Excimer-like emission of a novel σ-π alternating polymer with 2,2′-bipyridyl in the backbones

The luminescent properties of a novel σ-π polymer, poly(disilanylene-2, 2′-bipyridine-5, 5′-diyl) ruthenium complex (PDSBpy-Ru), have been investigated. A tetrahydrofuran solution of PDSBpy-Ru exhibits fluorescence with peaks dependent on the solution concentration. In a dilute solution, single PDSBpy-Ru molecules are excited, generating metal-to-ligand charge transfer excitons (or electron-hole pairs). The corresponding charge recombination produces fluorescence emission with a peak at about 650 nm. On excitation of a tetrahydrofuran solution of PDSBpy-Ru with a higher concentration, a linear PDSBpy-Ru molecule forms an excimer-like adduct with a neighbouring PDSBpy-Ru molecule. The excimer-like adduct emits fluorescence with redshifted peaks.