Dendritic tetranuclear Ru(II) complexes based on the nonsymmetrical PHEHAT bridging ligand and their building blocks: Synthesis, characterization, and electrochemical and photophysical properties

Dinuclear and tetranuclear Ru(II) compounds 1, 2, 3, and 4 based on the PHEHAT ligand (PHEHAT = 1,10-phenanthrolino[5,6-b]-1,4,5,8,9,12-hexaazatriphenylene) are prepared and characterized on the basis of the data for other related mononuclear species. Their electrochemical and spectroscopic behaviors are discussed. The nonspectroelectrochemical correlation obtained for 1, 2, 3, and 4 is explained on the basis of these data. From the behavior in emission, it is concluded that the internal energy transfer takes place from the core to the peripheral metallic units in 3 and 4.