Intramolecular electron transfer (ET) processes have been studied extensively in inorganic binuclear transition metal complexes; [1] organic donor ± acceptor systems that are bridged by s frameworks have been investigated in order to mimic biological ET processes. [2] In contrast, much less is known about purely organic Robin/Day [3] class II compounds with bridging p-electron systems and the electron transfer processes involved: Nelsen et al.[4] studied a number of bis(hydrazine)phenylene radical cations and related species; Bonvoisin et al.[5] investigated m-phenylene-bridged triarylamine systems. These radical cations are characterized by intervalence charge-transfer (IV-CT) bands in the NIR spectra which are associated with a photoinduced intramolecular electron transfer between two redox centers. As the coupling of redox centers over p-conjugated bridges is of central interest for the design of new optoelectronic materials, [6] it was our aim to study basic intramolecular electron transfer processes in simple symmetrically substituted p systems. We chose p-bridged triarylamine derivatives since triarylamines in general are important hole carrier systems, which are widely used in organic optoelectronic devices. [7] 4,4'-Bis(N,N-di-p-methoxyphenylamino)tolane (2) was synthesized by two Hagihara cross-coupling steps, and the corresponding trimer hexakis[4-(N,N-di-p-methoxyphenylamino)phenyl]benzene (3) was formed from 2 by catalysis with [Co 2 (CO) 8 ] (Scheme 1).[8] These derivatives should exhibit an intramolecular degenerate electron transfer in the singly and triply oxidized forms, respectively. Both neutral compounds are yellow, and their UV/Vis spectra in CH 2 Cl 2 contain a strong absorption band at 373 nm (2) and 308 nm (3, with a shoulder at 330 nm). The cyclic voltammogram (CV) [9] of 2 shows two waves at 200 and 340 mV (versus Fc/Fc ) in CH 2 Cl 2 (Figure 1) referring to two reversible oxidations. This corresponds to a comproportionation constant (K co 10 (DE/0.059) , where DE is the difference of redox potentials for the two oxidative steps) of 236 and suggests 2 to be a class II derivative. [1,3] In contrast, trimer 3 only shows one broad unresolved wave centered at 225 mV. This reversible oxidation process was calibrated by thin-layer coulometry with 2,5-bis(dicyanovinyl)furan as the reference, and it involves six electrons in total, leading to 3 6 . UV/Vis/NIR spectroelectrochemical investigation [10] of 2 shows that besides a band at 734 nm, which is characteristic for triarylamine radical cations, [11] a second very intense band 10 mm ethylenediamine tetraacetate (EDTA), 1 mm 1,4-dithiothreitol (DTT), and 1 % bovine serum albumen (BSA) at 4 8C in a volume of 400 mL. After 30 minutes this exchange reaction was stopped by the addition of MgCl 2 to give a final concentration of 25 mm and the enzyme´substrate (E´S) complex purified on a PD10 column. The purified E´S complex was divided into separate aliquots of 150 mL, and rGTP was added to give a final concentration of 50 mm. The reactions were...