Oligothiophenes with bipyridyl ligands

Multimetallic complexes are also of interest. Ru complexes (30 and 31, Chart 5.7) in which the two metals are bridged via oligothiophene ligands of varying lengths have been prepared and their electrochemical and spectroscopic behaviors characterized [44]. In these complexes, the first reduction is bpy-based and the first oxidation is thiophene-based. The metals are weakly interacting and transient absorption and photophysical studies reveal that the lowest excited state is an oligothiophene-based state. The Ru, 

Os and Re complexes 32-35 (Chart 5.7) are systems in which the metal centers are attached in a pendant fashion to a bipyridine-containing conjugated oligomer [45]. In the case of the mixed Ru-Os complex 33, energy transfer from Ru to Os is efficient and results in Os-based emission. The authors ascribed this to a Dexter-type double-electron transfer , mediated by the conjugated ligand. 

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