganic chemistry"
showing 10 items of 7339 documents
Hydrothermally Synthesized Strontium Peroxyapatite
2015
The current research focuses on peroxide ion incorporation in the structure of strontium hydroxyapatite (SrHAp) by exposure to H2O2 ina closed hydrothermal vessel under mild conditions at 130 to 170 °C. Peroxide enriched strontium apatite (SrPerAp) was characterized for structure by X-Ray diffraction, for peroxide content- by permanganometric titration and then viewed by SEM. This study continued from previous work that used 30%H2O2 and showed a higher included peroxide content after processing with 50% H2O2 at 130 °C 70% of the theoretical peroxide content in apatitic channels of strontium apatite. This is the highest peroxide content incorporated to date and employs a lower temperature th…
Protected but Accessible: Oxygen Activation by a Calixarene-Stabilized Undecagold Cluster
2013
DFT computations show that calixarenes stabilize subnanometer Au11 clusters allowing access of small molecules like O2 to reactive metal sites in the core. Maximum of three dioxygen molecules can bind to the cluster, and they are activated to a superoxo O2(-) state. This study predicts that gold clusters could act as viable oxidation catalysts at ambient conditions based on similar principles as the metal centers in enzymes.
Bioinspired Mo, W and V complexes bearing a highly hydroxyl-functionalized Schiff base ligand
2020
A series of bioinspired dioxidomolybdenum(vi), dioxidotungsten(vi) and oxidovanadium(v) complexes [MoO2(H2LSaltris)], [WO2(H2LSaltris)] and [VO(HLSaltris)]2 were prepared by the reaction of a hydroxyl-rich Schiff base proligand N-(1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)-3,5-di-tert-butylsalicylaldimine (H4LSaltris) with metal precursors in methanol solutions. Molybdenum and tungsten complexes crystallize as mononuclear molecules, whereas the vanadium complex forms dinuclear units. From the complexes, [VO(HLSaltris)]2 shows activity in the oxidation of 4-tert-butylcatechol and 3,5-di-tert-butylcatechol, mimicking the action of the dicopper enzyme catechol oxidase. peerReviewed
FTIR analysis of the high pressure response of native insulin assemblies
2013
It is widely recognized that a central role in conferring stability to the structure of proteins against misfolding and aggregation is played by the formation of oligomers. The case of insulin is prototypical in this respect: in our body it is stored up in stable inactive hexameric assemblies whereas only in its monomeric form it recovers the role of regulating carbohydrate and fat metabolism. In the present paper, exploiting the optimal coupling between FTIR spectroscopy and diamond anvil cell technique, we probe the stability of different insulin oligomeric forms under high pressure, namely over the ranges 0-15 kbar for water solution and 0-80 kbar for dry powder. Results obtained show di…
Gas-Phase Hydrogenation of Propionitrile Catalyzed by LnCu2 (Ln = La, Ce, Pr, Nd)
2007
The hydrogenation of propionitrile over binary copper−lanthanide intermetallic compounds (LnCu2, Ln = La, Ce, Pr, Nd) was studied in the gas phase. The results show that the reaction main product is the primary amine, the n-propylamine. To our knowledge, it is the first time that such behavior is reported for copper catalysts.
DOSY NMR, X-ray Structural and Ion-Mobility Mass Spectrometric Studies on Electron-Deficient and Electron-Rich M6L4 Coordination Cages.
2015
A novel modular approach to electron-deficient and electron-rich M6L4 cages is presented. From the same starting compound, via a minor modulation of the synthesis route, two C3-symmetric ligands L1 and L2 with different electronic properties are obtained in good yield. The trifluoro-triethynylbenzene-based ligand L1 is more electron-deficient than the well-known 2,4,6-tri(4-pyridyl)-1,3,5-triazine, while the trimethoxy-triethynylbenzene-based ligand L2 is more electron-rich than the corresponding benzene analogue. Complexation of the ligands with cis-protected square-planar [(dppp)Pt(OTf)2] or [(dppp)Pd(OTf)2] corner-complexes yields two electron-deficient (1a and 1b) and two electron-rich …
Ionic liquid binary mixtures: Promising reaction media for carbohydrate conversion into 5-hydroxymethylfurfural
2014
Abstract The conversion of carbohydrates into 5-hydroxymethylfurfural (5-HMF) has been studied in binary mixtures of ionic liquids (ILs), using strongly acidic resin Amberlyst 15 as the catalyst. In particular, both mono- and disaccharides, such as fructose, glucose and sucrose have been investigated. Considering the favorable effect exerted by chloride-based ionic liquids in the dissolution of carbohydrates, we used binary mixtures of 1-butyl-3-methylimidazolium chloride ([bmim][Cl]) with [bmim + ] based ionic liquids differing in size, shape and coordination ability of the anion ([bmim][BF 4 ], [bmim][N(CF 3 SO 2 ) 2 ], [bmim][N(CN) 2 ], [bmim][SbF 6 ] and [bmim][CF 3 SO 3 ]). Carbohydrat…
Determination of basic strenght of aliphatic amines through ion pair formation in some ionic liquid solutions
2010
To have an evaluation of the basic strength of aliphatic amines in ionic liquid solution, the stability constants relevant to the formation of amine/p-nitrophenol ion pairs were determined in different ionic liquids at 298 K. In particular, aliphatic (pyrrolidinium) and aromatic (imidazolium) ionic liquids were used. Imidazolium ions, bmim(+) and bm(2)im(+), having different hydrogen bond donor abilities were taken into account. Anions were chosen ([BF(4)(-)], [PF(6)(-)], and [NTf(2)(-)]; where NTf(2) = bis(trifluoromethansulfonyl)imide) showing different shape, size, and coordination ability. Several primary, secondary (cyclic or not), and tertiary amines were used to study the effect of a…
Dicationic organic salts: gelators for ionic liquids
2014
Diimidazolium and dipyrrolidinium organic salts were tested for their ability to gel both organic solvents and ionic liquids. Organic salts containing 1-(1-imidazolylmethyl)-3,5-di-(3'-octylimidazolylmethyl)-benzene and 1-(N-pyrrolidylmethyl)-3,5-di-(N,N-octylpyrrolidylmethyl)-benzene cations were used. In addition to the simple bromide anion, also dianions having a naphthalene core such as 1,5- and 2,6-naphthalenedisulfonate and 2,6-naphthalenedicarboxylate were taken into account. Gelation tests demonstrated that organic salts used were able to harden ionic liquids. The materials obtained were investigated for their thermal stability and also for electric conductivity properties using mic…
Dimethyl 2-(1-methyl-3-oxo-1,3-dihydroisobenzofuran-1-yl)malonate
2020
In this work we report a facile access to a 3,3-disubstituted isobenzofuranone by tandem addition/cyclization reaction to methyl 2-acetylbenzoate in the presence of dimethyl malonate, under basic conditions.