高分子体系中降冰片二烯的光异构化反应

PHOTO INDUCED VALENCE ISOMERIZATION OFNORBORNADIENE IN POLYMER SYSTEMS

本文合成了降冰片二烯和咔唑为侧基的甲基丙烯酸酯共聚物，并与仅带有降冰片二烯侧基的聚甲基丙烯酸酯进行了光异构化反应的对比研究。实验结果表明，当入射光波长小于３５０ｎｍ时，两种降冰片二烯聚合物均发生了光异构化反应；当入射光波长大于３５０ｎｍ时，只有共聚物的降冰片二烯侧基能够异构化为相应的四环烷。利用荧光猝灭实验及化学诱导动态核极化（ＣＩＤＮＰ）等研究了咔唑的敏化机理，利用三氟乙酸作催化剂实现了四环烷的反向异构化。

A copolymer bearing norbornadiene and carbazole as pendants was synthesized and apolymer only having norbornadiene pendants was also prepared for comparision. The valenceisomerization of the norbornadiene molety to quadricy clane moiety proceeded smoothly when the two kinds of polymers were irradiated with the light below 350nm. If the wavelength ofthe incident light was above 350nm, the isomerization reaction was only found in copolymersystem. Utilizing fluorescence quenching experiment and CIDNP technique, the mechanismof sensitized valence isomerization was studied. The isomerization of quadricyclane moiety tonorbornadiene moiety was also achieved by using trifluoroacetic acid as catalyst.