Processes of charge separation in porphyrin-quinone compounds with flexible bonding

1 Processes of charge separation in porphyrin-quinone compounds with flexible bonding 

Kong and Loach [30, 31] were the first to synthesize porphyrin-quinone compounds of the P-L-Q type. The structure of the compounds they obtained (n — 2, 3) is shown in Fig. 8(a). A strong quenching of the fluorescence of the 

The formation of P -L-Q ion radical pairs upon illumination of the P-L-Q compounds of the kind depicted in Fig. 8 and of their zinc complexes within a notably wider range of temperatures (up to 300 K) was detected by the EPR method [34, 40]. The quantum yield of charge separation and the time of charge recombination at 300 K amount to 5 x 10 3 and 10 3 s, respectively. In accordance with the modern models of electron transfer in condensed media (see Chap. 3) the efficiency of charge separation in P-L-Q grows with increasing solvent polarity [34]. 

An analysis of the EPR spectra of the P4 -L-Q ion radical pairs [41] made it possible to estimate the energy of magnetic dipole-dipole interaction between the paramagnetic fragments P+ and Q in these particles and to calculate from this energy the mean distance RPq 10-12 A between P and Q fragments in the molecule of the kind, depicted in Fig. 8 (n = 2), in which the dicarboxy bridge 

Two-step electron transfer along the gradient of the redox potential of acceptor groups was detected [47, 48] upon illumination of solutions of P-(CH2)4-Qi-(CH2)4-Q2 where Q4 was benzoquinone and Q2 trichloro-benzoquinone. Charge separation processes in these systems can be explained in terms of the scheme 

1 Processes of Charge Separation in Porphyrin-Quinone Compounds with Flexible Bonding 

The formation of the ion-radical pair P 1 -L-Q upon illumination of the P-L-Q species in vitreous solutions at T = 90-160 K was first demonstrated [129] using 

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