Search results for "radical ion"
showing 10 items of 57 documents
Anthelminthische Wirkstoffe, 5. Mitt.: Langkettig und hydroheterocyclisch substituierte Chlor-diallylamino-1,3,5-triazine
1988
Aus der Umsetzung von 2,4-Dichlor-6-(diallylamino)-1,3,5-triazin (1) mit den aliphatischen Aminen 2a–c gehen die langkettig substituierten Chlordiallylamino-1,3,5-triazine 3a–c, mit den Piperazinen 4a–c die hydroheterocyclisch substituierten Chlor-diallylamino-1,3,5-triazine 5a–c, hervor. Unter den zur Strukturcharakterisierung herangezogenen spektroskopischen Daten ist besonders in den Massenspektren des Strukturtyps 5 die Abspaltung des Neutralteilchens Phenyl-NH2 unter Ausbildung des Radikalkations bei m/z 277 auffallig. 3 und 5 zeichnen sich durch anthelminthische, trichomonazide, insektenwachstumsregulatorische und fiebersenkende Wirkungen aus. Anthelminthic Agents, V: Chloro(diallylam…
Electronic spectra of tetrathiafulvalene and its radical cation: analysis of the performance of the time-dependent DFT approach
2002
Abstract The electronic spectra of tetrathiafulvalene and its radical cation have been studied within the framework of the time-dependent density functional theory by using a conventional hybrid functional. The behaviour of the method has been analyzed through the computed vertical excitation energies for the low-lying electronic excited states. Although the procedure provides a correct description of many of the features of the spectra, deviations in the range 0.4–0.7 eV have been obtained for several transitions, from which one can conclude misleading assignments.
Metal- and Reagent-Free Electrochemical Synthesis of Alkyl Arylsulfonates in a Multi-Component Reaction.
2020
Abstract This work presents the first electrochemical preparation of alkyl arylsulfonates by direct anodic oxidation of electron‐rich arenes. The reaction mechanism features a multi‐component reaction consisting of electron‐rich arenes, an alcohol of choice and excess SO2 in an acetonitrile‐HFIP reaction mixture. In‐situ formed monoalkyl sulfites are considered as key intermediates with bifunctional purpose. Firstly, this species functions as nucleophile and secondly, excellent conductivity is provided. Several primary and secondary alcohols and electron‐rich arenes are implemented in this reaction to form the alkyl arylsulfonates in yields up to 73 % with exquisite selectivity. Boron‐doped…
Radical cation salts of BEDT-TTF, enantiopure tetramethyl-BEDT-TTF, and TTF-Oxazoline (TTF-Ox) donors with the homoleptic TRISPHAT anion
2011
International audience; The synthesis and crystal structures of five radical cation salts based on the organic donors bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF), racemic ethylenedithio-methyl-oxazoline-tetrathiafulvalene (EDT-TTF-MeOx) and the enantiopure (S,S,S,S) and (R,R,R,R) tetramethyl-bis(ethylenedithio)tetrathiafulvalene (TMBEDT-TTF) and the D3-symmetric anion tris(tetrachlorobenzenediolato)phosphate(V) (TRISPHAT) are reported. The salts are formulated as [BEDT-TTF][(rac)-TRISPHAT]·CH2Cl2 (1), [BEDT-TTF][(rac)-TRISPHAT]·2CH3CN (2), [(rac)-EDT-TTF-Ox][(rac)-TRISPHAT]·CH3CN (3), [(S,S,S,S)-TMBEDT-TTF][(rac)-TRISPHAT]·2CH3CN (4), and [(R,R,R,R)-TMBEDT-TTF][(rac)-TRISPHAT]·2CH3CN (…
Highly Conjugatedp-Quinonoidπ-Extended Tetrathiafulvalene Derivatives: A Class of Highly Distorted Electron Donors
2004
A new class of pi-extended TTF-type electron donors (11 a-c) has been synthesized by Wittig-Horner olefination of bianthrone (9) with 1,3-dithiole phosphonate esters (10 a-c). In cyclic voltammetry experiments, donors 11 a-c reveal a single, electrochemically irreversible oxidation-yielding the corresponding dicationic products-at relatively low oxidation potentials (approximately 0.7-0.8 V). Theoretical calculations, performed at the DFT level (B3 P86/6-31 G*), predict a highly-folded C(2h) structure for 11 a. In the ground state, the molecule adopts a double saddle-like conformation to compensate the steric hindrance. The calculations suggest that the intramolecular charge transfer associ…
DFT study on the cycloreversion of thietane radical cations.
