Formation of DMSO and DMF radicals with minute amounts of base

Øpstad, Christer L.; Melø, Thor-Bernt; Sliwka, Hans‐Richard; Partali, Vassilia

doi:10.1016/j.tet.2009.06.109

Cited by 89 publications

(71 citation statements)

References 36 publications

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“…In addition, a sharp signal (singlet) with g = 2.01 was observed. It is attributable to the DMSO Å (CH 3 SOCH 2 Å ) radical by referencing to a previous study [25]. Opstad et al found from their study [25] that CH 3 SOCH 3 (DMSO) was readily oxidized to the long-lived CH 3 SOCH 2 Å (DMSO Å ) radical via a C-H bond abstraction by an alkoxide base (RO À ) present in the solvent.…”

Section: Charge-transfer Absorption Of Uranyl(vi)-dmso and Related Chmentioning

confidence: 90%

“…It is attributable to the DMSO Å (CH 3 SOCH 2 Å ) radical by referencing to a previous study [25]. Opstad et al found from their study [25] that CH 3 SOCH 3 (DMSO) was readily oxidized to the long-lived CH 3 SOCH 2 Å (DMSO Å ) radical via a C-H bond abstraction by an alkoxide base (RO À ) present in the solvent. The stabilization of the radical was achieved by delocalization of the radical center within the solvent host via formation of a radical-solvent (DMSO-DMSO Å ) pair (cf.…”

Section: Charge-transfer Absorption Of Uranyl(vi)-dmso and Related Chmentioning

confidence: 90%

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Investigation of charge-transfer absorptions in the uranyl UO22+(VI) ion and related chemical reduction of UO22+(VI) to UO2+(V) by UV–Vis and electron paramagnetic resonance spectroscopies

Sun

Kolling

Mazagri

et al. 2015

Inorganica Chimica Acta

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a b s t r a c tThe uranyl UO 2 2+ (VI) cation (hydrated) exhibited strong charge-transfer absorptions at 350-400 nm in aqueous solutions containing bromide and iodide. The charge-transfer absorptions originate from a single-electron transfer from a halide anion to the uranium(VI) valence shell. Their intensities (represented by absorbance at 375 nm) were found to be directly proportional to molar concentrations of the halide (bromide or iodide) and UO 2 2+ in solution, respectively, showing the nature of a bimolecular interaction in the charge-transfer absorption transition. The absorptions were also greatly enhanced by sulfuric acid, and their intensity (absorbance at 375 nm) increased linearly as a function of the acid molarity. An electron paramagnetic resonance (EPR) study has indicated that the charge-transfer also took place slowly in the dark, resulting in appreciable thermal chemical reduction of diamagnetic UO 2 2+ (VI) (hydrated) to paramagnetic UO 2 + (V) (hydrated) (g = 2.08) by bromide and iodide. In the presence of sulfuric acid, CH 3 SOCH 3 (DMSO) was shown by EPR to undergo a charge-transfer oxidation by UO 2 2+(VI) to a stable CH 3 SOCH 2 Å (DMSO Å ) radical (singlet, g = 2.01), and UO 2 2+ (VI) was reduced to UO 2 + (V). A possible mechanism for this oxidation-reduction has been proposed. The charge-transfer absorption transition (350-400 nm) between UO 2 2+ (VI) and phenol (PhOH) in acetone was observed and characterized. A chemical oxidation-reduction of UO 2 2+ (VI) [in the form of U VI O 2 (acetone) 5 2+] and PhOH in acetone was found by EPR to give UO 2 + (V) [in the form of U V O 2 (acetone) 5 + ] and a stable phenoxyl (PhO Å ) radical (singlet, g = 2.00) via a simultaneous charge-transfer and deprotonation pathway.

