We present a joint experimental and theoretical investigation of the electronic excitations in transition metal-containing phenylene ethynylenes. The influence of the metal on the nature of the lowest singlet and triplet excited states is characterized. We find that π conjugation occurs through the metal sites, which deeply modifies the optical properties of the conjugated chains. We also analyze the chain-length dependence of the singlet-singlet, S0 → S1? singlet-triplet, S0 → T1t and triplet-triplet, T1 → Tn, transition energies; both experimental data and theoretical results indicate that the lowest triplet exciton, T1, is strongly localized on a single phenylene ring while the S1 and Tn states extend over a few repeating units. Finally, we estimate the geometric relaxation phenomena occurring in the lowest excited states and perform a Huang-Rhys analysis of the triplet emission spectrum in model systems.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry