Regioselectivity in the Photocycloaddition of 9-Substituted Anthracenes Incorporated within Nafion Membranes.
The photocycloaddition of five 9-substituted anthracenes [AnCH(2)N(+)(CH(3))(3)Br(-) (1), AnCH(2)COO(-)Na(+) (2), AnCH(2)OH (3), AnCOCH(3) (4), and AnCH(3) (5), An = 9-anthryl] incorporated within Nafion membranes has been investigated. While irradiation of the above compounds in homogeneous solutions, and 5 in Nafion also, mainly gave rise to their head-to-tail (h-t) photocyclomers, photoirradiation of the samples of 1-4 incorporated within Nafion membranes almost exclusively resulted in the head-to-head (h-h) photocyclomers. Furthermore, the h-h photocyclomers are significantly more stable in Nafion membranes than in homogeneous solutions. These observations can be explained in terms of the preorientation of the substrate molecules in the inverse micelle-like clusters of Nafion.
Tung
Chen-Ho
CH
Institute of Photographic Chemistry, Chinese Academy of Sciences, Beijing 100101, China.
Guan
Jing-Qu
JQ