Synthesis and photochemical properties of insoluble poly(styrene) beads containing pendant norbornadiene moieties

Insoluble polymer beads bearing pendant norbornadiene (NBD) moieties were synthesized by the substitution reaction of insoluble chloromethylated poly(styrene) beads with potassium salts of certain NBD derivatives having carboxylic acid or phenol groups using a phase transfer catalyst. The reaction proceeded smoothly in high conversions in DMF at 90°C for 72 h to give the corresponding insoluble polymer beads bearing NBD moieties. Rates of photochemical reaction of the obtained insoluble polymer beads were measured by IR spectrometry using KBr disk plates. The photochemical valence isomerization from 3-phehyl-2,5-NBD-2-carboxylate (PNCA) moiety to the corresponding quadricyclane (QC) group and catalytic reversion from QC to the NBD moiety were also examined in dichloromethane, and it was found that the photochemical valence isomerization and the catalytic reversion in insoluble polymer beads can be recycled in high conversions at last for 10 runs.