Oligothienoacenes versus oligothiophenes: impact of ring fusion on the optical properties

摘要: The impact of backbone rigidity on the optical properties thiophene-based compounds is studied by analyzing in detail geometrical, electronic, and vibronic features a family oligothienoacenes (nnTAs) comparison to non-fused α-oligothiophenes (nnTs) means quantum-chemical calculations. Ring fusion nnTAs provokes greater conjugation ground state. However, change bond length alternation upon electronic excitation very similar both systems, which also reflected evolution first transition energy with increasing oligomer size. Larger energies nnTAsvs.nnTs arise from an effect rather than structural one. present normal mode predicted at ca. 500 cm−1 displays significantly higher Franck–Condon activity compared nnTs leads pronounced differences spectra. Due rigid structure nnTAs, persistent mirror symmetry absorption emission observed, different nnTs.