Photochemical cis-trans isomerization of s-trans-1,3-pentadiene. A theoretical study

✍ Scribed by I. Baraldi; M.C. Bruni; F. Momicchioli; J. Langlet; J.P. Malrieu

• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 750 KB
• Volume: 51
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(77)85409-2

✦ Synopsis

The cis-trans photoisomerization pathway of the s-trans-1,3-pentadiene is investigated on the basis of excited state potential curves calculated using the CIPSI method in the excitonic (PCILO type) scheme. It is shown that both direct and sensitized excitation of either isomer are followed by equiprobable formation of two allyImethylcne intermediates, one of which can lead to isomerization, while the other undergoes radiationless decay to the starting geometrical isomer_ In the triplet state TI the intermediates are separated by rather low potential barriers. This suggests the occurrence of rapid interconversion of the biradical intermediates at room temperature and explains the relatively high efficiency of the sensitized 1,3-pentadiene photoisomerization.