Photochemically induced charge separation at the molecular level. A chromophore-quencher complex containing both an electron donor and an acceptor

Spin Relaxation in Ru‐Chromophore‐Linked Azine/Diquat Radical Pairs

“…The steps in this electron transfer cascade are first the oxidative quenching of the 3 MLCT state by the diquat acceptor followed by transfer of an electron from one of the donors to the oxidized chromophore; thus, in the resulting CSS the acceptor is reduced, one of the donors is oxidized and the chromophore is returned to the ground state. 11 This specific class of DCA triads is quite unusual in that the CSS state is formed with essentially unity quantum efficiency irrespective of the identity of the specific azine donor (i.e., PTZ, POZ, or PSZ) or diquat acceptor. 11 Detailed models of the energetics and kinetics of the CSS formation and decay back to the ground state in these specific DCA triad systems have been provided earlier.…”

“…11 This specific class of DCA triads is quite unusual in that the CSS state is formed with essentially unity quantum efficiency irrespective of the identity of the specific azine donor (i.e., PTZ, POZ, or PSZ) or diquat acceptor. 11 Detailed models of the energetics and kinetics of the CSS formation and decay back to the ground state in these specific DCA triad systems have been provided earlier. [11][12][13][14][15][16][17][18][19][20][21] Ru II Of particular relevance to the present discussion is the observation that the CSS, which is a biradical cation, is formed with essentially pure triplet spin correlation.…”

“…11 Detailed models of the energetics and kinetics of the CSS formation and decay back to the ground state in these specific DCA triad systems have been provided earlier. [11][12][13][14][15][16][17][18][19][20][21] Ru II Of particular relevance to the present discussion is the observation that the CSS, which is a biradical cation, is formed with essentially pure triplet spin correlation. 12 For energetic reasons, this triplet radical pair cannot recombine to form the 3 MLCT state and can only form the singlet ground state.…”

Vectorial Electron Transfer in Donor–Photosensitizer–Acceptor Triads Based on Novel Bis‐tridentate Ruthenium Polypyridyl Complexes

“…80 %) have been reported. [30,[47][48][49] In general, however, the overall yields of charge separation in Ru 2 + , the reported yields are very low, in large extent due to the short room-temperature lifetime of the chromophore. [18,53] The yield of the fully charge-separated state PTZ + Ru II Q À was evaluated from the spectroscopic signatures in the difference spectra at 5 ns (see Figure 4 a …”

“…Rapid electron transfer from PTZ has been observed before in other Ru II polypyridyl-based triads with comparable yields. [30,[47][48][49] Complexes 1 a and 3 a are the first examples known to us in which D-P-A triads based on bis-tridentate Ru II polypyridyl motifs give such high yields of charge separation. Perhaps more outstanding than the fast hole transfer from PTZ is the high yield of formation of the primary charge separation (almost unity).…”