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-H ₂Py₄P)]⁸⁺ ([1]⁸⁺) (bpy = 2,2′-bipyridine; trpy = 2,2′:6′,2″-terpyridine; H ₂Py₄P = 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.