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Section: Charge-transfer Absorption Of Uranyl(vi)-dmso and Related Chmentioning

confidence: 90%

Section: Charge-transfer Absorption Of Uranyl(vi)-dmso and Related Chmentioning

confidence: 90%

Investigation of charge-transfer absorptions in the uranyl UO22+(VI) ion and related chemical reduction of UO22+(VI) to UO2+(V) by UV–Vis and electron paramagnetic resonance spectroscopies

Sun

Kolling

Mazagri

et al. 2015

Inorganica Chimica Acta

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show abstract

“…Although DMF is generally considered to be an inert solvent it was recently shown that DMF radicals readily form in the presence of a base, (Scheme 2). [ 19 ] Therefore, we anticipated that under the applied basic reaction conditions some DMF radicals form and a radical reaction mechanism based on an earlier proposition by Katrizky et al [20] takes place (Scheme 2). As such, it is proposed that upon deprotonation by Cs 2 CO 3 base, the resorcinarene phenoxide B forms a radical C in the presence of a DMF radical.…”

Section: Synthesismentioning

confidence: 96%

“…Proposed reaction mechanism for the benzofuran ring formation via a radical pathway. [19,20] detail (Table 1). Using the aforementioned conditions and allowing tetramethoxy resorcinarene and Cs 2 CO 3 to react about 60 min in the specified solvent before the addition of one equivalent (entries 1, 2, 4 and 5) of tetraethylene glycol ditosylate, were set as a standard procedure.…”

Section: Synthesismentioning

confidence: 99%

The Structural Diversity of Benzofuran Resorcinarene Leads to Enhanced Fluorescence

Tero

Salorinne

Lehtivuori

et al. 2014

Chemistry An Asian Journal

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An unexpected and previously unknown resorcinarene mono‐crown with a fused benzofuran moiety in its macrocyclic core was obtained as a byproduct from a bridging reaction of tetramethoxy resorcinarene with tetraethylene glycol ditosylate. The formation of the fused benzofuran moiety in the resorcinarene macrocycle resulted in a unique rigid and puckered boat conformation, as shown by XRD studies in the solid state. Modification of the macrocycle was also observed to affect the photophysical properties in solution by enhancing the fluorescence brightness compared with a conventional resorcinarene macrocycle. The fluorescent properties enabled unique detection of structural features, that is, the rigid boat conformation with the conjugated benzofuran system and the more flexible crown bridge part, in solution.

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“…Covalent chemical reactions have already been proposed to be involved in perovskite degradation, but only with respect to reactions with water or oxygen. [12][13][14] When considering the reactivity of many components present in perovskite solar cells, such as TiO 2 , [15][16][17] DMF, 18,19 MAI, 20 PbI 2 , water, 21 or HI, 22 we wondered whether additional covalent chemical reactions might be at work during perovskite formation. We turned to time-of-flight secondary ion mass spectrometry (TOF-SIMS), the chemical microscope, to identify changes in chemical composition of perovskite films.…”

Section: Introductionmentioning

confidence: 99%

Transamidation of dimethylformamide during alkylammonium lead triiodide film formation for perovskite solar cells

et al. 2016

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Perovskite-based solar cells, typically CH 3 NH 3 PbI 3 , have reached power conversion efficiencies on par with single crystal silicon solar cells. Perovskite cells prepared with the most common perovskite solvent N,N-dimethylformamide (DMF) by different research groups exhibit disparate efficiencies and stability for nominally identical perovskite films. Although the differences can be related to processing conditions, a consistent physical cause for the differences has been lacking. Highly-sensitive time-offlight secondary ion mass spectrometry (TOF-SIMS) reveals significant dimethylamine (DMA) included in perovskite films. TOF-SIMS and x-ray photoelectron spectroscopy results suggest DMA levels ranging from roughly 10-50%. Only the highest levels register as perovskite peak shifts in xray diffraction; lower levels are invisible. We propose that methylamine (MA) can react with DMF solvent by transamidation to produce dimethylamine (DMA), which then displaces some MA in perovskite crystals, see Fig. 1. Transamidation of DMF can be catalyzed by TiO 2 , Al 2 O 3 , water, or acid, but in perovskite films transamidation is inhibited by water.

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Formation of DMSO and DMF radicals with minute amounts of base

Cited by 89 publications

References 36 publications

Investigation of charge-transfer absorptions in the uranyl UO22+(VI) ion and related chemical reduction of UO22+(VI) to UO2+(V) by UV–Vis and electron paramagnetic resonance spectroscopies

Investigation of charge-transfer absorptions in the uranyl UO22+(VI) ion and related chemical reduction of UO22+(VI) to UO2+(V) by UV–Vis and electron paramagnetic resonance spectroscopies

The Structural Diversity of Benzofuran Resorcinarene Leads to Enhanced Fluorescence

Transamidation of dimethylformamide during alkylammonium lead triiodide film formation for perovskite solar cells

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