15785-07-6Relevant articles and documents
Stereoelectronic factors in bridgehead C-H bond insertion: Studies toward the total synthesis of maoecrystal v
Jansone-Popova, Santa,May, Jeremy A.
, p. 3734 - 3747 (2016)
A strategy for the total synthesis of maoecrystal V is presented. The key interior vicinal quaternary carbon centers will be formed via sequential bridgehead C-H bond insertion and enolate functionalization. Studies herein validate the C-H bond insertion as feasible in model studies, though there are significant effects on the selectivity for the bridgehead position from neighboring groups. Both inductive electron withdrawing elements and sterics play a role in deactivating that position, with the former having a greater effect. Forming the second quaternary carbon is possible via enolate acylation and alkylation. Lastly, an approach to synthesize the cyclohexenone ring of maoecrystal V is described.
Electrochemical and spectroscopic study of Ce(III) coordination in the 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid containing chloride ion
Chou, Li-Hsien,Cleland, Walter E.,Hussey, Charles L.
, p. 11450 - 11457,8 (2012)
Cyclic staircase voltammetry, controlled potential coulometry, and electronic absorption spectroscopy were used to probe the coordination and accessible oxidation states of Ce3+ dissolved in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BuMePyroTf 2N) before and after the addition of chloride ion as BuMePyroCl. Controlled potential coulometry indicated that the oxidation of Ce metal in this ionic liquid produces only Ce3+. Spectroscopic examination of the resulting solutions indicated that Ce3+ was weakly solvated by Tf2N- ions as [Ce(Tf2N)x] (x-3)-, x ≥ 3. This species can be reduced at negative potentials, probably to a related Ce2+ species, but the latter is unstable and quickly disproportionates to Ce3+ and Ce0; the latter appears to react with the ionic liquid. The addition of Cl- to solutions of [Ce(Tf2N)x](x-3)- causes the precipitation of CeCl3(s), providing a convenient route to the nondestructive recovery of Ce3+ from the ionic liquid. However, as the Cl- concentration is further increased, the CeCl3(s) redissolves as the octahedral complex, [CeCl6]3-, and the voltammetric and spectroscopic signature for [Ce(Tf2N) x](x-3)- disappears. Absorption spectroscopy indicated that the bulk controlled potential oxidation of solutions containing [CeCl 6]3- produces [CeCl6]2-. Although stable on the time scale of voltammetry, this species slowly reacts with the ionic liquid and is converted back to [CeCl6]3-.
Luminescent CeCl3 nanoparticles by Tris(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)cerium diglyme photolysis in chlorinated solvents
Giuffrida, Salvatore,Condorelli, Guglielmo G.,Costanzo, Lucia L.,Ventimiglia, Giorgio,Favazza, Maria,Petralia, Salvatore,L. Fragalà, Ignazio
, p. 4043 - 4052 (2006)
Irradiation of [Ce(hfac)3(diglyme)] (hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionato and diglyme (DG) = 2,5,8,11,14-pentaoxapentadecane) in chlorinated solvents (CH2Cl2, CCl4) with UV light led to luminescent colloidal CeCl3 that was characterized by transmission electron microscopy (TEM) analysis. When a substrate, quartz or silicon was present in the reaction cell, photoluminescent films were obtained, containing either pure CeCl3 or mixtures of CeCl3, CeF3 and CeOx in function of the experimental parameters of irradiation. Nanostructured and luminescent pure CeCl3 films were obtained by irradiation of the cerium complex in CCl4 at high intensity light for a few minutes. The films were characterized by X-ray diffraction (XRD), Energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), TEM, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The kinetics of the [Ce(hfac)3(diglyme)] solution photodegradation, followed by UV spectrophotometry and spectrofluorimetry, pointed to CeCl3 formation by a solvent-initiated reaction, whereas the other inorganic compounds were the products of side reactions.
The morphology evolution, tunable down-conversion luminescence, and energy transfer of [CaY]F2crystals doped with Li+/Ce3+/Tb3+
Hu, Shanshan,Jiang, Li,Mao, Yini,Wang, Zhiyi,Yang, Jun,Ye, Rui
, p. 15433 - 15442 (2020)
Octahedral [CaY]F2 crystals with an average particle size of 1 μm were synthesized via a mild one-step hydrothermal route without employing any surfactants. Various morphologies, including cubes, truncated cubes, truncated octahedrons, and spheres, were achieved via manipulating the amount of EDTA used, and a possible growth mechanism was proposed based on the surface energies of different crystal planes and the influence of the surfactant. XRD, SEM, EDS, TEM, HRTEM, and PL analysis were used to characterize the products. The effects of the morphologies and Li+ doping concentrations on the luminescence intensities of the [CaY]F2:Ce3+/Tb3+ phosphors were explored, and the strongest luminescence intensity is obtained when the sample is cubic with (100) crystal faces and the doping concentration of Li+ is 0.25 mol%. Additionally, multicolor emission (blue → aquamarine blue → green) was obtained from [CaY]F2:Ce3+/Tb3+ phosphors via adjusting the doping concentration of Tb3+, which resulted from the Ce3+ → Tb3+ energy transfer behavior; the energy transfer here happened through a dipole-dipole mechanism. This work may result in the as-synthesized phosphors having great application potential in many optoelectronic device fields, such as in displays and multicolor lighting.
