Excited-state behavior of ortho-phenylenes

C. Scott Hartley*
J. Org. Chem. 2011, 76, 9188–9191
[Published version]


The excited-state properties of unsubstituted ortho-phenylene oligomers have been studied using TD-DFT. Calculations of vertical transitions at the helical ground-state geometries are in good qualitative agreement with the experimental UV–vis spectra. In the excited state, the spring-like compounds compress; for the longer oligomers, this compression is localized at one end of the oligomer. This behavior explains the unusual experimentally observed hypsochromic shifts in fluorescence spectra with increasing oligomer length.