The positional isomers of 1-(pyrid-n-yl), 4-phenylbuta-1,3-diene (n = 2, 3 and 4) have been synthesized and characterized by spectrometric techniques. All the four expected stereoisomers (EE, EZ, ZE and ZZ) were prepared for n = 2 while only three and two geometrical isomers were obtained for the positional isomers with n = 3 and 4, respectively. Their excited state properties were investigated by stationary and pulsed fluorimetric techniques and by laser ash photolysis. This paper describes the photochemical behaviour under direct and triplet sensitized excitation. The selective formation of photoproducts and the role of diabatic/adiabatic mechanisms are reported and compared with the results on the direct photoisomerization of the EE and ZE isomers in the singlet manifold described in a previous paper.
Photoisomerization mechanisms and photoselectivity of the stereoisomers of 1-(pyrid-n-yl),4-phenylbuta-1,3-diene
BARTOCCI, Giampiero;LATTERINI, Loredana;MARRI, Elena;MAZZUCATO, Ugo;SPALLETTI, Anna
2002
Abstract
The positional isomers of 1-(pyrid-n-yl), 4-phenylbuta-1,3-diene (n = 2, 3 and 4) have been synthesized and characterized by spectrometric techniques. All the four expected stereoisomers (EE, EZ, ZE and ZZ) were prepared for n = 2 while only three and two geometrical isomers were obtained for the positional isomers with n = 3 and 4, respectively. Their excited state properties were investigated by stationary and pulsed fluorimetric techniques and by laser ash photolysis. This paper describes the photochemical behaviour under direct and triplet sensitized excitation. The selective formation of photoproducts and the role of diabatic/adiabatic mechanisms are reported and compared with the results on the direct photoisomerization of the EE and ZE isomers in the singlet manifold described in a previous paper.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
