Diin‐Reaktion, XIX. Polarographische Untersuchungen von Acenchinonen und Heteroacenchinonen

Abstract

Das polarographjsche Verhalten einjger neuer Acenchinone und Heteroaceuchinone in Acetonitril als Lbsungsmittel wird untersucht. Bei allen untersuchten Chinonen werden zwei Ein-Elektroneniibergange beobachtet. Zwischen den Halbstufenpotentialen der ersten Stufe und der Summe der Hurnmettschen Substituentenkonstanten besteht bei substituierten Anthrachinonen eine lineare Beziehung. Die Heteroatome bewirken eine Verschiebung der Halbstufenpotentiale zu negativeren Werten.Eug. Miiller und W. Dilger Jahrg. 106

A Tailored Approach to the Syntheses of Electroactive Dendrimers Based on Diaminoanthraquinones

“…As can be seen in Figure , all the voltammograms are characterized by two quasi-reversible waves that reflect the sequential uptake of one electron by each of the anthraquinone moieties. ,, For the extended monomer 1 , the two E 1/2 potential values are shifted to more positive potential values as compared to those of the parent 1,4-DAAQ (Table ). This effect was expected since monoamidation not only decreases the electron release character of the diamine but also improves its intramolecular H-bonding characteristics with the quinone oxygen, thus making it more prone to reduction. − Consistent with this trend, CV experiments of the first-tier dendrimer 4 (Figure c) reflect a further positive potential shift due to bisamidation of the electroactive anthraquinone moieties. The voltammograms of the two higher generation dendrimers 6 and 8 (Figure d for 6 and voltammogram not shown for dendrimer 8 ) do not reveal important changes in the half-wave potentials, since no further chemical modification of the amine groups in the chromophoric units is involved in their preparation.…”

“…As opposed to the previous anthraquinone isomers, 2,6-derivatives do not form intramolecular H-bonds between the amine groups and quinone oxygens; therefore, the effect of amidation should correspond to the decrease in electron release character only. On the basis of previous electrochemical studies on substituted anthraquinones, − it is possible to suggest that such an effect in the CV response should be relatively small. This seems to be the case when comparing the mono- and bisamidated derivatives (Figure ) but is difficult to reconcile with the large positive potential shift observed when going from the 2,6-DAAQ to any one of the two-dendrimerized derivatives.…”

Anthraquinone-based extended dendritic monomers: electrochemical comparisons

“…Half-wave potentials, E 1/2 (mV), for 1, 3, 4, and 5 at 298 K Compound It is well known [20][21][22] that anthraquinones and their derivatives undergo two sequential reversible electron-transfer reactions in aprotic solvents at 25 • C. Depending on the electron-withdrawing or -releasing character of the substituents attached to the anthraquinone, the measured half-wave potentials have been shown to vary within a relatively large potential window [23][24][25][26]. The half-wave potentials of the related redox active monomers 1, and 3-5 were measured ( Fig.…”

Organic polarography

“…Reduction potentials were reported for seven 3-substituted phenanthrenequinones as a function of pH (104). Correlations between £1/2 and Hammett -constants for 23 acenequinones and heteroacenequinones were described (784).…”