Search results for "Organic chemistry"
showing 10 items of 17180 documents
.Single-Ion Magnetic Behaviour in an Iron(III) Porphyrin Complex: A Dichotomy Between High Spin and 5/2-3/2 Spin Admixture
2020
International audience; A mononuclear iron(III) porphyrin compound exhibiting unexpectedly slow magnetic relaxation, which is a characteristic of single-ion magnet behaviour, is reported. This behaviour originates from the close proximity (approximate to 550 cm(-1)) of the intermediate-spinS=3/2 excited states to the high-spinS=5/2 ground state. More quantitatively, although the ground state is mostlyS=5/2, a spin-admixture model evidences a sizable contribution (approximate to 15 %) ofS=3/2 to the ground state, which as a consequence experiences large and positive axial anisotropy (D=+19.2 cm(-1)). Frequency-domain EPR spectroscopy allowed them(S)= |+/- 1/2⟩->|+/- 3/2&Rig…
Effect of Er3+-doping on 65GeS2-25Ga2S3-10CsCl glass probed by annihilating positrons
2019
Abstract Effect of Er3+-doping resulting in pronounced mid-IR fluorescence functionality was examined first in chalcohalide 65GeS2-25Ga2S3-10CsCl glass using positron annihilation lifetime (PAL) spectroscopy. The detected PAL spectra were reconstructed from unconstrained x2-term analysis employing two-state simple trapping model for one kind of positron trapping free-volume defects, the parameterization being performed at the example of 65GeS2-25Ga2S3-10CsCl glass doped with 0.6 at. % of Er3+. The observed decrease in positron trapping rate was proved to be primary void-evolution process in this Er-activated glass, like in many other chalcogenide glasses affected by rare earth doping. The n…
Sponge‐Like Behaviour in Isoreticular Cu(Gly‐His‐X) Peptide‐Based Porous Materials
2015
We report two isoreticular 3D peptide-based porous frameworks formed by coordination of the tripeptides Gly-L-His-Gly and Gly-L-His-L-Lys to Cu(II) which display sponge-like behaviour. These porous materials undergo structural collapse upon evacuation that can be reversed by exposure to water vapour, which permits recovery of the original open channel structure. This is further confirmed by sorption studies that reveal that both solids exhibit selective sorption of H2 O while CO2 adsorption does not result in recovery of the original structures. We also show how the pendant aliphatic amine chains, present in the framework from the introduction of the lysine amino acid in the peptidic backbo…
Total oxidation of propene at low temperature over Co3O4–CeO2 mixed oxides: Role of surface oxygen vacancies and bulk oxygen mobility in the catalyti…
2008
Liotta, L. F. Ousmane, M. Di Carlo, G. Pantaleo, G. Deganello, G. Marci, G. Retailleau, L. Giroir-Fendler, A.; Co3O4, CeO2 and Co3O4-CeO2 mixed oxides with Co/Ce nominal atomic ratio 0.1:5, prepared by co-precipitation method with sodium carbonate, were tested in the oxidation of propene under lean condition and the catalyst stability was checked by performing three consecutive heating-cooling cycles. Characterization of the textural properties were performed by surface area measurement BET, X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements. Among the Co3O4-CeO2 mixed oxides, Co3O4 (30 Wt%)-CeO2 (70 wt%) gives the best activity attaining full propene conversion at …
Immobilization of proteins in silica gel: Biochemical and biophysical properties
2015
