The photophysical behavior of [(bpy) 2 Ru(L)] 2+ complexes (L ) 4-(1′′-pyrenyl)-2,2′-bipyridine, bpy-pyr; 2-(1′-pyrenyl)-1,10-phenanthroline, phen-pyr; and 2-(2′-naphthyl)-1,10-phenanthroline, phen-nap) was investigated in solutions and frozen matrices. The conformation of the linked pyrene differs in the two complexes: The pyrene moiety is conformationally constrained to be nearly perpendicular to the phenanthroline in the phen-pyr complex while the pyrene in the bpy-pyr complex has much greater flexibility about the C-C bond linking the ligand and the pyrene. The 3 MLCT excited state of the Ru(II) diimine complex and the 3 (π f π*) state of the pyrenyl substituent are nearly isoenergetic; the 3 MLCT state is the lowest energy state in the bpy-pyr complex, and the pyrene 3 (π f π*) state is lower in energy for the phen-pyr complex. The bpy-pyr complex is unique in that the 3 MLCT state has a very long lived luminescence (approximately 50 µs in degassed CH 3 CN). Luminescence decays for both pyrene containing complexes can be fit as double exponentials, indicating that the 3 MLCT and 3 (π f π*) states are not in equilibrium. Analysis of decays obtained at several temperatures reveal that energy transfer is slower than relaxation of the 3 MLCT state but more rapid than decay of the pyrene localized 3 (π f π*) state. The results also suggest that electronic coupling between the two states is weak despite the fact that the two chromophores are separated by a single covalent bond.

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The photochemical and photophysical behavior of (dodecafluorosubphthalocyanaoto)boron(III) chloride was examined in room-temperature solutions. The lowest energy absorption maximum of the complex is 570 nm, and the luminescence mirrors the absorption with a maximum at 586 nm (Stokes shift = 480 cm-1). The emission is strong, with a quantum yield in deaerated acetonitrile of 0.66 and a lifetime of 2.6 ns. The complex exhibits a reversible one-electron reduction in cyclic voltammetry (E° = −0.53 V vs SCE), and this, combined with the relatively high singlet energy, indicates the emissive excited state is a strong oxidant. Evaluation of the free energy dependence of the emission quenching with a series of substituted benzene donors yields a value of 1.7 V vs SCE for the excited-state reduction potential, E(*/−). The excited complex also reacts with tertiary amines. Photolysis in the presence of triphenylamine results in photoinduced electron transfer and back reaction. Triethylamine, however, reacts efficiently with the excited subphthalocyanine to yield a permanent photoproduct. The product has been characterized by FAB mass spectrometry as well as 1H and 19F NMR to be an adduct involving B−N bond formation.