Search results for "MR"
showing 10 items of 3001 documents
Ionic Liquids binary mixtures: the influence of the composition on their properties and catalytic ability
Geminal Ionic Liquids: A Combined Approach to Investigate their Tridimensional Structure
2009
Different investigations, such as 1D and 2D NMR spectroscopy, resonance light scattering spectroscopy and molecular dynamics simulations, have been jointly used to achieve a deeper understanding of the degree of structural order in two geminal ionic liquids. In particular, 3,3’-di-n-butyl-1,1’-(1,3- phenylenedimethylene)diimidazolium and 3,3’-di-n-butyl-1,1’-(1,4-phenylenedimethylene) diimidazolium bis- ACHTUNGTRENUNG[bis(trifluoromethanesulfonyl)imide] have been studied. These geminal ionic liquids were chosen because of the presence of both a rigid phenylenedimethylene link between two imidazolium rings, which should give a high degree of order to the solvent system, and the different sha…
The effect of the cation p-surface area on the 3D organization and catalytic ability of imidazolium-based ionic liquids
2011
The dichotomic nature of ionic liquids (ILs, simple solvents or supramolecular fluids) induced us to carry out a structural investigation of some mono-and dicationic ionic liquids using 1D and 2D NMR, resonance light scattering, and UV/Vis spectroscopy. Ionic liquids with different cation π-surface areas were used, namely [bmim][NTf2], [Bzmim][NTf 2], [Bzbim][NTf2], [p-Xyl-(bim)2][NTf 2]2, and [m-Xyl-(bim)2][NTf2] 2 [bmim = 1-butyl-3-methylimidazolium, Bzmim = 1-benzyl-3- methylimidazolium, Bzbim = 1-benzyl-3-butylimidazolium, NTf2 = bis(trifluoromethansulfonyl)imide]. In order to verify to what extent the structural investigation, coupled with the determination of solvent parameters, could…
Ion pair recognition by ditopic crown ether based bis-urea and uranyl salophen receptors
2016
Ligand-Centred Fluorescence and Electronic Relaxation Cascade at Vibrational Time Scales in Transition-Metal Complexes
2015
Using femtosecond-resolved photoluminescence up-conversion, we report the observation of the fluorescence of the high-lying ligand-centered (LC) electronic state upon 266 nm excitation of an iridium complex, Ir(ppy)(3), with a lifetime of 70 +/- 10 fs. It is accompanied by a simultaneous emission of all lower-lying electronic states, except the lowest triplet metal-to-ligand charge-transfer ((MLCT)-M-3) state that shows a rise on the same time scale. Thus, we observe the departure, the intermediate steps, and the arrival of the relaxation cascade spanning similar to 1.6 eV from the (LC)-L-1 state to the lowest 3MLCT state, which then yields the long-lived luminescence of the molecule. This …
A SIR based method for pancreas iron burden measurement in MRI T2* GRE sequences.
2009
A critical review of non invasive procedures for the evaluation of body iron burden in thalassemia major patients
2008
Jaunākā pirmsskolas vecuma bērnu vārdu krājuma paplašināšana rotaļās un spēles
2017
Kvalifikācijas darba temats: Jaunākā pirmsskolas vecuma bērnu vārdu krājuma paplašināšana rotaļās un spēlēs. Kvalifikācijas darba autors: Laura Grundšteine Darba vadītājs: Dr. paed. Inga Stangaine Kvalifikācijas darba mērķis: Teorētiski un praktiski noskaidrot bērnu vārdu krājuma paplašināšanu un tās sekmēšanu rotaļās un spēlēs. Darba pirmajā daļā izvērsta zinātniskā diskusija par valodas un runas jēdzienu skaidrojumu dažādu autoru atziņās, noskaidrots jaunākā pirmsskolas vecuma bērnu valodas un runas attīstības likumsakarības. Teorētiskajā daļā apskatīts rotaļu un spēļu raksturojums un skaidrojums pedagoģiskā un psiholoģiskā literatūrā, analizētas rotaļas un spēles izmantošana bērnu vārdu …
Do 2-coordinate iodine(I) and silver(I) complexes form Nucleophilic Iodonium Interactions (NIIs) in solution?
2022
The interaction of a [bis(pyridine)iodine(I)]+ cation with a [bis(pyridine)silver(I)]+ cation, in which an iodonium ion acts as nucleophile by transferring electron density to the silver(I) cation, is reinvestigated herein. No measurable interaction is observed between the cationic species in solution by NMR; DFT reveals that if there is an attractive interaction between this complexes in solution, it is dominantly the π-π interaction of pyridines peerReviewed
Experimental and computational investigation on the formation pathway of [RuCl2(CO)2(ERR′)2] (E = S, Se, Te; R, R′ = Me, Ph) from [RuCl2(CO)3]2 and E…
2022
The pathways to the formation of the series of [RuCl2(CO)2(ERR′)2] (E = S, Se, Te; R, R′ = Me, Ph) complexes from [RuCl2(CO)3]2 and ERR′ have been explored experimentally in THF and CH2Cl2, and computationally by PBE0-D3/def2-TZVP calculations. The end-products and some reaction intermediates have been isolated and identified by NMR spectroscopy, and their crystal structures have been determined by X-ray diffraction. The relative stabilities of the [RuCl2(CO)2(ERR′)2] isomers follow the order cct > ccc > tcc > ttt ≈ ctc (the terms c/t refer to cis/trans arrangement of the ligands in the order of Cl, CO, and ERR′). The yields were rather similar in both solvents, but the reactions were signi…