Photoisomerization of sterically hindered azobenzenes

✍ Scribed by Hermann Rau; Shen Yu-Quan

• Book ID: 103991623
• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 512 KB
• Volume: 42
• Category: Article
• ISSN: 1010-6030
• DOI: 10.1016/1010-6030(88)80075-3

✦ Synopsis

The photoisomerization yields of a homologous series of o,o,o',o'substituted azobenzenes have been determined by excitation of the low lying l(n,~*) and the higher lying I(~F,~F*) states. For more severe steric hindrance, i.e. with substituents more bulky than methyl, the E + 2 quantum yields are independent of the excitation wavelength, which is in contrast with those for unsubstituted azobenzene, and they seem to decrease with increasing volume of the substituents. This provides further support for our hypothesis of photoisomerization of normal azo compounds: inversion in the lowest states and rotation in the higher states.