Excited-state behavior of some all-trans-alpha,omega-dithienylpolyenes

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