Formation of the Charge‐Localized Dimer Radical Cation of 2‐Ethyl‐9,10‐dimethoxyanthracene in Solution Phase

Abstract

Although dimer radicali ons of aromatic molecules in the liquid-solution phase have been intensely studied, the understanding of charge-localized dimers, in which the extra charge is localized in as ingle monomer unit insteado f being shared between two monomer units,i ss till elusive. In this study,t he formation of ac harge-localized dimer radical cation of 2-ethyl-9,10-dimethoxyanthracene( DMA), (DMA) 2 C + is investigated by transient absorption (TA) and time-resolved resonance Raman( TR 3 )s pectroscopic methodsc ombined with ap ulse radiolysis technique. Visible-and near-IR TA signals in highly concentrated DMA solutionss upported the formation of non-covalent( DMA) 2 C + by association of DMA and DMAC + .T R 3 spectra obtainedf rom 30 ns to 300 ms time delays showedt hat the major bands are quite similar to those of DMA except for small transient bands, even at 30 ns time delay,s uggesting that the positivec hargeo fnoncovalent( DMA) 2 C + is localized in as inglem onomer unit. From DFT calculationsf or (DMA) 2 C + ,o ur TR 3 spectra showed the best agreement with the calculated Raman spectrum of charge-localized edge-to-faceT -shaped (DMA) 2 C + ,t ermed DTC + ,a lthought he charge-delocalizeda symmetric p-stacked face-to-face (DMA) 2 C + ,t ermedD F3C + ,i st he most stable structure of (DMA) 2 C + according to the energetics from DFT calculations. The calculated potentiale nergy curves for the association between DMAC + and DMA showed that DTC + is likely to be efficientlyf ormed and contributes ignificantly to the TR 3 spectra as ar esult of the permanent charge-induced Coulombic interactions and ad ynamic equilibrium between chargel ocalized and delocalized structures.

Dimer Radical Anions of Polyfluoroarenes. Two More to a Small Family

“…While there is a body of experimental evidence suggesting the existence of dimer radical cations (DRCs) of aromatic compounds (see refs − and references herein), little has been reported about the corresponding dimer radical anions (DRAs) (see ref and references herein). DRAs of anthracene are formed by radiolysis of a frozen solution of dianthracene .…”

Effect of an Aromatic Sulfonate Ligand on the Photovoltaic Performance of Molybdenum Cluster-Sensitized Solar Cells

“…In addition, the vibrational signals assigned to the Mo–O bonding appear at 487, 564, 726, and 955 cm –1 (Figure d) . Based on the NS reference sample, the Raman shift bands centered at 521 (C–C–C bending), 1054, and 1381 cm –1 (C–C stretching) are assigned to the C–C bond in naphthalene; 611 and 1119 cm –1 assigned to the S–O bond in the sulfonate (–SO 3 – ) group; 1468 (C–H bending), 1566, and 1624 cm –1 assigned to the C–C and CC stretching in an aromatic ring with resonances of the S–O vibrations. − In general, all the Raman bands of the MINS series show a similar signal. In comparison with the Raman bands of MI and NS, the MINS band is composed of vibration signals of its compositions with a slight modification.…”