INTRAMOLECULAR ENERGY-TRANSFER IN RUTHENIUM(II)-CHROMIUM(III) CHROMOPHORE LUMINOPHORE COMPLEXES - RU(BPY)2[CR(CYCLAM)(CN)2]2(4+)

A new trinuclear Ru(II)-Cr(III) chromophore-luminophore complex, Ru(bpy)2[Cr(cyclam)(CN)2]2(4+), has been synthesized and characterized. Visible light absorption by the Ru(bpy)2(2+) chromophore leads to emission from the Cr(cyclam)(CN)2+ luminophore, as a consequence of very efficient (greater-than-or-equal-to 99%) and fast (subnanosecond time scale) chromophore-luminophore exchange energy-transfer process. The emission is intense (PHI = 5.3 x 10(-3) in H2O) and long-lived (tau = 260 mu-s in H2O). The photophysical properties of the luminophore are slightly perturbed by interaction with the chromophore, resulting in a sharper emission band shape and shorter radiative and radiationless lifetimes. The presence of a Ru(II) --> Cr(III) intervalence transfer state, hardly detectable in the ground-state spectrum, is clearly revealed by the excited-state absorption spectrum of the chromophore-luminophore complex.