The development of silica-based sol-gel techniques compatible with the retention of protein structure and function started more than 20 years ago, mainly for the design of biotechnological devices or biomedical applications. Silica gels are optically transparent, exhibit good mechanical stability, are manufactured with different geometries, and are easily separated from the reaction media. Biomolecules encapsulated in silica gel normally retain their structural and functional properties, are stabilized with respect to chemical and physical insults, and can sometimes exhibit enhanced activity in comparison to the soluble form. This review briefly describes the chemistry of protein encapsulat…
Diversity of Isomerization Patterns and Protolytic Forms in Aminocarbene PdII and PtII Complexes Formed upon Addition of N,N′-Diphenylguanidine to Me…
2017
Reaction of the palladium(II) and platinum(II) isocyanide complexes cis-[MCl2(CNR)2] [M = Pd, R = C6H3(2,6-Me2) (Xyl), 2-Cl-6-MeC6H3, cyclohexyl (Cy), t-Bu, C(Me)2CH2(Me)3 (1,1,3,3-tetramethylbuth-1-yl abbreviated as tmbu); M = Pt, R = Xyl, 2-Cl-6-MeC6H3, Cy, t-Bu, and tmbu] with N,N′-diphenylguanidine (DPG) leads to DPG-derived metal-bound deprotonated acyclic diaminocarbene (ADC) species. This reaction occurs via a two-step process, involving the initial coupling of the guanidine with one of the isocyanides and leading to deprotonated monocarbene monochelated species, while the next addition grants the deprotonated bis-carbene bis-chelated metal compounds. DPG behaves as nucleophile, depr…
Multifacial Recognition in Binary and Ternary Cocrystals from 5-Halouracil and Aminoazine Derivatives
2018
A systematic analysis using single crystal X-ray diffraction was performed to explore the role exerted by potential intercomponent proton-transfer reactions in the supramolecular structures of A–B cocrystals formed by 5-haloderivatives of uracil (A), coupled with 2-aminoadenine simulants (aminoazines, B). Twelve new heterodimers were synthesized in different stoichiometries and cocrystallized by solvent cogrinding followed by solution crystallization. In the binary cocrystals, uracil or 1-methyluracil with halide modification at the 5 position (F, Cl, Br, I) was coupled with amino-aromatic N-heterocycles (melamine, 2,4,6-triaminopyrimidine, 2,6-diaminopyridine) as a multivalent site for pyr…
Intramolecular Hydrogen Bond, Hirshfeld Analysis, AIM; DFT Studies of Pyran-2,4-dione Derivatives
2021
Intra and intermolecular interactions found in the developed crystals of the synthesized py-ron-2,4-dione derivatives play crucial rules in the molecular conformations and crystal stabili-ties, respectively. In this regard, Hirshfeld calculations were used to quantitatively analyze the different intermolecular interactions in the crystal structures of some functionalized py-ran-2,4-dione derivatives. The X-ray structure of pyran-2,4-dione derivative namely (3E,3′E)-3,3′-((ethane-1,2-diylbis(azanediyl))bis(phenylmethanylylidene))bis(6-phenyl-2H-pyran-2,4(3H)-dione) was determined. It crystallized in the monoclinic crystal system and C2/c space group with unit cell parameters: a = 14.0869(4) …
(E)-1-(Pyridin-4-yl)propan-1-one oxime
2016
The asymmetric unit of the title compound, C8H10N2O, contains two crystallographically independent molecules of slightly different conformation, which are linkedviaan intermolecular O—H...N hydrogen bond. The dihedral angle between the pyridine ring and the oxime plane of moleculeA[2.09 (19)°] is smaller than in moleculeB[16.50 (18)°].
Poly[[tetramethanolbis[4-oxo-3-(pyridin-4-yl)-1-(2,4,6-trichlorophenyl)-4,5-dihydro-1H-pyrazolo[3,4-d]pyrimidin-6-olato]disodium]–diethyl ether–metha…
2016
In the title compound, [Na2(C16H7Cl3N5O2)2(CH3OH)4]·C4H10O·2CH3OH, the central pyrazolo[3,4-d]pyrimidine system makes dihedral angles of 82.98 (7)° with the trichlorophenyl ring and 13.11 (15)° with the pyridine ring. The sodium ion has an octahedral environment, being coordinated by four methanol molecules and one O and one N atom of two different heterocyclic ring systems.