Long-lived charge separated states

Williams R M, Koeberg M, Lawson J M, An Y-Z, Rubin Y, Paddon-Row M N and Verhoeven J W 1996 Photoinduced electron transfer to Cgg across extended 3- and 11 a-bond hydrocarbon bridges creation of a long-lived charge-separated state J. Org. Chem. 61 5055-62... 

Fukuzumi, S., Ohkubo, K., Wenbo, E., Ou, Z., Shao, J., Kadish, K.M., Hutchison, J.A., Ghiggino, K.P., Sintic, P.J. and Crossley, M.J. (2003) Metal-centered photoinduced electron transfer reduction of a gold(III) porphyrin cation linked with a zinc porphyrin to produce a long-lived charge-separated state in nonpolar solvents. Journal of the American Chemical Society, 125, 14984-14985. 

Figure4.12 TTF and extended TTF was attached to C q via the Prato-reaction in order to get dyads suitable for long-lived charge-separated states.

Figure 11.14 A ruthenium (II) complex of an annulated donor-acceptor (DA) ensemble, 4, 5 -bis (propylthio)tetrathiafulvenyl[i]dipyrido-[3,2-a 2, 3 -c]phenazine (TTF-dppz) exhibiting a long-lived charge-separated state TTF-dppz -Ru2+-dppz-TTF+ on photoexcitation.9...

The rate of energy and electron transfer in any of these systems is an ensemble average of all sites within the layered assembly, and thus there is no single rate for any of the processes in the assemblies. Nonetheless, in addition to the increased quantum yield, assemblies constructed with the HTiNbOs spacer exhibit a long-lived charge-separated state component not observed in the a-ZrP spaced assemblies, of x = 900 ps. While there is still much to be learned from the study of multi-chromophore arrays, this synthetic approach appears to hold much promise for the creation of organic-inorganic hybrid solid state devices. 

Ir(terpy)2+ is reminiscent of Ru(bpy)2+ by some of its photochemical properties but, it is at the same time very different as far as its geometrical properties are concerned and for its electronic and photochemical characteristics. This complex has been used both as a chromophore and as an electron relay, in relation to charge separation. It is expected that, in the future, long-lived charge-separated states will be obtained by constructing carefully designed molecular triads with an Ir(terpy)2+ central core. 

Ohkubo K, Kotani H, Shao J, et al. Production of an ultra-long-lived charge-separated state in a zinc chlorin-C(photoinduced electron transfer. Angew Chem Int Ed Eng 2004 43 853-6. 

Macrotetracyclic cryptate 87 containing a Zn-porphyrin complex as a photoactive subunit and two lateral [18]-N204 macrocyclic receptors was developed by Lehn and co-workers.146 In a CHC13/ CH3OH (9 1) solution, the two receptors were able to complex Ag+ to form a polymetallic cryptate, 87-Ag+. The Ag+ ion in the polymetallic cryptate quenches the typical Zn- porphyrin fluorescence by a 10-fold factor via a PET process and by forming a long-lived charge-separated state. 

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