CeO2 nanorods and gold nanocrystals supported on CeO2 nanorods as catalyst
Huang,Wu,Zhu,Gao,Zhu,Yan,Huang,Wu,Song
, p. 19169 - 19174 (2005)
The formation mechanism of uniform CeO2 structure at the nanometer scale via a wet-chemical reaction is of great interest in fundamental study as well as a variety of applications. In this work, large-scale well-crystallized CeO2 nanorods with uniform diameters in the range of 20-30 nm and lengths up to tens of micrometers are first synthesized through a hydrothermal synthetic route in 5 M KOH solution at 180 ?°C for 45 h without any templates and surfactants. The nanorod formation involves dehydration of CeO2 nanoparticles and orientation growth along the ???110??? direction in KOH solution. Subsequently, gold nanoparticles with crystallite sizes between 10 and 20 nm are loaded on the surface of CeO 2 nanorods using HAuCl4 solution as the gold source and NaBH4 solution as a reducing agent. The synthesized Au/CeO 2 nanorods demonstrate a higher catalytic activity in CO oxidation than the pure CeO2 nanorods. ? 2005 American Chemical Society.
Chlorination of cerium dioxide
Esquivel,Bohé,Pasquevich
, p. 81 - 91 (2003)
The chlorination of cerium dioxide was studied by thermagravimetry under controlled atmosphere between 800 and 950 °C. An apparent activation energy of 190 kJ mol-1 was observed. To discriminate the effect of the vaporization of the CeCl3 on the chlorination rate, this process was also studied with the same technique between 850 and 950 °C. An apparent activation energy of 184 kJ mol-1 was determined. The CeO2 chlorination rate was found to be under a chemical-mixed control influenced by the vaporization of CeCl3.
Thermodynamic stability of RECl3·xH2O (RE = Ce, Pr) determined by dynamic transpiration technique
Sahoo,Mishra,Kumar, Raj,Kain, Vivekanand
, p. 1183 - 1193 (2020)
In the present study, decomposition mechanism of CeCl3·xH2O(s) and PrCl3·xH2O(s) was investigated using thermogravimetry, differential thermal analysis and evolved gas analysis techniques. Intermediate products formed in the dehydration of RE (Ce, Pr) Cl3·xH2O(s) were characterized by X-ray diffraction analyses. Thermodynamic stability of the RECl3·xH2O(s) and their intermediate products has been determined from the vapor pressure of water measured over the compounds employing dynamic transpiration technique.
Refractive indices and molar refractivities of molten rare-earth trichlorides and their mixtures with alkali chlorides
Kochedykov, Victor A.,Khokhlov, Vladimir A.
, p. 44 - 51 (2017)
New experimental data on the refractive indices and molar refractivities of molten cerium, neodymium, samarium, and gadolinium trichlorides and CeCl3-ACl, SmCl3-ACl, Gd3Cl-ACl (A = Na, 0.5Na-0.5K, K, and Cs) mixtures depending on the temperature and composition are reported. It is shown that the relative deviations of the molar refractivity of mixtures from their magnitudes inherent to the hypothetic ideal solutions increase as the radii of alkali metal cations rises. The difference in variation of the Ln3+-ions electron polarizability with the atomic number or ionic radius is revealed for cerium and yttrium subgroups of the lanthanide row.
Luminescent coordination polymers for the VIS and NIR range constituting LnCl3 and 1,2-bis(4-pyridyl)ethane
Dannenbauer,Matthes,Müller-Buschbaum
, p. 6529 - 6540 (2016)
A series of 14 lanthanide containing coordination polymers LnCl3 with 1,2-bis(4-pyridyl)ethane (bpe) was synthesized from either thiazole or pyridine. Depending on the ligand content, a structural diversity from 3D-frameworks 3∞[LnCl3(bpe)2]·thz, Ln = Ce-Lu, to 1D-strands 1∞[La2Cl6(bpe)2(thz)6] and 1∞[LnCl3(bpe)(py)2]·(bpe/py), Ln = Gd, Er, was obtained and characterized by X-ray single crystal diffraction, powder diffraction, differential thermal analysis and thermogravimetry (DTA/TG), IR-spectroscopy and photoluminescence spectroscopy. The compounds exhibit a variety of luminescence properties and different phenomena. This includes ligand centred fluorescence, metal-centred 5d-4f/4f-4f emission in the visible and the NIR range, antenna effects via Dexter and F?rster energy transfer mechanisms, excitation dependent emission with a correlating shift of the chromaticity coordinates and inner filter effects by combined re-absorption/emission.
Oxa-adamantyl cannabinoids
Ho, Thanh C.,Tius, Marcus A.,Nikas, Spyros P.,Tran, Ngan K.,Tong, Fei,Zhou, Han,Zvonok, Nikolai,Makriyannis, Alexandros
, (2021)
As a continuation of earlier work on classical cannabinoids bearing bulky side chains we report here the design, synthesis, and biological evaluation of 3′-functionalized oxa-adamantyl cannabinoids as a novel class of cannabinergic ligands. Key synthetic steps involve nucleophilic addition/transannular cyclization of aryllithium to epoxyketone in the presence of cerium chloride and stereoselective construction of the tricyclic cannabinoid nucleus. The synthesis of the oxa-adamantyl cannabinoids is convenient, and amenable to scale up allowing the preparation of these analogs in sufficient quantities for detailed in vitro evaluation. The novel oxa-adamantyl cannabinoids reported here were found to be high affinity ligands for the CB1 and CB2 cannabinoid receptors. In the cyclase assay these compounds were found to behave as potent and efficacious CB1 receptor agonists. Isothiocyanate analog AM10504 is capable of irreversibly labeling both the CB1 and CB2 receptors.
