Structural, Redox, and Photophysical Studies of the Tetra(pyridyl)porphyrin Complex Containing Four (2,2‘-Bipyridine)(2,2‘:6‘,2‘ ‘-terpyridine)ruthenium(II) Groups

New hybrid complexes of polypyridyl ruthenium and pyridylporphyrins have been prepared by the coordination of
pyridyl nitrogens to the ruthenium centers. A 1:4 hybrid complex, [{Ru(bpy)(trpy)}4(μ4-H2Py4P)]8+ ([1]8+) (bpy =
2,2‘-bipyridine; trpy = 2,2‘:6‘,2‘ ‘-terpyridine; H2Py4P = 5,10,15,20-tetra(4-pyridyl)porphyrin), has been characterized
by the single-crystal X-ray diffraction method. A 1:1 complex, [{Ru(bpy)(trpy)}(H2PyT3P)]2+ ([2]2+) (H2PyT3P =
5-(4-pyridyl)tritolylporphyrin) has also been prepared. The Soret band of the porphyrin ring shifts to longer wavelength
with some broadening, the extent of the shift being larger for [1]8+. Cyclic voltammograms of the two complexes
show simple overlap of the component redox waves. The complexes are weakly emissive at room temperature,
which becomes stronger at lower temperatures. While [1]8+ at >140 K and [2]2+ at 77−280 K show only porphyrin
fluorescence, [1]8+ at <140 K shows ruthenium and porphyrin phosphorescence, in addition to the porphyrin
fluorescence.