Search results for "Note"
showing 10 items of 10709 documents
Photo-fragmentation of alkyl phosphates in the gas-phase
2018
Abstract Alkyl phosphates are experiencing an ever increasing use due to the current arising of new applications. This implies their increasing presence in the environment so their stability and reactivity under high-energy photons, which are still unknown, need to be clarified. In this study, a mass spectrometric investigation of the ionization and fragmentation processes of four representative alkyl phosphates (dibutyl, tributyl, bis-2-ethylhexyl, and tris-2-ethylhexyl phosphate) induced by vacuum ultraviolet (VUV) radiation has been carried out. The experimental data show that fragmentation occurs through a stepwise cleavage of the bonds between the phosphate group and the alkyl chains l…
A versatile viscometric method for the study of dissolved proteins, exemplified for casein micelles in ammoniacal solutions
2017
Abstract Viscosities of casein solutions were measured within the dilute range in ammoniacal water and in saline solvents containing different amounts and different kinds of salt. All these data are modeled quantitatively by means of an approach accounting for the polyelectrolyte character of casein micelles. Two parameters are required: The intrinsic viscosity [ η ] and a viscometric interaction parameter β . The behavior of casein is compared with that of chain-like polyelectrolytes. For both polymers one observes a pronounced reduction of [ η ] with increasing salt concentration. However, for casein the decline of [ η ] is less pronounced by more than an order of magnitude and depends on…
Amine N-Oxide Kinetic Hydrate Inhibitor Polymers for High-Salinity Applications
2020
A series of glycidyl amine N-oxide polyethers with cyclic and acyclic amine N-oxide side groups and their block copolymers with poly(propylene) oxide (Mn in the range of 1.8–6.4 kg/mol) have been s...
Sesquiterpene lactones from Artemisia lucentica
1997
Abstract The aerial parts of Artemisia lucentica yielded, in addition to several known compounds, a bicyclic monoterpene ketone, two germacranolides, an eudesmanolide, a 10- epi neudesmanolide, a 2-norelemanolide and three bisabolene derivatives. The stereochemistry of a germacranolide, described as 2α-hydroxyartemorin in a previous investigation of the species, has now been corrected and the compound has been renamed lucentolide.
Sesquiterpene lactones from iranian Artemisia species
1993
Abstract The aerial parts of Artemisia turcomanica and A. deserti yielded two new germacranolides, a new guaianolide, and several known mono- and sesquiterpenes.
Design and evaluation of sensory systems based on amphiphilic anthraquinones molecular receptors
2015
A new paradigm is described that allows one to create different types of sensors: from highly sensitive ones to practical household devices. Our approach relies on modular molecular receptors incorporating an intensely-colored aminoanthraquinone signaling unit equipped with both hydrophilic and hydrophobic modules, the number and size of which being configured in accordance with the targeted analyte and the sought detection method. An important advantage is the compliance with some principles of green chemistry, avoiding the use of toxic organic solvents. The proper functionalization of the anthraquinone scaffold afforded water-soluble chromoinophores capable of quantifying selectively Hg2+…
Insights into the Formation and Structures of Molecular Gels by Diimidazolium Salt Gelators in Ionic Liquids or “Normal” Solvents
2016
Insights are provided into the properties of molecular gels formed by diimidazolium salts both in “normal” solvents and ionic liquids. These materials can be interesting for applications in green and sustainable chemistry in which ionic liquids play a significant role, like catalysis and energy. In particular, two positional isomers of a diimidazolium cation have been examined with a wide range of anions for their ability to form gel phases. In particular, di-, tri-, and tetravalent anions bearing aliphatic or aromatic spacers were paired with the divalent cations. The properties of the organo- and ionogels formed have been analyzed by means of several different techniques, including calori…
Photoresponsive ionic liquid crystals assembled: Via halogen bond: En route towards light-controllable ion transporters
2017
We demonstrate that halogen bonding (XB) can offer a novel approach for the construction of photoresponsive ionic liquid crystals. In particular, we assembled two new supramolecular complexes based on 1-ethyl-3-methylimidazolium iodides and azobenzene derivatives containing an iodotetrafluoro-benzene ring as XB donor, where the iodide anion acted as an XB acceptor. DSC and X-ray diffraction analyses revealed that the preferred stoichiometry between the XB donors and acceptors is 2 : 1, and that the iodide anions act as bidentate XB-acceptors, binding two azobenzene derivatives. Due to the high directionality of the XB, calamitic superanions are obtained, while the segregation occurring betw…
Thioester-functionalised and oxime-based hexametallic manganese(iii) single-molecule magnets
2017
Two novel hexametallic MnIII complexes of formulae [Mn6(μ3-O)2(H2N-sao)6(3-atpa)2(EtOH)6]·2EtOH·2H2O (1) and [Mn6(μ3-O)2(H2N-sao)6(6-atha)2(EtOH)6]·6EtOH (2) [H2N-saoH2 = salicylamidoxime, 3-hatpa = 3-(acetylthio)propionic acid, 6-hatha = 6-(acetylthio)hexanoic acid] have been synthesised by using thioester-carboxylate ligands and magnetostructurally characterised. 1 crystallises in the triclinic system with space group P and 2 crystallises in the monoclinic system with space group P21/c. The study of the dc and ac magnetic susceptibility reveals single-molecule magnet behaviour for both compounds with spin-ground states S = 12 and S = 4 for 1 and 2, respectively. Hence, 1 and 2 are new mem…
A Step into the Future: Applications of Nanoparticle Enzyme Mimics.
2018
We describe elementary concepts, up-to-date developments, and perspectives of the emerging field of nanoparticle enzyme mimics (so-called "nanozymes") at the interface of chemistry, biology, materials, and nanotechnology. The design and synthesis of functional enzyme mimics is a long-standing goal of biomimetic chemistry. Metal complexes, polymers and engineered biomolecules capturing the structure of natural enzymes or their active centers have been made to achieve high rates and enhanced selectivities. Still, the design of new "artificial enzymes" that are not related to proteins but with capacity of production and stability at industrial level, remains a goal. Inorganic nanoparticles bea…