Absorption spectra, emission spectra (90 and 298 K), luminescence lifetimes, luminescence quantum yields, and photochemical behavior of a semicage bipyridazine (bpdz) Ru(II) complex K6 and related open-chain bpdz model complexes K1-4 have been studied and compared with those of Ru(bpy)32+ K5. The absorption bands in the visible spectra of K1-4 and Ru-podate K6 are close in energy to the corresponding bands of Ru(bPY)32+ whereas the emission bands are slightly red shifted. The luminescence lifetimes of K1-4/K6 (1500-3400 ns) are longer than that of K5 (600 ns). The open-chain bpdz model complexes K1-4 and especially K6 are highly photoinert (phi(p) less-than-or-equal-to 10(-5) relative to the photodissociation of Ru(bpy)32+ (phi(p) = 0.068). These excellent photophysical properties and stabilities of the complexes K1-4 and the Ru-podate K6 allow their effective use as photosensitizers in electron-transfer processes.