Dimerization of the perylene and tetracene radical cations and electronic absorption spectra of their dimers

Abstract

1 and 3 become less important relative t o reaction 2 due to their higher activation energies. Thus, in our samples (large [ClF]/ [Clt]), the CIF still disappears (via reaction 2) but now the [Clz] remains constant or even increases slightly depending on the actual temperature. ConclusionsThe thermal decomposition of C1F is complex in the temperature range 2000-2950°K, and a mechanism which adequately explains the experimental results is suggested. It is reemphasizedz6 that caution is in order when inferring mechanisms from semilog kinetic plots.The results reported here also indicate that k, and k3 are similar in magnitude although a more detailed study would be required t o evaluate IC1 explicitly.Acknowledgment. The authors wish to thank R. W. Anderson and H. R. Frick for the synthesis of ClF, and W. E. Eichorn for his help in obtaining some of the experimental data. (26) A different way in which aroblems can arise has been demonstrated recently: M. W. Slack and E. s. Fishburne, J . Chem. P h i s . , 52, 5830 (1970). Publication costs assisted by the Institute of Applied Electricity, Hokkaido UniversityThe reversible dimerizations of the perylene and tetracene radical cations in concentrated sulfuric acid have been studied spectroscopically. Equilibrium constants of the monomer-dimer equilibrium at various temperatures were determined by analyzing electronic absorption spectra. From the temperature dependences of the equilibrium constants, heats of dimerization were evaluated to be 8.8 and 5.6 kcal/mol of dimer for the perylene and tetracene cations, respectively. From the present study it has also been found that when the cation dimers are formed new absorption bands appear in the near-infrared region, and the ultraviolet and visible absorption bands shift toward shorter wavelength. The appearance of the near-infrared bands in the dimer spectra are discussed in terms of both a radical-radical charge resonance and an electronic transition between the bonding and antibonding MO's constructed for the dimer, on the basis of a symmetrical sandwich dimer structure. Interactions between the two cation radicals forming the dimer in solution are discussed.

Spectroelectrochemical Study of the Formation of the Radical Cation and Dication of Perylene in Molten Antimony(III) Chloride

“…These radical cation spectra have five absorption bands in the range 500-9.00 rim. As shown in Table II the wavelengths and molar absorptivity of the band maxima agree well with prior measurements of the perylene radical cation spectrum in molten SbC13 (10,29) and in other solvents (30,31).…”

A spectroelectrochemical study on perylene cation radical in polymer microchannel-microelectrode chips

“…Furthermore, the absorption intensity at 510 nm became stronger with decreasing the flow velocity and, the ratio of the absorbance at 510 nm to that at 538 nm increased from 0.63 to 0.88 with the decrease in u from 1.0 to 0.17 mm s 21 . The spectral characteristics agreed very well with those observed by the thin layer cell experiments at a high perylene concentration as well as with the report by Kimura et al 35 Therefore, we conclude that the new absorption peak at 510 nm is ascribed to that of the Pe dimer cation radical. At a low solution flow velocity, Pe is oxidized at the electrode very efficiently.…”

“…34 At a relatively high Pe concentration, in practice, Kimura et al reported that a new absorption band appeared in the shorter wavelength region of the absorption spectrum of the Pe cation radical, owing to formation of the perylene dimer cation radical. 35 Such spectral characteristics reported by Kimura et al are quite analogous to the absorption spectrum observed by the present thin-layer electrode cell experiments. Therefore, we suppose that the smaller absorbance change of the Pe cation radical, as compared to that predicted from the decreased amount of Pe in Fig.…”

Distribution of Hydrophobic Probe Molecules in Lipid Bilayers. 2. Time-Resolved Fluorescence Anisotropy Study of Perylene in Vesicles

“…4 All samples exhibited the typical monomeric perylene absorption and fluorescence spectra. [49][50][51][52] Experiments. The time-resolved anisotropy decay measurements were carried out using the synchrotron radiation source (SRS) in Daresbury, U.K. operating in the single bunch mode as a tunable light source with high repetition frequency (3 MHz).…”