100466-92-0Relevant articles and documents
ESR Spectroscopic Detection of Intramolecular Interactions in Radical Cations of Poly(α-methoxy)triptycenes
Quast, Helmut,Fuchsbauer, Hans-Lothar
, p. 1016 - 1038 (2007/10/02)
-Cycloaddition of 1,4-benzoquinone to the di- and tetra(α-methoxy)anthracenes 11 yields the diketones 12 which undergo an acid-catalyzed rearrangement to the triptycene hydroquinones 13.Methylation of 13 affords the poly(α-methoxy)triptycenes 4.Aluminium chloride in nitromethane oxidizes the triptycenes 4 to the radical cations 4+* having one 1,4-dialkoxybenzene ring (4b+*, 4c+*, 4e+*) or two (4a+*) or three (4d+*), respectively, of such potential radical centers.The protons of the radical center give rise to hyperfine splittings which are very similar to those found in the ESR spectra of simple cis-1,4-dialkoxybenzene radical cations.The other aromatic protons, but not the bridgehead protons, exhibit a long range hyperfine coupling of 0.011 mT.Selective line broadening in the ESR spectrum of the radical cation 4a+* indicates that intramolecular electron transfer between the 1,4-dimethoxybenzene moieties occurs at a moderate rate.The deceleration of the exchange rate compared to the rate expected for a free radical cation is interpreted in terms of ion pairing.