Excited-state behavior of some all-trans-α,ω-dithienylpolyenes

The photophysics and photochemistry of all-trans-alpha,omega-di(2-thienyl)polyenes (with chain length n = 2, 3, 4) and alpha,omega-di(3-thienyl)polyenes (with n = 3, 4) have been extensively studied by stationary and pulsed spectrometry. Fluorometric and laser flash techniques were used to measure the quantum yields and lifetimes of the lowest excited states of singlet and tripler multiplicity in nonpolar and polar solvents at different temperatures. The trans-cis photoisomerization was also investigated, at least for the shorter oligomers. The kinetic parameters of the radiative, nonradiative, and reactive relaxation pathways were evaluated and discussed by comparison with the parent compound having n = 1 (trans-1,2-dithienylethene) and the better known alpha,omega-diphenylpolyenes.