engleski

Heteroatom effect on the radiative and reactive photobehaviour of E,E-1,2-distyrylbenzene

The heteroatom effect on the radiative and reactive relaxations of EE-1, 2-distyrylbenzene has been studied by stationary and time-resolved techniques on three compounds where the side phenyl groups were replaced by 4’ -pyridyl, 2’ -thienyl and 2’ -furyl groups. Contrary to the case of the hydrocarbon, whose photoisomerization is accompanied by substantial degradation, the EE → ZE photoisomerization prevails in the hetero-analogues, particularly in the thienyl derivative. The lack of conjugation in these 1, 2-substituted benzenes leads to a decrease in the fluorescence yield with respect to their 1, 4 and 1, 3 analogues (particularly in the presence of the heteroatoms), which is accompanied by an increase of the photoreaction quantum yield for the pyridyl- (significant) and thienyl- (very small) derivatives, whilst internal conversion is the prevalent deactivation pathway of the furyl derivative.

di-(heteroarylethenyl)benzenes ; photoisomerization ; fluorescence

nije evidentirano