Photochemistry and Photophysics of Coordination Compounds
Photochemistry and Photophysics of Coordination Compounds
Photochemistry and Photophysics of Coordination Compounds
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196 S. Campagna et al.<br />
gave the predicted increase <strong>of</strong> Voc <strong>of</strong> 200 mV, which was in agreement<br />
with the obtained value (180 mV) [422]. It is interesting that an increase<br />
<strong>of</strong> the lifetime <strong>of</strong> the interfacial charge-separated state TiO2(e – )–Ru(II)–<br />
PTZ + has a direct influence on the overall efficiency <strong>of</strong> the cell. A similar<br />
approach inspired the design <strong>of</strong> the supramolecular species 74, basedon<br />
the “red dye” N3 sensitizer. Optical excitation <strong>of</strong> a nanocrystalline TiO2<br />
film dye coated with such a species showed a long-lived charge-separated<br />
state [423].<br />
8<br />
Miscellanea<br />
The fields that have been recently powered by Ru photochemistry are much<br />
more than those reported in some detail in this article. A few <strong>of</strong> those that are<br />
not discussed above will be briefly mentioned.<br />
Ru(II)-based chromophores have been linked to a plethora <strong>of</strong> receptor<br />
species, like calixarenes, crowns, <strong>and</strong> azacrowns, essentially for sensing<br />
purposes [280, 424, 425]. Ru(II) chromophores have also been embedded in<br />
oxygen-permeating polymers to yield luminescent sensors for molecular oxygen<br />
determination in atmosphere [426–429]. New systems have been designed<br />
<strong>and</strong> studied for obtaining OLED materials. In this regard, a dinuclear<br />
Ru complex has been used in conjunction with an organic luminophore to<br />
generate two-color electroluminescence [430].<br />
Multichromophoric species made <strong>of</strong> Ru(II) chromophores interfaced with<br />
organic aromatics having suitable triplet-state levels have been studied to extend<br />
the lifetime <strong>of</strong> the MLCT excited state by a sort <strong>of</strong> delayed luminescence<br />
involving intercomponent energy transfer, with the organic triplet states used<br />
as excited-state energy storage systems [431–440, 442]. A few such species are<br />
compounds 75 (which is the first reported example <strong>of</strong> such a behavior [431]),<br />
76 [437], <strong>and</strong> 77 [435]. Compound 77 is one <strong>of</strong> the species featuring the most<br />
outst<strong>and</strong>ing behavior: its emission in fluid solution at room temperature<br />
(with maximum at about 600 nm) has lifetimes ranging from 43 µs (acetone<br />
solution) to 61 µs (acetonitrile)to115 µs (DMSO solution) [435]. With<br />
the aim <strong>of</strong> increasing the excited-state lifetime as well as the luminescence