Inorganic Chemistry, Vol.41, No.25, 6688-6694, 2002
Synthesis and photochemistry of Ru(II) complexes containing phenanthroline-based ligands with fused pyrrole rings
Hydrolysis of 1,10-phenanthrolinopyrrole ethyl ester leads to the acid derivative which is unstable at room-temperature releasing CO2 and forming 1,10-phenanthrolinopyrrole (php). The ligand reacts with ruthenium(11) to form a series of complexes of the general formula [Ru(php)(n)(bpy)(3-n)](2+), where bpy = 2,2'-bipyridine and n = 1-3, The photochemical properties reveal that the complexes have longer-lived excited states than the standard complex, [Ru(bpy)(3)](2+). Their emission lifetimes range from 9.04 mus (n = 1) to 35.5 mus (n = 3) at 77 K compared to 7.57 mus for the standard. Similarly, at room-temperature, emission lifetimes range from 1.20 mus (n = 1) to 1.70 mus (n = 3) relative to the standard (0.56 mus). The emission quantum yields also have higher values than the standard [Ru(bpy)(3)](2+) under similar conditions. The temperature-dependent studies for the complexes establish the distribution among the radiative, nonradiative, and (MLCT)-M-3 to (3)d-d decay channels and are in agreement with the energy gap law.