2011
The molecular mechanism of the cycloreversion (CR) of thietane radical cations has been analyzed in detail at the UB3LYP/6-31G* level of theory. Results have shown that the process takes place via a stepwise mechanism leading to alkenes and thiobenzophenone; alternatively, formal [4 + 2] cycloadducts are obtained. Thus, the CR of radical cations 1a, b(center dot+) is initiated by C2-C3 bond breaking, giving common intermediates INa,b. At this stage, two reaction pathways are feasible involving ion molecule complexes IMCa,b (i) or radical cations 4a,b(center dot+) (ii). Calculations support that 1a(center dot+) follows reaction pathway (leading to the formal [4 + 2] cycloadducts 5a). By cont…
Electronic Transitions in Tetrathiafulvalene and Its Radical Cation: A Theoretical Contribution
2001
The low-lying electronic states of tetrathiafulvalene (TTF) and its radical cation (TTF+) have been studied using the multistate extension of a multiconfigurational second-order perturbation method (MS−CASPT2). The minimum-energy equilibrium geometries optimized at the CASSCF level have a boatlike conformation for the neutral molecule, with no significant barrier toward planarity. A more aromatic planar structure is, however, found for the ionic system. For TTF, the calculations of the vertical excitation energies comprise valence singlet and triplet states as well as the lowest members of the Rydberg series converging to the first ionization limit. Valence doublet states have been consider…
Xanthone-photosensitized detoxification of the veterinary anthelmintic fenbendazole
2013
Fenbendazole (1) is a common veterinary anthelmintic, toxic to water living microorganisms. Fluorescence quantum yields of 1 were found to be 0.11 in acetonitrile, 0.068 in methanol, 0.034 in cyclohexane, and 0.013 in water. The singlet excited state energy was ca. 96 kcal mol(-1) in all solvents. The phosphorescence spectrum of 1 in ethanol at 77 K displayed a maximum at 450 nm, leading to a triplet energy of 75 kcal mol(-1). Experimental excited state energies agree well with the results of OFT calculations at the time-dependent B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level. Laser flash photolysis (LFP) of 1 at 266 nm led to transients absorbing in the 300-700 nm range, ascribed to radical cat…
Neutral and oxidized triisopropylsilyl end-capped oligothienoacenes: a combined electrochemical, spectroscopic, and theoretical study.
2010
This work presents an analy- sis of the structural, electrochemical, and optical properties of a family of triisopropylsilyl end-capped oligothie- noacenes (TIPS-Tn-TIPS, n = 4-8) by combining cyclic voltammetry, spectro- scopic techniques, and quantum-chemi- cal calculations. TIPS-Tn-TIPS com- pounds form stable radical cations, and dications are only obtained for the lon- gest oligomers (n = 7 and 8). Oxidation leads to the quinoidization of the con- jugated backbone, from which elec- trons are mainly extracted. The absorp- tion and fluorescence spectra show par- tially resolved vibronic structures even at room temperature, due to the rigid molecular geometry. Two well-resolved vibronic p…
Negatively Curved Nanographene with Heptagonal and [5]Helicene Units
2020
Negatively curved nanographene (NG) 4, having two heptagons and a [5]helicene, was unexpectedly obtained by aryl rearrangement and stepwise cyclodehydrogenations. X-ray crystallography confirmed the saddle-shaped structures of intermediate 3 and NG 4. The favorability of rearrangement over helicene formation following radical cation or arenium cation mechanisms is supported by theoretical calculations. NG 4 demonstrates a reversible mechanochromic color change and solid-state emission, presumably benefiting from its loose crystal packing. After resolution by chiral high-performance liquid chromatography, the circular dichroism spectra of enantiomers 4-(P) and 4-(M) were measured and showed …