Spectral properties and photobehaviour of 2,5-distyrylfuran derivatives

Four novel trans,trans-2,5-distyrylfuran derivatives (E,E-X-DStFs, X = Cl, OCH3, N(CH3)2, NO2) have been synthesized and characterized by 1H and 13C NMR and UV-vis spectroscopy. The photophysical properties of the excited states of these poorly photoreactive compounds have been studied in two solvents of different polarities by stationary and pulsed techniques and also by the help of semiempirical quantum-mechanical calculations. The high fluorescence efficiency of these systems was accompanied by a modest triplet production (that becomes substantial in the nitro-derivative) investigated by nanosecond laser flash photolysis. The solvent effect on the absorption and emission spectra and on the photobehaviour allowed to evidence the presence of charge transfer (CT) excited states in the dimethylamino- and, particularly, in the nitro-derivative.