The photophysical properties of short, linear arrays of ruthenium(II) tris(2,2′-bipyridine) complexes

摘要

A series of linear polynuclear ruthenium(II) tris(2,2′-bipyridine) complexes has been synthesized whereby individual chromophores are separated by 1,4-diethynylenebenzene subunits bearing alkoxy groups for improved solubility. These arrays contain two, three, four or five metal centers. The compounds are reasonably soluble in polar organic solvents and they possess optical absorption spectral properties that are dominated by transitions associated with the polytopic ligand. Weak luminescence is observed for each complex in deoxy genated acetonitrile at room temperature that appears to be characteristic of emission from a metal-to-ligand charge-transfer triplet state. The emission lifetime is essentially independent of temperature, at least over a modest range. There is no indication for interaction between close-lying triplet states and no obvious sign of a low-energy τ, τ* triplet associated with the polytopic ligand. The photophysical properties suggest that the longer arrays are segmented.